Do Your OwnNeeds 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.netThanks 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 yearsThanks also to Jim Nitzberg, WX3B, for putting together one of the first Needs Analysis papersA more complete version of this PPT available at www.antennazoning.com, “Amateur Radio,” “Presentations & Articles”