[TowerTalk] Dipole resonates lower than expected.

[Rajiv Dewan, N2RD]

Commenting on Tom's comment, the shift in frequency of x=0 point  
occurs because the characteristic impedance of the feedline does not  
match that of the antenna.  If they did, the x=0 point, as measured  
inside the shack, would coincide with the resonant point of the antenna.

Raj

--
Rajiv Dewan, N2RD
n2rd at arrl.net
FN13fc

--

On Oct 17, 2005, at 10:14 AM, Tom Rauch wrote:

>> All the responses have addressed the effects of insulation
>>
> on the
>
>> wire, Bob.  But, no one has commented on what the analyzer
>>
> result was
>
>> in a 75 ohm system.  Does your analyzer evaluate 75 ohm
>>
> systems or
>
>> 52/50 ohm systems?
>>
>
> That doesn't matter Dale. He is reading R and X on the
> analyzer, not SWR.
>
> What you say about tuning the combined system does matter.
>
> If the feedline has standing waves the only time an analyzer
> inside the house will directly indicate actual antenna
> resonance  is when the feedline is an exact multiple of 1/4
> wl long. If the feeder is not an exact multiple of 1/4 wl
> and has standing waves, it will cause the X=0 point to shift
> frequency from the value at the antenna.
>
> I'd bet not many people consider that fact when setting
> resonance.
>
> 73 Tom
>
>
>
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