A Novel Simple and Compact Microstrip-Fed Circularly Polarized Wide Slot Antenna with Wide Axial Ratio Bandwidth for C-Band Applications

This communication presents a design of a new compact circularly polarized (CP) slot antenna fed by a microstrip feedline. The 3-dB axial ratio band can be achieved by simply protruding a horizontal stub from the ground plane toward the center of the wide slot (WS) and then feeding the WS with a microstrip feedline positioned to the side of the WS, underneath the protruded stub. The feedline and metallic stub are perpendicular to each other, and they resemble a T shape when viewed from the top. The proposed antenna is fabricated with an area of 25 × 25 mm2. Measurement results show that the antenna attains an S11 ≤ -10 dB impedance matching bandwidth of 90.2%, from 3.5 to 9.25 GHz, and a broadband 3 dB-AR bandwidth of 40%, ranging from 4.6 to 6.9 GHz. A peak gain of 0.8-4.5 dBi is achieved within the AR band. The proposed antenna is suitable for circular polarization applications in C band.