Propagation of surface waves in dielectric underneath a microstrip patch antenna poses serious hindrance to the radiation mechanism. Several methods are being tried for suppression of surface wave. Metamaterial substrate is presented here with periodic arrangement of metallic cylindrical pins except the area underneath the radiating microstrip patch. The periodic arrangement of metallic cylindrical pins with negative dielectric constant has considerably high reflection coefficient to drive the extraneous surface wave fields towards the fringing fields of the antenna. The textured pin substrate leads to generation of forbidden band gap for the propagation of TM0 surface wave modes and thus enhances radiation characteristics. The proposed structure proves to be highly beneficial for improving radiation efficiency and gain. Parametric analysis has also been presented for the gain enhancement by varying pin diameter, spacing between pins, and air gap between dielectric substrates. A uniform gain of 10 dB has been achieved for a Left Hand Circularly Polarized (LHCP) microstrip patch antenna. The axial ratio achieved in the described band is 200 MHz. The antenna has been designed for WLAN applications.
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