Isotron antennas
 

I don't know much about these antennas but I have a friend in Colorado who
has one and we often talk on 20 or 40 meters. He has only 100 watts output
and he puts a strong signal into Alabama. It certainly seems to work for
him. I have a Carolina Windom and I believe his Isotron performs better
than my windom.


Bill W4WEG


"Dave Oldridge" wrote in message
9...
I've been seeing pictures of these weird antennas for years. Near as I
can
tell from the picture, it's essentially a heavily-loaded very short dipole
with two large capacity hats at the ends. But it's impossible to tell
from
the pictures what the exact configuration is. Can anyone tell me exactly
what's happening? Is the mast part of the radiating system? The
feedline?
The literature (including the manuals) sort of implies that it is.

Also, from the pictures, I get the impression that the standard mast-mount
configuration is mostly vertically polarized. This would certainly
account
for reports I have read that the antenna is a bit of a dud at short range
on 80m.

If someone has a computer model for it for MMHAMSOFT's modeller, that
would
be GREAT!

The reason I'm asking is that I'm in the process of trying to design
something really low profile for a second floor apartment balcony for 75
and 80m.

--
Dave Oldridge+
VA7CZ
ICQ 1800667

Isotron antennas
 

Bill Grimwood wrote:
I don't know much about these antennas but I have a friend in Colorado who
has one and we often talk on 20 or 40 meters. He has only 100 watts output
and he puts a strong signal into Alabama. It certainly seems to work for
him. I have a Carolina Windom and I believe his Isotron performs better
than my windom.

Due, no doubt, to radiation from his feedline. If you both
replaced the vertical section of your feedline with a good
ground-plane vertical, it might improve even more.
--
73, Cecil http://www.qsl.net/w5dxp

Isotron antennas
 

Cecil Moore wrote:
Bill Grimwood wrote:

I don't know much about these antennas but I have a friend in Colorado
who has one and we often talk on 20 or 40 meters. He has only 100
watts output and he puts a strong signal into Alabama. It certainly
seems to work for him. I have a Carolina Windom and I believe his
Isotron performs better than my windom.


Due, no doubt, to radiation from his feedline. If you both
replaced the vertical section of your feedline with a good
ground-plane vertical, it might improve even more.


Bill;

The best antenna for you is the antenna that works. I use a B&W folded
dipole antenna daily. It does the job I need it to do. There are those
that deride it as a "lossy dummy load". What it is is an antenna that
dumps any excess energy into a 600 ohm resistor. The excess energy is
that which is reflected back into the finals by any other antenna. It
allows me to QSY and be tuned to any frequency I wish to use. In that I
use NTIA frequencies in addition to Ham frequencies this it the best
antenna for my use. As I said it works.

Dave WD9BDZ

Isotron antennas
 

David G. Nagel wrote:
The excess energy is
that which is reflected back into the finals by any other antenna.

Sorry, in a tuned system, the "excess energy" is re-reflected
back toward the antenna at the match point. Here's an example:

100w XMTR--50 ohm coax--+--1/2WL of 300 ohm twinlead--50 ohm antenna

More than half the forward power is reflected from the antenna
but it is turned around and re-reflected back toward the antenna
at the coax/twinlead junction at point '+'. The reflected energy
reaching the finals is ZERO!

Reflected energy, per se, is not bad. Reflected energy that is
allowed to reach the finals is bad. In most systems, an antenna
tuner solves the problem.
--
73, Cecil http://www.qsl.net/w5dxp