1. Carroll County Amateur Radio Club A Introduction to Terrain Modeling With K6TU.NET’s tools and the ARRL’s HFTA (N6BV) (a.k.a. finding that PERFECT HF radio location By Jim Nitzberg, WX3B February 12, 2018
May 14, 2019

2. WHY would YOU want to Model your Terrain?
How many of you have used HFTA and other tools to model terrain
How many of you did this BEFORE buying our current home?
How many of you would DO IT before considering another home?
Why do it even if you can’t change it?
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3. Terrain Modeling permits you to assess your stations strengths…and weaknesses.
What are your communication goals?
What are your favorite HF bands
Where do you wish to communicate the most frequently?
Are you a DXer? Do you like contests?
Are Domestic (USA) QSOs important?
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4. Terrain Modeling What is covered today?
N6BV’s (ARRL) antenna book HFTA program
Stu, K6TU’s web site and terrain service
General discussion about terrain and HF propagation
Sample placement of single antennas, over real ground
Comparison to alternate QTHs or flat ground
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5. Terrain Modeling What is NOT covered during this introduction??
Vertical Arrays
Antenna that do not behave like Yagis or dipoles
Stacked Yagis (Cover ALL the angles better)
Limitations of HFTA in super irregular terrain
Limitations of NASA shuttle data (it’s not perfect)
Reasons for ignoring HFTA and trying anyway (you should, if you’re stuck)
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6. GOALS of this presentation
Determine your station’s strengths and weaknesses so you know how and when to operate to meet your goals
Determine if improvements you can afford might be worthwhile.
Understand why it is SO critical to pick a good location, if you have an opportunity to move.
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7. What is HFTA? (High Frequency Terrain Analysis)
A windows program that has been around for quite some time
Created by Dean Straw N6BV with the ARRL
You have to buy the ARRL’s Antenna Book to get it.
Uses arrival angle coverage and frequency to model effectiveness for specific HF frequencies and antennas
Uses a Figure of Merit (FOM) in dB to describe overall efficiency, however the explicit arrival angle coverage tells a more detailed story.
Permits you to target specific geographic areas to measure your effectiveness (i.e. USA, EU, Asia, Africa, South America, etc.
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8. HFTA - Screenshots
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9. HFTA Terms and Parameters
Frequency (obvious)
Terrain files (You supply – you’ll see how to soon)
Elevation File: Provided by HFTA. You pick the source and destination you are interested in. Years of data of arrival angle coverage are stored in files within HFTA. In my example, I have selected propagation from the W3 area to Europe (of particularly interest to contesters on different HF bands)
Maximum Elevation Angle. Some folks don’t care about covering the super high angles, so you can select your cut-off.
Show Antennas and Terrain plots: A good way to view the terrain quickly. Over time you will be able to tell good terrain and bad terrain by site, almost instantly.
Options: You can change soil conductivity, diffraction, etc.
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10. HFTA sample results WX3B 20m to Europe
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11. HFTA sample results WX3B 20m to Japan
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12. HFTA sample results WX3B 20 to USA
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13. HF Terrain Patterns observed after years of experimentation
Flat ground provides the most reproduceable experience and predictability modeling. If you have an infinite amount of money for hardware, flat ground may be your best option.
The ‘cereal bowl’ terrain that slopes down and back up again potentially provides low angle gain without terrible sacrifice to the high angles
Slight slopes uphill are not the kiss of death you might think they are: you must model them
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14. HF Terrain Patterns observed after years of experimentation
Large slopes uphill, in the near field (i.e. first few thousand feet) do the most damage to your low arrival angle coverage
As frequency decreases, your arrival angle coverage can be higher.
The higher you get your antennas, the better you can cover the lower arrival angles
The low bands require much higher antennas to cover even the higher arrival angles
There is a such thing as having an antenna that’s too high, particularly if your terrain is hilly, or you are on 10 & 15 meters
Stacked arrays of antennas eliminate the NULLS and maximize your coverage of ALL arrival angles.
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15. K6TU’s Terrain Server How to retrieve the data
Register yourself. It’s FREE, however I heartily encourage you to donate the $30.00 if you use his tools.
His Terrain Server does not require a donation.
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16. How to generate Terrain profiles with K6TU
Get your desired GPS Coordinates. Google earth can help
Log on to and create yourself a free account
Select “terrain profile request”
Title your results file, give a unique prefix you’ll remember (i.e. N3SB)
Enter the latitude and longitude of the precise antenna location
Press “save”
Wait for your of zipped terrain files
You will get a file for each direction/degree (that’s 360 files!!) Now have fun with HFTA or use HFTASWEEP to model your terrain and antenna
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17. How to generate Terrain profiles with K6TU
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18. How to generate Terrain profiles with K6TU
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19. How to generate Terrain profiles with K6TU
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20. N3SB Example Using google earth (Notice Steve’s GPS Coordinates)
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21. N3SB Example: Coordinates plugged into K6TU’s program
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22. N3SB Example: terrain files generated
Retrieve your
It contains a single zip file with 360 files embedded in it
N3SB files have the prefix N3SB on them – one file for each degree
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23. Unzip and place these files in your HFTA directory or prepared to FISH for them
Typically the directory is something like this:
C:\Program Files (x86)\ARRL\AntBk21\Terrain
Return to HFTA
Let’s see how N3SB’s terrain to EU, JA and USA looks
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24. N3SB: 20 meters at 45 degrees up at 50 feet vs. flat ground
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25. N3SB: 20 meters at 45 degrees up at 50 feet vs. flat ground
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26. N3SB results at 45 degrees to EU
Note the gain at the low arrival angles
The high angles are covered well – almost like flat ground
The overall effectiveness is like flat ground (similar figure of merit)
I would have expected the result to be more dramatic.
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27. N3SB: 20 meters at 335 degrees to JA
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28. N3SB: 20 meters at 335 degrees to JA Significant gain for a range of low arrival angles
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29. N3SB results at 335 degrees to JA
Improved low angle coverage vs. flat ground
Somewhat degraded higher angle coverage
Figure of Merit still higher (2.3dBi) than being on flat ground
This confirms my day of running Japan on 15 meters at N3SB many years ago. N3SB’s location ROCKS to JA.
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30. N3SB: 20 meters to the USA
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31. N3SB: 20 meters to the USA
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32. N3SB: 20 meters to the USA General conclusions about N3SB
USA coverage Models similar to flat ground
N3SB has a GREAT HF location!!
Should model at least 20 degrees, degree by degree for each preferred direction, to get the most accurate report.
HFTASWEEP is the tool to do this, part of K6TU’s tools.
Can also be done by hand.
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33. It provides an excellent start for modeling
Summary of HFTA Modeling (Inspired with coaching from Dean Straw N6BV – HFTA Author)
It provides an excellent start for modeling
Accuracy may suffer with extremely varied terrain, particularly on the low bands (Mountainous)
Take it with a dB or two grain of salt.
Varying terrain in the near field (first few thousand feet) effects the outcome FAR MORE than further away.
Eyeballing terrain is dangerous, sometimes the outcome is much better…or worse than you expect. MODEL IT!!
May 14, 2019

34. Please DO try this at home. Model…BEFORE you buy.
K6TU’s Terrain Service and N6BV’s HFTA An effective one-two PUNCH THANK YOU!!
Please DO try this at home.
Model…BEFORE you buy.
Any questions??? Ask away.
May 14, 2019