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I live in a small valley, surrounded on three sides by 200-300 foot ridges. I'm trying to figure out where to place an antenna mast to receive 1280 MHz video from a long range aerial vehicle (20-30 mile radius).

At this frequency, how important will line-of-sight transmission be in this situation? Will it be worth it to haul a 50-foot mast to the top of one of the ridges, and set it up there? (requires a solar panel / battery, and possibly a wireless relay to my shack).

My current plan is a mast at my station; in the middle of the valley, which would get above the surrounding trees, but not above the ridges. Does it matter that aforementioned valley is populated with pine trees, which, as I understand it, will wreak havoc on the signal? What about a 433 MHz transmission from the valley floor to the aerial vehicle?

P.S.: Please presume that there isn't any HOA / building code in the area; this is a problem of physics, not legality.

Kevin Reid AG6YO
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Chris
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1 Answers1

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For the most part, propagation for VHF/UHF (1280 MHz is UHF) is line-of-sight because it doesn't tend to get the benefit of ionospheric reflection like HF does. This will also apply to your mentioned 433 MHz transmission, which is in the UHF range.

While there are occasionally atmospheric events that result in indirect UHF/VHF propagation (e.g. tropospheric ducting), they are not nearly as consistent as HF's ability to DX.

You'd almost certainly get much better reception (both ways) with an antenna located on the ridge where it can get a direct sight line to the aircraft.

Dan KD2EE
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Amber
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    Except that 1.2GHz, you start to really see random surfaces reflecting your signal, resulting in communication that is clearly not LOS. If you have large flat metal surfaces in the area, then you stand a better chance of knowing if you'll be able to get out. (Multipath problems excluded) The only real way to know is to experiment and find out. A relay on the ridge, however, is your only reliable choice. – Andrew Beals Nov 15 '13 at 15:24