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Old 5-Mar-2015, 10:47 PM   #7
GroundUrMast's Avatar
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
Originally Posted by Ultra View Post
Really??? Damn! I would have thought that the interference would only be a problem for the omnis with co-channel and adjacent channel problems. Or are you thinking of problems like intermod, cross-mod, harmonics, etc?
Incidentally, nearly all the stations in that report do have NM >20dB. The next weakest is a huge drop. It seems that if I did get a beam antenna, I would only get 2 more channels that I'd ever watch.
Multipath seems to be very common for most folks... The direct path signal is interfered with when a reflected copy of the signal arrives at the antenna out of phase with the direct path signal. An omni tends to let that undesired signal through at a higher level than a directional antenna would. As a result, the out of phase signal(s) will likely be stronger relative to the direct path version and therefor cancel to a greater degree. When the reflection point is unstable, the fluctuating multipath generated, will cause havoc for the dynamic equalizer circuits in the tuner. This is one of the main reasons trees are so problematic... They cause rapid fluctuations in the signal path that the dynamic equalizers can't track and adjust for, therefor loosing lock on the signal.

Re. intermod, cross-mod, harmonics, etc - These are usually caused by active electronic devises, not passive object in a signal path.
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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