Using mountain as passive UHF reflector to receive HD

[JimK2]

Have a 400 ft hill blocking the view to the transmitter 35 miles away South.
With a small loop antenna I can receive a very snowy but stable
analog picture (pointing to a different 500 ft hill West). Do you think a high gain antenna would have enough gain to give enough signal to receive HD using a mountain as a passive UHF reflector.

 

[NightHawk]

Probably not. It isn't a question of having enough gain. Gain isn't the problem. Complex surfaces scatter RF energy in complex directions, not like a mirror. While the scattering may not be too bad at UHF frequencies (it would be better at VHF) using a mountain as a reflector is a real shot in the dark.

 

[roashru]

The only success I have had using earthen terrain to help pull in a signal is to use a valley of a mountain range or a canyon to get a waveguide effect.

Found glossarys explaining a waveguide
http://www.voiceanddata.com.au/admin/glossary.asp?fn=display&keyword=Waveguides
http://amsglossary.allenpress.com/glossary/search?id=waveguide2

 

[Tower Guy]

Have a 400 ft hill blocking the view to the transmitter 35 miles away South.
With a small loop antenna I can receive a very snowy but stable
analog picture (pointing to a different 500 ft hill West). Do you think a high gain antenna would have enough gain to give enough signal to receive HD using a mountain as a passive UHF reflector.

I'd be surprised if you could get it to work. The hill would cause multiple points of reflection, each with different path lengths. That is exactly the dreaded multipath that DTV can't deal with using most decoder chips.

A better solution to to try to get the signal using knife edge refraction over the top of the hill between you and the station. You'll need an antenna with a high front to back ratio in order to eliminate the stronger reflection from the hill behind you.