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Interesting.
One respondent says position is a factor and the other says it is not according to Kraus ,who may well have been directing his comments at a Yagi model So I changed the feed point on my model, which is not a Yagi, to other elements to see if they lagging or leading. Surprise ! Some of the other elements were resonant also thus they could be fed in one or more places at the same time Since with the initial design they are not all directly fed these apparently do not fall into any catagory. I suppose literature in general can only apply definitions to that which is known by the author at the particular time Regards Art "Richard Harrison" wrote in message ... Art Unwin wrote: "When modeling close spaced element antenna assemblies it is possible that some elements are physically longer than the "driven" element. Is the length of an element sufficient to declare a "reflector" or are there other caveats involved (i.e. phase)?" Art answered his own question. The element doesn`t care how it gets a leading (capacitive) current, or a lagging (inductive) current. In our broadcast curtain antenna arrays, we used an RCA WM-30A phase monitor for the current angle in the ibnductive parasitic reflectors. Phase was adjusted to spec with a short-circuit stub connected to where the feedpoint would be if it were a driven element. Kraus is unequivocal on page 245 of edition no. 3 of "Antennas": "When the halfwave parasitic element is inductive (longer than its resonant length) it acts as a reflector. When it is capacitive (shorter than its resonant length) it acts as a director." Best regards, Richard Harrison, KB5WZI |
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