Compact Slotted Circularly Polarized Microstrip Patch Antenna with Surface Wave Suppressed Characteristics for WLAN Characteristics

Abstract

Surface wave propagation in the dielectric substrate is one the dominant factors leading to power loss in microstrip patch antennas. The surface waves are radiated from the edges of the dielectric substrate and does not contribute to the radiation of the antenna. To mitigate this problem discontinuity is required to be introduced in the direction of surface wave propagation. In this paper, surface wave suppressed antenna structures with circularly polarized radiation characteristics have been proposed. A square patch antenna has been designed at 6 GHz. Slotted perturbations for the same patch has been done to achieve compactness and circular polarization in the design. Two variants of the slotted antenna with side patches and PTH pins embedded at specific locations have been presented. For the 1st antenna design the axial ratio bandwidth of 120 GHz, compactness of 32.58 % and gain of 10.5 dB been achieved at resonant frequency of 8.9 GHz. For the 2nd antenna design the axial ratio bandwidth of 110 GHz, compactness of 34.7 % and gain of 9.8 dB been achieved at resonant frequency of 9.2 GHz. The improvement in gain of the proposed designs as compared to simple square patch antenna has been observed to be around 3 - 4 dB.