Optimization of the TEM feed structure for four-arm reflector impulse radiating antennas

This paper considers the optimization of the feed arm geometry of four-arm crossed-coplanar plate impulse radiating antennas (IRAs) when the angular p osition and extent of the arms are taken as free parameters. Previously opt imization of this class of antenna considered only the symmetric case a;her e tire two pairs of crossed feed arms were perpendicular to each other. Com parison is made using the prompt aperture efficiency, and the results indic ate that the efficiency of four-arm IRAs can be increased from similar to 2 5% for the perpendicularly crossed arms to similar to 35% for the optimum c onfiguration, In addition to tire optimization, the feed impedance of copla nar feeds is presented for general values of feed arm angle and plate width , and the optimum feed impedance is computed for each feed arm angle. The r esults can be used to design the optimal four-arm IRA with an arbitrary spe cified input impedance.