Re: NEC-LIST: cross field antennas

Hello Grant,

On Friday you wrote:

> Jack, I recall seeing an article showing the cross-field concept to
> be a fraud, but can't put my finger on it at the moment. Do you
> recall where that might have been published? I think there were
> some similar debunking articles perhaps 15 years ago in the IEEE
> Transactions on Broadcasting, re the Bibey antenna.
>
> Grant Bingeman
> Continental Electronics
> Dallas

I do not know anything about the Bibey antenna, but I do know a little
bit about the Hatley antenna.

In 1989 (see Electronics + Wireless World, March, July and November,
1989, and December 1990) and in following years, Maurice C. Hatley,
GM3HAT describes a cross-field antenna (CFA), in which quadrature E
and H fields are separately generated. In the words of the inventor,
reversing the form of Maxwell's equations led to the "realization and
development of this revolutionary new antenna system". Quite small
versions of it have (apparently) been fabricated and tested,
cf. reference [1], to demonstrate its ability to efficiently couple EM
energy to space --- but, notwithstanding, in my view this antenna fits
the category of a hoax.

The Hatley, Kabbary and Khattrab paper claims that the field strengths
and service area for a small (1.6 percent of a wavelength high) MF CFA
in Egypt is identical to that provided by a 75 m quarter wavelength
vertical. The antenna was a ground-plane type CFA on the roof of the
transmitter building, and after listening to the paper I questioned
whether the radiation realized was in fact generated by the GP CFA, or
by currents flowing on the outside surface of the coaxial cable
feeding the antenna --- since E X H fields in the far field are
produced naturally whether the radiating antenna was a dipole,
monopole or loop (?).

At a more recent IEE ICAP Meeting (Edinburgh, April 1997), I was
presenting a paper on elevated radials, I met Hatley and his Egyptian
colleague (Khattrab), or should I say they cornered me; and I learned
that the Broadcaster was happily still using the antenna --- or should
I say the authors still believed in the results of their experiment
--- in retrospect I am not sure now which is which.

Maurice told me that he was developing HF versions of this antenna for
use by radio amateurs, for mobile communications, and he would send me
details on it. I told him I would be glad to measure the radiation
efficiency of his amateur version --- but, no correspondence has to
date been received.

In 1992 Colin Davis, University of Surrey [2], conducted a study of a
VHF dipole version of the CFA, his model was a 50-percent scaling of
Hatley's original. His work, carried out to investigate whether the
CFA does operate as an efficient radiator, casts doubts about it,
which seem overwhelming. Despite his best efforts to make it work,
the best he could achieve was - 23 dBd.

["The great tragedy of science --- the slaying of a beautiful
hypothesis by an ugly fact", T.H. Huxley].

So, is the debate concluded, should the CFA RIP?

73, Jack, VE2CV

References

1. M.C. Hately, F.M. Kabbary and Khattab, "An Operational MF Antenna
using Poynting Vector Synthesis", Proceedings of 7TH International
Conference on Antennas and Propagation, Part 2, Conference Publication
No. 333, April 1991, pp. 645-648.

2. Colin Davis, "CFA --- RIP?", Electronics World + Wireless World,
May 1993, pp. 405-407.

_____________________________________________
John S. (Jack) Belrose, PhD Cantab, VE2CV
Senior Radioscientist
Radio Sciences Branch
Communications Research Centre
PO Box 11490 Stn. H
OTTAWA ON K2H 8S2
CANADA
TEL 613-998-2779
FAX 613-998-4077
e-mail <john.belrose_at_crc.ca>
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Received on Tue Feb 09 1999 - 19:49:16 EST