The Higher Mode Elimination in Microstrip Patch Antenna using Defected Microstrip Surface for Suppression of Cross Polarized Radiations and Improved Isolation

This paper proposes unique design technique using defected microstrip surface (DMS) for the suppression of higher mode, reduced cross polarization (XP) and improved isolation. The proposed technique can be easily adapted to any conventional working rectangular microstrip patch antennas (RMPA) in the practical applications. The modification can be made by etching the rectangular slots called DMS of optimized dimensions in the rectangular microstrip patch. This will enhance the radiations by suppressing XP radiations and eliminates nearby undesired higher order mode, which is the source for the XP radiations. In this design the conventional RMPA is designed to resonate at 3.04 GHz with broad side radiations with co-polarized peak gain of 5.2dBi and XP of -15.5dB. The proposed RMPA resonates at the same frequency with a gain of 6dBi. The XP is significantly suppressed by 31dB and it is -46.5dB over the span of ±500, with co-pol to cross-pol isolation of 52.5dB is achieved for S-band applications. The performances of the designed antennas have been experimentally verified.