Something either has capacitive or inductive reactance, both not both at the
same time.
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Blair S Balden
Sent: Saturday, August 08, 2009 12:10 AM
To: Clay W7CE
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Resonance is over rated
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@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@hidden-valley.com>
> To: <towertalk@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@comcast.net>
> >>Subject: Re: [TowerTalk] Resonance is over rated
> >>To: "Scott McClements" <kc2pih@gmail.com>,<towertalk@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
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
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