A Circularly-polarized Patch Antenna using Pin-loaded Technique with PSO

A circularly polarized (CP) microstrip patch antenna in the X-Band frequency is designed using Particle Swarm Optimization (PSO). Circular polarization is achieved in the proposed design by using the pin-loaded technique. First, two shorting pins are introduced in the single-fed patch to reduce S-11. Then, the position of the inductive pins in the initial design, obtained by numerical approaches, is optimized using the PSO algorithm to obtain an axial ratio < 3-dB in the required frequency range. The converged result from the PSO algorithm satisfied the objective and design specifications of reflection coefficient of S-11 <-10 dB, axial ratio < 3 dB, an omnidirectional radiation pattern and satisfactory gain.