Circular Polarization in Stacked Hexagonal Shaped Microstrip Antennas

The various perturbing structures for generation of circular polarization (CP) in a hexagonal shaped microstrip antenna (HMSA) with patch side length of 20 mm is used to resonate in the Mobile Satellite Service (MSS) band at a centre frequency of 2 GHz. The hexagonal geometry to achieve CP is perturbed in four different ways: first with a rectangular slot at centre, second with two narrow slits at opposite vertices, third with double conducting stub at opposite vertices and fourth with a single conducting stub at a vertex. With any of these perturbing structures embedded in the hexagonal geometry and single probe feeding the antenna along the diagonal line of the square substrate of dimension 60 mm x 60 mm, the antenna radiates left hand circularly polarized waves. Four such hexagonal antenna configurations are analyzed to determine the resonant frequency, impedance BW, axial ratio, gain and radiation patterns in the E-plane and H-plane. The performance of all antenna parameters in their single layer structure is enhanced further by means of stacking the driven antenna with the similar parasitic patch element. Due to stacking the antenna observes an overall increase in 10 dB impedance bandwidth (BW), 3 dB axial ratio BW (ARBW) and antenna gain by 2.58 %, 1.71 % and 0.1615 dB respectively.