[mythtv-users] HDTV antenna quandry
Rich Osman
rich at osman.com
Wed Apr 25 05:32:20 UTC 2007
Mark napsal(a):
> Maybe one of you guys has run into this before...
>
> I'm planning on moving to HDHOMERUN boxes in the near future, but I have
> a dilemma. I have multiple stations nearby, Lansing 30 miles to the north,
> Kalamazoo 45 miles west, and Detroit 60 miles East. I need higher gain
> antennas pointed in multiple directions. I could do it with a rotor,
> but then I might miss
> a show on a channel where the antenna isn't pointed. Best bet is
> separate antennas. Can antenna feeds for digital broadcasts be combined
> with a splitter/combiner?
> Or should I run each antenna feed to a separate hdhomerun and play with
> channel/input priorities until it works right? Currently this is my
> only avenue for recording HD.
> Cable and Sat don't carry what I want.
>
> Thoughts?Mark,
A plain old splitter rated for the highest channel (frequency) you
want to watch will do fine. The splitter will add loss, a two-way
splitter is half the signal level even when used as a combiner.
You don't mention the channels involved, so it's hard for me to
provide very detailed advice. I'm assuming that you want multiple
channels from each direction. If not, 'single-channel' (really, a
small number of channels) antennas are far more efficient for their
size.
If you mount multiple antennas on a single mast, make sure that you
space them far enough apart. A decent rule of thumb is half the width
of the widest element between antennas. This also applies to above
whatever you are mounting it to. I noticed another poster mentioned
cable lengths and such. That advice doesn't apply to your case. It's
for combining multiple antennas on the same signal, which is not what
I think you are asking. I believe that you want to have an antenna
pointed at each city, right?
In spite of the distance you may find that you get good signals off
the front or even the back of the antenna and make things work. I'd
start with one antenna and see what you can get. Watch an analog
station from the same city on a nearby channel. If you can get a good,
watchable picture on that it's likely that you'll have good margin on
HD. This is a function of terrain a bazillion other things.
Avoid amplification if you can. It can make things worse more easily
than better unless you really understand what you are doing. If you
need to add an amp, it's best to get it as close to the antenna as
practical. Use good cable and connectors. The thumb rule here is
'thicker is generally better' and use good connectors properly
applied. The new compression style F connectors can be bought in
weatherproof versions and tools to apply them can be had on eBay for
~$20. Make sure the connectors you get match the cable.
--
mailto:Rich at Osman.com http://www.rich.osman.com
Rich Osman; POB 93167; Southlake, TX 76092 (Near DFW Airport) ARS: N1OZ
Engineering is like having an 8 A.M. class and a late afternoon lab...
...every day for the rest of your life.
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