[AMRadio] antenna tuners


david knepper collinsradio at adelphia.net
Fri Apr 21 05:21:37 EDT 2006


Could you please explain, using an MFJ antenna analyzer, what is the meter 
showing on the instrument?

I would think that the total system, that is feedline and flat top or 
antenna if you prefer,  is resonating at the point shown on the meter? Or am 
I wrong?  In any case, I love that device for checking out the "resonant" 
point of the antenna system - note that I did not say just antenna.


Thank you

Dave, W3ST
Publisher of the Collins Journal
Secretary to the Collins Radio Association
www.collinsra.com - the CRA Website
Now with PayPal
CRA Nets: 3805 Khz every Monday at 8 PM EST
and 14255 every Saturday at 12 Noon EST
----- Original Message ----- 
From: "Gary Schafer" <garyschafer at comcast.net>
To: "'Discussion of AM Radio'" <amradio at mailman.qth.net>
Sent: Thursday, April 20, 2006 10:12 PM
Subject: RE: [AMRadio] antenna tuners


> This is another tidbit to keep in mind for those that still may think that
> an antenna has to be resonant to give 1:1 swr.
>
> A dipole antenna rarely is 50 ohms at resonance. It is very dependent on
> height above ground as to what impedance it presents at the feed point. It
> can range anywhere from below 30 ohms to above 70 ohms.
>
> So if you cut your antenna so that you have 1:1 swr at the transmitter end
> of the coax, the antenna is probably not tuned to resonance! You have
> detuned the antenna to change its impedance that the coax sees.
>
> Only rarely does a resonant antenna turn out to be 50 ohms.
>
> 73
> Gary  K4FMX
>
>
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