Many households find themselves between the coverage areas of VHF and UHF TV stations for two or more media markets - for instance, New York and Hartford/New Haven; Los Angeles and Bakersfield; Washington, DC and Baltimore, etc. However, the transmitters for those stations may be in cardinally opposite directions. Some of the highest-gain TV antennas are Yagis, with dozens of elements pointing in one direction. What if you want to maximize your gain from multiple antennas?
There's actually a very simple solutions - combine two antennas in a
phasing harness, coupling both antennas with 2 sections of RG-6 cable with a Tee connector. The best way to do this would be to calculate quarter-wavelength lengths of cable before cutting, stripping, and crimping connectors on them. But it can work with a quick-and-dirty approach described below, done in my attic.
If you don't have a Tee connector, you can also use a 5-850 MHz 2-way splitter. And if you don't have a spool of RG-6 cable or crimping tools, you can eke by with existing cabling.
Just locate the transmitter directions, point the antennas those respective directions, and couple the antennas to your phasing harness, leading down to your cabling distribution point. Depending on the length of the cabling run, you'd likely want to offset
attenuation, if not also add gain to offset non-line-of-sight path loss, with a preamplifier.
Adjustable preamplifiers can avoid adding excessive noise (especially important when you're within a 40-mile range of a transmitter) by dialing the amplification up or down, but some models may fail to work with certain antennas, so trial and error may be unavoidable.
While the setup described above works reasonably well, it's not perfect. The downside to using different antenna models with different cabling lengths to a Tee connector or splitter is
passive intermodulation, creating third-order harmonics that add spurious noise. If you have the budget and time, you should use identical antennas, and identical cabling lengths with identical connectors, to a Tee connector.
While an attic isn't as good as a roof for antenna placement, it does spare you trouble with your homeowners' association and the need for lightning arrestors on the coax line. If you haven't explored your attic because it's dark, there's a solution for that without calling an electrician: An extension cord to the closest outlet below,
extension lamp cords, and
light-bulb adapters with integrated sockets. You can then bring up some attic decking to walk between beams (at your own peril, of course) and find a suitable mounting spot for your antenna(s) and fish cabling down as needed.
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