A Systematic Analysis of Top-Hat Monopole Antennas Loaded with Radially Layered Materials

Abstract

Top-hat monopole antennas have many desirable characteristics that include high polarization purity and low fabrication cost. A major drawback of such antennas is their inherently narrow bandwidth. Among many techniques developed to overcome this problem is to load the antenna with dielectric materials. Loaded top-hat monopole antennas have been analyzed numerically only via a mode-matching technique that is both limited and mathematically involved. In this research, we present a systematic analysis and an optimization process based on finite-difference time-domain (FDTD) method for top-hat monopole antennas loaded with layered dielectric material and radiating above an infinite and finite ground plane. Both lossless and lossy dielectric loadings are used. Results are verified by comparison with corresponding published data. New results are presented which show wider matching bandwidths and higher antenna efficiencies.