Results of Optimization of Yagi-Uda Arrays of Shaped Dipoles,

Abstract : The method for maximization of the directivity of Yagi-Uda arrays of shaped dipoles as outlined by Liang and Cheng was employed to optimized a three-element array of shaped dipoles, each 1.5 wavelengths in length and 0.01 wavelengths in radius. Liang and Cheng's optimal three element array was confirmed to yield a maximum directivity of 11.8 dB using the moment method with second-order expansions as formulated by Harrington. Two simplex minimization routines were alternately used to independently determine optimal element shapes and eliminate saddle points for a three-element array of the same dipole lengths and radii, 1.5 and 0.01 wavelengths, respectively. Using this procedure, a shaped-dipole Yagi-Uda array different from Liang and Cheng's example was found to yield a maximum directivity of 12.6 dB.