[Amps] *** SPAM *** Re: Antenna traps
Steve Thompson
g8gsq at eltac.co.uk
Fri Dec 16 10:27:05 EST 2005
Ian White GM3SEK wrote:
>
> Let's think of two totally generalized impedances, (R1 in series with
> jX1) and (R2 in series with X2). In this context X1 and X2 can have
> either sign.
>
> Now add series elements -X1 and -X2 to cancel both reactances out. We
> now have resistive impedances R1 and R2, which can be matched with the
> minimum-Q solution using two elements in one of the L-network
> configurations.
This is where I started - but you can always add a first element to take
you to a pure resistance that's nearer your target than (say) R1 is.
Then, the L match from the new resistance to target will have a lower Q
than the one from R1 to target and the three elements give you lower Q
than two.
I think the train of thought can be valid where you can't choose
whichever of the L match permutations is needed for minimum Q - that's
the trap I fell in to.
Steve
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