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On 14 Dec 2006 21:04:08 -0800, "art" wrote:
All in all the array represents a band pass filter where effort is made for constant gain across a band of frequencies Hi Art, D.E. Isbell did this 46 years ago. which is a different requirement from the Yagi It has been used for TV antennas for lo those same 46 years and to any casual view looks like a Yagi. where amateurs are only interested in gain without due referance to constancy across the frequency span or with regard to the corresponding beam width Isbell got that too. It was, afterall, everyone's goal and he got: 1. More gain; 2. Better match; 3. More bandwidth; than 5 un-optimized wires hanging in the air. Isbell understood Gaus, Maxwell, McGuffey, and the rest and never appealed to bundles to explain his design (which really bore no more relation to his antenna than explaining why a car works in terms of how zippo lighters create a flame). D.E. Isbell's antenna is included free as an example with every copy of EZNEC. It contains 5 wires and exhibits: 1. 10% BW 2. 10 dBi gain 3. a serviceable match Isbell wrote the design up, submitted it to his peers, a jury passed on his work, it was published, it was patented (3210767) and it has stood the test of time. Isbell also explained how to achieve different: 1. Gains; 2. Matches; 3. Bandwidths; in terms that others could actually build working models. In regard to this last, I am sure amateur publications offer simple formula to achieve these goals too. However, if all one has to read is a book about fields, Isbell's invention may come as a surprise. Ramo and the boys don't really talk all that much about "antennas," so citing them as authorities on the subject makes as much sense as crediting Jane Goodall for the Theory of Evolution. 73's Richard Clark, KB7QHC |
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