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Old July 26th 07, 11:30 PM posted to rec.radio.amateur.antenna
Owen Duffy Owen Duffy is offline
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First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default matching masts as vertical antennas.

"Wayne" wrote in
news:Ll4qi.15820$U47.4532@trnddc08:

....
Owen

I spent some time pondering this with EZNEC and a smith chart. No, I
can't come up with an inductive way to match it. I learned somthing
today...thanks!


The components for a L matching network may both be L for some range of
loads, but not in the case discussed.

There will also be loads where only a shunt component is required, and
this is often achieved on a short vertical by using less inductive
loading than needed to bring the feedpoint to a purely resistive load.
You can think of it as an L network where the series element is supplied
by the antenna. For example, a short antenna on 3.5MHz with a feedpoint
resistance of say 20 ohms, and a large capacitive reactance can be
inductively loaded to deliver 20-j24.5, and it will require only a shunt
inductor of about 0.9uH to match it to 50 ohms.

(Neither of these are solutions to the original questions, but
interesting sidepaths that show why some configurations work in some
situations.)

Owen