Topband: Modeling the proverbial "vertical on a beach"

[Rik van Riel]

On 08/13/2014 09:47 AM, Tom W8JI wrote:

> Transmitting is a different story, if lower angles are used. I doubt,
> however, it is ever close to 10-20 dB unless it is groundwave
> propagation. I'm sure people somewhere have actual numbers on that.

One big question is, where does the path loss on top band come from?

Is the path loss due to energy lost with each hop?

If so, bending some of the radiation around the earth a little bit,
and reducing the number of hops that way, could be a significant
factor.

On the other hand, going through the D layer at a shallower angle
could also mean more signal absorption at certain times of the
day. This may explain the "I got more signal on my horizontal
dipole right around sunrise/sunset than I got on my vertical"
anecdotes.

IIRC, this difference has been reported to be 1-2 S points
by some people.

A similar difference (1-2 S points) when going the other
direction (lower angle, over a low loss medium) seems
reasonable. 20dB does seem a little out of place, unless
the losses incurred with each ionospheric hop are larger
than I suspect :)