Study of Polarization Purity of Rectangular Microstrip Antenna Integrated with Pentagon Dumbelled Shaped Defected Ground Structure

Abstract

A single element pentagon defected ground integrated rectangular microstrip antenna (RMA) on two different substrates like Fr4 and RT-Duroid has been studied to improve the polarization performance of the conventional microstrip antenna. The regular pentagon defects are placed on the ground plane just below the corners of the rectangular patch and two slots are placed symmetrically below the non radiating edges of the rectangular patch to connect the pentagon heads to get the structure. Polarization purity around 28 dB and 25 dB over full elevation angle (±180°) has been achieved through the proposed structure with Fr4 substrate and RT-Duroid substrate respectively. Optimum defect size has been obtained using parametric studies in both cases. Both structure shows good impedance matching and stable radiation pattern within the operational bandwidth of the proposed structure. The defected ground structure geometry is very simple and easy to fabricate. Therefore the proposed antenna might be ideal for the applications where stable radiation pattern with high co-polarization to cross-polarization isolation over wide elevation angle is required.