Circular polarisation design of a triple fed equilateral-triangular microstrip antenna using FDTD

A design of triple-feed equilateral-triangular microstrip antenna for circular polarization (CP) is proposed. In this design, by feeding the patch through three points and applying proper phase differences between the feeds, CP with axial ratio close to 1 can be achieved. Finite Difference Time Domain (FDTD) method has been applied to analyze this microstrip-fed antenna. The return loss, input impedance, far field pattern, and axial ratio are calculated and compared with the same results which are derived by HP-HFSS software.