Electromagnetic Radiation
& Satellites
Antenna Design
Pete Arvedson
California Science Conference
October 26, 2013
Hosted by Satellite Educators Association
Lesson plan development supported by a grant from NOAA-CREST West
Session Objectives
Relate wavelength and frequency
Construct 1/10th scale model wave
Calculate antenna length
Apply to 5-element Yagi antenna design
Build 1/10th scale antenna
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Antenna Design - 2

Solar radiation
reaches Earth
surface
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Antenna Design - 3


Surface features
reflect solar
radiation to
remote sensors
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Antenna Design - 4



Satellite sends
radio signal from
remote sensors to
Earth station
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Wave Properties
wavelength, λ (meters)
amplitude
crest
trough
How many waves pass a point each second
= frequency,
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ν (1/sec or Hertz)
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Electromagnetic Spectrum
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Wave Properties
c
λν
c = λν
λ=c/ν
ν=c/λ
c = speed of light = 299,792,458 m/s
-in vacuum ~ 300 x 106 m/s
-in metal = 280.225 x 106 m/s
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Wavelength from Frequency
POES WEFAX frequency = 137.50 MHz
λ=c/ν
6
300 x 10 m/s
 2.18m
λ =
6
137.5x 10 Hz
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Build Wave Model: 1/10 Scale
wavelength: λ = 2.18 m
1/
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10
scale model wave:
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λ = 21.8 cm
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Antenna Size – First Look
EMR energy resonates in antenna metal
wire producing current
Antenna length should match radio signal
wavelength
Wavelength for 137.5MHz = 2.18 m
½ or
¼ wavelength is best!
 2.18 / 2 = 1.09 m
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Antenna Size - Actual
velocityin vacuum 300 x 106 m/s
λ


6
frequency
137.5x 10 Hz
2.182 m
velocityin metal 280.225x 106 m/s
λ


6
frequency
137.5x 10 Hz
2.038 m
½ wavelength = 1.019 m
1/
10
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scale model antenna length =
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10.19 cm
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Yagi Antenna
 1926 Hidetsugu Yagi & Sintaro Uda
Tohoku Imperial University, Japan
 Driven element; parasitic directors & reflector
 Highly directional & wavelength selective
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Brent Stirton, http://ngm.nationalgeographic.com
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Design Your Antenna
3.0 cm
87.4 cm
8.74 cm
92.0 cm
9.20 cm
96.8 cm
9.68 cm
18.3 cm
10.19 cm
4.1 cm
112.1 cm
11.21 cm
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Extension
Build scale models other antenna types
Calculate antenna length for 1693 MHz
Build several real antennas & determine
which is best for satellite reception
Compare/Contrast crossed Yagi with QHA
Build chicken wire parabolic reflector
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CA Science Standards
Grades 9-12: Physics
4. Waves have characteristic properties that do
not depend on the type of wave (a, c, e)
5. Electric and magnetic phenomena are related
and have many practical applications (e, f, h)
Grades 9-12: I & E
1. Scientific progress is made by asking
meaningful questions and conducting careful
investigations (a, d, g)
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Contact Information
 Pete Arvedson - arvedson@aol.com
 Check out lesson plans in Satellite Educators Association
(SEA) monthly Newsletter…
http://www.SatEd.org
 More opportunities to involve students doing research:
SEA’s M.Y. S.P.A.C.E.* Program - an international high
school collaborative environmental research program
using satellite-based data…
http://www.calstatela.edu/programs/crest/
* (Multinational Youth Studying Practical Applications of Climatic Events)
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