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First off, what does 1/2 signal loss mean? If I have an antenna with 16 db of gain for a particular channel, does that mean the output is 8 db, or 16-3=13 db?
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Half the signal loss is 3 dB. But that's not the main problem when using a splitter in reverse as a combiner.
If you combine two identical antennas aimed in the same direction, with identical length feed lines, the gain is 3 dB minus the internal splitter loss of 0.5 dB, for a max possible gain of 2.5 dB.
If you combine two identical antennas not aimed in the same direction, the same signals will interfere with each other when they reach the combining point if they are not in phase. The length of the feed lines is irrelevant in this case.
If you combine two antennas, one for VHF (real channels 2-13) and one for UHF (real channels 14-51), with a UVSJ diplexer, they will not interfere with each other because the UVSJ keeps the two bands separate.
If you use one of the new 8-bay UHF antennas with separate panels that can be aimed in different directions, sometimes it works and sometimes not because of the phase interference mentioned above. It's trial-and-error, with the two panels at 90 degrees apart for your best chances.
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And finally, is any of this correct? Someone once told me the loss is only true if the same channel is on both antennas. In my case with 70 degrees, the reception should be close to zero in the "other" antenna for every channel.
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Yes, it is, but it is a matter of the strength and phase of interference, not all-or-nothing. What usually happens when there is a problem, some of your channels will be missing after combining.
We have several members here that can do a good job with the antenna theory, but the guys in your area at DHC can do a better job with the specifics of your location. But we will give it a try anyway, if you so desire.
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I do get a reasonable selection of channels from both directions.
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What are you getting now by callsign and real channel number?
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But its not a *great* selection.
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What would you consider great, that you aren't getting now?
But first, as Jake V requested, please post a link to an exact address (which will not show) or coordinates (which will be shortened) tvfool report so that we can make an accurate analysis.
How close are my guesses to your exact address report?
http://www.tvfool.com/?option=com_wr...8e03088b382880
http://www.tvfool.com/?option=com_wr...8e03cd784464bd