From: "Aldo Marchetto" <a.marchetto@iii.to.cnr.it>
Organization: CNR
To: rsgb_lf_group@blacksheep.org
Date: Wed, 21 Jun 2000 13:06:08 +1
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Subject: Re: LF: CFA Antenna: miraculous?
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I agree with you that CFAs seen in the literarture are too big for 
135 kHz, and not enough efficient

To avoid to be flamed, I states immediately that I'm not a supporter 
nor a detractor of CFA, but I'm only intrigued to see the results of 
accurate testing of the antenna 

>-So far I have not found any report that a CFA antenna has been 
>built by a ham for any frequency.

On the contrary, I read on the Antennex magazine that some OM have 
built CFA for 40 and 80 m, someone are testing one for 160 m and 
someone also reported a CFA working in VHF (around 100 MHz)

I had some interesting exchange of e-mail with some of them and I too 
I built one for 40/80 meters, 25 cm high.
However in most cases (mine included) there was no measurement of the
actual performance of the antenna.

Most of the OM which built CFAs (including me) did some QSO in the 
range of 1000 km with the antenna indoor, reported satisfaction or 
unsatisfaction, but had no instrument or experience to make an 
accurate comparison among HF antennas.

CFA antennas for the ham bands can also be purchased:
in December 8th, 1999, G3SMW trasmitted a 10-W beacon Hellschreiber 
signal in 20 meters using a commercial Crossed-Field (Horizontal 
Monoband Loop) Antenna 10m above ground, and got several reports.
I received his signal in Northern Italy with signals comparable to 
other G or PA stations running 100 watts to ground planes. However 
this is only an episodic report, and he was not trying to test the 
performance of this antenna (we were testing the relative performance 
of different Hellschreiber codes).

I found only two papers reporting field strenght measurement, one 
from supporters and one from a dectractor of CFAs:

1) WA6HZT and N6YIP in Antennex (June 2000) report a loss of 24 db 
respect to the filed strenght predicted by models for a 
quarter wave monopole with 120 radials, for their 1.6-m high CFA on 
160 meters. However they declare that this result is provisional, 
while they are still trying to build better tuning networks.

2) VE2CV in the same journal reports a radiation efficiency of about 
1% for his 1.2-m high CFA on 80 meters

In my opinion most of the debate is related on the claims that the 
CFA should perform as well or better than a quarter wave monopole.
Probably it would be more proficient evaluate it against other 
antenna of similar height.

It has also been supposed that CFA could represent an alternative way 
to feed a short, fat monopole and, in this case, it would be 
interesting to evaluate advantages and disadvantages of this 
alternative feeding.

73 Aldo IZ1ANT