[TowerTalk] Tower height- V- landscape undulations

[John E. Cleeve]

Good afternoon gentlemen. 

I write to seek the group's advice on the ideal height of a tower, with
respect to surrounding undulations in the landscape. I have read that the
ideal site for a radio transmitting location is either on an island, or on
high ground, both locations having a clear "take off" to the horizon.
However, if you are faced with a transmitting site, surrounded by undulating
ground, then in theory, how close to the antenna do the peaks in the ground
undulation have to be, in terms of wavelength, before they cause any
significant distortion to the radiation pattern of an antenna?  I am sure
that this subject must be written up somewhere and I would be most grateful
for information leading to a source. 

 

The reason for the question is, I am planning to raise a tower, or two, on
what used to be a VLF/HF radio station site, and where there were no
restrictions on mast/tower height, the tallest being some 600ft, way above
the local ground variations. Sadly, only the tower bases and guy anchor
points, together with the buried ground systems remain, and I must make
application to the local government planning department to erect any "aerial
supports" or towers, even if I make use the original mast concrete bases and
guy anchor points. It remains to be seen if the previous use of the site
will provide a precedent. 

 

However, when looking at the surrounding ground, some of the fairly close,
that is, within half a mile or so, rising ground could be around 60 - 100ft
above the ground level of the transmitting site in question. My thoughts are
that the height of a tower must place the antenna above the undulations in
the landscape. If that proves to be correct, then by how much.  A scientific
answer to that question could be included with my application, and justify
the height of tower for which permission is sought. I look forward to your
response with interest. Sincerely, John. G3JVC.