A goood rough approximation is that the take-off angle is reduced by the
angle of slope of the Fresnel Zone. The equations for Fresnel Zone size
are readily available in any good antenna handbook.
To paraphrase The Antenna Engineering Handbook (Second Edition) page
26-38:
Terrain Slope
If the ground at an antenna site slopes down in the direction of radiation
by an "angle of slope," the TOA is decreased from the value for a flat
site by the "angle of slope." Conversely if the ground slopes up in the
direction of radiation, the TOA is increased by "the angle of slope."
73
Frank
W3LPL
donovanf@sgate.com
On Sat, 9 Aug 1997, Hawkins, Bill wrote:
> What happens to the takeoff angle of a vee beam or rhombic
> when it is constructed on the side of a hill. If it is pointed downhill,
> is the angle smaller (to horizontal) thereby making it a better dx antenna
> than if it was over flat ground?
> Bill W5EC
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search
|