[Antennas] resonance

[Robert Lay (W9DMK)]

I don't see the problem, Frank. Of course you can verify what Steve says, 
just as easily as you can verify the 75 ohms at 1/4 wavelength above ground. 
Where's the problem?

73 de W9DMK - Bob Lay, Dahlgren, VA
http://zaffora.f2o.org/W9DMK/W9dmk.html
w9dmk at crosslink.net

> Steve wrote:
>> Resonance is actually a function of the antennas
>> electrical length. The fact that the exact center of a
>> half wave dipole is purely resistive at resonance is a
>> happy coincidence. It is possible (common actually) to
>> have a resonant antenna who’s feed point isn’t purely
>> resistive or even close to the 75 ohm value of a dipole.
>> For instance if you were to keep the length of the dipole
>>  exactly the same and tap it at a point other than the
>> exact center the feed point wouldn’t be purely resistive
>> or anywhere near 75 ohms but the antenna would remain
>> resonant.
>
> How would you know that it remained resonant?  How would you test that? 
> The only test I have is to verify 75 ohm resistive impedance at the center 
> with the antenna 1/4 wavelength above electrical ground.
>
> I figure if it cant be verified, it may not be true regardless of how 
> logical is sounds.
>
> Regards,
> Frank Kamp