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Re: [TenTec] OT SWR VS Power Loss

To: tentec@contesting.com
Subject: Re: [TenTec] OT SWR VS Power Loss
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Reply-to: geraldj@storm.weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 07 Jul 2008 18:36:43 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
On Mon, 2008-07-07 at 14:52 -0700, Alfred Lorona wrote:
> Zero reactance in a wire antenna feedpoint is a necessary but not sufficient 
> condition for it to be truly resonant. Citing the Antenna Fundamentals, chap 
> 2, page 2-1 of my 16th addition of The ARRL Antenna Book, a resonant wire is 
> defined as 'The shortest length of wire that resonates at a given frequency 
> is one just long enough to permit an electrical charge to travel from one 
> end to the other and back in the time of one RF cycle.'

That limits a resonant antenna to those without any loading. That
definition is too narrow because of that.
> Clearly, a short wire with a finite pure resistive radiation impedance is 
> too short physically for the required condition to exist as stated in the 
> Handbook definition..

So having a resistive feed Z by adding a loading coil to a short wire is
not resonant. I disagree. 
> On the other hand, elsewhere in the book, a zero reactance 'resonant' 
> condition does not mention the required physical length of the wire.

Perhaps because that is allowing for loading coils and/or trimming

> If this 
> is all that is required, ANY wire can be called resonant and there is 
> nothing to distinguish such wires from a halfwave wire.

Not so, because if loading coils or trimming capacitors are not allowed
the only way a wire can have resistive feed point impedance is for that
wire to be a multiple of 1/4 wave long, or there is no wire, only a

> Somehow this doesn't 
> sit right with me. What do you think? Do you think that this discrepancy 
> begs for a minor clarifying rewrite?
> 73, AL 
73, Jerry, K0CQ

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