On Wed, 9 Feb 2005 20:35:14 +0000 (UTC), "Reg Edwards"
wrote:

The elevation angle of a radio wave is not related to antenna construction.

It is calculated by trigonometry and is geometrically related to the
distance between two points on the Earth's surface, the height of the
ionospheric reflecting layers involved, and the number of hops.

If a radio wave leaves the Earth at one end of the path and returns to Earth
at the other end, then the elevation angles of the path taken are the same
at both ends. And the same in the other direction. (To forestall
nitpickers let it be said things can vary around averages.)

The optimum angle at which to point a radio antenna, either for transmit or
receive, is obviously the same as the elevation angle of the radio path.

BUT NO AMOUNT OF WAVING THE ANTENNA ABOUT WILL AFFECT THE ELEVATION ANGLE OF
THE RADIO PATH.

For given points on the Earth's surface, height of reflecting layer, and
number of hops, the angle of elevation of the radio path is fixed.

The angle at which the radiation from an antenna is a maximum is an entirely
different matter.

Calculation of a path elevation angle on a curved Earth not very difficult
but is a little too complicated to be written here.

Up to 1500 groundpath miles the Earth can be considered to be flat. Trig
calculation is then schoolkids stuff.

Full formulae can be found in maths books under "Spherical Trigonometry" or
in practical radio engineering books.

Calculations can be interesting but are invariably roughly approximate
because layer height involves guesswork. And by the time you've finished a
calculation the height has shifted. Or the number of hops has changed from 2
to 3. The only things which remain static are your own latitude and
longitude.

To calculate propagation statistics of one and two hop radio paths,
including elevation angles, download simple program TWOHOPS in a few seconds
from website below and run immediately.

The original poster, John, had already indicated the answer to his own
question - but Reg was the only one who recognized that and had the
correct follow up. Congrats, Reg.


Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html