Do Your Own
Needs Analysis
Dennis Egan W1UE
Thanks



A big thanks to Dean Straw N6BV for his work
in this area over the past 25 years.
There are frequent changes to the procedure
I'm about to describe, as software changes.
Current instructions for downloading and using
terrain files, MicroDem, and HFTA are
available, latest revision dated Feb 22, 2013:
Required Software

MicroDem

HFTA

MakeVOA

VOACap
Preliminary Steps
1.Get the Latitude/Longitude of your tower
location in decimal degrees (example:
42.353269N, -71.508921W)
2.Tower Height: decide on your tower height(s)
3.Antenna: # of elements
4.Target area
5.Any parameter can be changed as we proceed,
but you need an idea of your direction
Today's Choices

Use the Lat/Long of W1UE location
42.353269N, 71.508921W

Tower heights: 35 feet, 70 feet

Antenna: 4 element 20M beam

Target Area: Japan
Step-by-Step Procedure
1. Get your Terrain File
Step by Step Procedure
1.Get your Terrain File
2.Get the file into MicroDem
3.Plot your radials
Step by Step Procedure
1.Get your Terrain File
2.Get the file into MicroDem
3.Plot your radials
4.Look at your PRO Files
Step by Step Procedure
1.Get your Terrain File
2.Get the file into MicroDem
3.Plot your radials
4.Look at your PRO Files
5.Get your data into HFTA
Step by Step Procedure
1.Get your Terrain File
2.Get the file into MicroDem
3.Plot your radials
4.Look at your PRO Files
5.Get your data into HFTA
6.Produce your terrain/antenna files
Step by Step Procedure
1.Get your Terrain File
2.Get the file into MicroDem
3.Plot your radials
4.Look at your PRO Files
5.Get your data into HFTA
6.Produce your terrain/antenna files
7.Use MakeVOA to convert your terrain/antenna
file to a VOACAP antenna file
Step by Step Procedure
4. Look at your PRO Files
5. Get your data into HFTA
6. Produce your terrain/antenna files
7. Use MakeVOA to convert your terrain/antenna
file to a VOACAP antenna file
8. Start up VOAAREA and set your parameters
Step by Step Procedure
4. Look at your PRO Files
5. Get your data into HFTA
6. Produce your terrain/antenna files
7. Use MakeVOA to convert your terrain/antenna
file to a VOACAP antenna file
8. Start up VOAAREA and set your parameters
9. Now Run the Projections for the first antenna
Step by Step Procedure
4. Look at your PRO Files
5. Get your data into HFTA
6. Produce your terrain/antenna files
7. Use MakeVOA to convert your terrain/antenna
file to a VOACAP antenna file
8. Start up VOAAREA and set your parameters
9. Now Run the Projections for the first antenna
10. Now run the projections for the second
antenna, changing ONLY the antenna
NEW TOPIC
VHF/UHF Coverage Analysis

Software needed: MicroDem, and the same
USGS file you used for the HF Needs
Analysis
Procedure Overview
1. Open MicroDem and load your terrain file
Procedure Overview
1. Open MicroDem and load your terrain file
2. In MicroDem, setup the screen for a “Horizon
Blocking,” and input the first antenna height in
meters (35 ft = 10.7 m)
Procedure Overview
1.Open MicroDem and load your terrain file
2.In MicroDem, setup the screen for a “Horizon
Blocking,” and input the first antenna height in m
(35 ft = 10.7 m)
3.Using MicroDem “Area” calculation, you must
manually trace the outline of the polygon you have
on the map.
Procedure Overview
1.Open MicroDem and load your terrain file
2.In MicroDem, setup the screen for a “Horizon
Blocking” and input the first antenna height in m
(35 ft = 10.7 m)
3.Using MicroDem “Area” calculation, you must
manually trace the outline of the polygon you
have on the map.
4.Repeat the procedure, using the other tower
height (70 ft = 21.4 m)
Do the Math

Coverage from 35 ft tower = 59.9 sq mi

Coverage from 70 ft tower = 158.1 sq mi

Increase in coverage:
(158.1 – 59.9) / 59.9 = 163.9% increase
Over perfectly flat ground or the ocean, a circle
with a 15.5 mile radius would encompass an
area of 754 sq miles, so even a 70 ft tower can
“see” only 21% of the possible area
Credits & URL
Email: W1UE@arrl.net

Thanks to Pete Smith N4ZR for his work with this
over the years.

Many thanks to Dean Straw N6BV for everything
he's done in this area for the past 20 years

Thanks also to Jim Nitzberg, WX3B, for putting
together one of the first Needs Analysis papers

A more complete version of this PPT available at
www.antennazoning.com, “Amateur Radio,”
“Presentations & Articles”
