Topband: Hairpin match to inverted L?

[Tim Shoppa]

Pete, broadly in matching theory, a series-capacitor match can often be
replaced with a series L and shunt C to ground.

Often the topology will be chosen on component value reasonableness and
convenience of what's grounded where. Other times you might have a strong
preference for a matching network with hi-pass vs lo-pass characteristics.

In the specific case of my 160 transmit antenna, the series-capacitor
solution was some ridiculous value. And I found that series L with shunt C
had more workable component values with the added advantage that a regular
old air variable could be used for the C and tuned to accommodate large
QSY's from top to bottom of the 160M band.

OTOH if you have vacuum variables laying around you may find that a more
convenient solution for you.

Tim N3QE

On Sun, Sep 1, 2019 at 2:46 PM N4ZR <n4zr at comcast.net> wrote:

> The other day a ham friend suggested using a coil ("hairpin") to match
> the low impedance of a well-radialed inverted L to 50-ohm coax.  This
> struck me as a potentially-attractive alternative to a series vacuum
> capacitor, but I don't know enough to evaluate it. Thoughts?
>
> --
>
> 73, Pete N4ZR
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