On Sep 30, 4:37*pm, Owen Duffy wrote:
JIMMIE wrote :

...

The evaluation of this antenna should start with connecting a choke
type BALUN at the input to isolate feedline radiation. A few feet of

Then it is not the same antenna as described.

I agree with your implication that an antenna of this type warrants an
attempt to minimise common mode current on the feedline... but that is
not a part of the design as described.

I have not said anywhere that this antenna doesn't 'work' or does 'work'
whatever that means, just commented on their opinion that it defies
conventional explanation.

They haven't suggested that the problem is their own limitation in
modelling or explaining, so it is reasonable to assume that their
implication is that it just cannot be explained in conventional terms and
using accepted tools.

I have questioned that assertion, I think it is not all that difficult to
model. It presents no more challenges than dealt with in my models of a
Bazooka (http://www.vk1od.net/DoubleBazooka/index.htm)andG5RV
(http://www.vk1od.net/G5RV/index.htm) assuming an ideal balun.

I know the ideal balun condition appears inconsistent with my first par,
the problem is that including the feedline common mode path in the model
is complicated by the huge variability from one installation to another,
both the length and route. (It is possible to model the antenna with a
specific common mode configuration... it is just that is has limited
applicability.)

I am tempted to do it one day. Although it isn't the same antenna in that
it has a balun, it is revealing. My gut feed is that the antenna with
balun is probably not that band on at lease many of the HF bands... more
if you ditch the coax section and use open wire feeder to a balanced
ATU... but we are moving further from the original.

Having said that, I do think the published VSWR figures at 145.3MHz are
fanciful and highlight your average ham's obsession with VSWR, as if that
single metric was a good indicator of system performance.

Owen

With enough RG58 any antenna's VSWR looks pretty good.

Jimmie