[BC] Commercial Station Feeding A Commercial Translator Question

[R A Meuser]

If you visit Death Valley where there is between very little to no 
broadcast signals, you can pretty repeatably pull in LA FM stations if 
you know where to find the knife edge refractions.




Richard Fry wrote:
> More comments on this based on the data in the OP...
> 
> The radio horizon for an antenna at 300 feet AGL is about 24.5 miles 
> over a smooth earth (4/3 radius).  So even if the translator receive 
> antenna was at 300 feet AGL, that still leaves a lot of a ~90 mile 
> direct path needing to travel through the earth.
> 
> It can't do that, so whatever signal arrives at the translator site has 
> to refract over the terrain elevation peaks along the path, in 
> line-of-sight segments.  Each refraction can reduce the signal by 15 dB 
> or more, so it doesn't take many of them before the signal is too weak 
> to be usable.  Also the signal strengths over long paths have a lot of 
> time variability.
> 
> For some insight, I use a 10-element FM receiving antenna at about 35 
> feet AGL to listen to St. Louis FM stations, using a  McIntosh tuner.  
> The path is about 90 miles long, over fairly flat terrain to Quincy, 
> IL.  The stations using 100 kW at ~1,000 feet AGL will vary over large 
> blocks of a 24-hr period from being rather quiet (maybe 40 dB SNR) to 
> being totally unlistenable.
> 
> RF
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