Isotron-antenna ?
Joachim Seibert
Dear reader,
I am looking for information on the Isotron-antennas. My main interest
is in
"home-building" such a thing... What kind of experience did You make
with
Isotrons?
Best 73s, Joachim DL1GSJ
--
best regards, Joachim Seibert
Cecil Moore
Mandy Wright wrote:
> Can you explain what you mean by "Isotron"? Can you check the
> definition and English translation? Then we may be able to help.
Hi Mandy, the "Isotron" antenna is a trade-name used by Bilal Co.
for an extremely folded antenna attempting to fool Mother Nature.
IMO, almost anything short of a dummy load would be more efficient
and it is not worth the money.
As far as I know, they haven't published any gain figures. Their
main claim to fame seems to be, "Six Excellent Reviews Just Don't
Happen By Chance", whatever that is supposed to mean.
73, Cecil, W6RCA, OOTC (not speaking for my employer)
Mandy Wright
In article <32674A...@hpfr01.physik.uni-freiburg.de>, Joachim
Seibert <sei...@hpfr01.physik.uni-freiburg.de> writes
>Dear reader,
>
>I am looking for information on the Isotron-antennas.
Can you explain what you mean by "Isotron"?
We think this refers to magnetic deflection of isotopes.
Therfore we assume isotropic and this is a theoretical concept used in
antenna design!
Can you check the definition and English translation? Then we may be
able to help.
Good luck.
>My main interest
>is in
>"home-building" such a thing... What kind of experience did You make
>with
>Isotrons?
>
>Best 73s, Joachim DL1GSJ
>
>--
>best regards, Joachim Seibert
>
>Mailto:sei...@hpfr01.physik.uni-freiburg.de
Mandy
(Replying on behalf of my husband (G1BCR / G9BZW) who hates computers
despite being a practising RF Engineer!)
Sussex
UK
Stephen Walters
Hi mandy,
There is a simple rule with antennas:- Get as much metal in the sky as
possible.
It's as simple as that.
Steve
G7VFY
R. L. Measures
> Dear reader,
>
> I am looking for information on the Isotron-antennas. My main interest
> is in
> "home-building" such a thing... What kind of experience did You make
> with
> Isotrons?
>
> Best 73s, Joachim DL1GSJ
>
> --
> best regards, Joachim Seibert
>
> Mailto:sei...@hpfr01.physik.uni-freiburg.de
===============================
When the Isotron antenna appeared on the market, the manufacturer tried to
advertise the Isotron in *QST*. In those days, *QST* required
manufacturers who wanted to advertise a product in *QST* to send a sample
for evaluation in the ARRL Lab. When an Isotron antenna was Lab tested at
400W, it reportedly smoked and caught on fire. Since Isotron antenna
advertising in other magazines showed a picture of a baby standing next to
an Isotron antenna, *QST* staffers nicknamed the product the "Isotron Baby
Burner". Would you want to put one of these babies in your attic,
Joachim? Subsequently, *QST* declined to accept advertising for the
product.
A safer, virtually invisible, and more effective antenna is the thin,
end-fed wire. The optimum length is about 10% less than a halfwave at the
lowest operating frequency, although one as short as quarterwave works
semi-OK. The wire can be quite thin. #30 (0.25mm) copper will easily
handle 2kw if it is a quarter wave or more in length. The end-fed antenna
is fed against ground or a counterpoise. The total angle of bends in the
antenna should not exceed around 85 degrees. The best matching device is
the simple L-network, which should reside on a wood shelf under the window
from which the antenna enters the house. The measured Z of my 160m
end-fed antenna is 5000 ohms at halfwave-resonance, so such an antenna
needs to be well insulated where it passes through the window. A 0.3mm
carbide drill can be used to make a hole in the glass windowpane. The
center and far end of the antenna should be as high off the ground as
possible. Black100%-Dacron' heavyweight thread can be used to support
the middle and far end of the wire. (Dacron is RF resistant, and black is
UV resistant.) I tried nylon monofilament fishing line, and it melts
when it is fastened to a voltage node on the wire.
30 gauge end-fed wires don't last very long. In this neighborhood the
most common problem is the Great Horned Owl. Fortunately, owls are
intelligent, so once the word gets out that you have a wire up in a
certain place, they will avoid it in the future. The good news is that
end-fed antennas are quite cheap to replace.
One way to facilitate hanging the antenna from high objects is with a
fishing weight and a slingshot. The far end of the antenna should be at
least 2m away from any tree.
--
--Rich-- ag6k, 805.386.3734
rog...@ibm.net
In <SbYJHOAs...@mrwolf.demon.co.uk>, Mandy Wright <Ma...@mrwolf.demon.co.uk> writes:
>In article <32674A...@hpfr01.physik.uni-freiburg.de>, Joachim
>>Dear reader,
>>
>>I am looking for information on the Isotron-antennas.
Isotron antennas are a trade name for a type of antenna manufactured and
sold by Bilal Co. in Colorado. They sell by mail order, and normally have
a monthly ad in CQ and QST.
I've used them. E-mail me if you have questions.
Roger J. Buffington
W6VZV
rog...@ibm.net
USC Law School, Class of '97
--------------------------------------------------
"I want to die peacefully, in my sleep, like my Grandfather."
"Not screaming, and in terror, like his passengers."
--------------------------------------------------
Claude Frantz
rog...@ibm.net writes:
>Isotron antennas are a trade name for a type of antenna manufactured and
>sold by Bilal Co. in Colorado. They sell by mail order, and normally have
>a monthly ad in CQ and QST.
>I've used them. E-mail me if you have questions.
Please give us your opinion here. There are probably many hams interested.
--
Claude
(cla...@bauv106.bauv.unibw-muenchen.de)
The opinions expressed above represent those of the writer
and not necessarily those of her employer.
Curt Phillips
Joachim Seibert <sei...@hpfr01.physik.uni-freiburg.de> wrote:
>I am looking for information on the Isotron-antennas. My main interest
>is in
>"home-building" such a thing... What kind of experience did You make
>with
>Isotrons?
A retired radio engineer in the Raleigh Amateur Radio Society has built a
couple of "homebrew, Isotron-type" antennas with pretty good success.
I don't think he's on Internet, but I'll check. If he can't e-mail you,
I'll see if I can get him to put some of his experiences on diskette, and
I'll e-mail them to you.
========= Opinions expressed are solely those of the author ==========
Curt Phillips, CEM KD4YU (ex-WB4LHI)|"I don't want to achieve
Engineer/Writer/Gadgeteer/Raconteur | immortality through my work.
Chairman, Tar Heel Scanner/SWL Group| I want to achieve it through
ARRL Life; QCWA; Raleigh ARS; NRA | NOT DYING." -- Woody Allen
==== cphi...@pobox.com ==== [Copyright 1996 All rights reserved]====
rog...@ibm.net
No problem. I was in a hurry yesterday.
20M Isotron:
My 20M Isotron worked, but not well. It had a good SWR curve. However,
its signal on both receive and send was consistently 2 to 3 S-units (not DB)
below a wire dipole at a similar height. The antenna is definitely inferior
to a wire dipole by a huge margin.
My 40M Isotron loaded up OK, but did not appear to work at all well. It
essentially acted as nothing but a dummy load. It was completely unusable.
This was my experience, as well as another local ham's, using two different
Isotrons. Bottom line: I don't think that the 40M Isotron is a working product.
My advice is that any wire antenna of a conventional type will be a much better
choice than the Isotron. I would not recommend the Isotron to anyone for
any purpose.
Mandy Wright
In article <54qsmf$3ebe$2...@news-s01.ca.us.ibm.net>, rog...@ibm.net
writes
1) For less than 1/4 wavelength Radiation resistance is proportional to
the square of the length
2) Loss resistance is proportional to the length
3) Earth losses are constant, determined by the location
Efficiency = Rr/Lr+Er+Rr
Where Rr = radiation resistence
Lr = conductor loss resistance
Er = earth loss resistance (This is known as SODS LAW!)
Mandy
(Replying on behalf of my husband, Tim (G1BCR / G9BZW), who hates computers
despite (or maybe because of) being a practising RF Engineer.)
(He's going to *have* to learn to type!) Sussex UK