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Old 02-15-2008, 04:22 PM
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DaveInDenver DaveInDenver is online now
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Join Date: Jun 2006
Location: Larimer County
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Hey Bruce, you already have your ticket, no cheating.
Originally Posted by 60wag View Post
a. higher freq
It is absorbed more readily by vegetation and objects and does not bounce well. UHF doesn't really experience tropospheric bending and sporatic-E & F-layer skips or meteor reflection like lower VHF. It also does not favor sky wave propagation like VHF, so it tends to be even more line of sight than VHF and much more so than HF. With UHF generally if you don't have a good LOS, you probably aren't gonna communicate.
b. Shorter distance propagation ?
Higher frequency means shorter antennas and longer antennas tend to be more directional. But see (a) for why the FCC put FRS there, it tends to stay more local and so you get less interference using a Talkabout at Copper from people talking in Vail.
c. It'll bounce off of stuff.
Sort of. It's called tropospheric ducting and it happens here because of temperature inversions. Over the ocean they say you can talk between Hawaii and the West Coast with VHF with the right conditions. This is one (probably the only) type of propagation anomaly where UHF can have odd propagation. Otherwise just about everything reduces the range of UHF, which means your little traveling group is likely not to interfere with other people and you experience less interference other than localized noise and close stations.

All of this (with the exception of the rare tropospheric bounce) is why the UHF, EHF and SHF bands are so much in demand. Cell phones in particular want to be as high in the UHF band as possible so that each cell does not interfere with its neighbors.
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