[mythtv-users] HDTV antenna quandry

Rich Osman rich at osman.com
Wed Apr 25 05:26:13 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.

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.

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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