Hi to all,

NEC gives the pattern for an antenna mounted at a certain height above
an infinite flat ground.

But suppose that we are on a mountain top (summit) with a relatively
steep grade. Does the pattern changes, i,e. is the TO angle going
lower above an horizontal line coming from the antenna?

If so, is there a kind of 'correcting factor' giving the modified
height applicable?

On Mon, 10 Aug 2009 05:19:41 -0700 (PDT), ve2pid
wrote:

Does the pattern changes, i,e. is the TO angle going
lower above an horizontal line coming from the antenna?

Depends on wavelength vs. distance to nearest ground vs. angle of that
distance.

All things about the pattern are related to phase/time/distance.

73's
Richard Clark, KB7QHC

On Mon, 10 Aug 2009 05:19:41 -0700 (PDT), ve2pid
wrote:

Hi to all,

All too high.

NEC gives the pattern for an antenna mounted at a certain height above
an infinite flat ground.

But suppose that we are on a mountain top (summit) with a relatively
steep grade. Does the pattern changes, i,e. is the TO angle going
lower above an horizontal line coming from the antenna?

If so, is there a kind of 'correcting factor' giving the modified
height applicable?

See:
http://www.cplus.org/rmw/english1.html
Locate the antenna exactly on the terrain model (SRTM2) and you'll get
the real antenna pattern. You can input the actual antenna pattern
into Radio-Mobile for better accuracy instead of using generic omni,
cardioid, yagi, etc patterns.

Bad examples (but all I have online):
http://802.11junk.com/jeffl/coverage/kg6nri/



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558