Design of ultra-broadband loaded monopoles

The authors develop two approaches for the design of ultra-broadband loaded monopole antennas for spread-spectrum communication. The first of these, designated as the conventional design, utilizes several parallel L-C circuits that are initially placed along the monopole such that the effective electrical length of the antenna remains approximately one-quarter wavelength over the frequency range of interest. This method is based upon a two step procedure: (1) design a loaded antenna that meets the gain requirements; and, (2) devise its matching network to obtain the desired VSWR. The second method uses a genetic algorithm to design both the loaded monopole and the matching network simultaneously in an optimal manner.<>