Gents:
Fig. 5 in the URL is a good depiction of how only a few of the total
elements are actually active on any one frequency. If one could run similar
models for increasing frequencies across the design BW of the LP one would
see the peak current move from the back of the LP (longer elements) towards
the front. It is for this reason that the gain of an LP is considerably
lower for a given boom length than a similar Yagi - only a few elements out
of the six or eight or ten are active at a time. However, the SWR is
maintained at a low level throughout the entire BW, the main advantage of
LPs over Yagis.
73 de
Gene Smar AD3F
----- Original Message -----
From: "jimlux" <jimlux@earthlink.net>
To: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Sent: Sunday, January 24, 2010 1:30 PM
Subject: Re: [TowerTalk] lp V stepIR
> Stuart Browne wrote:
>> Has anyone built an inverted LPDA? Not practical unless you have the
>> land
>> and towers to support it but looks cheap to build and rugged. If you had
>> the
>> height it looks practical for 7-30 mhz.
>>
>> http://plasma.newcastle.edu.au/plasma/research/tiger/venice/Inv_V_antenna_paper.pdf
>>
>> Stu,
>> WH6H
>>
>
> This kind of thing is a mainstay of the commercial HF broadcasting
> world.. take a look at the TCI website. They even make ones that
> rotate! (you move the base around)
>
> A HF broadcast station near me (KVOH) has something that looks much like
> this, using two towers.
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