[mythtv-users] Automatic antenna aiming?

Simon Hobson linux at thehobsons.co.uk
Mon Dec 2 09:23:11 UTC 2013


Don Brett wrote:
>RF Channel 33 - 18 miles @ 109 °
>RF Channel 25 - 49 miles @ 140 °
>RF Channel 09 - 48 miles @ 180 °
>
>RF Channel 45 - 18 miles @ 240 °
>RF Channel 23 - 50 miles @ 273 °
>RF Channel 47 - 38 miles @ 278 °
>
>RF Channel 41 - 02 miles @ 311 °
>RF Channel 19 - 02 miles @ 312 °
>RF Channel 36 - 02 miles @ 329 °
>RF Channel 44 - 03 miles @ 336°
>RF Channel 20 - 03 miles @ 336 °

OK, so a wide spread of channels, so you need a wideband antenna. In reverse order :

That last group should be a good signal, so an old coat hanger should pick them up - try a pair of rabbit ears or a small antenna in the loft.

The middle group. Point an antenna at around 270˚ - both 273 and 278 are well within the acceptance angle of even a high gain antenna. The one at 240 is much closer, so even though it's 30˚ off axis, you'll probably find you get a decent enough signal. May need some experimentation (eg try 260˚) to find the sweet spot that maximises the signal from 240˚ without degrading the signal from 278˚

First group. Again, try an antenna pointed towards around 140˚ to 150˚. You might have more of a problem as a lowish gain antenna giving a wide acceptance angle might not pick up the distant signals, while a high gain antenna might not have the acceptance angle.

Stating the transmitter power would be useful, as well as receiving conditions - a 100MW transmitter at 40 miles will give the same (roughly) singla as a 250kW one at 20 miles, or a 60kW one at 10 miles. Line of sight gives a good signal, buildings, or worse, hills, gives a poor signal.
Over here, we're lucky in having a site likehttp://www.wolfbane.com/cgi-bin/tvd.exe which will tell you not only what transmitters are in your area, but also an estimate of received signal strength. We also have the advantage of having a national system so in general we can get all our channels from one transmitter.


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