EEVblog Electronics Community Forum
Electronics => RF, Microwave, Ham Radio => Topic started by: Peabody on August 15, 2018, 01:51:47 am
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It looks like I'll be needing to cut the cord, and I'm trying to figure out the OTA TV situation. I see indoor antennas which claim to be omnidirectional, but they are flat, and hang on the wall. I don't understand how they could not be directional. Also, wouldn't a truly omnidirectional antenna have considerably less gain than a directional antenna?
There are six channels that I would watch, 15 to 19 miles away. Five are at azimuth 100 or 101 degrees, and the other one (channel 10) is 110 degrees. However, my TV is on the West side of the house, so the signals have to go through interior walls, and I have topographic issues. I have three VHF channels (real channels 8, 10 and 11) and three UHF (real 22, 42 and 45).
I have an RCA model ANT112R, and it doesn't do so well, particularly with channel 45, and it is highly directional.
https://www.walmart.com/ip/RCA-UHF-VHF-Digital-Indoor-Antenna/20976672 (https://www.walmart.com/ip/RCA-UHF-VHF-Digital-Indoor-Antenna/20976672)
I don't know if that means no indoor antenna will work, or just that I need a better one.
Any insights would be appreciated.
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It looks like I'll be needing to cut the cord, and I'm trying to figure out the OTA TV situation. I see indoor antennas which claim to be omnidirectional, but they are flat, and hang on the wall. I don't understand how they could not be directional.
Those wall hanging antennas are called dipoles.
"A dipole is omnidirectional in the plane perpendicular to the wire axis, with the radiation falling to zero on the axis" (https://en.wikipedia.org/wiki/Dipole_antenna)
It can receive signals equally in the plane parallel to the ground, which makes it omnidirectional. It cannot receive signals from directly above or below, but this isn't usually an issue.
Also, wouldn't a truly omnidirectional antenna have considerably less gain than a directional antenna?
Gain is entirely a measurement of how directional an antenna is. The smaller the "field of view" of the antenna, the higher the gain. TANSTAAFL.
Some antennas are powered and have internal LNA (low noise amplifiers), which could improve reception considerably for weak signals.
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You might take a look at this little antenna that I bought.
https://www.eevblog.com/forum/projects/questions-about-digital-tv-antennas/msg1610263/#msg1610263 (https://www.eevblog.com/forum/projects/questions-about-digital-tv-antennas/msg1610263/#msg1610263)
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Those wall hanging antennas are called dipoles.
"A dipole is omnidirectional in the plane perpendicular to the wire axis, with the radiation falling to zero on the axis" (https://en.wikipedia.org/wiki/Dipole_antenna)
It can receive signals equally in the plane parallel to the ground, which makes it omnidirectional. It cannot receive signals from directly above or below, but this isn't usually an issue.
The little antenna I have now has a simple rounded-off rectangle sticking straight up for UHF. I think that's functionally similar to the flat ones you hang on the wall. Mine is highly directional, which suggests it doesn't receive signals equally in the horizontal plane, but must be pointed toward the transmitter. Why would that be?
The VHF rabbit ears portion also appears to be directional, although not as much.
Well, I obviously need to read up on antennas.