[TowerTalk] Resonance is over rated

[Blair S Balden]

Hi everyone,
Wouldn't a better definition of a resonant circuit be a circuit that has reactance, but where the capacitive reactance is equal to the inductive reactance?  That would exclude a purely resistive circuit.  The concept of resonance does not seem appropriate for purely resistive circuits, where the response is not frequency-dependent.  
Blair
 

----- Original Message -----
From: Clay W7CE <w7ce at curtiss.net>
Date: Friday, August 7, 2009 4:45 pm
Subject: Re: [TowerTalk] Resonance is over rated

> The definition of electrical resonance is when the circuit 
> reactance is 
> zero.  An antenna has zero reactance and is only resistive at it's 
> resonant 
> frequency.  A perfect dummy load has no reactance on any frequency 
> and is 
> resonant on all frequencies.  Resonance has absolutely nothing to 
> do with 
> the ability of an electrical circuit (antennas and dummy loads are 
> both 
> electrical circuits) to radiate electromagnetic energy.
> 
> 73,
> Clay  W7CE
> 
> ----- Original Message ----- 
> From: "Jeff Carter" <towertalk at hidden-valley.com>
> To: <towertalk at contesting.com>
> Sent: Friday, August 07, 2009 12:52 PM
> Subject: Re: [TowerTalk] Resonance is over rated
> 
> 
> >I respectfully submit that none of that makes any sense in the 
> context> of a dummy load.
> >
> > A dummy load isn't resonant, it's resistive.  It's a big ol' 
> resistor> mounted in some sort of heat-dispersing set up.  When 
> the other poster
> > said he read 55 + j0 he wasn't kidding: The zero part of that means
> > that it's a resistive measurement.  A negative j (or i, if 
> you're a
> > math major) means the system is more capacitive, a plus j is more
> > inductive.  A zero means it's neither from a practical point of 
> view.>
> > Or so they told us in college.
> >
> > Jeff/KD4RBG
> >
> > ---- Original message ----
> >>Date: Fri, 7 Aug 2009 14:17:47 -0500
> >>From: "Perry - K4PWO" <k4pwo at comcast.net>
> >>Subject: Re: [TowerTalk] Resonance is over rated
> >>To: "Scott McClements" <kc2pih at gmail.com>,<towertalk at contesting.com>
> >>
> >>Resonance, in the normal sense has nothing to do with the value 
> of 
> >>impedance
> >>only in a minimum (for a series tuned configuration) or maximum 
> (parallel>>tuned).  While its possible to make the argument that a 
> dummy load is a
> >>resonant "antenna" with a Q of 1 (Q=Fr/BW or infinity/infinity) 
> the 
> >>concept
> >>of a "resonant frequency" of infinity is counter intuitive.  
> Since "dummy
> >>loads" are made with real world components, we know that the 
> "resonant>>frequency" can not be infinity.  So in that sense, the 
> "dummy load" is a
> >>very low, non unity Q "resonant circuit" but it fails in fitting 
> a second
> >>order differential equation for circuit analysis.  If the shoe 
> doesn't>>fit...
> >>That still doesn't negate the fact that radiation efficiency is 
> the key to
> >>propagating a signal.
> >>BTW, I operate a fairly effective "dummy load" on HF... a B&W 
> BWD-180
> >>terminated folded dipole.  It's pretty flat from 1.8 to 30 MHz. 
> but its
> >>efficiency is all over the place in that range.
> >>It works but...
> >>
> >>73 de Perry - K4PWO
> > _______________________________________________
> >
> >
> >
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> 
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> 
> 
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