Inverted L's have similar bandwidth to a 1/4 wave vertical...and it isn't
"real broad" without excessive return loss. All measurements need to be made
at the feedpoint. I've done radial studies on my Inverted L and as radial
numbers increase, vswr bandwidth DECREASES, exactly as it should. I made
measurements of feedpoint Z at resonance and 2:1 vswr bandwidth with the
following number of radials:
VSWR bandwidth was best with 0 radials (DUH...lots of resistive loss!)
Feedpoint Z dropped from 79 ohms with 0 radials to 29 ohms with 26 radials.
The predicted Rrad is 25.4 ohms
----- Original Message -----
From: "Robert Chudek - K0RC" <firstname.lastname@example.org>
Sent: Thursday, July 13, 2006 5:50 PM
Subject: Re: [TowerTalk] Question on Multiple Inverted L Antennas
> Here we go again... so which is it? Inverted L's have plenty of bandwidth
> or Inverted L's little bandwidth???
> First, let me say if you are not taking your measurements AT THE
> FEEDPOINT, you are not seeing the true story. Second, a large bandwidth is
> not necessarily a good thing. The longer and more lossy your transmission
> line, the better your antenna is going to look from the shack.
> Here's an example of what I'm talking about... I have a low 160m inverted
> vee which I plotted VSWR graphs at the feedpoint and again at the end of
> 230 feet of rg8x coax. I made absolutely no antenna changes between these
> two measurements. I posted the superimposed VSWR and RETURN LOSS curves on
> my website, here: http://tinyurl.com/oh87y The two PDF files are 72-KB
> each and can be downloaded and viewed using Adobe Acrobat Reader.
> In this specific example, measuring at the end of the coax leads you to
> believe you have 35% better bandwidth than in reality.
> 73 de Bob - K0RC
>> On 13 Jul 2006 13:20 WA3AFS wrote:
>> Please be aware that the bandwidth for a coaxial inverted L is very
>> broad. My SWR at 1.800 is 1.3 and slowly rises to 1.7 at 2.000Mhz.
> But then on 13 Jul 2006 at 13:11, K4SAV wrote:
>>> The biggest problem you have with low band multiple L antennas is
>>> matching and bandwidth. To start with, a 160 meter L will not have a lot
>>> of bandwidth...
> TowerTalk mailing list
TowerTalk mailing list