Quote:
Originally Posted by gossamer
It was doing a little reading, and learned that the low VHF and FM reduces the gain at the HD UHF band, which is what I really need. Do you think this is correct?
Thanks again,
Dave
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Well.... almost. The low VHF channels, 2 through 6 are affected by radio noise more than high VHF and UHF channels. Propagation of these frequencies is also a problem at times, the upper atmosphere can act like a 'duct' or 'pipe', causing distant stations hundreds or thousands of miles away, to interfere with a station on the same channel. This makes reliable reception of the low VHF channels more difficult. I don't think it's correct to say that low VHF channels affect the gain of channels in the UHF band though.
FM stations can interfere with television reception. This often occurs when the FM signal is quite strong and the FM signal is 1/3, 1/5 or 1/7 the frequency of the TV channel. Amplifiers that are overloaded by strong signal(s) will distort the signals passing through the amplification circuit which will generate additional frequencies, usually 3, 5, 7 and other odd multiples of the input frequency.
Even though there are some challenges, it has been found, that the current DTV signal format used for OTA broadcasting in North America is more successful on high VHF and UHF channels.
On the plus side, high VHF and especially UHF antennas are quite a bit smaller than low VHF antennas. This makes it practical to build antennas with much more gain and directivity for channels 7 and higher.