[mythtv-users] HDTV antenna quandry

[Brad Templeton]

On Tue, Apr 24, 2007 at 10:40:17PM -0400, Mark wrote:
> Hmm.  Did find some info on this on the net, seems like a black art.  
> Have you ever heard of
> channel specific yagi's combined on a single line to give each desired 
> channel?  I know it'd be ugly,
> but with uhf yagi's being small, at least I wouldn't have 50 lbs on my 
> tower...  I used to have an old
> channel 32 yagi sitting around from the old ON-TV service from the 80's, 
> so I know they are available...
> 

Here's one page with info:

http://www.kyes.com/antenna/stacking.html

Note that you don't want your antennas too close to one another or they will
resonate.  But with UHF that's not so hard to do, wavelength is short.  For
VHF like channel 12 you want them 1.4 meters apart.

Here's another trick:

http://www.hdtvprimer.com/ANTENNAS/ganging.html#TAT


Of course it would be ideal if you could see an analog signal on the same
channel or nearby and you could eliminate ghosts, which means low multipath
which is better for your digital signal.  You can't "see" ghosts/multipath
on digital tv, you only see signal problems.

This guy:
    http://www.kb9vbr.com/J-Pole_Order_Form.pdf

Seems to sell custom tuned antennas for hams, have no idea how good they are,
perhaps he would make them for tv.

These look expensive but I hear they might be in the $40 range

    http://www.microwavefilter.com/tunabletraps.htm


But I would try other tricks, then see what interference you are
getting and then buy a filter to fix that if you can't fix it
with plain old antenna aiming.

Go to antennaweb and it will give you a map of the real frequencies
of your channels and their direction.  Compare it to the lobes on
some antennas.  You may find that you can get an antenna with lobes
that do the right thing for you, depending on what local things
are bouncing multipath on you.