Calculation of Increased Range By Raising Antenna

It is repeatedly said that antenna height is very important, but before I do that I want to know how much range improvement I will get over a given obstruction. Is there a form somewhere into which parameters may be entered.

For example, an antenna at 500 m ASL, a mountain ridge at 800 m located 20 km distant. What would be the tracking range improvement at say 10,000 m flight level if the antenna were raised by 1 m?

I can get 220+NM (in a good direction. one not blocked by terrain) with an antenna that is <30M AMSL.

check out
Put in your location details, run a report, then select up in the air.
It won’t be finely tuned enough to work out 1m.
It will give you an idea of the possibilities.

Trees are a big factor for me. I get blocked to the NNW and NNE by trees.

I raised my antenna about 6 feet and it cleared a roof access door and a slight lip of the building edge and is now fully clear of everything. Range went up around 10-15% 250NM+ reports up 30-50%

Please follow the steps in the FIRST Post of the thread linked below. This method automatically takes into account existing natural terrain around antenna location (such as your case: a hill ridge 800m above sea level 20 km from antenna location).

When entering your data in heywhatsthat site, you can try various antenna heights and aeroplane heights to find affect of antenna height on range.

What is the Maximum Range I can Get?

To see calculation and formula, please see these two posts:

  1. post178100.html#p178100

  2. post178106.html#p178106


Heywhatsthat is a good tool but limited to the accuracy of its database as well as lack of data on nearby structures. Trees and buildings will block some of the signal, but not as much as terrain will.

If you can save your data and draw point cloud graphs from it, you will notice that if there are obstructions, they will appear on the graph as spokes radiating from your location. Those spokes, where planes disappear, can be eliminated by elevating the antenna above the height of the obstruction. Sometimes that is not possible.

If you’ve cleared all nearby obstructions (buildings and trees) what you see on heywhatsthat should be pretty accurate.

I wish there were a way to have it indicate heights other than 10000 and 30000. Most useful to me, in addition to those, would be 1000 feet and 41000 feet.

You are right about man made object and trees not taken into account by Since these obstructions are known to the antenna owner, the very logical way is to raise antenna above height of these objects. However in case of Robbwell, the obstruction is NOT man made but a natural terrain feature (hill ridge 800 m heigh at 20 kms). Such terrain features are taken into account by, and that is why I reffered him to the thread giving the procedure.

I wish there were a way to have it indicate heights other than 10000 and 30000. Most useful to me, in addition to those, would be 1000 feet and 41000 feet.

You can change the elevation of aeroplanes to desired value of 1000 and 40000 feet. Please see step 10 of the procedure given in first post of thread What is the maximum range I can get?.