RE: Toroidal Antennas and other Remarks

Jack,

In my opinion there was a landmark paper in the August 1966 Proceedings of
the IEEE pp. 1033-1045 which established the limitations on antenna gain
for ANY ARBITRARY ANTENNA. It was authored by Y. T. Lo et. al. from the
University of Illinois, and they established the relation between the
optimized size (in wavelengths), gain, and bandwidth of any antenna "array".
  It does not make any difference what you make it out of, (including
superconductors, and remember when you have AC, superconductors have
resistance) or whether it uses "magnetic" or "electric" coupling or
combinations thereof.

It basically says you can make it physically as small as you wish (within
the constraints of tolerances), and you can get large gain, but you will
have diminishingly small bandwidth. If you make it physically small and of
reasonably large bandwidth, you get diminishingly small gain. If you want
large gain and large bandwidth, it must have physically large size (again,
this is in wavelengths).

So, if it looks too good to be true, it probably is. And this paper should
allow one, who has the time to spend, to quantify how much too good it is.

Allen Davidson
Member of the Technical Staff
Motorola Inc., Room 2240
1301 E. Algonquin Rd.
Schaumburg, IL 60196

Phone: 708/576-5972
Email: CASR04_at_email.mot.com

________________________________________________________
To: nec-list_at_ee.ubc.ca
From: john.belrose_at_crc.doc.ca on Thu, Nov 9, 1995 6:06 PM
Subject: Toroidal Antennas and other Remarks

An antenna is sometimes described as a coupling device, coupling
electromagnetic energy to space, and following on with this line of
thinking, antenna amateurs/specialists have wondered whether there were
ways of achieving this process in more efficient ways than provided by use
of monopoles, dipoles and loops.

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   .
   .

I would be pleased to receive views on these new "revolutionary" toroidal
antennas. Correspondence concerning performance of toroidal antennas has
ranged from skeptical to beyond belief!!

73, Jack, VE2CV

John S. (Jack) Belrose, VE2CV
Director, Radio Sciences
PO Box 11490 Stn. H
OTTAWA ON K2H 8S2
CANADA
TEL 613-998-2308
FAX 613-998-4077
Received on Fri Nov 10 1995 - 14:56:00 EST