Design of Slotted Ground Hexagonal Microstrip Patch Antenna and Gain Improvement with FSS Screen

Three hexagonal patch antennas are designed for circular polarization and experimentally validated. These antennas are labeled; simple hexagonal patch, hexagonal patch with slotted ground and hexagonal patch with parasitic element. The measured impedance bandwidths of the three antennas are 2% for the simple patch, 5.2% for the patch with slotted ground and 6.35% for the antenna with parasitic element. The axial ratio (measured) obtained is 4.73% for the patch with slotted ground and 3.33% for the hexagonal patch antenna with parasitic element. The measured radiation patterns of these antennas are found to be in good agreement with the simulated radiation patterns. The average gain of all the three antennas is also evaluated. A frequency selective surface (FSS) is proposed with dimensions smaller than that of a conventional FSS structure. The measured gain improvement with the proposed FSS is around 3 dB in the operating band.