[Top] [All Lists]

Re: Topband: Inverted L Dimensions

To: "mrtman777" <>, "topband topband" <>
Subject: Re: Topband: Inverted L Dimensions
From: "Edward Swynar" <>
Date: Fri, 24 Sep 2010 07:15:54 -0400
List-post: <">>
On 23rd September, Trey wrote:

"...By increasing the length of the inverted L to 5/16 wl, you move the
current maxima up the antenna. If you kept lengthening the antenna, you
would eventually get the current maxima to the junction of the vertical and
horizontal parts. In this case the horizontal part would have as much
current and radiate as much as the vertical part. So by lengthening the
antenna over 1/4 wl, you decrease the percentage of
the total antenna current that is flowing in the vertical portion from the
1/4 wl case. This isn't what we want..."


Hi Trey et al,

Most interesting to me personally, because my system here uses three
inverted "L" elements, each 3/8-wave long & tuned at the respective bases by
large air variable capacitors...

I like that latter feature because it greatly facilitates the resonating of
each "L": you simply adjust the cap, check the SWR in the shack relative to
the design frequency, then repeat as necessary(!)---no pruning, trimming, or
lengthening of wires required...

On the other hand, I would like to maximize the low-angle take-off radiation
of each "L", in order to facilitate the working of DX.

So allow me to run this by the group for comments & criiques, i.e., what if
I was to shorten each "L" from the existing 3/8-wave length, to something
approaching, say, ""...? And what if I left
the tuning capacitor at the base of each "L"...?

I believe that by doing so I'd accomplish two things:

(1) The current node of each "L" would be more concentrated in the vertical
portion of the wire away from the horizontal, thus aiding & abetting the
pursuit of DX, and,

(2) I could still benefit from resonating each "L" with base-mounted
variable capacitors (albeit with much SMALLER "C").

Let the flaming & the sniping begin...! Hi Hi

~73~ de Eddy VE3CUI - VE3XZ

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

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