Reg Edwards wrote:
"Ron" wrote hello all,

is there anybody who can give me detailt information about the
dimensions of a isotron-antenna for the 160m-band? any links or
homebrew-descriptions?

============================
Ron, my guess is that none of the replies to your question are from people
who have ever used or have even seen the antenna.

Not used, but I have seen them. Arguably the most attractive antenna out
there. i hop

With plenty of idle time to spare they are just repeating old wives'
rumours
for a little mischievous amusement.

I've read a fairly in depth report on one of the EH antennas. They said

it worked. And the feedline radiation seemed to be what made it work. I
haven't used a backpacker, but their work looked good enough to give it
some credibility.

What do you think about the information that they publish

http://www.rayfield.net/isotron/isohow.htm

Claiming the transmit performance is the same as a half wave dipole, and
the noise on receive is 3 db down from a half wave dipole? This would
seem to indicate that the Isotron is a *superior* antenna as compared to
a dipole. They don't mention anything about radiating feedline. So okay,
maybe the feedline doesn't radiate.

Its *hard* to imagine why anyone would use anything else!


From its construction I estimate its performance to be marginally worse
than a magloop of the same physical size and operating frequency. And
magloops don't do too badly, do they?


- Mike KB3EIA -


The isotron design is low efficiency, approximately 2-15%, depending on the
frequency/model you have. Efficency isn't everything though in real antenna
systems:
It approximates a point source in a highly multipathed environment. Therefore
there are positions of placement/times where the antenna is in a gain-volume
(as opposed to a null-volume) from the multipath. Ergo it will have a
measureable dBm approximating a dipole in the far field. This is a transient
effect and depends on ground; environment; and height.

However, there are times where an isotron can be placed quite high, whereas the
phase center of a dipole cannot (because the dipole is much bigger; bulkier;
unsightly.) Then the enhancement over higher ground can give a seeming
approximate equality or advantage over the much lower dipole.

In true free space, the isotron is a mediocre/poor antenna, in my opinion. In
real environments, it does have a useful niche, especially if you do 30, 40, or
80 M and can get it 50 or more feet up. There are reports of folks who put
isotrons on top of apartment buildings and really kick butt. I doubt they win
contests, but I'm sure they have a good time!

I have never seen anything deceptive in isotron's ads.

73,
Chip N1IR