Reg Edwards wrote:
Richard, why don't you just say that the angle of elevation of the
radio path has nothing whatsoever to do with the type of transmitting
and receiving antennas, or the directions in which they may be
pointing or elevated, or even the operating frequency.

Or even the existence of the human race and their radio transmitters.
The propagation paths are still there, and even if we had never invented
radio they would still exist.

Antenna engineering is all about making the best use of the propagation
paths that Nature provides[*].

That basic fact should be "bleedin' obvious".

[*] The HAARP project does aim to change the ionosphere itself - but the
colossal size and power of HAARP only goes to show that "the rest of us"
can NOT do that. We cannot change propagation; we can only use it.

When communication has been established between A and B, the angle of
elevation depends only on the locations of A and B on the Earth's
surface, on the number of hops, on the height of the ionospheric
layers, and on the slope of the layers.

The elevation angle is determined purely by trigonometry.

A handy phrase that hasn't been mentioned yet is "ray tracing". That is
what we're doing, same as in optics.


Received signal strength depends on the two antenna gains in the
direction of the path. The take-off angle predicted by Eznec-type
programs is an altogether different thing.

Hmm... at the risk of proliferating TLAs, how about making a fresh start
and calling that the antenna's BVA - Best Vertical Angle?

BVA belongs to the antenna, and TOA belongs to the propagation path.

It doesn't get around the fact that the antenna radiates something at
*all* vertical angles, but it's better than the present situation of
(mis)using TOA for two different things.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek