[mythtv-users] OT Question About OTA Antennas

[William Munson]

Brian Wood wrote:
> James Oltman wrote:
>   
>> I just purchased an HDHR.  Very cool device BTW.  I currently live in
>> the country of Central Illinois.  There's an antenna on the top of a
>> mast attached to the house.  It's probably above the tree line.  The
>> antenna is on a rotor however, the rotor is broken.  This is what the
>> antenna looks like.
>>
>>
>> Top View:
>>
>> | | | | | | | | 
>> | | | | | | | |  || || || || ||
>> --------------------------->
>> | | | | | | | |  || || || || ||
>> | | | | | | | |
>>
>> That's kinda how it looks.  Anyways.  The pointy, narrow tip is
>> currently facing North.  I need to turn it South West.  However, I don't
>> know if the smaller end faces that direction or the larger (wider) end. 
>> Which way should it face?  The way that I'm judging the signal strength
>> is by hooking up the antenna feed (which runs through an amplifier,
>> can't remember model or make) into the VCR and tuning to the analog
>> channel and if that starts to come in better, then I'm assuming the
>> digital will come in better as well (since they come from the same
>> transmitter).  This is all assumptions and hopes and dreams at this
>> point.  AntennaWeb says I should only receive my local FOX station
>> (which I do just fine), but it didn't say anything about the religious
>> channels which I also get.  Any help with the antenna anyone could
>> provide would be helpful.  Thanks!
>>     
>
> The smaller/shorter elements face towards the direction you wish to
> receive signals from (generally the transmitter site unless you have
> HORRENDOUS reflections to deal with.
>
> The basic element of this type of antenna (a "log periodic", which is a
> modified "yagi") is the "driven element". This is the one the signal is
> received from ("driven" refers to when the antenna is used for
> transmitting).
>
> Passive elements are used to increase the directionality of the antenna.
> A "reflector" is larger than the driven element, and is placed behind
> it. A "director" is smaller than the DE, and is placed in front if it.
>
> Usually a combination of many directors and reflectors is used, to
> increase the directionality (or "front-to-back ratio") of the antenna.
>
> (This is an extremely simplified explanation)
>
> So, to answer your question, point the smaller elements towards the signal.
>
> beww
>
>   
To clarify the above point imagine that you are sighting down the main 
shaft of the antenna which is the long shaft attached to the support 
pole. The end with the longest elements is the backside and the short 
elements are the front. Depending on how long that coax cable has been 
up there you may find it does not work very well and may need to be 
replaced.