[mythtv-users] OT - Antenna tuning/aiming

[Brian Wood]

On Nov 5, 2006, at 9:53 AM, Brad Fuller wrote:



> My problem station is KNTV (11-1). It is the only one that doesn't  
> quite
> come in. It worked better if I skewed the antenna 45degrees. The
> stations didn't seem to be effected much.

It's hard for me to be too sympathetic if you are having problems  
with only 1 out of many channels :-)

Remember also that UHF frequencies are effected more by things like  
leaves on trees than VHF, so things might change with the seasons.

>
> I have a question, though. I placed this antenna (which is a small
> VHF/UHF antenna http://winegard.com/offair/products.htm) below a  
> typical
> VHF/UHF antenna (dipole) that is on a mast. It's about 3 feet above  
> the
> new antenna. Would the older antenna effect reception of the newer one
> below it?
>


Any antenna will be affected by any metallic object placed near it,  
obviously the farther away the less the effect, though this can  
change if the distance is a precise multiple of a wavelength or  
fraction thereof, thus changing with the frequency (phasing effects).  
The total effect would also be somewhat dependent on how high above  
the ground the total package is, how massive any metallic tower  
structure might be and other minor factors.

But I doubt that, in the situation you describe, you would notice  
much if any change. This is because the major effect would be to  
distort the vertical component of a primarily horizontal pattern.

Any changes you would notice would be more likely to be in the VHF  
reception, the distance between the antennas being a larger portion  
of a wavelength at the UHF frequencies, unless you happen to have  
them an exact WL or fraction apart at some UHF channel.

Any problems you might notice are just as likely to help as to hinder  
reception, and would probably not be consistent over all channels.