On the quality factor of strip and line source antennas and its relationship to superdirectivity ratio |
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Authors: | Rhodes D |
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Affiliation: | North Carolina State University, Raleigh, NC, USA; |
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Abstract: | Exact formulas are derived for the quality factorQof strip and line source antennas. Contrary to popular opinion, none of them is equal to Taylor's superdirectivity ratiogammaor togamma - 1. But in the case ofE-plane strip sources (the complement of the type of strip source treated by Woodward and Lawson) the value ofQis precisely equal togamma_{alpha}^{-1/2}- 1, wheregamma_{alpha}^{beta}is a generalized superdirectivity ratio that reduces to Taylor'sgammawhen the edge exponentalphaand the pattern weighting exponentbetaare both zero. In the case ofH-plane strip sources the value ofQis approximately equal togamma_{alpha}^{1/2} - 1, and forH-plane line sources of vanishing widthait is approximately equal to(2/pi) ln (2.516lambda/pi a)]gamma_{alpha}^{1}. |
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