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From: X Member
Date: 08 Apr 2003
Time: 11:34:32
Remote Name: 193.235.3.218
Alan – I’m glad that you agree with me that NEC can’t simulate the CFA. NEC does of course what it has been programmed to do. It treats the two plates as two separate “complete” antennas and that is not how they work, as they are two parts of the same antenna. One of them can’t operate without the help of the other, as one plate is generating the E-field and the other plate is generating the H-field, completed to a radio wave by the Poynting Vector Synthesis. -- And it comes to no surprise, that people who are using NEC on this type of antenna, comes to the conclusion that the D-plate does not contribute anything to the radiation and that it can as well be taken away. Furthermore it treats the E-plate as a very short monopole with it’s well known shortcomings wrongly treated as a conventional resonant antenna. So it’s a waste of time using the incomplete NEC-code on the CFA. -- I’m very impressed with the theoretical skills regarding the conventional resonant antenna techniques as yours. But I feel that there is a strange lack of insight into the CFA operation, which I feel is a shame. To get updated I recommend a membership in a discussion forum like - http://groups.yahoo.com/group/x-field/ - that is dealing with this kind of antennas. – I must warn you about the article of Mr.Belrose that you found interesting earlier. I think this man has misled you, as he has done to so many others. He not at all impresses me. He does not understand this antenna very well. Further more no referee has approved this article. The “From the Shack”-column is a kind of chronical where anybody can express his or her personal opinions. So don’t pay too much attention to it. This article is full of groundless speculations about the CFA and contains no scientific proof against the Poynting Vector Synthesis. Over the years I have not seen any scientific proof whatsoever against this mechanism. What we have is silly speculations, false calculations and a lot of dismissive noises. All this fuss about the CFA is of course a good measure of how revolutionary this device is. -- You pointed me towards AntenneX for information, but I feel that this publication has lost it's leading position it once had on this type of antennas. More interesting information is to be found at http://www.geocities.com/vk2edb/CFA.htm Here we see a brilliant example of a Crossed Field Antenna. Mr.Van Der Byl have done an excellent and important work and presents it very well on this web page. It’s a good example of what a man can do with the right intentions in the heart and soul. And he has done it in the right way, after studying papers written by the inventors. So nobody can blame those three men not to providing enough of information. – The data presented is an experimental proof of Poynting Vector Synthesis. No conventional resonant antenna of this size can provide this kind of bandwidth and at a high efficiency; in fact the efficiency of such a conventional resonant antenna ought to be in the region of about 5%. So there is something else and different happening here. Notice this: ” Some test were performed comparing the CFA against a quarter wave vertical as a reference antenna; Ground wave signals: it was generally found that the CFA was equal to or slightly better.” I’m also pleased to read: “A little probing with a field strength meter and you will find the field squirts well out of the side and not much at all at higher angles”. – A field strength meter is a relative simple and efficient instrument to operate and can be used to evaluate what is radiating and how much. The readings simply show good geometry around the source of radiation. I’m sure Mr.Van Der Byl has done it and the inventors did this before investing large sums of money into the patents. Hands on experiences are a very good complement to theoretical skills. – Of course there are difficulties in the beginning with a revolutionary new device like the CFA. I’m thinking of it as a young child starting to rise for the first time and falls over. It continues over and over again and suddenly one day it runs freely wherever it wants and without any problems.—Regards Håkan