G3JKV was right too. Please let us stop this discussion before
more internet bandwidth is wasted. Such a discussion will not
lead anywhere because of the laws of nature.
It was stupid of me to enter the thread. I apologize.
73 de Johan Bodin, SM6LKM
I think that it was unnecessary for Johan to apologise for starting a
discussion on unconventional LF antennas. And surely the purpose of
the the LF reflector is to discuss technical matters.
What Johan was probably not aware of is the controversy (in the UK)
surrounding the Cross-Field antenna CFA, which was invented by
Maurice Hately, GM3HAT. The CFA has been advertised by GM3HAT in
Radcom for more years than I care to remember. It was also described
in the Wireless World several times (although the last article called
'CFA-RIP' described a research graduate's unsuccessful attempts to
get this antenna working).
About 3 years ago I attended a lecture by GM3HAT on the CFA antenna,
which appeared to have now evolved into a loop antenna with a tuner
unit with lots of switches. The lecture was professional enough and
we were all baffled with science with Maxwell equations and Pointing
Vectors. When it came to the practical demonstration the lecturer was
zapped by RF when he pressed one of the tuner switches, which could
be an indication that it was radiating. On receive it seemed to work
as well as any one metre length of wire. I suggested that the host
club review this antenna, although nothing ever emerged.
Terry Littlefield, KA1STC, (editor of Communications Quarterly) wrote
an editorial about junk science, quoting Cold Fusion as an example.
In this he says: "Like other forms of science, amateur radio has its
junk disciples. Most often these guys are heavily invested in an
experiment gone wrong (and they just don't know it) concerning an
antenna or feed system." Terry then goes on about objectivity in
experimental work and that he had been caught out a couple of times
by an idea that sounded incredibly interesting and innovative, but
lost its lustre in the bright light of day.
My first big editing job when I became Technical Editor at the RSGB
in 1994 was Roger's, G2AJV, toroid antenna. I felt that such a
radical antenna, see [1], could only be published if it could be
shown to work. I built one but had a few difficulties with it until
the problems of feeding it were overcome. I then made two more and
the results were described in [2].A double-toroid antenna used as a
mobile antenna gave about 1S-point less than a conventional centre
loaded mobile antenna. EZNEC2 predicts a gain of a centre loaded
mobile antenna of around 0.19dBi. If we could get a gain figure of
around -7dBi for an LF antenna, then big PAs would be redundant!
The toroid antenna is not new. It was first mentioned in Amateur
Radio Literature by Pat Hawker in Radcom's TT in October 1983[3],
which described a patent on this antenna by James Corum, K1AON[4].
The Marconi antenna, which most of us use on LF, was invented over
three quarters of a century ago and is described in The Admiralty
Handbook of Wireless Telegraphy 1925. While compiling the material
for the LF chapter of the Communications Handbook, I received a
description and extensive comparison testing of HB9ASB's helical
antenna, which exhibits at least 3dBs gain over a Marconi of the same
size. Toni's description is a good example of how good objective
antenna experimentation should be done.
Finally, some years ago a description of CFA antenna appeared in the
SPRAT (G-QRP Club) magazine although the construction was totally
different to the GM3HAT antenna. This guy was having QRP QSOs with
this little antenna. Has anyone got some old SPRAT mags with these
(there were 2) articles?
REFERENCES
[1] 'The G2AJV Toroidal Antenna', Roger Jennison, G2AJV, Radio
Communication, April and May 1994.
[2] 'Evaluation of the G2AJV Toroidal Antenna', Peter Dodd, G3LDO,
Radio Communication, August 1994
[3] 'Toroidal Helix Antennas', Pat Hawker, G3VA, Technical Topics,
Radio Communication,October 1983.
[4] The James Corum patent on the toroid antenna is available from
The British Library, Science Reference and Information Service, 25
Southampton Buildings, London WC2A 1AW; enclosing a cheque for £10
and quoting Patent Application EP 0 043591. (check the price - this
was correct in 1994!).
--
Regards, Peter, G3LDO
<[email protected]>
|
