Wideband High Directive Aperture Coupled Microstrip Antenna Design by Using a FSS Superstrate Layer

in this communication a high directive electromagnetic bandgap (EBG) antenna operating in wide frequency band for both return loss (RL) and directivity is examined. In this EBG antenna an aperture coupled microstrip antenna (ACMA) is used as a feeding source and a frequency selective surface (FSS) is used as a superstrate layer. Suitable use of the superstrate layer, microstrip patch and coupling aperture simultaneously, leads to produce separate resonance frequencies and therefore the wide frequency band for RL. Also, high directivity is achieved only by using the superstrate layer that has been made by the FSS layer with square loop elements. At first, a wideband ACMA is designed to operate in x-band. In this step appropriate design of coupling aperture is of a great importance. Secondly, after the design of optimum superstrate layer by the FSS structure, it is added to the ACMA in order to increase both bandwidth and directivity.