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VHF vs. UHF in hills

posted Feb 3, 2013, 5:49 PM by Charles Boling   [ updated Feb 3, 2013, 5:55 PM ]
On occasion, we've discussed the differences in propagation between VHF and UHF in rugged terrain on the net, but it's usually in general terms.  Now I'm going to provide an example.

topo map showing 70cm loss & 2m fade
The other day, part of my family was hiking around Woolford Hill (that's what I call it, anyway -- I don't know that it has an official name -- it's a foothill of Woolford Mtn., and Woolford Rd. climbs it).  We knew that GMRS was worthless on longer hikes -- we always use the 2m band unless we're close to the house -- but I'd never actually mapped out a comparison of the two.  We decided that today was the day, so we kept in radio contact with home, to see where UHF and VHF signals actually started to die.

A picture's worth a thousand words, so I present a topographical map to the right.  As soon as we "turned the corner" UHF quickly became unusable; we were able to go much further and into another little hole before VHF started fading noticeably.  Note that I'm using a decent base antenna at the house, and on the hike we used little HT's.   Of course, there's going to be some variation with surrounding terrain and multi-path signals, etc., but this gives you a general idea of how the two bands behave -- 2m has a definite advantage over 70cm when it comes to bending around/over mountains!   On the non-ham front, GMRS vs. MURS behaves similarly -- both bands are just a little above their respective amateur radio bands, so will tend to be slightly more line-of-sight.

144-148 MHz = 2m
151-155 MHz = MURS
420-450 MHz = 70cm
462-468 MHz = GMRS
 
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