Design and realization of GA-optimized wire monopole and matching network with 20:1 bandwidth

This paper presents the successful design and physical realization of broadband loaded wire monopoles with matching networks. The loads are parallel inductor/resistor circuits that are adjusted by means of genetic algorithm (GA) optimizers to maximize bandwidth, and the matching networks are transmission-line transformers. The micro-GA is shown to be more convenient and efficient for optimizing these loaded antenna systems than is the simple-GA. The measured voltage standing-wave ratio (VSWR) of the loaded antennas confirm broadband performance and agree with data obtained from moment method computations. Antennas having bandwidth ratios of 12.6 : 1 and 18 : 1, with measured VSWR less than 3.5 and calculated system gain greater than -4.5 dBi, are presented. Finally, an antenna system is given that has measured VSWR less than 3.0 and calculated system gain greater than -3.2 dBi over a 20 : 1 band.