Design and application of a microwave moisture meter
by Joseph Lacy Kowalski
A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE in Electrical Engineering
Montana State University
© Copyright by Joseph Lacy Kowalski (1974)
Abstract:
A specific application of microwave techniques to the measurement of moisture content of fuel
materials of the forest floor is discussed in this paper. The principle of absorption of electromagnetic
energy passed through a layer of water is used to derive the equation for calculating the moisture
content of a given sample. Detailed experimental and theoretical study showed the attenuation of
microwave energy in water is a strong function of the temperature of the water. A plot of calculated
attenuation verses temperature and a table of the derived multiplying factor (k) used in the moisture
meter equation are given and compared to experimental results.
It was observed experimentally that the method used for oven drying as a check on the moisture meter
was not consistant. It was found to be necessary to remove the moisture from the air in the oven to
allow the sample materials to dry out completely. This was achieved by placing a drying agent
(calcium sulfate) in the oven. The drying agent absorbed the moisture, in the air and allowed the
sample material to dry out completely.
Methods of further study to determine the accuracy of the meter and improvements that could be made
on the moisture meter are. given in the last two chapters of this paper. In p r e s e n tin g t h i s th e s is in p a r t i a l
f u l f i l l m e n t o f the r e q u ir e
ments f o r an advanced degree a t Montana S ta te U n i v e r s i t y ,
t h a t the L i b r a r y s h a ll make i t
I agree
f r e e l y a v a i l a b l e f o r in s p e c t io n .
I
f u r t h e r agree t h a t perm ission f o r e x te n s iv e copying o f t h i s th e s is
f o r s c h o l a r l y purposes may be granted by my. major p r o f e s s o r , o r , in
his absence, by the D i r e c t o r o f L i b r a r i e s .
It
is understood t h a t
any copying o r p u b l i c a t i o n o f t h i s th e s is f o r f i n a n c i a l
gain s h a ll
not be a llow ed w ith o u t my w r i t t e n perm is s io n .
z ry ~
Date
:
/2 , / f f /
7
DESIGN AND APPLICATION OF A MICROWAVE MOISTURE METER
by
JOSEPH LACY KOWALSKI
A th e s is subm itted to the Graduate F a c u lty in p a r t i a l
f u l f i l l m e n t o f the requirem ents f o r the degree
of
MASTER OF SCIENCE
E le c tric a l
E ngineering
Approved:
Head, M a jo r Department
Chairman, Examining Committee
Graduate Dean
MONTANA STATE UNIVERSITY
Bozeman, Montana
August, 1 974
ACKNOWLEDGEMENT
The a u th o r wishes to express h is a p p r e c ia t io n to P ro fe ss o r
Bruce McLeod f o r his many s u g g e stio n s , encouragement, and guidance
du rin g th e course o f t h i s graduate work and th e s is re s e a rc h .
He i s g r a t e f u l
f o r the f i n a n c i a l
support provided by his
p arents and t h a t provided by th e E l e c t r i c a l
E ngineering Department
o f Montana S ta te U n i v e r s i t y in th e form o f Graduate Research A s s is ta n ts h ip .
The a u t h o r 's v ery s p e c ia l a p p r e c ia t io n is expressed f o r the
help r e c e iv e d from Mrs. S a l l y Jean P eters who c o n tr ib u te d in her
own s p e c ia l way to make t h i s th e s is p o s s ib le .
iv
TABLE OF CONTENTS
Page
LIST OF TABLES............... ................................................................. ..
vi
LIST OF FIGURES............................................. ............... ..; . . , v i i
■CHAPTER
1.
INTRODUCTION.. . . ......................... . . . . . . ; ........... ...................... ....
.1
2.
PRINCIPLE AND DESIGN OF MICROWAVE MOISTURE M E T E R .....
2
Microwave Absorption in W a te r.............. ...........................—
.'.
Absorption a t Resonance- Frequency.....................................
. A bsorption o f Microwaves in M a t e r i a l s C ontaining
W a t e r . ............ ................................................; .......................... . . . ' .
/ 2
2
4
..
Components o f M o is tu re M e t e r . .............. ............... .....................
3.
5
Microwave Components.............. ..................................
5
E l e c t r o n i c C o m p o n e n ts ....,...................................'............... ....
6
C o n s tru c tio n D e t a i l s o f M o is tu re M e t e r . ........... ....: ---------
6
■ C a l c u l a t i o n o f % Water from A tt e n u a tio n .a n d W e i g h t . . .
8
TECHNIQUE OF GATHERING AND ANALYZING DATA. . . . . . . . . . . .
13
Method o f Making Measurement................................. ..
13
Measure Techniques f o r th e M o is tu re M e t e r . --------- ---
13 .
M a t e r i a l s being I n v e s t i g a t e d ............ ..........................; . . .
14
F illin g
15
Sample Box.....................................................................
. Overi■Dry Techniques f o r Checking M ois ture M e t e r . . . . . .
15
C o l l e c t i o n o f Data a t Lubrecht F o r e s t . . . . . . . . . . . . . . . .
18
V
Page
M o is tu re M eter P r o j e c t ........................................'.......... .............
18
P re s c rib e d Burning P r o j e c t . ; ....................................
19
A n a ly s is o f Data Using a Computer Program............................
20
D e s c r ip tio n o f Program............................................ ............ . . .
20
A n a ly s is o f Program O u t p u t . . . . . ............................................
21
. Temperature E f f e c t s on Measurements..........................................
22
Method o f D e te rm in a tio n o f E f f e c t s .....................................
22
Measurement Made on Sample M a t e r i a l .............. .....................
30
D i r e c t Measurement on W a te r..................................................... ' 31
T h e o r e t ic a l
C a l c u l a t i o n s .................. .................................... ..
38
M o d ifie d M o is tu re Meter Equation C ontaining
T e m perature................................................................................... .............
41
E r r o r in Oven Dry Measurements..................
44
4.
SUMMARY OF RESULTS.................................................................................
52
5.
CONCLUSIONS.................................................................................................
53
REFERENCES CITED......................................................................................
55
Appendix I ...................................................................................
59
Appendix I I .......................................................................
62
Appendix I I I ..................................
66
Appendix I V .................................................................................................
69
Appendix V .....................................
89
Appendix V I .......................................
Appendix V I I . . . .......................
109
. 112
vi
LIST OF TABLES
Table
Page.
1.
M o is tu re Measurements Made on L i t t e r , as a Function
of. the Sample M a t e r i a l Tem perature....................... ........................ . 32
2.
M o is tu re Measurements Made on S tic k s as a Function
o f the Sample M a t e r i a l Tem perature..................... ...........................
33
D i e l e c t r i c C o n s ta n t, Loss Tangent, and C a lc u la te d
A tt e n u a tio n o f W a t e r . a t Various Tem peratures...........................
42
Measured and C a lc u la te d A tt e n u a tio n o f Water a t
V arious Tem peratures....................
43
3.
4.
5.
M u l t i p l y i n g F a c to r k a t V arious Tem peratures------------- . . . .
6.
Oven Dry Measurements o f 15 Hours and 30 Hours
W hile Under Vacuum............................................... ....................................
50
Oven Dry Measurements o f 15 Hours and 30 Hours
w it h Drying Agent P r e s e n t . ..................... ........................................ ....
50
7.
47
v ii
. LIST OF FIGURES
i
Figure .
1.
2.
■Page
Loss F a c to r f o r Pure
Water vs.
Frequency_______________
3
. Loss F a c to r o f Water and P r e v a le n t M a t e r i a l s
a t K-Band F r e q u e n c ie s .............................................................................
3
3.
Block Diagram o f Microwave M o is tu re M e te r ___ .................... -...
7
4.
Top View o f the. Microwave M o is tu re M eter Showing Test
C e ll and M eter C o n t r o l s . ................................................... ....................
5a.
5b.
6.
In s id e View o f the Microwave M o is tu re Meter Showing
E l e c t r o n i c s and the.M icrow ave G ear......... .......... . . . . . . . . . . . .
9
10
In s id e View o f th e Microwave M o is tu re Meter Showing
the Two S ix V o l t Rechargeable B a t t e r i e s . ....................
11
V ie w .o f the Three Types o f M a t e r i a l s Found. on the
F o re s t F l o o r . ....................... .................. ......................................................
16
7.
Side View o f F o re s t F lo o r Layer Showing the Separation.
in the D u ff L i t t e r L a y e r------------------------------------------------------ - 16
8.
S c a t t e r P l o t o f Oven Dry % and C a lc u la te d % f o r .
D u ff.
1972 D a ta ......... ; . . .................... ' . ................... ............. ..
9.
10.
11.
12.
13.
23.
. S c a t t e r P l o t o f Oven Dry % and C a l c u l a t e d .% f o r
■
Li t t e r . . 1972 D a ta ................................................ ' . . " . . . . . . . . . . >■.,: 24
S c a t t e r P l o t o f Oven Dry % and C a lc u la te d % f o r
S tic k s .
1972 D a t a . . . . . ____ __________. . . . . . . . . . . . . . . . . . .
25
' S c a t t e r P l o t of.O ven Dry % and. C a lc u la te d t f o r .
D u f f.
1973 D a t a . . . . . . ......... ........... '.................: : : . . . . . . . . .
26
S c a t t e r P l o t o f Oven Dry t and C a lc u la te d % f o r
L itte r.
1973 D a ta ......... ........................ ...................... ■..........................
27
S c a t t e r P l o t o f Oven Dry % and C a lc u la te d % f o r
S tic k s .
1973 D a ta .............. ................................................. ..
28
v iii
Figure
14.
,
Page
Block Diagram o f Bench Setup f o r Measuring Microwave
A tt e n u a tio n in W a te r....................... .................................................. ..
35
View o f the Bench Setup Used to Measure the A tte n u a tio n
o f Microwaves through a I -cm Layer o f W a te r ......... ...................
39
The V a r i a t i o n w ith Temperature o f the D i e l e c t r i c
Constant and Loss Tangent o f W a te r......... — ................................
40
17.
P lo t o f M u l t i p l y i n g F a c to r (k ) vs. T e m p e ra tu re ......................
45
18.
P lo t o f A tt e n u a tio n o f Microwave. S ignal vs. Temperature
a t 1 0.5 25 GHz through I -cm o f W a t e r . ............ ..................................
46
View o f S cale and Oven w ith Door Open,Showing Pans
C o n tain in g Drying Agent on the Upper S h e l f o f the Oven,
and the Drying Cans f o r th e Sample M a t e r ia l on the
Bottom Shel f .............................. '................................. ....................................
51
15.
16.
19.
ix
ABSTRACT
A s p e c i f i c a p p l i c a t i o n o f microwave techniques to the measure­
ment o f m oistu re c o n te n t o f fu e l m a t e r i a l s o f the f o r e s t f l o o r is
discussed in th is , paper.
The p r i n c i p l e o f ab so rp tio n o f e l e c t r o ­
magnetic energy passed through a l a y e r o f w ater i s used to d e r iv e the
e q u atio n f o r c a l c u l a t i n g . t h e m oistu re c o n te n t o f a given sample.
D e t a i le d e x p e rim en tal and t h e o r e t i c a l study showed the a tt e n u a t io n
o f microwave energy in w a te r is a strong fu n c tio n o f th e tem perature
o f the w a t e r .
A p l o t o f c a l c u l a t e d a t t e n u a t i o n verses tem perature
and a t a b l e o f the d e r iv e d m u l t i p l y i n g f a c t o r ( k ) used in the
m oisture meter eq u atio n are given and compared to e xperim ental
re s u lts .
I t was observed e x p e r im e n t a lI y t h a t th e method used f o r oven
d ry in g as a check on the m oistu re meter was not c o n s i s t a n t .
It
was found to be necessary to remove the m oisture from the a i r in
the oven to a llo w th e sample m a t e r i a l s to d ry out c o m p le te ly .
This
was achieved by p la c in g a d ry in g agent (c a lc iu m s u l f a t e ) in the
oven. ■ The d ry in g agent absorbed th e m oisture, in the a i r and allowed
th e sample m a t e r i a l to. dry out c o m p le te ly .
Methods o f f u r t h e r study to determ ine the accuracy o f the
meter and improvements t h a t could be made on the m o istu re meter a re.
given in the l a s t two c h ap ters o f t h i s paper. .
CHAPTER I
INTRODUCTION
th e need f o r a c c u r a t e , continuous m oisture m o n ito rin g equipment
in the pro d u c tio n o f pa per, t e x t i l e ,
f l o u r and v a rio u s o th e r products
has brought about th e use o f microwave techniques to measure m oisture
l e v e l s where d i r e c t c o n ta c t w ith the m a t e r ia l
i s u n d e s ira b le [ 1 , 2 ] .
The te c hnique o f measuring m o istu re i s based on th e f a c t [ 3 ] t h a t
the amount o f microwave energy absorbed i s a fu n c tio n o f th e amount
o f w a te r p r e s e n t.
T h e r e f o r e , by t r a n s m i t t i n g microwave energy through
a sample arid measuring the d i f f e r e n c e in t r a n s m it te d and re c e iv e d
energy, th e m o istu re c o n te n t o f the sample can be determ ined.
This i n v e s t i g a t i o n was undertaken to determ ine how th e absorption
o f microwave energy behaved as a fu n c tio n o f m oisture c o n te n t o f
s everal p a r t i c u l a r m a t e r i a l s .
A ls o , p a r t o f the work was concerned
w ith f i n d i n g o th e r v a r i a b l e s t h a t would have to be considered to
o b ta in a p o r t a b l e microwave m oisture m eter t h a t could be used by the
F o re st S e rv ic e to measure m oisture c o n te n t o f fu e l s on th e f o r e s t
f l o o r w ith a t l e a s t as good i f not b e t t e r accuracy than methods
p r e s e n t l y being used.
,
, CHAPTER I I
PRINCIPLE AND DESIGN OF MICROWAVE MOISTURE METER'.
This c h a p te r discusses the p r i n c i p l e o f the a b s o rp tio n o f e l e c t r o ­
magnetic energy in w a te r.a n d how t h i s p r i n c i p l e is a p p lie d in the .
design o f a m oisture m eter.
A. 1 Microwave Absorption in Water
I ..
Absorption a t Resonance Frequency
The absorption, o f microwaves in w a te r i s due to a resonance o f the
w ater molecule w ith th e microwave s ig n a l
[4 ].
Several authors have
shown t h a t microwave a b s o rp tio n in w a te r peaks, out about 2 2 ,0 0 0 MHz
[3,5];
The shape o f the a b s o rp tio n peak was f i r s t determ ined by Becker
and A u l t e r [ 5 ] f o r w a te r vapor.
It
has been shown t h a t t h e . a t t e n ­
u a tio n f o r pure w a te r is 40 dB/cm a t a frequency o f 1 0 ,0 0 0 MHz [ 6 ] .
Above 1 0 ,0 0 0 MHz the c o n d u c t i v i t y of. w a te r is independent o f i t s
s a lt
■
c o n te n t.a n d t h e r e f o r e th e a b s o rp tio n 1 o f e le c tr o m a g n e tic energy i s .
independent o f s a l t c o n te n t [ 6 ] .
F ig u re
(I)
f a c t o r o f pure w a te r verses frequency. [ 4 ] .
gives a p l o t o f the toss
It
is seen then from Figure
(T ) t h a t the choice o f frequency to o b ta in a high loss f a c t o r and hence
good s e n s i t i v i t y f o r the meter would be in the microwave frequency
range.
3
. AUDIO
RADIO
[ Q
^MICRO.
C
R
INFRARE
k — *
IO 0
IO 2
WAVE
IO 4
IO 6
ULTRAVIOLET
m-----------------t
VISIBLE
IO 8 TO10 TO12 I O 14 TO16
FREQUENCY, h e r tz
F ig u re I .
Loss Factor f o r Pure Water vs.
LOSS FACTOR
F ig u re 2.
Frequency.
LOSS FACTOR
Loss F a c to r o f Water and P r e v a le n t
M a t e r i a l s a t K-Band Microwave.
4
2.
A bsorption o f Microwaves in M a t e r i a l s C on tain in g Water
Since the i n t e r e s t o f t h i s
o f m a t e r i a l s , th e q u e stio n
study was measuring m oistu re c o n te n t
o f how e le c tr o m a g n e tic waves were at.ten-
uated by w ater contained in s p e c i f i c m a t e r i a l s was r a is e d .
I f the
a tte n u a tio n , o f microwaves due to w a te r contained in s p e c i f i c m a t e r i a l s
was much g r e a t e r than the a t t e n u a t i o n due to the m a t e r i a l s themselves
the amount o f w ater p re s e n t could be r e l a t e d . d i r e c t l y . t o
th e a t t e n ­
u a tio n measured.
The f a c t t h a t the a b so rp tio n o f microwaves in m a t e r i a l s is
p r o p o r tio n a l
to the loss f a c t o r o f the m a te r ia l
[ 4 ] im p lie s t h a t the
loss f a c t o r o f w a te r i s much h ig h e r than t h a t o f the s p e c i f i c m a t e r i a l s
of in te re s t.
F ig u re ( 2 ) compares the. loss f a c t o r o f w a te r to v arious
o th e r m a t e r i a l s
[4 ],
The f i g u r e shows t h a t a r a t i o o f 100 to I
between w a te r and base, m a t e r i a l s should e x i s t .
s im ila r r a tio
m a te ria l.
T h is means, t h a t a
should e x i s t f o r the a b s o rp tio n o f w a te r and the base
'
..
.
.
..
T h e o r e t i c a l l y then the m oisture c o n t e n t . o f a sample o f m a te r ia l
could be. determ ined from the a t t e n u a t i o n o f a microwave s ig n a l passed
through i t .
T h e r e f o r e , f o r a m oistu re m e te r, a source o f microwave
s ig n a l plus a means o f guiding the s ig n a l
through th e sample m a te r ia l
and measuring the re c e iv e d s ig n al a t th e o th e r side o f the sample is
needed.
.
5
B.
Components o f M o is tu re Meter
I.
Microwave, Components
The h e a r t o f the microwave m oisture meter is i t s
wave energy-
source o f m icro -
The re quirem ent t h a t the m oisture meter be p o r ta b le
placed r e s t r i c t i o n s on the choice o f microwave source.
to be s m a ll, l i g h t w e i g h t , and most o f a l l
v o lta g e source.
it.is
The source had
had to be powered by a dc
A Gunn o s c i l l a t o r was chosen as the source because
s m a ll, l i g h t w e i g h t and r e q u ir e s o n ly a 12 v o l t dc power supply.
The Gunn o s c i l l a t o r chosen o pe rates a t 1 0,5 25 MHz.
s e le c te d so t h a t the e f f e c t s due to s a l t s
This frequency was
in the w a t e r .c o u ld be ignored
as p r e v io u s ly s ta te d .
Microwave horns are used to t r a n s m it and r e c e iv e the microwave
s ig n a l.
The horns a re placed a p p ro x im a te ly 2 inches a p a r t .
Each horn
has an a p a tu re area o f 2 .5 " x 2 .2 5 " = 5 .6 2 5 square in c h e s , and each
has a gain o f a p p ro x im a te ly 9 db over a d i p o le antenna.
For d e t e c t io n o f the microwave s ig n a l a standard I N23 s i l i c o n diode
d e te c t o r i s used.
The diode d e t e c t o r r e c t i f i e s
and has a dc v o lta g e o u tp u t p r o p o r tio n a l
the microwave s ig nal
to the microwave in p u t l e v e l .
A p r e c is io n r o t a r y vane a t t e n u a t o r i s used to s e t th e le v e l o f
microwave s ig n al
t h a t is tr a n s m it te d i n t o the sample.
The accuracy
o f the a t t e n u a t o r is +2% o f db re ading or +0.1 db whichever is g r e a t e r
over a 0 to 50 db range..
The s c a le on the a t t e n u a t o r can be read to. the
n e a re s t t e n th o f a db in the 10 to 50 db range.
6
2.
E l e c t r o n i c Components
The e l e c t r o n i c s o f the meter a re composed o f a m o d u la to r, a m p li­
fie r,
and power source (two s ix v o l t b a t t e r i e s connected in s e r i e s ) .
The m odulator s u p p lie s a I
KHz square wave w ith i t s
v o l t s and high le v e l a t 12 v o l t s .
low l e v e l a t 0
The m odulator d r iv e s th e Gunn
o s c i l l a t o r which in tu rn outputs a 1 0,5 25 MHz s ig n al modulated by a
I KHz square wave.
o u tp u t.
The diode d e t e c t o r then has a I KHz square Wave
This o u tp u t is fed to the a m p l i f i e r
has a v a r i a b l e gain o f 0 to 40 db.
(tuned to I
KHz) which
The a m p l i f i e r in tu r n d r iv e s a
c u r r e n t meter which is used to s e t a r e fe re n c e le v e l on the re ce ive d
s ig n a l.
Appendix I c o n ta in s p i c t u r e s o f the Gunn o s c i l l a t o r ,
d e t e c t o r , p r e c is io n a t t e n u a t o r , m odulator and a m p l i f i e r .
horns, diode
Appendix I I
c o n ta in s the schematics and s p e c i f i c a t i o n s o f the m odulator and
a m p lifie r.
C.
C o n s tru c tio n D e t a i l s o f M o is tu re Meter
F ig u re ( 3 ) is a block form r e p r e s e n t a t io n o f the m oisture meter
in terms o f i t s microwave and e l e c t r o n i c components.
S everal authors
show s i m i l a r diagrams o f m oisture meters t h a t work on the same p r i n ­
c i p l e o f a t t e n u a t i o n measurements [ 6 , 7 , 8 ] .
.
The m o istu re meter being discussed in t h i s i n v e s t i g a t i o n was
designed and b u i l t by Dr.
Bruce R. McLeod, o f Montana S ta te U n i v e r s i t y .
The f i r s t model was r a t h e r l a r g e and d i f f i c u l t to c a r r y in the f i e l d .
M odulator
Ampli f i e r
■
V aria b le
— l/X jSk ,1
Gunn
O s c illa to r
P r e c is io n
A tte n u a to r
^ X
11Z
C ry s ta l
D e te c to r
Horns
i
6
Output
Meter
Fig u re 3.
Block diagram o f microwave m oisture m eter.
8
The second model shown in Figure ( 4 ) was b u i l t a p p ro x im a te ly 2 years
l a t e r in 1973.
Fig u re
It
i s much s m a lle r and e a s i e r to c a r r y in the f i e l d .
( 5 ) shows a r e a r view o f the f r o n t panel and i n s id e view o f
the case w ith b a t t e r i e s
meter i s t h a t a l l
in p la c e .
A design convenience o f the m oisture
the p a r ts are a tta c h e d to the removable top panel
making r e p a i r s v ery easy.
Since i t
is im p o rta n t t h a t th e measurement
be c o n s is te n t from sample to sample, a guide is a tta c h e d to the bottom
o f th e case in which the sample box f i t s .
Thus, the sample box is
held, in v ery n e a r l y the same pla ce f o r e ve ry measurement.
I t was found e x p e r im e n t a lly t h a t glass tape was th e best way o f
fa s te n in g the f r o n t and back faces to the sample box.
v a rio u s o th e r glues were t r i e d
ta p e .
D.
Epoxy and
but none held up as long as the glass
The sample box dimensions a re 5" x 5" x 2".
C a l c u l a t i o n o f % Water from A tt e n u a tio n and Weight
The e q u atio n f o r r e l a t i n g the m oisture c o ntent o f a sample m a te r ia l
to i t s w eight and a t t e n u a t i o n o f microwave energy was d e riv e d by
Dr. Bruce R. McLeod.
The d e r i v a t i o n o f the e q u atio n given below can
be found in Appendix I I I .
100
% HpO = i, w. _ i
where k = M u l t i p l y i n g Factor
w = Weight o f Sample
x = Measured A tte n u a tio n
("I)
Figure 4.
Top View o f the Microwave M o is tu re Meter
Showing T e s t C e ll and M eter C o n tro ls .
Fig u re 5 ( a ) .
In s id e View o f the Microwave M oisture Meter
Showing E le c tr o n ic s and the Microwave Gear.
F ig u re 5 ( b ) .
In s id e View o f the Microwave M ois ture Meter Showing
the Two S ix V o l t Rechargeable B a t t e r i e s .
12
As can be seen from the e quation the a t t e n u a t i o n should go up as
the w eight o f the m a t e r ia l
c o n te n t.
goes up f o r a f i xed p e rce n t o f moisture
This would mean t h a t the measurement should b e . independent
o f packing d e n s it y as long as the m a t e r ia l
c o n te n t and the packing o f the m a te r ia l
is uniform in m oisture
in the box is uniform . ■
The rem ainder o f t h i s paper deals w i t h - t h e work done to determ ine ..
the accuracy o f the m oisture meter and i f th e r e were any f a c t o r s t h a t
might in tro d u c e s i g n i f i c a n t e r r o r i n t o m oisture c o n te n t measured w ith
the meter.
CHAPTER I I I
'TECHNIQUES OF GATHERING AND ANALYZING DATA
This c h a p te r e x p la in s the procedure f o r using th e m oisture
m e te r, techniques used f o r g a th e r in g d a t a , i t s a n a l y s i s , . a n d .th e
e f f e c t s o f v a rio u s f a c t o r s on the accuracy o f the measurement
te c h n iq u es .
A.
Method o f Making Measurements
I ..
Measurement Techniques f o r th e M o is tu re Meter
Since the f u n c tio n o f the m oisture meter was to measure the a tte n
u a tio n o f microwave energy in a sample o f m a t e r i a l , th e l e v e l o f micro
wave energy being re c e iv e d w ith o u t the sample p re se n t must be s e t
be fo re i n s e r t i n g the sample between th e horns.
The l e v e l
o f re c e iv e d
s ig n a l was s e t by p la c in g the empty sample box between the horns, p r e ­
s e t t i n g the p r e c is io n a t t e n u a t o r to 30 db and then a d j u s t in g the
v a r i a b l e gain a m p l i f i e r so t h a t the o u tp u t meter was p r e s e t to a
r e fe re n c e p o in t (such as f u l l
range o f m oistu re l e v e l
re a d in g s .
f i l l e d w ith the m a t e r ia l
horns.
s c a le ).
The 30 db range perm its a wide
The sample box was then u n ifo rm ly
to be measured and in s e r te d back between the
I f th e r e was w a te r p re se n t in th e sample m a t e r i a l , the outpu t
meter read down s c a le ( i . e .
was a d ju s te d to g ive f u l l
l ess s ig n a l
r e c e iv e d ) and th e a tt e n u a t o r
s c a le re ad in g on the o u tp u t m eter.
The
amount o f a tte n u a tio n , in (db) is th e d i f f e r e n c e between, the f i r s t and
14
fin a l
s e t t i n g s o f th e a t t e n u a t o r . .
The sample box is then weighted
and. the p e rce n t o f w a te r in th e sample can then be c a l c u l a t e d .
Below i s a b r i e f s t e p -b y -s te p summary o f the procedure used f o r
making a m oistu re measurement.
Step I :
Set a t t e n u a t o r to 30 db and pla ce empty sample box
between horns.
Step 2:
tu r n on power and a d j u s t gain ,on a m p l i f i e r so t h a t
the o u tp u t meter reads f u l l s c a le .
Step 3:
F ill
Step 4:
Turn on power and a d ju s t th e a t t e n u a t o r so t h a t
th e o u tp u t m eter again reads f u l l s c a le .
Step 5:
Note d i f f e r e n c e in f i r s t and f i n a l s e t t i n g on
a t t e n u a t o r , w eight m a t e r i a l , and c a l c u l a t e pe rce nt
o f w a te r c o n te n t.
2.
sample box and place back in case.
M a t e r i a l s Being In v e s t i g a t e d
Since th e m oistu re meter w i l l
p robably be used by the F ore st
S e rv ic e to measure m o istu re c o n te n t o f f u e l s on the f o r e s t f l o o r , a l l
the data taken was on these m a t e r i a l s .
The fu e l m a t e r i a l s can be
broken up i n t o th r e e m ajor c a t e g o r ie s .
The f i r s t is the upper la y e r
which is composed o f th e s t i c k s .
S tic k s a re d e fin e d as any branches
t h a t a re broken from the p a re n t t r e e and a re not connected to anything
t h a t is s t i l l
rooted in the ground.
For t h i s i n v e s t i g a t i o n only s t i c k s
up to one q u a r t e r inch in d ia m e te r were measured.
( v i s u a l l y th e s u rfa c e l a y e r )
The n e x t l a y e r down,
i s c a l l e d th e l i t t e r l a y e r .
L i t t e r is
15
composed o f le a v e s , pine needles and small
tw ig s .
The low est la y e r
(which i s n ext to the ground. s u r fa c e ) i s the d u f f l a y e r .
the s ev e ral previous y e a r ' s l i t t e r
f i n e l y ground p a r t i c l e s .
The d u f f is
la y e r s which have, decomposed to
Fig u re ( 6 ) shows p ic t u r e s o f d u f f , l i t t o r and
s t i c k s and F ig u re ( 7 ) shows a cross s e c tio n o f a l i t t e r - d u f f l a y e r
emphasizing the s e p a r a tio n o f l a y e r s .
3.
F illin g
Sample Box
Since the e q u a tio n f o r p e rce n t o f m oisture was d e r iv e d assuming
uniform packing d e n s it y o f the m a t e r ia l
in the sample box i t
t a n t to achieve uniform packing in th e f i e l d .
best method o f f i l l i n g
a t a tim e .
I t was observed t h a t the
the box was to add the sample m a t e r i a l a handful
Then, w h ile holding the sample box f l a t and le v e l
shaken back and f o r t h so t h a t the m a t e r ia l
la y e r.
is impor­
This was done u n t i l
i t was
spread out in a uniform
th e m a t e r ia l was le v e l w ith o r above the
box edge. . Now the box l i d was c lo s e d , packing the m a t e r i a l
in a n e a r l y
uniform fa s h io n .
I f the m a t e r ia l
contained lumps i t was necessary to break up these
lumps be fo re p u t t in g the m a te r ia l
rubbing the m a t e r ia l
B.
i n t o th e box.
This was done by
between the hands w h ile adding i t
to the box.
Oven Dry Techniques f o r Checking M o is tu re Meter
The oven dry technique o f d e te rm in in g the m oisture c o n te n t o f
m a t e r i a l s is w id e ly used as a standard [ 9 ] .
e s s e n t i a l y o f weighing a sample, d ry in g i t
The method c o n s is ts
in an oven f o r some s p e c i f i e d
Duff
F ig u re 6.
L itte r
Sticks
View o f the Three Types o f M a t e r i a l s Found on the F ore st F lo o r .
Fig u re 7.
Side Vi ew o f F o re st F lo o r Layer Showing the
S ep a ra tio n in the D u ff L i t t e r Layer.
17
pe rio d o f time and then weighing the sample again.
The d i f f e r e n c e in
w eights is the w eight o f w ater evaporated from the sample.
The
m o i s t u r e .c o n te n t is then c a l c u l a t e d using the f o l l o w i n g form ula:
%.w ater
For a l l
___________ w a te r w eig h t___________
wet sample w eight - w a te r w eight
x 100
the oven dry data taken d u ring t h i s i n v e s t i g a t i o n ,
(2)
15
hours was the minimum oven tim e w ith the oven te m peratu re s e t a t 5°C
below the lo c a l
the lo c a l
b o i l i n g . p o i n t o f w a te r .
The reason f o r s ta y in g below
b o i l i n g p o in t o f w a te r is to p re v e n t o th e r v o l a t i l e s
sample from being l i b e r a t e d
in the
[9 ].
A f t e r a measurement was taken on a sample w ith th e m oisture meter
p a r t o f t h i s sample was put in a small sample can and pu t through the
oven dry process.
The m a t e r ia l
the c e n te r o f . t h e sample box.
f o r the oven dry sample was taken from
This was done so t h a t th e m a te r ia l
d i r e c t l y between the horns was being used in the oven and a ls o f o r the
m eter.
To reduce the e r r o r caused by non-uniform packing in the sample
box, f i v e to s ix measurements were taken on one sample.
The a t t e n ­
u a tio n readings were then averaged and t h i s average was then used to
c a l c u l a t e the p e r c e n t.m o is tu r e c o n te n t.
I t was observed each time the
sample m a t e r ia l was dumped out and repacked t h a t the a t t e n u a t i o n loss
got S in a lle r i.
This was caused by the m a te r ia l
d ry in g out in the a i r
18
d u ring th e dumping and re packin g.
Since the above method was o b v io u s ly in tr o d u c in g e r r o r i t was
decided a b e t t e r method would be t o g a th e r enough m a t e r i a l
in the f i r s t
pla ce to make a t l e a s t f i v e s e p a ra te measurements w ith the m oisture
meter and to make an oven dry measurement f o r each m oisture meter
measurement.
With t h i s method b e t t e r consis ta n c y o f measurements was
observed w ith re s p e c t to the m oisture c o n te n t o f a s e t o f samples from
the same batch o f m a t e r i a l .
C. .
-
C o l l e c t i o n o f Data a t Lubrecht F o re st
I .
M o is tu re M eter P r o je c t
Two summers were spent a t Lubrecht F orest ta k in g data w ith the
m oisture m eter.
Lubrecht F o re st i s owned and operated by the U n i- ■
v e r s i t y o f Montana a t M is s o u la , Montana.
The f o r e s t lan d i s used
p r i m a r i l y by the f o r e s t r y school and f i r e
labs to conduct various
research p r o j e c t s .
The f i r s t summer o f ta k in g data r e s u l t e d in e f f o r t s to decrease
the s iz e o f the m oisture meter to make i t e a s i e r to c a r r y in the f i e l d .
The second summer was used to t e s t th e new and s m a lle r meter and
c o l l e c t more data p o in ts f o r a n a ly z in g the accuracy o f th e meter.
Much o f the tim e was spent in th e f i e l d c o l l e c t i n g d u f f , l i t t e r
and s t i c k samples.
The samples were c o l l e c t e d and put in p l a s t i c bags
so t h a t the w a te r would not e va porate be fo re the samples could be
taken back to the la b .
U s u a lly enough o f each m a te r ia l was c o l le c t e d
I
-
19
to make th r e e o r fo u r measurements on each m a te r ia l
8 0 0 . grams).
(a p p ro x im a te ly
.....................................................
At the la b a t Lubrecht th e r e was. a la r g e oven and a s ca le f o r use
in c a r r y in g out the oven dry measurements. . When the samples were ,
brought, in each day from the f i e l d , measurements were.made w ith the
m oistu re m eter.and oven dry samples were taken and run through the .
d ry in g process. . For measurements in the f i e l d ,
used to weigh the sample box and m a t e r i a l .
a hand held s ca le was
A s l i d e r u l e was used to
c a l c u l a t e the p e rc e n t o f m o istu re.
2.
P re s c rib e d Burning P r o je c t
The m oistu re c o n te n t o f the s t i c k s was measured each day in the
f i e l d as w e ll
as in the la b .
This in fo r m a tio n was used by the Northern
F o re st F i r e Labs a t M is s o u la , Montana in d e te rm in in g when they could
run a c o n t r o l l e d burn s a f e l y and e f f e c t i v e l y .
An e f f e c t i v e burn was
d e fin e d as a f i r e which burned through t h e . f o r e s t le a v in g the l a r g e r
tr e e s e s s e n t i a l l y u n e ffe c te d .
With the f o r e s t f l o o r c le a n e d , the
l a r g e r tr e e s can grow unhampered by the small scrub t r e e s .
A s e c tio n o f Lubrecht was sec tio n e d o f f i n t o 32 p l o t s .
The
p r e s c rib e d burning p r o j e c t used the p l o t s f o r running t e s t burns to
determ ine the c o n d itio n s necessary f o r e f f e c t i v e burning as d e fin e d
p r e v io u s ly .
O n e . c r i t e r i a necessary f o r proper burning, is t h a t the s t ic k s be
a t a s p e c i f i c m oisture l e v e l .
Since th e m oisture c o n te n t has been
20
observed to change in j u s t a few hours i t
is necessary to be a b le to
measure the m oisture c o n te n t j u s t p r i o r to s t a r t i n g th e burn.
where the microwave m oisture meter can p la y a key r o l e .
ment can be made r i g h t in the f i e l d
This is
The measure- .
ta k in g only the tim e r e q u ire d to
g a th e r the sample w h ile o th e r methods ta k e s ev e ral
hours and are im­
p o s s ib le to use in the f i e l d .
D.
A n a ly s is o f Data Using a Computer Program
I .
D e s c r ip tio n o f Program
The program was w r i t t e n in F o rtra n IV f o r running on th e Sigma 7
computer a t Montana S ta te U n i v e r s i t y .
The program makes comparisons
between the c a l c u l a t e d p e rce n t from the m oisture meter and the measured
oven dry p e rc e n t o f a sample.
Data cards were.punched c o n ta in in g the
type o f m a t e r i a l , y e a r ta k e n , a t t e n u a t i o n , w e ig h t, and th e oven dry
p e rc e n t corresponding to each measurement.
data by type and y e a r .
e quation ( I ) .
The program then s o rts the.
The m oisture meter percents a re c a l c u l a t e d using
The m u l t i p l y i n g c o n stan t used in the c a l c u l a t i o n is read
in on a n o th e r c o n tr o l
c o n s ta n t ( k ) t h a t w i l l
card .
The program then c a l c u l a t e s the m u l t i p l y i n g
y i e l d the measured oven dry p e rc e n t (using the
a t t e n u a t i o n and w eight found from th e m oisture meter measurement).
The
data i s ordered a ccording to in c r e a s in g c a l c u l a t e d p e rc e n t f o r each,
m a t e r ia l
group.
A data number, a t t e n u a t i o n , w e ig h t, c a l c u l a t e d p e r c e n t,
oven dry p e rc e n t and c a l c u l a t e d k i s p r i n t e d out in a t a b l e f o r each
m a t e r ia l
ty p e .
21
The program c a l c u l a t e s the mean and standard d e v i a t i o n o f the
k v a lu e s .
A p l o t is done o f c a l c u l a t e d p e rc e n t on th e y a x is and
oven dry p e rce n t on the x a x i s .
A l i n e x = y is drawn on the same
graph so t h a t the s c a t t e r o f c a l c u l a t e d versus oven dry percents
around the l i n e o f equal c a l c u l a t e d and oven dry percents
can be observed.
(x = y )
The program a ls o t a b u l a t e s how many and how f a r
the c a l c u l a t e d percents f a l l
above or below the corresponding oven
dry p e rc e n ts .
The purpose o f the program was to determine, the expected accuracy
o f the microwave m oisture measurement technique and what could be done
to improve the accuracy.
A l i s t i n g o f the m a in lin e program, sub­
r o u t i n e s , and in p u t data can be found in Appendix TV.
The output
ta b le s a re in Appendix V.
2.
A n a ly s is o f Program Output
The o u tp u t t a b l e f o r 1972 data shows t h a t 55% o f a l l
c a lc u la t e d
m oisture percents were below the corresponding oven dry percents w h ile
64% o f the 1973 c a l c u l a t e d percents were below the oven dry pe rce nts .
For both years 80.9% o f a l l
c a l c u l a t e d m oisture percents were w it h in
5% o f the corresponding oven dry p e rc e n t w h ile only 20% o f a l l
c a l­
c u la te d percents were w i t h i n I % o f t h e i r corresponding oven dry values
This was not good enough accuracy f o r the m oisture meter (assuming the
oven dry measurements were c o r r e c t ) .
The f a c t t h a t 60% o f a l l
the
c a l c u l a t e d m oisture l e v e l s were below the corresponding oven dry value
22
and 40% being above suggested no obvious changes in th e formula f o r
c a l c u l a t i n g the m oisture c o n te n t.
I t was observed t h a t th e m oisture
meter was v ery c o n s is te n t f o r sets o f measurements from the same
batch o f m a t e r i a l .
It
i s a ls o observed t h a t the oven dry technique
was c o n s is te n t f o r sets o f samples from the same batch o f m a t e r i a l .
Figures 8 - 1 3
p e rc e n ts .
It
g iv e a v is u a l
comparison o f oven d ry and c a l c u l a t e d
.
The p l o t s a re separated i n t o type o f m a t e r ia l and y e a r.
i s observed t h a t a lthough th e r e a re m any.points t h a t l i e
o f f the
l i n e o f equal p e r c e n t, th e p o in ts f o r th e most p a r t a re in a region
d i r e c t l y around the l i n e o f equal p e r c e n t.
The c a l c u l a t e d mean k values g iv e no new i n s i g h t i n t o the problem
because o f the f a c t t h a t th e standard d e v ia tio n s a re r e l a t i v e l y l a r g e .
Thus, 63% o f the c a l c u l a t e d k values f a l l
in a r e l a t i v e l y la r g e range
o f values around the mean v a lu e .
A l l o f th e above p o in te d toward a need f o r a r e - e v a l u a t i o n o f
both th e microwave and oven d ry techniques o f measuring th e m o is t u r e . '
c o n te n t o f the sample m a t e r i a l s .
E.
I .
Temperature E f f e c t s on Measurements
Methods o f D e te rm in atio n o f E f f e c t s
The d e r i v a t i o n o f th e equation f o r p e rcent o f m oistu re as a
fu n c tio n o f a t t e n u a t i o n and w eight o f sample m a te r ia l
o f a t t e n u a t i o n o f microwave energy in w a te r .
used the p r i n c i p l e
A value o f 40 db o f
a t t e n u a t i o n per c e n t im e te r o f pure w ater was used in th e d e r i v a t i o n .
23
+->00
1
TGO
Oven Dry Percent
Figure 8
SCATTER PLOT OF OVEN DRY % AND CALCULATED %
FOR DUFF. 1972 DATA.
JLK
24
C a lc u la te d Percent
O
O
Oven Dry P ercent
Fig u re 9
SCATTER PLOT OF OVEN DRY % AND CALCULATED '/.
FOR L IT T E R . 1972 DATA.
JLK
25
C a lc u la te d Percent
9
Oven Dry P ercent
Figure IO
SCATTER PLOT OF OVEN DRY % AND CALCULATED %
FOR S T IC K S . 1972 DATA.
JLK
26
o
o
CXJ
Oven Dry P ercent
Figure 11
SCATTER PLOT OF OVEN DRY % AND CALCULATED X
FOR DUFF. 1973 DATA.
JLK
27
C a lc u la te d Percent
R
Oven Dry Percent
Figure 12
SCATTER PLOT OF OVEN DRY % AND CALCULATED %
FOR L IT T E R . 1973 DATA.
JLK
28
8
Oven Dry P ercent
Figure 13
SCATTER PLOT OF OVEN DRY % AND CALCULATED %
FOR S T IC K S . 1973 DATA.
JLK
29
A ssum ing.that the value o f a t t e n u a t i o n in w ater is a c o n stan t th e re
should be no. charge necessary in the e q u a tio n .
Since i t
has a lr e a d y
been observed t h a t above 10 GHz the a t t e n u a t i o n o f w a te r is independent,
o f s a l t c o n te n t [ 6 ] t h i s was r u le d out as a v a r i a b l e f o r improving
the m oisture meter in t h i s d is c u s s io n .
In re s e a rc h in g v a rio u s papers i t was observed t h a t several
authors s ta te d t h a t tem peratu re had an e f f e c t on the a tt e n u a t i o n o f
w a te r [ 3 , 4 , 7 , 8 , 1 0 , 1 1 , 1 2 ] .
The m a j o r i t y o f the a r t i c l e s agreed t h a t
the e f f e c t o f an in c re a s e in te m p e ratu re is a decrease in a t t e n u a t i o n .
V arious e x p la n a tio n s were given as to th e reason, f o r the tem perature
e f f e c t s but no data was a v a i l a b l e g iv in g the a t t e n u a t i o n in db/cm as
a fu n c tio n o f te m p e ra tu re .
To c o r r e c t f o r any e r r o r in the m oistu re meter data due to tem­
p e r a tu r e changes, the a t t e n u a t i o n o f w a te r a s .a fu n c tio n o f tem perature
had to be d eterm ined.
There were th r e e approaches t h a t could be taken
to determ ine th e te m peratu re e f f e c t s :
Method one is to measure the m oisture c o n te n t o f a sample m a t e r ia l
a t d i f f e r e n t tem peratures using both microwave and oven dry te c h n iq u es .
I f th e r e i s a tem peratu re e f f e c t th e oven dry and microwave measurements
w ill
d i f f e r as a fu n c tio n o f tem peratu re
fo r a ll
cent,
the m oisture meter c a l c u l a t i o n s ) .
( i f the same k value i s used
The measured oven dry p e r ­
sample w e ig h t , and a t t e n u a t i o n a t a s p e c i f i c te m peratu re can be.
used to. c a l c u l a t e k a t s p e c i f i c te m p e ra tu re s .
The a t t e n u a t i o n in db/cm
30
o f w ater a t v a rio u s tem peratures can then be c a l c u l a t e d from the k
v a lu e .
Method two is p robably the most, d i r e c t but a ls o th e most d i f f i c u l t
This method r e q u ir e s measuring the a t t e n u a t i o n o f w a te r as a fu n c tio n
o f te m peratu re using microwave te c h n iq u e s .
The k v a lu e can then be
c a l c u l a t e d as a fu n c tio n o f te m p e ratu re .
Method th r e e is the e a s i e s t and d o e s n 't r e q u ir e any la b work.
This l a s t technique is j u s t a p p ly in g e le c tr o m a g n e tic f i e l d
th e o ry and
d e r iv i n g an e quation f o r the a t t e n u a t i o n o f a microwave energy in
w a te r .
Once the a t t e n u a t i o n o f w ater as a
d e te rm ine d, the equation f o r p e rce n t o f
th e te m peratu re o f the m a te r ia l
methods w i l l
a.
fu n c tio n o f te m peratu re i s
w ater can be changed to
as one o f the v a r i a b l e s .
c o n ta in
The th re e
now be discussed in the o rd e r l i s t e d .
Measurements Made on Sample M a t e r i a l
The measurement o f m oisture le v e l was done on l i t t e r over a tem­
p e r a tu r e range o f 15°C to 50°C in steps
o f S0C. The sample was placed
in the oven f o r a h a l f hour pe rio d w ith
the Oven s e t a t / a d e sire d
te m p e ra tu re .
The sample was then taken out and a measurement made w ith
the m oisture meter and an oven dry sample ta k en .
I t was observed
from the f i r s t s e t o f data t h a t the sample was d ry in g o u t too much to
g iv e a c c u ra te r e s u l t s a t the h ig h e s t te m p e ra tu re .
. There w a s n 't any
c o n s is te n c y in the way the c a l c u l a t e d k values changed w it h tem perature
31
T h e r e f o r e , on the next run a pan o f w a te r was a ls o placed in the
oven t o p re v e n t the sample from d ry in g out and a thermometer was placed
in the sample.
The sample w a s n 't taken out u n t i l
the m a t e r i a l
had
reached the te m peratu re d e s ir e d .
Tables I and 2 a re data ta b le s o f two runs over a tem perature
range o f I B 0C to. BO0C in. steps o f B0C.
Table I is a s e t o f data taken
on l i t t e r and Table 2 is a s e t o f data taken on s t i c k s .
Each t a b l e
shows th e te m peratu re measured a t t e n u a t i o n , w e ig h t, oven d ry p e r c e n t,
and c a l c u l a t e d k v a lu e .
The data taken on the s t i c k s show a strong tendancy f o r the k
value to in c re a s e as the tem peratu re goes up.
This would correspond
to an in c re a s e in a t t e n u a t i o n as the tem peratu re goes up which is
opposite o f what was expected.
h e a tin g o f the m a t e r i a l
This in c o n s is te n c y might be due to uneven
in the oven ( i . e .
tem perature g r a d i e n t e x i s t i n g ,
w ith h ig h e r te m peratu re a t o u te r edge o f sample and de cre a sing toward
c e n te r o f sample) .
m oisture le v e l
A m oisture g r a d ie n t could als o e x i s t w ith higher
a t c e n te r o f sample decreasing toward the o u te r edge.
Both o f these f a c t o r s could account f o r th e a p p a r e n tly i n c o r r e c t data .
t h a t was o b ta in e d .
b.
D i r e c t Measurement on Water
The goal o f t h i s method was to measure the a t t e n u a t i o n o f a
microwave s ig n a l
passing through a one c e n t im e te r l a y e r o f w ater as a
fu n c tio n o f te m p e r a tu re ^
The. method used is e x a c t l y th e same as the
32
Table I
M o is tu re Measurements made on L i t t e r as a Function o f the
Sample M a t e r i a l Temperature
Temperature
A tt e n u a tio n
Oven Dry %
Weight
15°C
6 .0
1 1 6 .8
20°C
6 .6
1 1 7 .7
25°C
6 .9
30°C
C a l.
1 6 .4 0
. .365
17.65
.317
1 3 1 .5
16.8 7
.364
6 .2
1 1 8 .5
1 5 .2 0
.397
35°C
6.1
1 1 5 .9
15.95
.383
40°C
6 .8
1 1 8 .9
1 5 .3 8
.366
45°C
S.S
1 2 8 .8
14.7 6
.332
BO0C
5 .2
1 2 0 .6
14.87
.3 3 3
.
k
.
33
Table 2
M o is tu re Measurements Made on S tic k s as a Function o f the
Sample M a t e r i a l Temperature
Temperature
A tt e n u a tio n
Weight
■ JDven Dry %
C a l. k
15°C
2 .8
1 5 5 .9
1 2 .9 8
20°C
2 .9
1 5 7 .6
1 0 ,7 6
■ 25 °C
3 .3
164.1
1 2 .8 7
.176
30°C
4 .4
1 6 4 .5
. 1 2 .0 4
.249
. 35°C
7 .8
1 6 4 .0 ,
13.7 8
.393
40 0C
7 .9
1 5 6 .9
1 3 .9 4
.412
• 45°C
7.1
1 6 4 .6
13.3 3
.366
SO0C
4 .6
1 6 4 .0
7 .2 7
.414
.156
,
.189 ,
34
the te c hnique used to measure th e a t t e n u a t i o n o f the sample m a t e r i a l s
in the m o is tu re m e te r.
Fig u re (1 4 ) is a block diagram o f bench s e t-u p
used in th e f i r s t measurements.
A H e w le tt Packard Model 8090B Sweep
O s c i l l a t o r was used as the source o f microwave energy.
.
An i s o l a t o r
was used to p re v e n t the r e f l e c t e d wave from re ac hing the source and
th e frequency meter was used to check the frequency o f th e source
s ig n a l.
The frequency o f the source was s e t a t 1 0.5 25 GHz, the f r e ­
quency o f the Gunn o s c i l l a t o r used in the m oisture m e te r.
l i n e was used to measure th e standing-w ave r a t i o
A te s t c e ll
g la s s .
The s l o t t e d
(SWR).
to hold the w ater was made out o f .25 inch p l e x i ­
The in s id e dimensions o f the c e l l
a re I cm. x 5" x 5 ".
The
t e s t c e l l was cen tere d between an open-ended waveguide (one end o f
s l o t t e d l i n e ) and a horn.
The horn was on the r e c e i v i n g s id e and wave­
guide was the t r a n s m i t t i n g s id e .
This was done so t h a t.m o s t o f the
tr a n s m it t e d energy would be re c e iv e d b y .th e horn.
The te m p e ratu re o f the w ater was s e t by r e g u l a t i n g hot and cold
tap w a t e r .
The te m p e ratu re o f the w a te r was measured a t th e tap and
again in the c e l l .
I t was observed t h a t the tap w a te r had to be h ig h e r
than the te m p e ratu re d e s ire d f o r the measurement because o f coo lin g
o f the w a te r as i t was poured i n t o th e c e l l .
For each te m p e ratu re the t o t a l
a t t e n u a t i o n and SWR were measured.
The SWR was used to c a l c u l a t e the db o f r e f l e c t e d energy.
was s u b tr a c te d from the t o t a l
This value
measured a t t e n u a t i o n l e a v in g the value
SWR
Meter
SWR Meter
HP 8690B
Sweep
O s c illa to r
Microwave
Is o la to r
V a ria b le
P r e c is io n
A tte n u a to r
LU
LH
S lo tte d
Line
Horns
C ry s ta l
D e te c to r
Frequency Meter
Fig u re 14.
Block diagram o f bench s e t-u p f o r measuring microwave a tt e n u a t i o n in w a te r .
36
o f a t t e n u a t i o n due to a b s o rp tio n o f e le c tr o m a g n e tic energy in the
w a te r .
The procedure f o r the above c a l c u l a t i o n s i s given in
Appendix V I.
A f t e r making th r e e sets o f measurements from 15°C to SO0C in steps
o f 5°C i t was observed t h a t the le v e l o f the w a te r in the c e l l
the amount o f measured a t t e n u a t i o n .
changed
This was due to r e f l e c t i o n o f the
s ig n al o f f the w a te r a i r i n t e r f a c e a t the top o f the c e l l
back down
i n t o the cel I .
To a void the problem o f r e f l e c t i o n , the horn on th e r e c e iv in g
s id e o f the c e l l
was re p la c ed by a n o th e r open ended waveguide.
The
waveguide d id not r e c e iv e the r e f l e c t e d s ig n a l as s t r o n g l y as the
horn.
I t was observed t h a t the h e ig h t o f th e w a te r s t i l l
measurements.
e f f e c t e d the
A l a y e r o f microwave absorbing m a te r ia l was placed on
top o f the c e l l
to decrease the le v e l
the r e f l e c t i o n was s t i l l
of re fle c tio n .
observed to be the same.
d id not reduce the r e f l e c t i o n to a le v e l
The e f f e c t o f
The absorbing m a te r ia l
low enough to o b ta in c o n s is te n t
measurements.
A new c e l l was made out o f .125 cm t h i c k p l e x i g l a s s to reduce any
r e f r a c t i o n t h a t might be caused by the plane wave not being norm ally
i n c id e n t on the p l e x i g l a s s l a y e r . '
in s id e w id th and h e ig h t.
of re fle c tio n
The c e l l was a ls o made 5" x 6 .2 5 "
The added h e ig h t helped reduce th e amount
but changes o f th r e e to f i v e db were s t i l l
observed
between d i f f e r e n t s ets o f measurements a t the same te m p e ra tu re .
37
The n e x t approach was to b u ild a new c e l l
p l e x i g l a s s again but to make i t s
cm.
out o f .125 cm th ic k '
in s id e th ic k n e s s .5 cm in s te a d o f I
This presented a s m a lle r w ater a i r s u rfa c e f o r r e f l e c t i o n s and
a ls o reduced th e o v e r a l l
c e ll
again 5" in s id e dim ension.
w ith th e c e l l
th ic k n e s s .
The w idth and h e ig h t were
The measurements were s t i l l
.
being made
between two open-ended waveguides.
Two s ets o f measurements were made over the tem peratu re range and
both sets o f data came out e x tre m e ly c lo s e w ith no n o t i c e a b l e r e f l e c ­
t i o n t a k in g pla ce o f f the top s u rfa c e o f water..
There was a problem
w ith the measured a t t e n u a t i o n in t h a t th e values were too high a t room
te m p e ratu re where the a t t e n u a t i o n was known to be 40 db/cm a t 25°C [ 1 3 ] .
The measured value o f 5 3 .4 5 db/cm p o in te d toward some o th e r e f f e c t s coming i n t o p la y .
I t was concluded t h a t th e placement o f the two
waveguides so close to g e th e r was s e t t i n g up an i n t e r a c t i o n causing the
s ig n a l to lose i t s
plane wave c h a r a c t e r i s t i c s through th e w ater l a y e r .
The n e xt step was to re p la c e both waveguides w ith horns to p re ­
serve th e plane wave propagation through the c e l l .
a p a tu re a rea o f 1 .5 5 " x . 9 " .
c e ll
The horns had an
A gain, th e horns were c entere d on the
and a d ju s te d f o r maximum re c e iv e d s i g n a l .
Two sets o f measure­
ments were made, one a t 1 0 .5 GHz and an o th e r a t 1 0.525 GHz.
Both sets
agreed c l o s e l y w ith each o th e r and to th e 40 db/cm value a t 2.50C.
F ig u re (1 5 ) shows th e f i n a l
ments.
la b setup t h a t was used to make th e measure­
The measured values o f a t t e n u a t i o n match w ith th e known value
38
a t 25°C, but the r e s t o f th e p o in ts s t i l l
fin a l
have to be v e r i f i e d b efore any
changes can be made in the m o istu re meter e quation (eq.
The n ext s e c tio n w i l l
(I)).
discuss c a l c u l a t i o n o f the a t t e n u a t i o n in w ater
from a f i e l d s p o in t o f view.
c.
T h e o r e t ic a l
C a lc u la tio n s
The a t t e n u a t i o n c o n s ta n t o f an e le c tr o m a g n e tic plane wave t r a v e l i n g
in a lo s s y d i e l e c t r i c m a t e r ia l can be c a l c u l a t e d as a f u n c tio n o f the
d i e l e c t r i c c o n s ta n t, los s ta n g e n t and frequency o f e le c tr o m a g n e tic
energy.
One a u th o r used t h i s approach to c a l c u l a t e the a tt e n u a t io n
o f a s ig n a l
[1 3 ].
in a given th ic k n e s s o f d i e l e c t r i c m a te r ia l
such as w ater
The d e r i v a t i o n o f t h i s e quation r e l a t i n g a t t e n u a t i o n to the
th ic k n e s s , d i e l e c t r i c c o n s ta n t, loss ta n g e n t and frequency o f signal
is in Appendix V I I .
The f i n a l
■ A = 8.686 it
eq u atio n fo llo w s below:
Xl
Xo
/e~
ta n
6 (db)
(3 )
The f r e e space wavelength (Ao) and th ic k n e s s o f d i e l e c t r i c l a y e r
(a) are both in c e n t im e te r s .
Given the d i e l e c t r i c c o n s ta n t (e ^ ) and
loss ta n g e n t (ta n 6) the a t t e n u a t i o n can be found f o r a s p e c i f i e d
frequency and th ic k n e s s .
F ig u re 16 i s a graph o f the los s ta n g e n t and d i e l e c t r i c constant
o f w ater as a f u n c tio n o f te m peratu re a t v a rio u s fr e q u e n c ie s .
'I
The
F ig u re 15.
View o f the Bench Setup Used to Measure the A tte n u a tio n
o f Microwaves Through a I -cm Layer o f Water.
40
d i e l e c t r i c c onstant
120
0 ---------- ----------- ----------- ----------- ----------- ----------- ----------- ----------0
10
20
30
40
50
60
70
80
loss ta n g e n t
te m peratu re ( 0 C)
te m peratu re ( 0 C)
F ig u re 16.
The V a r i a t i o n w ith Temperature o f
the D i e l e c t r i c Constant and Loss
Tangent o f W a te r.
41
d i e l e c t r i c c o n stan t and loss ta ngent were taken o f f t h i s graph a t
v a rio u s tem peratures f o r the 10 GHz fre q u e n cy .
The previous equation
was then used to c a l c u l a t e the a t t e n u a t i o n o f a 1 0.525 GHz s ig nal
a one c e n t im e te r l a y e r o f w ater a t v a r io u s .te m p e r a tu r e s .
in
Table 3
gives the d i e l e c t r i c c o n s ta n t, loss ta n g e n t, and c a l c u l a t e d a t t e n ­
u a tio n
(db/cm) a t v ario u s te m p e ratu re s .
Note t h a t er and tan 6 were f o r 10 GHz r a t h e r than 1 0.525 GHz
used in the above c a l c u l a t i o n s but t h i s amounts to o n ly a . 5% e r r o r
in frequency and er and tan 6 would show a p p ro x im a te ly th e same
amount o f change [ 1 4 ] .
Table 4 gives the measured and c a l c u l a t e d a t t e n u a t i o n in db/cm
f o r a s ig n a l
propagated through w ater a t v ario u s te m p e ra tu re s .
It
is observed t h a t the two values a re v ery c lo s e a t the v a rio u s tem­
peratures.
With two methods g iv in g e s s e n t i a l l y the same values something can
now be done to m odify the m oisture meter e quation to ta k e account o f
the tem p e ratu re o f the m a te r ia l, being measured.
2.
M o d ifie d M o is tu re Meter Equation Containing Temperature
Now t h a t the a t t e n u a t i o n o f w a te r as a fu n c tio n o f tem perature
has been dete rm in e d , the m u l t i p l y i n g f a c t o r k as a f u n c tio n o f tem­
p e r a tu r e can be c a l c u l a t e d .
This was done and then a l e a s t squares
s o l u t i o n , given below, was d e riv e d f o r k ( T ° C ) . . A computer program was
w r i t t e n to c a l c u l a t e k f o r tem peratures from 15°C to 50°C in steps
42
Table 3
D i e l e c t r i c C ons ta nt, Loss Tangent, and C a lc u la te d A tt e n u a tio n o f
Water a t Various Temperatures
Temperature
tan 6
er
A tt e n u a tio n .
15°c
5 1 .2
20°C
5 4 .4
25°C
5 6 .0
.561
30°C
5 9 .2
.504
3 7 .1 3 db
35°C
6 0 .8
.465
3 4 .7 2 db
40° C
6 2 .4
.432
3 2 .6 7 cb
45°C
6 2 .4
.400
3 0 .2 5 db .
SO0C
6 2 .4
.376
2 8 .4 4 db
:
.
.723
4 9 . 5 3 . db
.640
4 5 .2 0 db
■
4 0 .2 0 db
43
Table 4
Measured and C a lc u la te d A tt e n u a tio n o f Water
a t V arious Temperatures
•
Temperature
Measured ,A tte n u a tio n
C a lc u la te d A tte n u a tio n
IB 0C
49. BO
20°C
4 6 . S4
25°C
4 0 .9 6
4 0 .2 0
3 O0 C
3 8 .0 4
3 7 .1 3
35°C
3 4 .8 6
3 4 .7 2
40°C
3 1 .7 8
3 2 .6 7
. 2 9 .4 6 .
3 0 .2 5
2 6 .6 6
2 8 .4 4
45°C .
BO0C
49. S3
'
-
V
4 5 .2 0
44
o f one degree using the l e a s t squares s o l u t i o n .
The a t t e n u a t i o n f o r
w ater over the same te m peratu re range was c a l c u l a t e d from the c a l ­
c u la te d k v a lu e s .
Fig u re
F ig u re (1 7 ) i s a p l o t o f k verses tem peratu re and
(1 8 ) is a p l o t o f a tt e n u a t io n through one c e n t im e te r o f w ater
verses te m p e ra tu re .
Table 5 gives the value o f k over th e 15 to 50
degree range in one degree steps.
k (T 0C) = .39 4 4 -
( 6 .4 1 4 X IO " 3 ) T + (3 .7 1 4 X IO " 5 ) T2
(4 )
When a measurement is made on a sample, the te m p e ratu re i s . t a k e n
and the m u l t i p l y i n g f a c t o r k f o r t h a t te m peratu re i s taken o f f Table 5
The c o r r e c t m oistu re c o n te n t can then be c a l c u l a t e d .
t a b l e f o r fin d in g , the c o r r e c t k value w i l l
a p p e a lin g f o r use in the f i e l d
The use o f the
d e f i n i t e l y be more
by t h e . f o r e s t e r than using equation (4 )
to c a l c u l a t e k.
F.
E r r o r in Oven Dry Measurements
S everal questions were r a is e d du rin g th e course o f t h i s work con­
c e rn in g the oven dry technique o f measuring m oisture in m a t e r i a l s .
Is 15 hours enough tim e to d r i v e a l l
th e w a te r out o f the samples?
What happens i f many v ery wet samples a re put in the oven.
W ill
they
dry out c o m p le te ly in 15 hours?
For one s e t o f oven dry measurements i t was observed t h a t th e re
were w a te r d r o p le ts on the in s id e o f the oven door a f t e r th e m a te r ia ls
had been in the oven f o r 15 hours a t 95°C.
This would mean t h a t the
m oisture was not g e t t i n g out o f the oven but s a t u r a t in g the atmosphere
45
M u ltip ly in g fa c to r
(0
Temperature °C
F ig u re 17
PLOT OF M U LTIPLYIN G FACTOR (K )
VS. TEMPERATURE.
JLK
46
A tte n u a tio n db/cm
o
<-o
Temperature 0C
Fig u re 18
PLOT OF OTTEN. OF MICRONAVE SIONAL VS. TEMP.
AT 1 0 .5 2 5 GHZ. THROUGH I CM. OF WATER.
JLK
47
Table 5
M u ltip ly in g
Temperature
15°C
16°C
I 7°C
18°C
I 9°C
20°C
21 °C
22°C
23°C
24°C
25°C
26°C
27°C
28°C
29°C
30°C
31 °C
32°C
33°C
34°C
35°C
36°C
37°C
38°C
39°C
40°C
41 °C
42°C
43°C
44°C
45°C
46°C
47°C
48°C
49°C
SO0C
F a cto r k a t Various Temperatures
k Value
.307
.301
.296
.291
.286
.281
.276
.271
.267
.262
.257
.253
.248
.244
.240
.235
.231
.227
.223
.21 9
.215
.212
.208
.204
.201
.197
.194
.191
.187
.184
.181
.178
.175
.172
.169
.167
48
in the o v e n .'
With the atmosphere s a t u r a t e d , the m oistu re le v e l o f
the samples would be the same as the oven a i r .
T h erefo re, i t
is.
obvious t h a t not o n ly is i t necessary to d r i v e the water, out o f the
sample m a t e r i a l
but to a ls o keep the m oisture c o n te n t o f the atmos­
phere o f the oven as low as p o s s ib le .
I t was i n i t i a l l y
thought t h a t by p la c in g a vacuum in th e oven and
s e t t i n g the oven a t a low er te m peratu re the m a te r ia l
out b e t t e r and f a s t e r .
of l it t e r .
could be d r ie d
This method was t r i e d on f i v e d i f f e r e n t samples
The samples were l e f t in the oven a t 85°C f o r 15 hours.
A f t e r the tim e was up the samples were weighed and p e rc e n t o f m oisture
c a lc u la te d .
Because m o istu re was observed on the in s id e o f the oven
door the samples were put back in the oven under zero vacuum f o r a n o th e r
15 hours.
The samples were again weighed and p e rce n t o f m oisture
c a lc u la te d .
Table 6 is a l i s t o f the data ta k e n .
From th e t a b l e i t
is observed t h a t the c a l c u l a t e d p e rc e n t m oisture c o n te n ts increased
by 2 .2 to 3 . 4 p e r c e n t.
There was no way f o r the m o istu re to escape
from the oven w ith a vacuum on i t .
What was needed was some way to absorb the m o istu re d riv e n out o f
the samples.
' Thus, the idea o f p u t t in g a d ry in g agent in th e oven
w ith the samples was conceived.
was found to be a f a i r l y
Anhydrous calcium s u l f a t e
( CaSO^)
ine xpe ns iv e d ry in g agent.
The oven was. again s e t a t 95°C and th r e e s hallow pans, c o n ta in in g . .
the ,d ryin g agent were placed on the upper t r a y in th e oven.
The
49
samples to be d r ie d were placed below on the bottom t r a y .
shows the oven w ith i t s
Figure (1 9 )
door open w ith the pans o f d r y in g agent and
the samples in p l a i n view.
The s c a le used f o r weighing a l l
the samples
is a ls o shown.
The samples were taken out a f t e r 15 hours, weighed, and put back
in f o r a n o th e r 15 hours.
again weighed.
At the end o f the second 15 hours, they were
Table 7 is a l i s t o f th e d a ta ta k en .
t h a t the a d d i t i o n a l
It
i s observed
15 hours made no marked d i f f e r e n c e in th e w eights.
The d ry in g agent was a ls o weighed to check f o r any a b s o rp tio n o f w a te r .
The c r y s t a l s inc re a se d in w eight by 1 8 .0 5 grams w h ile th e samples de­
creased by 2 2 . 4 grams.
From t h i s data the assumption can be made t h a t
the samples are d r ie d out c o m p le te ly a f t e r 15 hours and t h a t the dry in g
agent is absorbing alm ost a l l
the m oisture d rive n out o f th e s a m p le ..
I t can be s aid now t h a t the best method so f a r f o r oven d ry in g to
assume a c c u ra te r e s u l t s
is to use a d ry in g agent in th e oven during
the d ry in g process.
The d ry in g agent can be reused as many times as necessary by p u t t i n g
it
in an oven a t a h ig h e r te m p e ra tu re , say. 120°C to b o il
absorbed m o is tu re .
to the p r o j e c t .
The d ry in g agent adds o n ly a small
o f f the
in itia l
cost
50
T a b le 6
Oven Dry Measurements, a t 15 Hours and 30 Hours
While Under a Vacuum
. C a l. % o f
W a te r■
Weight
30 Hours
1 5 .0 g r '
12.3%
1 4 .5 gr
2 1 .0 gr
1 8 .7 g r
11.0%
18.1
gr
; 13.8%
1 6 .9 g r
1 4 .8 gr
12.4%
1 4 .5 g r
14.2%
1 7 . 4 gr
1 5 . 4 gr'
11.5%.
1 4 .8 g r
14.9%
1 8 .2 g r
1 6 * 3 . gr'. '
. 1 5 .7 g r
13.7%
T o ta l
Weight .
Weight
15 Hours.
17.1 gr
.
.
10.4%
. C a l. % (
Water
15.2%
T a b le 7
Oven Dry Measurements o f 15 Hours and 30 Hours
With Drying- Agent Present
T o ta l
Weight
Weight
15 Hours
. C a l . %' o f
Water
Weight
30 Hours
C a ! . %. o f
Water
1 6 .6 gr
1 3 .6 gr
18.1%
■ 1 3 .6 gr. .
1 7 .3 gr
1 4 .3 gr
17.3%
1 4 .2 g r
1 5 .3 gr
1 2 .7 gr
17.0% .
1 2 .7 g r
2 0 .8 gr
1 7 .2 gr
17.3%
1 7 .T gr
17.8%
1 8 .4 gr
15.1 gr
17.9% .
1 5 .0 g r ’
18.5%
18.1%
'
17.9%
- '
17.0%
F ig u re 19.
View o f Scale and Oven w ith Door Open Showing Pans Containing
Drying Agent on the Upper S h e lf o f the Oven, and the Drying
Cans f o r the Sample M a t e r i a l on the Bottom S h e l f .
CHAPTER IV .
SUMMARY OF RESULTS
It
has been shown t h a t the m oisture c o n te n t o f , a m a te r ia l
be c a l c u l a t e d from th e a t t e n u a t i o n o f a microwave s ig n a l
through t h a t m a t e r i a l .
can .
propagating
This p r i n c i p l e was then used in b u i l d i n g a
p o r ta b le microwave m oistu re m e te r.
This meter was used in the measure­
ment o f the m oistu re c o n te n t o f f u e l m a t e r i a l s on the f o r e s t f l o o r ;
A computer program was w r i t t e n to a n a ly ze .two y ears o f data
taken a t Lubrecht F o r e s t.
a d d itio n a l
The program showed t h a t th e r e was an
f a c t o r t h a t was i n f l u e n c i n g the.measurements.
The a t t e n u a t i o n o f th e e le c tr o m a g n e tic s ig nal
in w a te r was
shown to be a fu n c tio n o f the te m peratu re o f the w a te r.
been shown both e x p e r i m e n t a l l y and t h e o r e t i c a l l y .
This has
.An e quation was
d e r iv e d r e l a t i n g th e m oistu re c o n te n t o f a m a te r ia l
.
to th e a t t e n -
n a tio n and te m peratu re o f the m a t e r i a l .
A b e t t e r method o f oven dry in g , th e sample m a t e r i a l s was developed.
The use o f a d r y in g agent in the oven w ith the sample assures f a s t e r
and complete d r y in g o f the samples.
The n ext s e c tio n w i l l
g iv e some ideas as to what f u r t h e r in v e s ­
t i g a t i o n s should be c a r r i e d out to check the accuracy o f the m icrowave te c hnique o f m oisture measurement.
CHAPTER V
CONCLUSIONS
This study was undertaken w ith, the goal o f b u i l d i n g a m icrowave m o istu re meter t h a t could be used by the F o re st S e r v ic e .
The accuracy o f th e oven d ry m oistu re measurements used in
checking th e m oistu re meter was found to be poor.
was a r r i v e d a t which gave b e t t e r c o n s is te n c y .
A b e t t e r method
The oven d r y technique
should be in v e s t i g a t e d f u r t h e r to determ ine the necessary tim e r e ­
q u ire d t o d ry a, sample and how t h i s tim e changes w ith th e le v e l o f
m oisture in th e m a t e r i a l .
The e quation r e l a t i n g the m oistu re c o n te n t o f a sample to a t t e n ­
u a t i o n , w eig h t and te m peratu re should be v e r i f i e d .
should be spent c o l l e c t i n g d a ta .
m a te r ia l
Another summer
This tim e the te m peratu re o f the
should be measured and recorded be fo re the microwave m oisture
measurement i s .made. , The k value can then be found from a t a b l e s i m i l a r
to T a b le 5 o f t h i s paper and then the p e rc e n t o f m o istu re can be
c a lc u la te d .
A s u b ro u tin e can be, added to the data a n a ly s is program t h a t w i l l
c a l c u l a t e k given, the tem peratu re o f th e sample.
This k w i l l be used
by th e program to c a l c u l a t e the p e rc e n t o f m o istu re. ■ A . b e t t e r com- .
p a ri son between th e oven dry and c a l c u l a t e d percents should be .seen
i f th e tem p e ratu re e f f e c t s a re c o r r e c t .
54
t h e r e a re f u r t h e r m o d ific a t io n s t h a t could be done to the
•m o is tu r e meter to make i t e a s i e r to use.
The a d d i t i o n o f a b u i l t - i n
e l e c t r o n i c s c a le w ith d i g i t a l
readout
would e l i m i n a t e the need f o r c a r r y in g a s c a le along in th e f i e l d .
pressure tra n s d u c e r load c e l l would serve as the w eight sensor.
analog s ig n a l could then be converted to a d i g i t a l
cessing to. pro v id e a re ad o u t in grams.
A
The,
s ig n a l f o r pro­
By mounting, a small f o u r .
fu n c tio n c a l c u l a t o r on the f r o n t p a n e l . t h e c a l c u l a t i o n would be made
f a s t e r and more a c c u r a t e ly . ,
The replacem ent o f the p r e c is io n a t t e n u a t o r w ith a pin diode
a t t e n u a t o r would save in c o s t , w eight and s i z e .
The diode a t t e n u a t o r
would be c a l i b r a t e d in steps, o f 10 db from 0 db to 40 db. ■The meter
s c a le would then be c a l i b r a t e d to read in db.
This way th e a t t e n ­
u a tio n re a d in g could be read d i r e c t l y o f f the m eter.
A ll
o f the above would make the m oisture meter a more e f f i c i e n t
device to use and a ls o Would make i t
to ta lly
s e l f - c o n t a i n e d . 1:
-
REFERENCES CITED
56
1.
Lowery, D. P. and E. S. Kotok, "E v a lu a tio n o f a Microwave Wood
M o is tu re M e t e r , " F o re st Products J o u r n a l , V o l . 1 7, No. 10
( O c t . , 1 9 6 7 ), pp. 4 7 -5 1 .
.
2.
Botsco, Ron, "Microwave M o is tu re Measurement," Instrum ents and
Control Systems, (May, 1 9 7 0 ), pp. 1 16-1,17.
3.
Busker, L. H ., "Microwave M o is tu re Measurements," Instrum ents
and Control Systems, ( D e c . , 19 6 8 ) , pp. 8 9 -9 2 .
4.
Busker, I . H . , "Measurement o f Water Content Above 30% by
Microwave Absorption M e th o d ," T a p p i , V o l . 5 1, No. 8
(A u g ., 1 9 6 8 ), pp. 348 -3 5 3.
5.
Becker, E. G. and S. H. A u t l e r , "Water Vapor Absorption o f
E le c tro m a g n e tic R a d ia tio n in the C e ntim eter Wave-length
Range," Physical Review, V o l . 70, No. 5 and 6 ( S e p t . , 1 9 4 6 ),
pp. 3 0 0 -3 0 7 ..
6.
W ex le r, A. ( e d . ) . Hum idity and M o i s t u r e : Measurement and Control
in Science and I n d u s t r y .
V o l . I V , P r in c i p l e s and Methods .
o f Measuring M o is tu re in L iq u id s and S o l i d s .
Washington
DC/New York:
R e in h o ld , 1965, pp. 8 7 -9 3 .
7.
T a y l o r , H. B . , "Microwave M o is tu re Measurements," AEI E n g in e e rin g ,
( J a n . / F e b . , 1 9 6 5 ), pp. 3 9 -4 6 .
8.
Sumrnerhi 11, S . , "Microwave in the Measurement o f M o is tu r e ,"
In s tru m e n t Review, ( O c t . , 1 9 6 7 ) , pp. 4 1 9 -4 2 2 .
9.
Geary, P. J. Measurement o f M o is tu re in S o l i d s .
South H i l l ,
C h i s l e h u r s t , Kent: S ir a I n s t i t u t e , 1970, pp. 16.
10.
'
W a lk e ri C. W. E . , "Microwave M o is tu re Measurements," Pulp and
Paper Symposium.
Proceedings, V o l . 4 ( 1 9 6 3 ) , pp. 2 3 -26 .
11.
I n c e , ■A . : D. and A. Tuner, "The D e te rm in a tio n o f M o is tu re in .
P la in Cakes by a Microwave A tt e n u a tio n Tech n iq u e ," A n a l y s t ,
V o l . 90 ( N o v ., 1 9 6 5 ), pp., 6 9 2 -6 9 6 .
12.
Gray, W. A . , "The Rapid D e te rm in a tio n o f M ois ture in Coal Using
M icrowaves," Journal o f the I n s t i t u t e o f . F u e l , ( S e p t . , 1 9 7 0 ),
. pp. 3 50 -3 5 4.
57
13.
Sliresh, N . , J. C.. Callaghan and A. E. Creel m a n " M ic r o w a v e
Measurement o f th e Degree o f Binding o f Water Absorbed
i f S o i l s , " The Journal o f Microwave Power, ( S e p t . , 1967)
pp. 129 -1 3 7.
14.
Von H ip p ie , A r th u r R. ( e d . ) .
D i e l e c t r i c M a t e r i a l s and
A ppli c a t i o n s .
New York: . The Technologoy Press o f M . I ;T
. and.John W iley & Sons, I n c . , 1954, pp. 361.
APPENDICES
Appendix I
This s e c tio n c o n ta in s th e p i c t u r e s o f th e Gunn o s c i l l a t o r , diode
d e t e c t o r , horns, m o d u la to r, and a m p l i f i e r used in th e microwave
m oisture m e te r.
F ig u re .( I )
shows th e a m p l i f i e r on th e l e f t and the modulator
r i g h t w ith a HP-45 inc lu d e d to show r e l a t i v e s iz e .
F ig u re ( 2 ) shows a horn w ith th e diode d e te c t o r a tta c h e d on
the l e f t and a n o th e r horn w ith waveguide to coax a d ap to r and coax
c a b le on th e r i g h t w it h HP-45 in th e c e n t e r included s c a le .
Fig u re ( 3 ) shows the p r e c is io n a t t e n u a t o r used in th e m eter.
F ig u re ( 4 ) shows th r e e views o f th e Gunn o s c i l l a t o r with, a
fifty
c ent piece for. s c a le .
60
Fig u re I .
Fig u re 2.
Top View o f A m p l i f i e r and M odulator.
View o f Horns, Diode D e te c t o r , Coax and Adaptors.
61
Figure 3.
Figure 4.
View o f P r e c is io n A tt e n u a to r .
Three Views o f Gunn O s c i l l a t o r .
A p p e n d ix .I I
This s e c tio n c o n ta in s the schematics, and s p e c i f i c a t i o n s o f the
a m p l i f i e r and m odulator used in the microwave m oisture m e te r .
The
s p e c i f i c a t i o n s f o r the c i r c u i t s a re proceeded by the c i r c u i t
schematics.
F ig u re I is the schematic o f the a m p l i f i e r .
a m p l i f i e r i s a d ju s te d by th e 2 . BK p o te n tio m e te r .
T h e 'g a in o f the.
The a m p l i f i e r uses
a FET in p u t f o r high i n p u t impedance and low c u r r e n t d r a in on the
source.
p lifie r
The FET i n p u t i s fo llo w e d by a v a r i a b l e gain o p e r a tio n am­
(OP. amp) stage which i s fo llo w e d by two a c t i v e f i l t e r
which were designed f o r a c e n t e r fre quency o f I KHz.
filte r
stages .
T h e . l a s t a c t iv e
stage feeds another OP-amp stage which in tu r n d r iv e s an e m itte r ,
f o l l o w e r which prov ides the low outp u t impedance to d r i v e th e output
meter c i r c u i t .
-
F ig u re 2 is the schematic o f th e m odulator which was b u i l t by
Mr. John Rompel, an e n g in e e r a t Montana S ta te U n i v e r s i t y . . the. mod­
u l a t o r c o n s is ts o f a s in g le IKHz o s c i l l a t o r and the a p p r o p r ia t e i n t e r - .
fa c in g to. pro v id e low. o u tp u t impedance with, high c u r r e n t c a p a b i l i t i e s
t o d r i v e th e gunn o s c i l l a t o r .
.
63
IRFtnoo
I OOOpf.
In p u t
Diode
D e t.
.1
I 50K T
I OOOpf.
2N4124
C a le c tr o
D l-912
0-1 DC ma.
1N270
o +10
+12 o
10 mh.
= Z lO O
Op. Amp. Supply
Ground
Ground
F ig u re I .
A m p l i f i e r Schematic
o
+12V (Red)
TR 56
Output (B lue)
2N4124
vI t X
I NI 351A
CD401I
°
F ig u re 2.
Modulator Schematic
Ground (B la c k)
65
A m p l i f i e r S p e c i f i c a t io n s
Gain:
0 to 40 db.
Center Frequency:
.
1000 Hz.
‘
'
.
^V
'
12 V o lts Minimum
A l l R e s is to rs 1 /4 Watt Unless S ta te d O therw ise.
A ll
C a p a cito rs Given i n M ic ro fa ra d s Unless S ta te d Otherwise
M odulator S p e c i f i c a t i o n s
12 V o lts Minimum
O utput:
1000 Hz. Square Wave
460 ma. Maximum Output Drain
Al I R e s is to rs T /4 Watt Unless S ta te d O therw ise.
A ll
C a p a cito rs Given in M ic ro fa ra d s Unless S tated O therwise
Appendix I I I
This s e c tio n presents the d e r i v a t i o n o f the e q u a tio n .u s e d to c a l ­
c u l a t e the m oistu re c o n te n t o f a sample m a te r ia l
given i t s w eight and
amount o f a t t e n u a t i o n o f a microwave s ig n a l passed through i t .
The
d e r i v a t i o n f o l l o w i n g was: f i r s t done by Dr. Bruce McLeod a t Montana
S ta te U n i v e r s i t y .
The value o f a t t e n u a t i o n o f a microwave s ig nal passed through a
one c e n t im e te r l a y e r o f . w a t e r is 40 db a t 2 5 0C.
This f a c t i s the
h e a r t o f the d e r i v a t i o n .
. Assume t h a t two microwave horns were placed X cm a p a r t . . I f the
area between the horns was f i l l e d
would be X •
40 db.
This would correspond to an " a l l . w ater" sample.
S in c e .t h e a t t e n u a t i o n
is to be j u s t due to ab so rp tio n in th e w a te r ,
the area o f w ater or m a t e r ia l
area.
w ith w a te r the a t t e n u a t i o n measured
is made l a r g e r .than th e horn apature
This is done to p revent the s ig n a l from r e f r a c t i n g around the .
sample and back i n t o the r e c e iv in g horn.
Now i f the w ater between the horn i s r e p la c e d .b y some m a te ria l
c o n ta in in g w a te r and a tte n u a tio n , measured, the p e rcent o f w ater w eight
seen by the horn would be
' % H2O w eight = ( ^ )
t
x 100 ..; g r
'
remembering that,
.
I CC = I gr H9O
where Am i s the a t t e n u a t i o n measured, A^ i s a t t e n u a tio n f o r a l l
w ater.
67
arid V^1 is the volume seen by the horn
- Vh = (Horn ap atu re a r e a )
(d is ta n c e between horns.) .
The p e rc e n t o f w eig h t seen by th e horn would be ...
V
% wet w e ig h t = , h\
W,
% '
t
V
where
i s the t o t a l
x 100
volume o f the box c o n ta in in g the sample m a te r ia l
and Wt i s the t o t a l w eig h t o f the sample.
The p e rc e n t o f m o istu re f o r any sample is given .by th e f o llo w in g
e q u atio n
%H?0 =
HpO w eig h t
r
. .= wet w eight - HgO w eight
x 100
and a f t e r s u b s t i t u t i n g in the terms f o r % HpO w eight and % wet weight
seen by the horns th e f o l l o w i n g e q u atio n i s o b ta in e d :
By making th e f o l l o w i n g m a n ip u la tio n s the f i n a l , e q u a tio n is o b ta in e d
68
( /)
&
I H2O
x 100
$
A,
(r )
Since
and
-
100
W
(A
^
- I
a re known th e f i n a l
% H9O =
e quation i s j u s t
100
k & H
Am
.
where k i s a c o n s ta n t in terms o f s iz e o f th e sample box and a tt e n u a t io n
o f a microwave s ig n a l
in one c e n t im e te r w idth o f w a te r.
. For the m o istu re meter o f t h i s s tu d y , the horns were, looking a t a
5 .0 8 cm l a y e r o f m a t e r i a l and the sample box was 1 2 .7 cm square by
5 .0 8 cm. w ide.
This giv es the f o l l o w i n g values f o r
At = (4 0 )
( 5 . 0 8 ) = 2 0 3 .2 (db)
Vt = ( 1 2 . 7 ) 2 ( 5 . 0 8 ) = 8 1 9 . 3 5 . (c c )
and a k value equal to .2 4 8 .
and V^,
-
Appendix IV
The f i r s t p a r t o f t h i s
.
s e c tio n c o n ta in s the l i s t i n g o f the
program used to a n a ly z e th e data taken w ith the microwave m oisture
m eter.
The program l i s t i n g c o n s is ts o f the m a in lin e program and
s ix s u b ro u tin e s .
The second p a r t o f t h i s s e c tio n c o n ta in s a l i s t i n g o f the
data t h a t was read in on cards f o r a n a ly s is by the program.
data c o n s is ts o f c o n tr o l
The
cards f o r c o n tr o l o f the program and the
data cards o f 1973 and 1974.
PROGRAM
L IS TIN G
C
C
C
D I l vE N S i n N A ( 5 0 O ) , w ( 5 O C I # C P ( 5 C C ) # T P ( 3 H D P A ( 5 C 0 ) / C P W ( 5 C C I # I Y P E ( 3 ) #
» C P I 500 I * I S ( 5 0 C I , I D ( S C C ) , I L I E C O ) , I T Y p E I S C O , 3 I , I F O R P ( 3 , 2 ) ,
* IM J M 5 O G > ,D F (5 O 0 ) , X d C C ) , Y (ICC ) , IT ( 24 )
REAL K I 5 0 0 ) , LK
INTEGER D S , C C # f YP F/2H C
, 2HL , 2HS /
IF C R M Il,!L k H D U F F
IFCRMI I , 2 ) "4H
IFCRMI 2 ,1 L k H S H C
IF 0 R M (2 ,2 )-k H K S
IF C R M I3 , I )-k H L IT T
IF 0 R M (3 ,2 )-k H E R
T H I S P R O G R A M W I L L S E R R A T E D A T A A C C O R D I N G TQ Y E A R ANC
TYPE
AND T H E N C A L C U L A T E THE K V A L L E S AND P E R C E N T CF
MOISTURE VALUES,
AND D E L T A P FOR A ANC D E L T A P FOR W •
C
DATA
C
C
C
C
C
C
C
C
C
C
C
T P -T IM E P E R I O D , DPASDPW DELTA
THE ORDERED ARRAYS OF DATA
VALUES
AND
CALCULATED
VALLES
ARE
AS
FOLLOWS'
V A L U E S ,IS ,ID ,S IL
ARE
READ DATA CARDS'
THE F I R S T CARD W IL L C O N T A IN THE D A TA SET CODE,COMMAND
CCDE,TIME PERIODaK VALUES,
AND LP TO FOUR D E L T A X
V A L U E S ' D S - O E N D OF D A T A ,
D S -I
MORE DATA
CC-O ANALYZE DATA SEPERATELY C C - I ANALYZE TOGETHER
THE DATA CARDS W IL L C O N T A IN
TYPE,TIM E
ATTENUATION,
WEIGHT,
OVEN DPY X*
k
5
3
2
20
PERIOD,
ILAST-O
READ!1 0 5 , S ID S ,C O ,I TPI I ) , 1 -1 ,3 I , O K ,L K 'S K ,D
FORMAT I 2 1 2 , 3 A 2 , 3 F 5 ' 3 , F k e 2 )
IBLANK-2H
J - I
R E A D 1 1 U 5 , 2 ) I I T T P E l J , I I , I - 1 , 3 ) , A I J ) , w I J I , OP I J )
FORMATl3 A 2 , ? X , 2 F 7 . 2 , F 8 '5 I
IN U M (J )-J
IF I I T Y P E I J # I I .EOeIBLANKIGO
TO 2 0
J -J + l
N-J
GC TO 3
I - I
J - I
M -I
N O -N -I
DC 1 0 L - I , N O
IC
SC
nnnn
4C
no no
nnnn
SC
IK ( I T Y f eF-( L » l I SbQeTYPE < I U G C TC SC
I F ( I TYI aF t L i l ) . E Q . T Y P E t S ) )GC TC 40
IS III-L
I-I* !
CONTI NUE
GC TC bC
IC(J)=L
J-J +l
GC TC 10
IL(IT)-L
M= M+ 1
GC TC 10
I - I - I
J - J - I
M -M -I
CALL P L R C E N T tA iW iD K iID iJ iC P I
g s tt
NCW O R D E R S E T S A C C O R D I N G
PERCENT VALUES•
CALL
CALL
CALL
TC
INCREASING
CALCULATED
S O R T !IS # I< C P )
S O R T ( ID # J * CP I
S O R T tIL#M #CPI
NCW C A L C U L A T E T H E AC T U A L
K VALLES GIVEN
ATTENUATION#
AND THE SAMPLE W E I G H T .
60
DC 6 0 N - I i N O
K t N ) - ( l v O*OP(N) ) /
CONTINUE
TK-LK
ALOW-O
AHIGH-O
CALL P R I N T t I F O R M
CALL P S O R T tC P iO P
CALL S T A T ( K i J iI D )
ALOW-ALOW+SN
AHIGH-AHIGH+SG
CALL P R IN T t IF Q R M
IO P ( N ) * t W lN I /A ( N )
OVEN
I I
iT P iliu i ID # A iW iC P iC P iK iC K I
# J , I D # I F O R M # T P # I # S N # SG I
iT P iG iM iIL iA iW iC P iO P iK iL K I
Eitt ^T^OP.M-.L.ZFCRr.TP.a.SN.SC,
ALOW-ALOW+SN
CRY
PERCENT#
AHIQH-AulGH-tSG
C A L L P N I N T t I F Q N M , T P , 2 , I , I S , A , h # C P , O P > * , SK I
CALL P S O R T lC P iO P ,I , I S , ! F O R M , T P , 2 , SN,SG I
CALL S T A T ( K , I , I S )
ALCW*ALOw+SN
AhIGM-AHIGH+SG
CCUNT-J+M+I
PLO M -I ALOW/COUNT ) M O C
M R I^ E T lo a llO O ^ V p I I M M A -I ,2 ) ,PL0M ,PH IG F
F O R M A T M X , / , '% OF S C A T T E R CF D A T A F Q N
' , 2 A 2 , / I X , F 6S • 2 ' X Q F A L L P O I N
M S
ARE B E L O w Q V E N QRY P E R C E N T • / , I X , F 5 • 2 , * X QF ALL P O I N T S ARE ABOVE
* CVEN DRY P E R C E N T ' )
WRITE (1 0 8 , H O )
F C R M A T tlX ,/,6 7 ' - ' J
W R IT E t1 0 8 ,1 2 0 )
FORMATtlHl I
CALL PGRAPH( C P , O P , J , I D , I L A S T )
CALL PGRAPH(C P ,O P ,M, I L , I L a s T )
CALL PGRAPHt C P , O P , I , I S , ! L A S T )
I F ( D S . E Q . I IGO IO 4
END
SUBROUTINE PERCENTU * w *D K ,I C
CP)
D IM EN SIO N A ( 5 0 0 ) , W( 5 0 0 # ID ( 5 0 C ) # C P ( 3 0 C )
OC 10
1 1 -1 ,J
I - I D d O
B - ( ( W ( I ) Z A ( I ) )*D K )-1
CP( I I-IO O Z B
CONTINUE
RETURN
END
S L B R O U I I N E S O R T ( I S , I , CP I
DIMENSION
I S I 5 O 0 ) , CP(SCC)
I F ( I • EQ • I ) GO t o 2 0
1
I l eI
2
IF < ^ P ( lg ( I l > > 'L E i C P t IS< I l M
5
I l - I l +
I F ( I I .
GC TO
1 2 -1 8 (
IC
l
E Q .I )
2
1 1 )
GO
TO
) ) )GC
TC
5
2C
1 3-18 1 11 + 1 I
2C
I S ( I l ) - I S
I S ( I l + l > - 1 2
GC TO I
RETURN
END
^sl
CD
IC
SUBROUTINE P R IN T ( T F O R h > T p ,11>
DIMENSION IF 0 R M ( 3 ,2 ) # T P ( 3 ) ,ID (
♦OPISOOI
REAL K(SCO)
W R I T E ( 1 0 8 * I C M I F O R M I 11 * I ) * I - 1
F O R M A T d H l*? O X *'E R R O R
A N A L YS I
J i I D #A#h >C P >CP>K, C I
S C O )# A I5 0 C )> W (5 C O ),Cp(SCO)*
* 2 )* I T P ( I ) * I *1 * 2)
S « # / 2 X * 'T A B L E CF OVEN
CRYX*
CALCULATE
* 5 8 h i « o « i ^ ‘ TED
15
SC
3 C
45
4C
sc
F O R M A T * 8 X * ' K V A L U E USED I N C A L C U L A T I O N S
I S -'* F 4 .3 * / / )
W R IT E !1 0 8 *2 0 I
FORMAT! I X * • D A TA #• , 2 X * ' A TTE N U A TIO N !A ) ' * 2 X # • WEIGHT! W) • *3X*
V C L C ( X ) ' * 5 X * 1O O ( X ) U S X * l Ki )
W R ITE(108* 30)
F O R M A T ! l X * 5 '- '* 2 X * 1 4 '« '* 2 X * 9 , - ' * 2 X * 6 ' - , * 5 X * 5 , - d 4 X >
CO-O^
CN-O
D O 4 0 K I —1 * J
K 2 - 1D ( K l )
W R IT E !1 0 8 * 4 5 )K 2 *A (K 2 )* w (K 2 )* C P (K 2 )*C P (K 2 )* K (K 2 )
F O R M A T * IX * I3 # 5 X * F 8 « 2 * 7 X * F 8 .2 * 3 X * F 7 » 2 * 3 X * F 7 .2 * 3 X * F 4 .3 )
CN-CN+1
I F ( C N • E Q • 5 ) GO TO 5 0
CONTINUE
GO TO 1 0 0
W R ITE(1 0 8 *7 0 )
FORMAT * 2H
)
CO-CO+1
CN-O
10 80
I g ^ 8 i 8 ,5,GO
W R IT E !1 0 8 * 1 0 ) ( !F O R M !1 1 « I )* 1 - 1 * 2 ) # I T P ( I )* I - I * 2)
W R I T E ! 1 0 8 * 1 5 IC
W R IT E !1 0 8 *2 0 I
WgIJE(1 0 8 * 3 0 )
ICC
GO TO 4 0
RETURN
END
CTl
SUBROU I INE
P S O R T ( C P * C F > J / I R * I F O R H i T P i 1 1 / SN * S G )
DIMENSION C P ( S O O ) , 1 0 ( 5 0 0 ) , C P ( S O C ) , T P O ) * I F 0 R M ( 3 ' 2 ) , DF(BCC)
D L l-O
D L2-0
0 L 5 -0
DLG-O
DGl-O
IC
SC
4C
SC
ICC
6C
?c
SC
2C
l i e
d g I - o
DGG-O
B-J
DO 1 0 K 1 - 1
K 2 - I D ( K l )
D F IK l )-Q P (
CONTINUE
DC 2 0 K - I ,
I F l D F ( K ) . L
I F I D F ( K ) . Q
D L l - D L l f l
GO T O 2 0
IF I D F ( K ) .Q
0L2-D L2+1
GO TO 2 0
,J
K 2 )-C P (* 2 )
j
T . 0 . ) GO
T . I . IGO
TC
TC
ICC
3C
T . 2 . > GO
TC
40
4 [ ^ § J i Q T , 5 , ' ° 0 T0
50
GO T O 2 0
DLG -D LO fl
GO T O 2 0
J F U g S jD F ( K ) I ,G T . ! . )
GC
GO T O 2 0
I F ( A B S ( D F I K ) ) . G T . ? . )GC
Be2Tg0IS1
J H A g S ^ D F I K ) ) , G T . 5 . )GC
TC
60
TC
70
TC
gC
GO T O 2 0
DGG-DGQfl
plH5msi;(§v45s?nij<i4fi-)teidiTfi,^cH?'.RGUKD ^
f •
S
S
S
S
P
P
PERCENT•/3 0 X , 2 A 4 ,2 A 2 ,/ / / / )
T l-D L lfD G l
T2-D L2fD G 2
TS-DLSfOGS
TG-DLGfDGG
1 -( S T 1 /B ) * 1 0 0
2 -( S T 2 /B ) * 1 0 0
c,
I SC
125
I SC
135
14C
145
I SC
155
P 5 « ( S T 5 / B ) ¥ l OO
P G -( S T G /B )¥100
SM-DL1+DL2+DL5+DLG
SG-DG1+DG2+DG5+DGG
PTL- I S N /B I ¥100
P T G -(S G /B )¥ 1 0 0
W R IT E !1 0 8 ,1 2 0 )
FORMAT! IX , 'A B S l O D ( X ) - C A K X ) ) ' 2 X '
¥ ' , 2X, ' ACAL( X ) > 0 0 ( X ) ' )
W R IT E !1 0 8 ,1 2 5 I
F O R M A T ! 1 X , 1 7 ' " ' , 2 X , 1 7 ' - ' , 2 X , 1 S '
W R IT E !10 8 , 1 3 0 ) M l , D L l >CGl
FO RM ATISX,'O X
TO 1 X I > 1 2 X , F 5 » 2 , ' X
W R IT E !1 C 8 ,13 5 )P ? ,D L 2 # D G 2
F O R M A T I 5 X , ' I X TO 2 X ' , 1 2 X , F E • 2 , ' X
WR I T E ( 1 0 8 , 1 4 0 ) P 5 , D L 5 # D G 5
F O R M A T (5X ,'2X
TQ 5 X • i I 2 X , F g • 2 , « X
W R IT E !1 0 8 , I 4 5 ) P Q ,DLGiCGG
FORMAT I 4 X ,'G R E A T E R 5 X ' , l l X , F 5 * 2 , '
W R IT E !1 0 8 , ISO)
X
CF
r £ ASLRFMENTS' 2 X ' #CA L( X K C C ( X )
- ' , 2 X ' 1 3 ' - ' / I
', 1 4 X , F 3 . 0 # 1 2 X , F 3 . 0 )
o
,
' , 1 4 X, F 3 • C, 1 2 X , F 3 • O )
' , I 4 X , F 3 • O, I 2 X , F 3 . C )
X « , 1 4 X , F 3 . 0 i l 2 X # F 3 . 0 )
w r i Te I i o b I i s I I p t k p t g
F O R M A T ! l X , F 5 ' 2 i ' X OF M E A S U R E M E N T S WERE L O W E R T H A N C v E N D R Y P E R C E N T
¥ ' / / , I X i F S • 2 , ' X OF M E A S U R E M E N T S WERE H I G H E R THAN O VEN DRY P E R C E N T ' )
SHIIt108' 150'
END
C
SUBROUTINE PGRARHI
DIMENSION C P (S O O )i
REAL MCP#M0P#MAX
F I R S T F I N D P E R C E N T TO
IL A S T -IL A S T + 1
NUMPTS- J
LABEL-4H
MCP-O
MOP-O
DC 1 0 K - 1 # J
K l - ID ( K )
I F ( C P ( K 1 ) «GT«MCP)Q
GO T O 3 0
4 C
M C P -C P (K l)
30
I F ( 0 P ( K 1 ) .GT»MOP)G
GO T O 1 0
SC
M C P-O P(K l)
CP' CR>J , I C* !LAST)
O P t5 0 0 # I C t 5 d 0 ) # X ( 1 0 0 ) # Y ( l 0 0 1 # I T t 24)
BE
PLOTTED
O
TC
40
O
TC
SC
1C
C
5 P l(l M i p » § T . M O P J Q O T O 6 0
MAX-MOP
GO T O 7 0
60
MAX-MCP
70
MAX-MAX/10
IMAX- M A X + !.
IM AX-IM AX+10
y m a x - i m a x
XMAX-IMAX
XSCALE-XMAX/6
y s c a l e - y m a x / 6
PLOT OVEN ORY ALONG X A X I S
DC H O
K - I i J
?k I 2 J p !k i )
Y ( K ) - C P I K l )
CONTINUE
READ(1 0 5 # S O )( I T ( I ) ,1 - 1 * 2 4 )
x
HG
2C
I SC
CALLADRAwfx#Y?NUMPTS#l i l * LABLE#IT iX S C A L E iYSCALEiOiO#6 # 6 # 0 ,L A S T )
XN-XMAX/J
DO 1 2 0 1 - 1 # J + l
CONTINUE
I F ( ILA S T.E Q »6)LA S T-4H LA S T
CALL DRAW IX#YiNUM PTS#3 * C #LA B L E #IT iX S C A L E #Y S C A L E iO iO #6 # 6#C,LAST I
RETURN
END
non
SUBROUTINE STAT I k * J # IO
DIMENSION
1 0 (5 0 0 )
REAL K ( 5 0 0 !,M E A N ,*5
FIRST
nono
10
DETERMIN
MEAN
VALUE
OF
* ' S •
TOK-O
DC 1 0 1 - 1 , J
T C K -K (ID (I))+ T O K
m e a n - t q k / j
STANDARD D E V IA TIO N
SGUARE MEAN SQUARE
IS MEAN
ROOT*
SGLAfiE
MINUS
noo
SM-MEAN**2
NCR
MEAN
2C
TKS-O
DO PO 1 - 1 , J
T K S - ( K d D d ) I ) * * 2 + TKS
M S-TK S/J
D EV-(ABStSM -M S) ) * * . 5
30
40
SQUARE
F O R M A T ! i x ? / / ? j x d M E A N VVALUF OF K IS
»N CF K I S 1, F4 • 3 )
W R IT E !1 0 8 ,4 0 )
F ORMAT! I X, / , 6 7 ' - ' )
RETURN
END
og
°
' , F 4 » 3 , / , 1 X , ' S T A N D A R D DEVI AT I C
INPUT
DATA L I S T I N G
FOR 1 9 7 2
I
L
D
D
L
D
L
D
L
D
L
S
h
D
D
°0
D
D
D
L
L
L
L
L
L
L
L
D
D
D
D
D
D
D
*
D
L
L
D
L
D
D
L
S
S
S
.156I *210
CSU72
142*0
7?
3.16
214*0
7?
7.36
7?
179*0
8.2
72
152*0
3.40
227*0
72
9«6
194*0
72
4.7
21*47
72
241*0
153*0
72
5.84
72
242*0
12*65
72
159*0
5.51
72
211*0
7.76
?!
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
72
15*1/
13*10
12*90
iSM JflSc
27*90
399*00
412*0
13:|o i3i:8
436*0
10*43
19*33
22*36
!3:5?
3.7
3.6
12*13
12*60
11*97
13*17
11*00
12*80
8*2
10*00
6.95
7.02
5.95
9*43
6.73
6*9
4*35
5*57
3*9
19*07
15*30
3*25
6*4
4*9
5*8
* 1 7 3 'CS
16*10
26*30
33*70
15*37
27.85
12.85
87.50
21*85
43.50
24*30
21 *50
295*0
341*0
276*0
266*0
175*0
185*0
244*0
267*0
155*0
192*0
§!!:§
231*0
261*0
277*0
311*0
277*0
254*0
242*0
159*0
233*0
289*0
149*0
245*0
366*0
145*0
344*0
337*0
325*0
26*10
l?:?o
20*60
64*00
63*90
84*50
41*80
14*10
14.80
35.20
35*50
45.00
43.00
36.00
35.10
23.70
19.75
15*30
15*20
14*30
31*00
18*80
24*70
14*50
14.15
16*40
84.00
37*00
14.90
11.80
10.45
10.45
CD
ro
S
S
L
S
L
D
L
L
L
D
S
D
D
L
L
S
L
L
L
L
L
L
L
L
tL
L
L
L
L
L
L
L
L
L
L
L
L
L
72
?!
72
72
72
72
72
72
72
72 2
72
72
72
72
72
72
72
72
72
72
4*8
§•03
4 #6
3.13
}§:§?
4*0
4*6
19*25
6*46
11*03
8*33
3*55
5*07
5*33
3*45
19*78
21*20
23*63
19*10
305*0
lit: S Ha8°
10*55
278*0
182*0
259*0
209*0
184*0
202*0
311*7
241*0
223*3
183*0
153*6
122*0
227*0
180*0
231*0
251*0
279*0
224*0
7P !1:81 !%:;
12*60
72
218*0
?!
72
214*0
72
72
72
72
72
72
72
72
72
72
72
72
72
4.0
6*67
7*07
7*3
15*41
17*12
18*20
4*62
4*9
8*02
8*92
11*77
12*83
15*11
11*10
215*0
242*0
257*0
210*0
232*0
260*0
211*0
213*0
212*0
244*0
225*0
255*0
244*0
13*70
37*50
34*70
17*50
17.20
56*90
3§ »50
28*40
17*84
12*40
96*70
95*20
96*00
68*00
36*30
?§:?§
13*85
20.70
20*20
49*30
48*20
17*30
18*50
27*40
27.80
34*90
34*50
43*00
?!
§?Z
:8 i4 i3:* 90o°0o
b
H:?8
17*30
72
367*3
D
D
D
D
D
D
72
72
72
72
72
18*10
13*43
17*86
8*5
9*3
392*0
271*5
364*0
391*0
416*0
43*50
46*20
43*90
18*85
19*10
OO
CO
D
S
L
L
L
S
D
L
L
L
S
72
72
72
72
72
72
72
72
72
72
72
13*97
5*18
10*30
5*3
14*60
7*2
14*8'
4*14
11*87
3*45
5*33
377*0
294*0
219*0
152*0
242*0
290*0
298*0
193*0
237*0
180*0
227*0
32*40
8*65
25*00
17*90
41*80
11*60
44.20
17*25
34.90
12*40
17.84
S C A T T E R P L O T C F O V E N DRY X A N C C A L C U L A T E D
D LFF• 1972 DATA*
JOE KOWALSKI JUNE 1 9 7 4
S C A T T E R P L O T O F O V E N DRY X A N D C A L C U L A T E D
X
FCR
X
FOR
p E!o ? Qf t Ov e n 0 DRY0 X a An o 1 c a l c u l a t e d
1 9 7 2 DATA* JOF KO kALSKI JUNE 1 9 7 4
X
FCR
scatter
STICKS.
oo
-t*
INPUT DATA L I S T I N G
FOR 1973
. 2 4 8 *C5
1 9 . SC
IfiIc
IIfi4
ISlco
Hi:!
a lto c
7 3 . CO
76.00
66.50
17.10
16.40
6.20
7.50
iifi=
18S:i
l:l§
W il0
99.0
194*3
15.95
16.3
\ m
\t:i°c
? s i:f
104*3
94.1
i:s :i
8.00
7.85
10.40
10.60
}?:lo
150*7
7.90
\ m
Zilf
118:8
155*4
i m
160*6
156*0
87.7
132*7
$
:1B
15.90
11:28
10.30
11.1
11.40
19*80
CD
Ot
S
73
3.1
156*2
9.15
I
?3
I:!
?:§
l!i:|
Io 8
tL
D
S
S
S
L
L
D
D
S
?!
73
73
1.9
9.6
117*8
180*3
?!
1 :5
?!
!:!
3.3
155:8
73
73
73
73
73
73
I:?
l?i:g
177*2
99.5
6*0
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E ?!
I:!
I:!
2.5
ill:?
g
? :!
L
I
S
L
L
L
O
73
73
73
?! !:§
2.6
?!
2.0
73
73
I:*
73
5.0
?!
73
?!
S
L
L
L
L
73
73
73
73
73
i:5
4.2
2.7
2.6
2.1
m
*
95*3
252*0
269*2
144*5
166*6
158*6
111*4
117*4
110*7
IfIif
8.30
1:88
7.10
OO
"-U
7 :}?
6*87
9.60
10.47
9.09
17.22
U?:8
m
165*0
90*0
89.0
S
73
S
L
73
73
2.9
2.6
Siil
11.64
84.0
95*0
?! I?:?
3.3
?! 1:5
31.60
158*0
§:i
?! 18:!
S
1 1 .1 0
i
10.36
15.99
15.16
iii:§
Ii? :?
50.06
36.61
142*0
10.01
I??:?
18
il
10**9
166*0
88.0
13*08
L
L
L
D
D
D
D
S
S
S
73
73
73
73
73
73
73
73
73
73
t
n
L
D
D
D
D
S
S
S
L
L
73
73
73
73
73
73
73
73
73
73
I:!
2.5
6.9
6.8
6.6
6.7
3.1
3.3
2.9
1:1
5.6
2.5
2.1
l:l
i$;:i
6.0
73
73
4 .7
4.8
6«5
?! V . l
?! !:!
73
6.8
6.0
?!
73
1:1
13.05
12.74
13.73
!3 :3 =
22.74
21.97
1:3?
?li:§
165*0
9.10
m °.o
116*0
172*0
164*0
164*0
174*0
143*9
146*8
2.9
9.9
6.3
?! 1:1
b 73
D
D
S
S
L
L
L
D
D
D
S
93.0
89.0
100*0
143'0
151*0
147*0
156*0
262*2
iS8:i
167*4
176*0
147*0
? o 3 !c
11.03
27.79
21.27
20.98
19.24
8.98
8.96
9.35
8.33
7.95
CO
Co
iifS .
15.72
15.04
17.10
g llg
“ 111 I2 0) :. 0? 88
190*3
m u
139*5
9 .0 2
SCATTER PLOT OF OVEN DRY X AND CALCULATED
DUFF* 1 9 7 3 DATA.
JOE KOWALSKI JUNE 1974
i w i t f Itf7I
g :T r5 o g " Z o :A ^ i% E M ;%
i m
^ j W % W K 0u
t f
m
^ i cm
Lm
X
FOR
X FOR
X FOR
Appendix V
This s e c tio n c o n ta in s a l i s t i n g o f th e outp u t generated by the
program.
The o u tp u t c o n s is ts o f the t a b le s o f oven d ry p e r c e n ts ,
m oisture meter p e r c e n ts , k values and v a rio u s s t a t i c a l
c a r r i e d o u t by the program.
litte r,
a n a ly s is
The o u tp u t i s separated i n t o d u f f ,
and s t i c k s f o r 1973 and 1974.
.
OUTPUT L I S T I N G
ERROR
TABLE
CF
K
DATA#
4 C
35
13
DRYXA
CVEN
v a l u e
u s e d
ANALYSIS
CALCULATED*,
AND
:B u r» L C L L S t? ! NS
A T T E N U A T I O N ! A)
W EIG HT!W)
CALCULATED
K•
I S * . 156
CLC(X)
CD(X)
■A
I
1 4 .1 5
1 4 .3 0
155
172
5 .5 7
5 *9 5
2 8 9 .0 0
2 7 7 . CC
1 4 .1 0
1 5 .9 7
8:18
? t t : 8 8
WM
}|:!8
3 1 1 .0 0
1 6 *9 2
1 5 .2 0
1 0 .4 3
1 0 .2 0
6 .9 5
6 .7 3
12«90
4
4
2
2
4
3
0
7
4
1
6
8
7
2
2
*
.
.
.
.
0
0
0
0
0
0
0
0
0
0
1 8 .1 1
2
2
1
1
2
0
1
5
8
6
,
.
.
.
.
6
1
3
8
1
0
0
0
0
0
140
16
14
2
31
96
13«83
1 3 .1 0
7 .3 6
8 .2 0
1 3 .9 7
4
3
2
2
3
3
9
1
3
7
6
9
4
1
7
*
*
.
*
*
0
0
0
0
0
0
0
0
0
0
2 5 *5 2
5
7
6
3
2
.
.
.
.
.
9
9
3
7
4
0
0
0
0
0
154
2 9 .4 6
3 1 .1 5
2
2
2
2
3
13
1 5 .1
1 0 .0
1 5 .3
9 .6
1 1 .0
7
0
0
0
0
4
2
3
2
2
0
6
6
2
5
6
1
6
7
4
.
.
.
.
.
0
0
0
0
0
0
0
0
0
0
3 1 *5 0
3 1 .3 0
i3 m
8 .4 3
2 7 .8 5
3 6 .0 0
1 2
8
8
1 8
1 4
0
3
0
0
0
2
1
1
3
3
9
8
7
9
1
2
3
9
2
8
*
.
.
.
*
0
0
0
0
0
0
0
0
0
0
3 9 .0 8
4 1 *2 0
3 5 .1 0
3 8 .4 0
4 2 *1 1
4 4 .0 0
34
7 .0 2
18
17
33
37
15
?!
5
29
SC
6C
si
89
.
*
.
.
.
8
3
2
1
7
2 1 *6 9
2 5 .1 1
ii: it
w.n
2§:S8
W
I
165
i:
151
I
TABLE
OF
K
ORYX#
VALUE
USED
FR90R ANALYSIS
C A L C L L A T E O X # AND C A L C U L A T E D
DUFF
SU72
IN CALCULATIONS IS " * 1 5 6
ATTENUATION!A)
W EIG HT!L )
CLC(X)
K •
v•
DATA#
OVEN
OD(X)
90
53
93
59
92
1
1
1
1
1
7
2
7
1
3
.
.
.
.
.
3
2
8
0
4
0
3
6
3
3
3
2
3
2
2
6
5
6
2
7
7
9
4
3
1
.
.
.
.
.
3
0
0
3
5
0
0
0
0
0
4
4
4
4
4
3
3
5
6
6
.2
.4
*8
.3
*4
5
1
8
4
3
4
3
4
3
4
3
7
3
7
6
.
.
.
.
.
9
5
9
5
2
0
0
0
0
0
•154
102
9
57
20
19
1
1
1
2
1
4
2
9
2
9
.
.
.
.
.
8
6
2
3
3
7
5
5
6
5
2
2
3
3
2
9
4
1
4
9
8
2
1
1
5
.
.
.
.
.
0
0
7
0
0
0
0
0
0
0
4
5
6
7
7
7
0
5
2
2
.
.
.
.
.
3
9
3
1
5
4
4
5
6
6
4
3
6
3
4
.
.
.
.
.
2
5
9
9
0
0
0
0
0
0
•
•
•
•
•
42
7
1 9 .0 7
2 1 .4 7
2 4 5 .0 0
2 4 1 .0 0
0
3
5
5
5
9 9 .5 8
1 3 3 .1 4
8 4 .0 0
8 7 .5 0
• 161
'.iS
163
172
170
168
168
• 170
•191
VO
IX)
I
VARIATIO N
A B S IC D IX I-C A U X ) )
OF
X
OF
Cx TO I X
IX
TO PX
H X TO 5 X
GREATER 5 X
CALCULATED
DUFF
MEASUREMENTS
AROUND
CF
MEASUREMENTS
WERE
LOWER
f c4 • 8 6 X
CF
MEASUREMENTS
WERE
HIGHER
«166
OF k
is
#018
OVEN
*CAL( X X C D ( X )
DRYPERCtNT
# C AL ( X >> C D ( X I
5#
4 *
4»
0#
1 8 .9 2 X
2 1 #62X
27 * CaX
32.43%
3 5 # I AX
MEAN V A L U E OF K I S
STANDARD D E V IA TIO N
PERCENT
SU72
THAN
THAN
OVEN
OVEN
CRY
DRY
?•
4 *
6 ‘
12'
PERCENT
PERCENT
I
TABLE
OF
K
DATA#
OVEN
ORYX'
VALUE
USED
ERROR A N A L Y S I S
,
CALCLiLATEOXi
AND C A L C U L A T E D
LITTER
S L 72
IN
CALCULATIONS
IS -.g lC
A T T E N U A T IO N t A)
W EIGHT( W)
CLC(X)
K •
CD(X)
K
SC
52
39
74
64
3
3
4
4
3
.
,
.
.
.
0
1
3
0
4
3
3
5
0
5
2
1
2
2
1
0
8
3
1
8
1 ,4 0
2 * OC
3 . OC
4 . OC
0 . OC
7
8
9
9
1 0
.7
.9
.7
.7
*0
2
2
6
7
4
1
1
1
1
7
3
4
3
2
.
.
.
.
.
2
7
5
8
4
0
0
0
5
0
• 224
*143
•147
• 154
• 174
105
73
24
23
103
3
3
3
3
4
.
.
.
.
.
4
7
6
7
1
5
0
0
0
4
1
1
1
1
1
8
9
8
7
9
0
3
5
5
3
0
0
0
0
0
1
1
1
1
1
0
0
0
1
1
*0
.0
.2
.2
.3
4
5
1
0
8
1
1
1
1
1
2
2
4
4
7
.
.
.
.
,
4
9
8
1
2
0
5
0
0
5
•
*
•
•
*
174
167
151
171
146
55
81
I
4
44
4
4
3
3
3
*
.
*
.
.
0
6
1
4
2
0
2
6
0
5
1
2
1
1
1
8
1
4
5
4
4 . OC
1 . OC
2 .0 0
2 *0 0
5 . OC
1
1
1
1
1
1
1
1
1
1
*
*
*
*
*
5
4
5
2
5
1
1
1
1
1
7
7
6
5
4
.
.
.
.
.
5
3
1
3
9
0
0
0
7
0
•
•
•
•
*
14
14
16
16
17
56
4 .6 0
?!
6
41
77
76
12
75
IC
*
*
*
*
*
0
0
0
0
0
2C2.CC
5
6
8
9
9
1 2 *1 6
1 7 .2 0
6
8
0
8
3
*155
11:19
48:18
1 9 4 .0 0
1 4 9 .0 0
1 3 *0 4
1 4 *2 4
•ttl
4 .7 0
3 *9 0
1 2 .8 5
1 6 .4 0
*213
*186
7
7
4
6
5
2
2
1
2
1
1 5 *6 4
1 6 *1 6
1 6 *3 9
2
2
1
2
2
• 206
•181
• 177
S:S8
.3
.0
.1
.6
.5
0
7
6
7
1
141:88
5
4
4
1
5
7
2
0
5
9
.
.
.
*
*
0
0
7
0
0
0
0
0
0
0
0
0
6
0
4
.
*
*
.
.
3
2
8
7
3
0
0
0
0
0
:?95
vo
-Pa
I
ERROR ANALYSIS
, ___
TABLE CF OVEN DRYX< CALCULATED*; AND CALCULATED K»
LI TTER
SU72
K VALUE USED IN CALCLLATICNS I S«»21C
DATA#
ATTENUATION!A)
5.30
1:21
5.84
5.07
6.90
10.30
12*60
ills?
12:11
llWo
13*60
fi
I?
WEIGHT( W)
CLC(X)
CD(X)
1 5 2 .CO
244.00
2 1 2 * CC
153.00
122*00
19.91
17.90
22.21
24.67
21.85
28.40
159.00
219.00
267*00
244.00
237*00
26*05
24.70
IS:I8
ii:!f
21:91
29:11
is:i§
11:18
21:18
28:18
121:88
111:88
234.00
11:8?
38.27
¥>\lo
36.50
15.74
14.60
1 6 * 90
15.11
13.17
266*00
242.00
C9 7r 7/ •* nn
Uv
244.00
192.00
39.23
48.51
43.00
43.00
ill??
11:15
23.22
IfoIoo
121:88
276.00
Si:;?
18:11
66*84
88:18
12:28
84.50
:8:li
4 1 *8 2
im
230
\tt
213
188
Wo
lit
lit
W
TABLE
OF
K
DATA#
OVEN
VALUE
ORYX#
USED
ERROR A N A L Y S I S
CALCLLATEDX#
AND C A L C U L A T E D
LITTER
SU72
IN CALCULATIONS
IS « *2 lC
ATTENUATION*A)
WEIGHT(W)
CLC(X)
Ki
OO(X)
■
■
IX
I
1$
68
65
69 "
m : 8 §
224,00
231*00
245*40
l?:!l
68*36
68*85
69*11
U : l co
19,10
19.78
21.06
68.00
96*70
67.00
•211
*174
.214
7 i
21.06
245.40
69*11
67.00
•2 1 4
CTi
I
VAR IA TIO N
ABStOD(X)-CAL(X))
CF
CALCULATED PERCENT
LITTER
SL72
x OF MEASUREMENTS
71.A 3X
CF
MEASUREMENTS
WERE
LOWER
2 8 • 57X
OF
MEASUREMENTS
WERE
MIGhER
*188
OF K
IS
.028
OVEN
#C A L ( X ) < 0 D I X )
DRYPERCENT
#CAL ( X ) >CD ( X >
4*
4 *
6'
2 •
I •
4«
22*
13*
8 • 93X
1 4 .2 5 X
sc.OCX
26 • 7 9 X
OX TO I X
IX
TO 2 *
2X TO 5X
GREATER 5 X
MEAN V A L U E OF K I S
STANDARD D E V IA TIO N
ARCUND
THAN
THAN
OVEN
OVEN
DRY
DRY
PERCENT
PERCENT
TABLE
OF
K
DATA*
OVEN
VALUE
ORYX#
USED
ERROR A N A L Y S I S
CALCULATED*,
ANC C A L C U L A T E D
STICKS
SU72
IN
CALCULATIONS
I9 " * l7 3
A T T E N U A T IO N t A)
**************
W E I G H T t w)
*********
K«
CLC( X)
******
CD( X)
46
48
SI
97
47
4.90
4.80
4.60
5.18
5.80
337.00
3 0 5 . CO
278.00
294.00
325.00
9.18
10.01
10*58
11*34
11*50
1C.45
11.10
10.55
8.65
10.45
#5
49
63
1C6
101
6.40
6.90
5*33
533
7.20
344.00
316.00
227.00
227.00
290.00
12*05
14*44
15*70
15*70
16*76
11.80
12.00
17,84
17.84
11.60
I t i :88
m
if:88
31.00
I?
36
9.43
254*00
t
27*32
I
VAR IA TIO N
A B S (C D tX )-C A L (X ) I
OF
X
OF
CALCULATED PERCENT
STICKS
S I 72
MEASUREMENTS
OF
MEASUREMENTS
WERE
LOWER
6 1 .5 4 X
CF
MEASUREMENTS
WERE
HIGHER
OF
K
IS
e v i a t i o n
'1 8 3
OF k
IS
DRYPERCENT
SCA L <X ) > U D ( X )
0.
2«
30 «77X
3 8 •4 6 X
1 5 .3 8 X
3 8 .4 6 X
OVEN
# C A L (X X O D ( X )
I 5•38X
CX TO i x
IX
TO 2%
2X TO SX
GREATER 5X
MEAN VALUE
STANDARD d
AROUND
2*
2'
2‘
3»
2'
0»
THAN
THAN
OVEN
OVEN
DRY
DRY
-027
' i B i r r H ’i E i M i i Eili Eli ISlEH
PERCENT
PERCENT
I
TABLE
CF
K
DATA*
OVEN
VALUE
ORYX#
USED
ATTENUATIO N!
ERROR A N A L Y S I S
CALCULATED*#
AND C A L C U L A T E D
DUFF
SU73
IN CALCULATIONS
IS » e 2 *8
A)
WEIGHT(w)
CLC( X)
166.20
177.90
ioliS
'I!
?:§8
1:88
7.20
269.20
i!$:§8
IV .il
12.09
1 S^
120
43
41
4.70
4.10
4.60
t:88
Ut:§8
167.40
47
129
34
63
78
Ke
CD( X)
K
18:88
11:18
:18?
11:11
12.77
iilsS
15.72
140.20
155.40
13*37
13*55
15.60
15.90
:ISo
• 207
• 217
*216
4.10
5*50
4.50
5.80
4.70
132.70
177.80
145*30
186*20
149.80
14*23
14.25
14.27
14*36
14*48
19.80
18.96
15.90
16.60
15.35
•187
*194
*226
*219
*236
62
68
112
128
77
6.00
8.10
5.60
6.00
4.50
187.30
252*00
174.00
184*60
137.30
14.83
14*89
14*91
15*08
15.23
17.10
12.50
19.24
19.14
15.00
•219
•289
• 199
• 202
*251
33
127
5*00
6.80
76
5.00
140.50
190*30
164.00
164.00
129.20
16.75
16*83
17.31
18.33
18.49
17.30
20.08
20.98
21.27
17.22
* 241
*214
•211
219
• 263
U
69
in
110
6*00
6.30
9.70
:?§:
• 302
•
I
t a b l e
OF
K
DATA*
1C2
IC l
ICC
95
54
OVEN
VALUE
ORYX'
USED
ERROR A N A L Y S I S
CALCLLATEDX'
»
DUFF
SL73
IN CALCULATIONS
ATTENUATION(A)
W E IG H Ttw )
n
C
CALCLLATED
K•
lS -« 2 4 8
CLC( X)
OD(X)
K
• 238
6.70
6.60
6.80
6.90
9.60
156.00
147.00
151.00
143.00
180*30
2
0*95
0<9 „ 4 4
C C * 11
22*19
c4 * I 6
27.34
21.97
9
„ 7
it
C9
C*
f 4
24.35
9
C9
J .6 AA
7U
31.60
8.60
9.90
10.50
10*60
11*40
158.60
172.00
145*00
145*00
132*00
27*98
30*22
41.24
41.80
53.43
28.20
Cr • f 7
50.06
36.61
42.76
10.90
23.90
1 2 4 . CO
240*30
54.91
42.12
82.00
*297
.994
• Ce*
26*20
244*80
75.92
11:18
76.00
:12I
*248
25*60
232.40
266*80
193.10
79.91
85.00
.240
51:88
:lll
11:11
II: is
»9 i i 9
.230
»oe
• CD a
™
.222
*247
9 Z. 3
A
•o CO
:1H
.288
I
VAR IA TIO N
A B S l C D ( X ) e CAL(X) I
CF
CALCULATED
DUFF
X OF MEASUREMENTS
18.6
6.9
48.8
25.5
OX TO I *
I X TO 2%
2 X TO 5%
GREATER 5X
CF
MEASUREMENTS
WERE
LOWER
30 • 23X
OF
MEASUREMENTS
WERE
HIGHER
'2 3 2
OF K
IS
ARCUND
.0 3 3
OVEN
# C A L <X ) < C D ( X )
DRYPERCENT
# CA L ( X ) > C D ( X I
5«
2*
18«
5*
C X
8%
4%
8%
6 9 .7 7 X
MEAN V A L U E OF K I S
STANDARD D E V IA TIO N
PERCENT
SU73
THAN
THAN
OVEN
OVEN
DRY
DRY
3
I
3
6
PERCENT
PERCENT
'
•
'
'
i
error
analysis
TABLE CF OVEN ORYX# CALCULATEOX# AND CALCULATED K •
L I T T ER
SU73
K VALUE USED I N CALCULATIONS I 9 « * 2 4 8
OATAA
ATTENUATI ON( A)
WEIGHT(W)
CLC( X)
OD(X)
K
117
118
24
23
22
!•50
1.20
1*00
1.00
1.00
262.20
146.30
109.20
IC O .00
95.10
2.36
3.42
3*83
4.20
4.43
7.95
7.89
9.10
10.30
9.20
078
116
39
38
52
32
1*40
1.50
1.70
1*90
1*50
124.80
118.90
111.10
121*40
94.10
4,74
5*36
6.58
6*74
6*87
8.33
4.55
4.85
11.50
10.60
146
290
331
152
166
53
40
1.90
1.90
6*96
7*49
11.10
5.20
161
75
1:88
2.00
117.80
110.00
111.70
111*40
110*70
91
46
1:18
1.90
m
:S8
87*70
;:§1
9*57
106
6C
2*20
2.30
12
61
1:18
2.70
107
98
2.80
2.50
?:iS
7*86
1IlIg
9.09
18:i9
11.40
98*00
99*50
9*95
10*28
llllO
11:88
18:82
10*58
10.78
11*21
12.30
113*80
116*00
100.00
illo !
110
III
III
217
III
IfS
212
III
217
I!’
I
TABLE
OF
K
DATA*
1C8
67
83
95
25
OVEN
v a l u e
DRYX#
ERROR ANALYSIS
CALCULATED*#
AND
u s e d
I
A TTENUATIO N!A)
2
2
2
2
3
.
.
'
.
.
9
5
6
6
0
0
0
0
0
0
n i
C
a l c u l a
V
i
W EIG H T!WI
1 1
9
9
8
9
6 . CO
5 .3 0
0 *0 0
8 .0 0
9 .0 0
S
ns
CALCULATED
K •
is*.2 4 8
CLC(X)
1
1
1
1
1
1
1
3
3
3
.2
.8
.1
*5
*9
1
3
8
2
2
CD(X)
1 1
7
1 5
1 3
1 5
.
.
.
.
.
0
1
9
0
9
K
3
0
9
8
5
«252
• 396
*210
*255
*220
85
5
2 .6 0
2 > 60
8 4 .0 0
8 2 .1 0
1 4 .2 6
1 4 .6 4
1 6 .2 6
2 0 .0 0
'221
• 190
8&
66
1 :? 8
2 .6 0
7 9 .3 0
!SiN
1 5 .2 3
IIlfS
6 .9 0
• 508
124
97
3 .6 0
3 .0 0
1 0 9 .1 0
8 9 .0 0
1 5 .3 5
1 5 .7 3
1 5 .8 9
1 2 .7 4
*241
*298
1II
f:i£
H O . 20
ISlH
1 6 .1 5
I?:1S
3 .8 0
1 4 .5 8
HBI
*271
3 .2 0
3 .6 0
3 *0 0
8 8 *5 0
9 6 .7 5
8 0 *4 0
1 7 .0 7
1 7 .6 5
1 7 .7 1
1 6 .4 0
1 8 .5 0
1 7 .1 0
*257
«238
*256
125
16
14
13
:m
I
VARIATIO N
A B S (C O (X )-C A L (X ))
U
Ig
OF
X
OF
CALCULATED PERCENT
LITTER
SL73
MEASUREMENTS
ARCUND
# C A L (X K C D ( X )
I l ii:§IS
39.53%
11.63%
2X TO 5X
G R E A T E R SX
69.77%
CF
MEASUREMENTS
WERE
LOWER
30.23%
CF
MEASUREMENTS
WERE
HIGHER
MEAN V A L U E QF K I S
STANDARD D E V IA T IO N
«223
OF K
IS
.077
OVEN
THAN
THAN
OVEN
OVEN
ORVPERCtNT
#CA L( X >>00<X »
I:
I-
14.
4 *
3'
DRY
DRY
I •
PERCENT
PERCENT
I
TABLE
OF
K
DATA#
OVEN
DRYXi
v a l u e
u s e d
ATTENUATIO N!
FRROR A N A LYSIS
CALCULATED*;
AND
STICKS
SU73
in c a l c u l a t i o n s
i
A)
WEIGHT(W)
114
36
2 '1 0
2 .2 0
1
1
1
1
1
3
45
82
72
115
2
2
2
2
2
1
1
1
1
1
21
1 .5 0
15
1:18
.
.
.
.
.
3
5
7
6
7
0
0
0
0
0
CALCULATED
K •
s * . 2*8
CLC(X)
CD(X)
K
7 .9 5
145
1:14
7:18
!11
6 .1 2
6 .4 8
8 .9 6
7 .3 0
4
5
6
4
4
0
4
3
6
5
.
.
.
.
.
5
6
4
8
8
0
0
0
0
0
4 . SC
4
5
6
5
6
4
6
5
8
4
.
.
.
.
.
9
0
0
6
3
0
0
0
0
0
6
6
7
7
7
*8 4
.91
.0 6
.0 8
.1 0
7 .
1 1 .
1 0 .
6 .
9 .
6
1
3
8
3
9
0
6
7
5
7 .9 0
7 .3 5
174
222
22
16
17
25
19
2
0
4
5
?
227
244
2 .5 0
2 .9 0
1 5 0 .7 0
1 7 3 .3 0
7 .1 7
7 .2 4
,fi
1:18
2«90
H§:§8
1 6 6 *0 0
v.n
7 .5 8
1 0 .4 9
184
1C5
2 .9 0
0
0
0
0
0
7 .6 3
9 .1 0
211
8 .2 0
8 .2 0
8*70
35
19
94
93
59
2 .9 0
3 .3 0
1
1
1
1
1
80
18
48
2 *8 0
2 .6 0
3 *1 0
1 4 9 . CO
1 3 8 .3 0
1 5 6 .2 0
1:48
!58:88
Il
1Sl
1:88
6
6
6
5
7
5
6
0
9
7
.
.
*
.
.
0
6
6
0
2
7:81
7 .9 4
8 .1 2
1:18
V.tt
iolio
If?
1
11
192
1 0 .5 1
8 .3 0
243
1 0 .4 2
6*66
9 .1 5
199
301
237
i8:18
m
TABLE
OF
K
DATA#
_ ——
104
6
17
49
64
OVEN
VALUE
DRYX*
USED
Ca£ c l £ a ^[$X>
AND C A L C U L A T E D
STICKS
SU73
IN CALCULATIONS
I S " »248
A T T E N U A T I O N t A)
WEIGHT(W)
* * * * * * * * *
3
2
2
3
3
.3 0
*5 0
»80
*2 0
.4 0
1 6 2 .0 0
1 6 5 .7 0
3
3
2
2
3
.3 0
.0 0
.9 0
.9 0
.8 0
1 5 9 ,4 0
1 4 4 .5 0
1 3 9 .5 0
91
30
81
3
3
3
3
4
.5 0
*5 0
.3 0
*9 0
.1 0
SI
SC
JS
9
58
56
57
m
l c c •tow
1 3 6 .7 0
43
KtA
aO
%
o•
cA
O
CLC(X)
* * * * * *
K •
CD(X)
* * * * *
K
* * *
8 .9 5
?:21
9 .0 0
9 .0 2
6 .2 0
8 .70
7 .4 0
9 .1 1
8 .0 0
279
S:3S
I? !
O•
a?
qte
o
o
3?
Q a• rUt nU
4
*3QaBU
n
loo•D
§:1S
Q
D
Qa•Qce
1 7 8 .0 0
9 ,4 2
Mi
256
298
1 2 *6 0
8 .1 5
187
283
.0 0
.0 5
.0 1
.8 5
.4 2
296
301
255
320
277
1 4 2 .0 0
1 0 .3 4
1 5 7 .0 0
1 1 .7 7
8
8
1 0
7
1 0
*:S8
1S!:88
11:8)
1IiSi
m
2:38
m :38
l?:fi
IS!
1 5 9 .6 0
4
ce .Cf)
I 3 to • J U
4
*4kUft
*tzo7
/•
9 .7 0
Q aQ Q
4
rte*37
IViJf
I
VARIATIO N
ABS(CD(X)-CALm)
a ?8 v *
2X TO 5%
GREATER 5X
CF
CALCULATED
PERCENT
STICKS
SU73
X OF MEASUREMENTS
!!:§?$
3 4 , 09 %
.00%
ARGUND
OVEN
#CAL( X X C D ( X )
DRYPERCtNT
#C AL <X ) >CC ( X )
?:
11*
o.
5 2 • H7X CF MEASUREMENTS WERE LCwFR THAN OVEN DRY PERCENT
47* 73% OF MEASUREMENTS WERE HIGHER THAN OVEN DRY PERCENT
Sf ANDA^buS E v f A f l J N
IS
»051
X CF SCATTER OF DATA FOR SU73
6 3 » 8 5 X OF ALL POI NTS ARE BELOW OVEN DRY PERCENT
36 • 15X OF ALL POINTS ARE ABOVE OVEN DRY PERCENT
.2:
4*
C*
Appendix VI
This s e c tio n shows how the a t t e n u a t i o n o f an e le c tro m a g n e tic
s ig n al
in w a te r is c a l c u l a t e d from the measured a t t e n u a t i o n and SWR.
The block diagram below re p re s e n ts the measured a t t e n u a t i o n loss in
terms o f a b s o rp tio n and r e f l e c t i o n
lo s s .
The a b s o rp tio n loss would be the measured a t t e n u a t i o n minus the
re fle c tio n
loss in db.
The r e f l e c t i o n c o e f f i c i e n t can be c a lc u la t e d from the SWR using
the f o l l o w i n g e q u a tio n .
- SWR - I
SWR + I
Ip I
Remembering t h a t
2
Ip I
Pr
Pi
no
where
Pr = Power R e fle c te d a t p o in t A
and ■
Pi = I n c id e n t Power a t p o in t A
the p e rc e n t o f power r e f l e c t e d i s found.
The p e rce n t o f power t r a n s ­
m itte d through to p o i n t B is
W ‘ \ The r e f l e c t i o n
M 2-
loss in db in then given by
Ar = 10 log ( I
-
|p|
).
The a b s o rp tio n los s between p o in ts B and C is
Aa = Am - 10 log ( I
-
|p|
( (db)
where Am is the measured a tte n u a tio n .
As an example suppose a t o t a l
is measured.
a t t e n u a t i o n o f 10 db and SWR o f 4
The r e f l e c t i o n c o e f f i c i e n t is
.6
Ip I
and
.36
.
Ill
The r e f l e c t i o n
loss in db is then
Ar = 10 log ( I
-
.3 6 )
Ayi = 1 .9 4 db.
The a t t e n u a t i o n due to a b s o rp tio n in the w ater i s then
A =
a
10 - 1 .9 4 (db)
Ag = 8 .0 6
(db)
.
This is the method used to c a l c u l a t e the a b s o rp tio n los s in w ater
a t v a rio u s te m p e ra tu re s .
Appendix V II
This s e c tio n pre se nts th e d e r i v a t i o n o f the e q u atio n used to
c a l c u l a t e the a t t e n u a t i o n o f a microwave s ig n a l passed through a
d i e l e c t r i c m a te ria l
such as w a te r as a f u n c tio n o f i t s d i e l e c t r i c
c o n stan t (Evi) , loss ta n g e n t (ta n 6 ) , th ic k n e s s ( &) , and f r e e space
I
wavelength ( X o) o f th e microwave s i g n a l .
S t a r t i n g w it h M a x w e ll's equation
>
>
VxH = J
where
>
>
J = oE
>
>
D = eE
arid assuming tim e v a r i a t i o n o f the form
then
J3_
3t
jo) .
A f t e r making a p p r o p r ia t e s u b s t i t u t i o n s , the f o l l o w i n g equation
is o b ta in e d
>
>
VxH = ( a + .J(Oe )E .
L e ttin g
113
and a gain r e a r r a n g in g one gets
>
VxH = eo ( Gr - j o
>
) jcoE
which can be w r i t t e n as
>
.
>
VxH =' E0 Er JuiE
where
er = ( e r - j o _ )
UlE
■( I )
0.
which i s equal to
e
'
-
j e
f o r a d i e l e c t r i c w ith f i n i t e
"
lo s se s .
Now one can solve f o r th e p ropagation v e c to r by d e r i v i n g and s o lv in g
the wave e q u a tio n .
By t a k in g the c u rl o f
>
A
>
VxH = EoCr JuiE
one gets
where
>
. >
VxVxH = E0 Er JuiVxE
>
>
p>
VxVxH = V (V 'H ) - v"H
and since
' >
V-B = O
then
>
V'H = O
114
>
-^B_.
>
and given
vxe
=
>
at
>
B = wH
>
one gets
>
V
xE = -Jw
yH
t h i s gives th e f o l l o w i n g equation
2>
2
* >
V H+ wye^EpH = 0
where
U = y 0yr
Assuming y
= I f o r most d i e l e c t r i c m a t e r i a l s we f i n a l l y g e t ,
2>
2
>
VH + a) yeeH = 0
o o r
where th e pro p a g a tio n v e c to r is
,
/2
~
k = + W y^oE r,
(2)
and we ta k e th e n e g a tiv e term f o r our s o l u t i o n .
By assuming th e f o l l o w i n g form o f a t r a v e l i n g wave in the + z
d i r e c t i o n , one can express the e quation o f the t r a v e l i n g wave in com­
p le x form as
E -
-jkz
^ e i
115
and
jk = a + j3
where a is th e a t t e n u a t i o n c o n s ta n t and
3
th e phase f a c t o r .
S u b s t i t u t i n g in f o r k from e q u atio n ( 2 ) and f o r er from
e quation
(I)
one gets
CX + j3 = jco A iqE0
/e
-
a
me
which can be re a rra n g e d to g e t
.
a + j3 - jw ZiTso / T
/T
-J a
(3)
WEoEr
Remembering t h a t
er = e' = Je"
and
tan S = —r
E
Equation ( 3 ) can be r e w r i t t e n as
a + j 3 - jm A q Eq
Ze^
A - j tan 6
By a p p ly in g th e binom ial expansion to th e l a s t r i g h t hand term
and keeping the f i r s t two terms (s in c e tan 6 « T ) one gets
ex + j 3 z _ j w
At E
0 0
A~
r
(I
- j
t an 6)
2
Tl 6
Now e q u a tin g r e a l , p a r ts one gets th e a t t e n u a t i o n c onstant
/ eZ
a = 03 /y e
o o
r
tan ■<5
— 2—
where
o) = 2irf
■’
i - K
■
This can be s u b s t i t u t e d i n t o th e above e q u atio n to g iv e th e fo llo w in g
ir
a =
/ e~
x
tan 6
O
We now have a p ropagation wave in + z d i r e c t i o n in terms o f
a t t e n u a t i o n c o n s ta n t given as
E = Di e " aZ
.
Since the a t t e n u a t i o n i s d e s ire d as a fu n c tio n o f d is ta n c e in to
the d i e l e c t r i c
l a y e r ( i n d b ) , the f o l l o w i n g equation i s used:
Eo
A tt e n u a tio n = 20 log
t==-
(db).
E1
where E2 i s s ig n a l a t z =
and E1 i s equal to s ig n al a t z = 0.
117
A = 20 Ioq E1 e -a £
E1
A = 20 log e " a£
|A| = -20 a£ log e
Remembering t h a t
log e = .4343
th e a t t e n u a t i o n is
A = 8 .6 8 6 aSL
which a f t e r s u b s t i t u t i n g in a gives th e f i n a l
A = 8 .6 8 6 ^
/E I
equation
tan 6 (db)
.
MONTANA STATE UNIVERSITY LIBRARIES
3 1762 1001 4666 9
/rrs /3