[Antennas] Isotron antenna <was> Re: 40m mobileantennae.r.p.compared

Sun May 1 11:41:24 EDT 2005

----- Original Message -----
From: "James Duffer" <dufferjames at hotmail.com>
To: <df3kv at aol.com>; <antennas at mailman.qth.net>
Sent: Sunday, May 01, 2005 4:58 PM
Subject: Re: [Antennas] Isotron antenna <was> Re: 40m
mobileantennae.r.p.compared
>>> snip
>>> >it´s quite typical for dummyloads to have large bandwith...
> >
> >as efficiency is depending on bandwith (Q) you can
> >imagine what to expect
>> Are you saying the wider the bandwidth, the greater the efficiency? Or
are
> you saying the the efficiency is inversely depending on bandwidth?

efficiency is inversely depending on bandwidth
>> I have never owned an Isotron, but I believe they have a very narrow
> bandwidth and have to be tuned, i.e. high Q-narrow bandwidth requiring
> retuning for just a small shift in frequency within the band.

yes, thats which one would expect, any large bandwith shows either
poor concept or poor components when comparing antennas of same
physical lenght
I never tried an Isotron either, but was answering the comment that
its bandwith was wider then a normal vertical which would proof
poor efficiency
a good mobile antenna 2,50m long with high-Q base loading coil
has a bandwith for SWR=2 of about 30KHz on 80m
73
Peter, DF3KV