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Topband: 160 metre vertical with 'top loading'

To: "160 reflector" <topband@contesting.com>
Subject: Topband: 160 metre vertical with 'top loading'
From: "Tom Boucher" <tom@telemetry.demon.co.uk>
Reply-to: Tom Boucher <tom@telemetry.demon.co.uk>
Date: Tue, 26 Apr 2011 09:49:42 +0100
List-post: <topband@contesting.com">mailto:topband@contesting.com>
I take your point Yuri, but my simplistic way of looking at the current 
decreasing along a straight quarter wave of wire is due to the current flow 
through it's distributed capacitance to ground. Maybe that is wrong and I 
should go back and look at my transmission line theory.  

Surely the fact that it is an electrical quarter wave is due to the straight 
wire being part of one very large coil turn and therefore having an inductance, 
combined with that distributed capacitance causing resonance at one particular 
frequency? If that is so, then isn't my theory of the current decay being due 
to flow through distributed capacitance along it's length still correct?

AA7JV said that the argument against current at both ends of the loading coil 
being the same, is that you cannot have high current and high voltage at the 
top of the coil because that represents much higher power than you are sticking 
into the base of the antenna. That's not true because we are talking about VA 
not Watts, i.e. there is a phase difference between V and I.

73
Tom G3OLB


<He is not correct!
<Have you looked at the "piece" of wire - quarter wave antenna, having the max 
current at the base and ZERO at the tip? And voltage low at the base and high 
at <the tip - corona?
<Where did the current go?
<It is the STANDING WAVE circuit, with superimposed forward and reflected RF 
currents creating cosinusoidal distribution ALONG the wire and not the DC 
<circuit.
<Why is it hard so understand that if current can vary along the straight wire, 
it can wary along the coiled wire too?


<Yuri K3BU.us

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UR RST IS ... ... ..9 QSB QSB - hw? BK

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