An Analytical Approach of Designing Compact Microstrip Patch Antenna using Metal-Ring Superstrate for Wideband and Broadside Radiations

Abstract A compact design of microstrip patch antenna is presented to realize wideband characteristics. An annular metal-ring has been used as a superstrate as well as an inductive load to the rectangular patch. Robust analytical technique is applied to choose the dimensions of the ring and the patch where they resonate very close to each other. This strategic approach ensures a wide matching bandwidth with a broadside radiation pattern. An additional enhancement of bandwidth has been achieved by employing a unique design strategy. A set of antenna prototype has been fabricated for experimental validation. As much as 34% matching bandwidth has been revealed experimentally using a compact antenna (∼λ×λ). The boresight gain is maintained about 10 dBi over the operating frequency band. The cross-polarized isolation in E- and H-planes are maintained above 40dB and 30dB respectively over the operating bandwidth. The back-radiation of the antenna is also maintained below −20dB over the wide matching bandwidth.