Re: NEC-LIST: CFA in short

Thanks to Kok Chen and Alexandre Kampouris for details about the CFA
claims (cross field antenna.) I can now summarize them for readers who
are interested in the facts, but not in the lengthy story!

They are: a size reduction (of about 100, compared with a 1/2 wave
antenna) and at the same time a relatively large frequency range
(about 1/20 to 1/50 of the operating frequency) and finally about the
same gain as a dipole.

This is extraordinary, because resonant antenna structures as we know
them, could not achieve this. The first two claims would only be
possible with a very low gain, which is in contrast with the third
claim.

To be specific: a shortened dipole (1/100 times the half-wave length)
when tuned with an ideal inductor, would have a Q-factor of about one
million. This would give it a 10000 times smaller bandwidth than the
CFA claim. If this Q is reduced by Ohmic losses to about 100 (more in
line with the claimed frequency range) then the gain would also be
reduced to -40dB, much lower than the CFA claim.

This should explain that the CFA claims are extraordinary. I leave it
to others to speculate whether they are true.

Greetings,
Jos

--
  Dr. Jozef R. Bergervoet                      Electromagnetism and EMC
  Philips Research Laboratories,             Eindhoven, The Netherlands
  Building WS01                                     FAX: +31-40-2741114
  E-mail: bergervo_at_natlab.research.philips.com    Phone: +31-40-2742403