The Cross Field Antenna

If you thought the small transmitting loop was unlikely, look at this!

Steve G0KYA has reviewed the Cross-Field antenna in Radio Communication (2002) 78(5).28-30. He states that it was first described in 1988 by Hately, Kabbary and Stewart (I am told but have not yet seen that there was an article by by F.M. Kabbary, M.C. Hately and B.G. Stewart in March 1989, Electronics and Wireless World entitled "Maxwell's Equations and the Crossed-Field Antenna". ).

There are several CFA antennas in use as AM broadcast antennas.

An electromagnetic wave consists, we are told, of an electrical and a magnetic component. It is certainly an oversimplification to say that a conventional dipole produces a largely electrical disturbance and induces a magnetic one, and that a magnetic loop does the opposite. In both cases however the resulting radio wave density (or photons of radio energy) are referred to (in mathematical models) by describing the Poynting Vector.

The bit that has been overlooked, it seems, is that whilst a varying electrical or magnetic field is the way to produce electromagnetic radiation, it is not necessary to have a current flowing to achieve this. All antennas prior to the CFA carry a varying current - magnetic loops especially so.

I wish I understood this. I keep getting flashbacks of physics A-level homework.

Still, lets get on. Now where were we? Oh yes...

The Cross Field antenna purports to directly synthesise a spherical wavefront of electromagnetic radiation by generating both electrical and magnetic components of the Poynting Vector. If you look at the way the radiation emanates from a CFA it appears to be coming from a much larger antenna- hence overcoming the concerns about it being too small to work!

The CFA is perhaps a kind of virtual antenna, just as your face when you peer in the mirror in the morning isn't really 'there'....

The patent, apparently goes on to say, that 'a CFA radiator can be efficient even if only 2% of the designed wavelength in size'.

Well well. Handy for my little 2w ssb 20m handi then?

I am looking for Cross Field Antenna links and information. This sounds just the kind of antenna that would appeal to me - and might make /P QRP operation a doddle!

There is a YAHOOGROUPS list for the CFA

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