Increasing the impedance bandwidth of dipole and monopole antennas with parasitic elements

Thin resonant dipoles and monopoles are typically narrowband. Increasing the thickness of the cylindrical dipole or monopole radiator (or the width in the case of their strip counterparts) is one way to increase the impedance bandwidth. Using loading with resistive, inductive, and capacitive components is another way to improve the bandwidth (although it may add loss to the antenna). In this paper, we investigate the use of metal parasitic elements placed in the vicinity of the driven element with the goal of increasing the bandwidth. Antenna Toolbox (MathWorks, Inc.) is used extensively for analysis of the various configurations. It will be shown that moderately thin dipoles and monopoles can achieve bandwidths of 18-35% with the addition of identical parasitic structures adjacent to the driven element.