Broadband Proximity-Fed Modified Rectangular Microstrip Antennas

Abstract

The bandwidth of a microstrip antenna is increased by using a thicker and lower-dielectric-constant substrate, or by using multi-resonator gap-coupled and stacked configurations, or by cutting a resonant slot inside the patch. However, with all of these methods, the bandwidth of the antenna is limited by the probe's inductance for substrate thicknesses greater than 0.06λ0 to 0.07λ0. For substrate thicknesses larger than 0.07λ0, the bandwidth of the antenna can be increased by using a proximity-feeding method. In this paper, by using a combination of the proximity feeding technique and a thicker substrate, various broadband configurations of gap-coupled rectangular microstrip antennas, E-shaped and half-E-shaped microstrip antennas, and gap-coupled half-E-shaped microstrip antennas are proposed. All of these configurations give bandwidths in excess of 350 MHz (>;35% ), with gains of more than 7 dBi, in the 800 to 1200 MHz frequency band, with a broadside radiation pattern.