[mythtv-users] Understanding HD Antennas ( was HDHomeRun and jumpy video)

Drew Tomlinson drew at mykitchentable.net
Mon Oct 1 14:46:01 UTC 2007


On 9/26/2007 1:32 PM Brian Wood said the following:
> Drew Tomlinson wrote:
>   
>> On 9/15/2007 8:51 PM Brian Wood wrote:
>>     
>>> Kevin Hulse wrote:
>>>   
>>>       
>>>> On Sat, Sep 15, 2007 at 11:29:42AM -0600, Brian Wood wrote:
>>>>     
>>>>         
>>>>> Michael T. Dean wrote:
>>>>>
>>>>>       
>>>>>           
>>>>>> I tested the antenna balanced on a ladder in my front room and found it
>>>>>> worked pretty well.  It worked significantly better in the attic
>>>>>> (because it was higher).
>>>>>>         
>>>>>>             
>>>>> The general rule is: twice the height, twice the signal.
>>>>>       
>>>>>           
>>>> 	Now that's a handy bit of information... thx.
>>>>     
>>>>         
>>> As was pointed out it's a "rule of thumb", not entirely accurate and
>>> subject to a lot of possible factors that can change it, but it is more
>>> or less correct most of the time.
>>>   
>>>       
>> I had read somewhere that there are "heights" or "rows" (?) that provide 
>> better reception than others.  In other words, if one mounts his antenna 
>> in between the good reception "heights", lowering it into the next lower 
>> good "height" will get better reception even though it's lower.  Is this 
>> true and if so, how can one tell at what heights are optimum for mounting?
>>     
>
> It is *theoretically* true, under some conditions (generally only found
> on an antenna test range).
>
> At the extreme, at microwave frequencies (over 3Ghz.), you can get
> "fresnel zones" where this effect shows up clearly.
>
> At TV frequencies, even UHF ones, with common TV antenna designs and
> under real world conditions you can pretty safely ignore it.
>
> TV antennas are designed to receive a very wide range of frequencies,
> and the effects you speak of are very frequency-dependent. So, if you
> found an "ideal" height for one channel it would almost certainly not be
> ideal for other channels.
>
> All broad-band TV antenna designs are a series of major compromises.
>
> This is of interest to wave propagation and antena design experts, and
> is not really of practical use to homeowners.

Thanks for the explanation.  I have a Winegard Square Shooter mounted to 
the chimney that works very well for me at about 35 miles from the 
towers.  There are 11 cable runs in the house (which I know is WAY too 
many but that's what was there when we bought it) and I get signal 
strengths of 70% or more.

Cheers,

Drew

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