Abstract
A Fabry-Perot resonator excited by a microstrip patch antenna that has a superstrate with a stepped dielectric constant is designed to operate at 5.8 GHz. The antenna is fabricated and is shown to provide enhanced directivity over that achievable using uniform dielectric slabs, with either epsilon(r) = 4.4 or epsilon(r) = 10.2 as superstrates. The measured maximum gain of the patch antenna with a step-index dielectric constant superstrate with a dimension of 2 lambda(0) x 2 lambda(0) was found to be 13.44 dBi, whereas the corresponding values for the uniform dielectric superstrate are 11.25 (epsilon(r) = 4.4) and 12.44 dBi (epsilon(r) = 10.2). As shown in this article, the aperture efficiency of the step-index dielectric is also higher than those of the other two. (C) 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:711-715, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26614