Re: NEC-LIST: CFA - Questions and Comments

Max,

Your questions and comments all relate to what we have been discussing
for several weeks now. My thinking as I go has perhps confused the
issue.

As Duncan

>1. How was it possible to obtain patents for the CFA ? Do the people
>who assign a patent know more about the physics of this mysterious
>antenna, than experienced professionel engineers and scientists ?

You can patent any idea, provided a previous patent cannot be found.
Did you know that Reginald Aubrey Fessenden, a Canadian born radio
scientist at the turn of the century, patented the concept of
continuous waves. At that time it was not possible to generate CW.

The patented idea behind the CFA is that of producing E- and H-fields
separately (at least so they say) with the correct spatial orientation
and phase to produce an out-going E x H Poynting vector.

But this not mean that the CFA works. That is a separate issue.

>2. How come, that one does not find articles, discussing the CFA in
>the prof. literature, like IEEE Transactions on antennas and
>propagation, or e.g., electronic letters, etc. ?

That is curious, since the antenna has been around for ten years?
Have you seen the Kabbary et.al NAB'99 paper. The so-called enhanced
CFA is sprouting like mushrooms in Egypt --- one photograph shows two
of them on the roof of a building, working on different frequencies.
They are said to work perfected with almost no coupling, since the
induction fields for a CFA is said to be small.

I say the induction fields are large, they say they are small.

>3. Why can we not obtain actual test data of the CFA's, which
>apparently have been built and are operating ?

We intend to fabricate a CFA, scaled by a factor of 1/3.15, so that
the MF antenna we have been modelling at 1.161 MHz, falls in the 80M
amateur radio band, viz. 3.657 MHz.

Forrest Gehrke has written: I'm reading your NEC-list posts and note
you mention having a photo of this CFA. Is that photo capable of
being emailed? The word description with dimensions sounds like a
very strange looking antenna. Not too clear, however, is the
description of the drive network. Is this antenna fed with 50 ohm
coax?

[Please see http://members.home.net/propagation/CFA.rtf for a Rich
Text Format document containing drawings and images of CFA's. It
should be readable using WordPerfect, Word, ApplixWare, and/or
StarOffice.]

>4. Would it be realistic to build a scaled down version of the CFA,
>let's say for VHF, to minimize the size ? Should the scale factor not
>be linear ?

Scaling the MF antenna (From davem_at_fs1.ece.ubc.ca Mon Jun 14 21:58:33 MET 1999
Received on Mon Jun 14 1999 - 16:54:05 EDT