[Top] [All Lists]

Re: [Amps] Antenna traps

To: "R.Measures" <>, Jim Brown <>
Subject: Re: [Amps] Antenna traps
From: Peter Chadwick <>
Date: Thu, 15 Dec 2005 09:16:18 +0100 (CET)
List-post: <>

Rich said:
>One advantage of a trap-less center-fed wire fed with ladder-line and a 
balanced L network tuner is that if it turns out that a reactance arcs 
or melts down, retrofitting a more capable L or C does not require 
bringing down the antenna.<

However, the classic parallel or series tuner has the advantage that the 
working Q can be controlled, which is not the case with an L network. In the L 
network, the working Q is fixed by the impedance transformation ratio. So an 
impedance which leads to the matching network working Q being high in an L 
network can lead to flashover or melting, while the parallel or series tuned 
circuit can have its proportions set to prevent this. Suitable designs appeared 
in ARRL handbooks 50 years ago.
But the other advantages of the centre fed open wire line dipole remain. Plus 
it's inherently capable of use over a very wide frequency range.
Peter G3RZP
Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>