Modified Psi-shape Microstrip Antenna For Circularly Polarized Response

A circularly polarized antennas are required to reduce the signal loss resulting due to the multi-path propagation. The modified Ψ-shape microstrip antenna design is reported in the literature which gives axial ratio bandwidth of more than 19% in 5300 MHz frequency range, radiating away from the broadside direction. For the optimized design, resonant modes and the equivalent circuit model are mentioned in the reported paper without a comprehensive study to explain the antenna functioning attributed to effects of each of the modifications made in the Ψ-shape patch on the realized axial ratio bandwidth. Initially in this paper comprehensive study based on resonant mode explanation attributed to each modification is presented. Also paper gives a thorough study which brings out the resonant mode based description for the effects of every modifications made in the modified Ψ-shape geometry starting from the equivalent Eshape geometry. The modifications made in the Ψ-shape patch yields optimization of the resonance frequency and the input impedance at modified TM21 mode which yields circular polarized response. Further simpler design using different length of slots in the Ψ-shape geometry is presented which yields dual band circular polarized response with axial ratio bandwidth of 12.03% centered at 4500 MHz and 5% centered at 6100 MHz. The proposed design is simpler in optimization and can find its applications in the frequency agile systems.