Design and Characterization of a Ring Shaped Circular Polarized Microstrip Patch Antenna for X Band Applications

A ring-shaped patch antenna with a 50-ohm feed was designed, to produce a circular polarized antenna for the applications in the X band frequencies. The suggested microstrip antenna consists of a patch with a ring form and a microstrip line extending along its diameter. The ring patch produces two orthogonal degenerative modes which makes circular polarization possible with a single feed. Outside the ring patch a stub is placed along the microstrip line for impedance matching purpose. Varying feed position from the center along the length of the microstip line is considered to tune the antenna in desired frequency. The ring patch and the microstrip line is positioned above the substrate material which is made of Teflon has a height of 0.8 mm. The patch and ground plane uses copper with 0.018 mm of thickness. The return loss of the designed structure shows excellent impedance matching with values of -65.564 dB at the resonant frequency.