ANTOP AT-415B antenna: vertical reception?
This antenna claims to have 360 degree horizontal plus 360 degree vertical reception. What kinds of advantages would vertical reception confer? I'm wondering because first of all I've never seen such an antenna with two directions of reception, and secondly I thought that TV signals in the US were horizontally polarized anyway.
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Just another antenna that puts cash in the pockets of
those involved in the manufacture and sale of such garbage. The only advantage I could think of with "vertical" reception would be if you have a nearby transmitter that is highly elevated versus the location of the receiving antenna. The antenna would be pointed / rather than --- |
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Without going into and discussion of the merits (or lack thereof) of the antenna in question:
The default (mandatory) polarization for North American TV broadcasting is horizontal. A substantial number of US broadcasters have, or are planning to add as they go through repack, a vertical component to their signal that is said to improve reception for indoor antennas. The power of vertically polarized signal can be some fraction up to 100% of the horizontal component and is phase shifted by 90 degrees. The resulting signal is either then circularly polarized (100%) or elliptically polarized (<100%). The additional polarization certainly isn't free. A station running a million watts horizontal would also have to run another million watts vertical (2 million watts total ERP) through an appropriately designed antenna. Doubles their transmitter electricity consumption as well as the expense of the second transmitter, the phased combiner, the antenna, etc. When it comes to antennas that are supposed to be "omni-directional", it's my conclusion that they receive equally poorly in all directions since they have no capability to focus on anything. In multipath-prone areas, they're going to be the first to fail. In very simple locations with widely scattered towers, they usually do okay for short to medium range applications. |
KFPH, Flagstaff Rf 13, tested, as you indicated, ADTech,
the vertical polarization in addition to the standard horizontal polarization of their Rf 13 signal and the UHF translator signal down in Phoenix. The reception improvement over the rugged terrain of Northern Arizona was minimal. Indoor antennas simply are insufficient to receive good, consistent reception here. Very, very few people here use indoor antennas. Down in Phoenix however, they did find a significant improvement with indoor penetration/reception. If I understand correctly, the plan is to use some percentage of vertical polarization to their horizontal UHF translator signal in Phoenix only. |
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