Performance Enhancement of Broadband Circularly Polarized Slot-Microstrip Antenna Using Parasitic Elements

In this letter, two novel broadband circularly polarized (CP) slot-microstrip antennas (SMPA) with circular and square structures are elaborated. The circular SMPA is composed of four crown patches as parasitic elements, four crown slots etched on a circular ground, and a circular loop sequential phase feeding structure (SPFS). However, the square SMPA consists of four parasitic rectangular patches, four square slots with cut corners, and a square-loop SPFS. In the circular SMPA, the parasitic crown patches and crown slots are used to excite multiple CP resonant modes, which are fed by a circular loop SPFS through capacitive coupling. Combined with these CP modes, the CP bandwidth of the presented antenna could be improved. Eventually, the proposed circular SMPA has a broad 3 dB axial ratio bandwidth of 20.6% (5.20-6.40, 5.8 GHz) and a wide -10 dB impedance bandwidth of 25.8% (4.92-6.38, 5.65 GHz), which could occupy the wireless local area network (5.725-5.85 GHz), ITS (5.8 GHz), and WIFI (5.85-5.925 GHz) bands.

Automated summary

The letter introduces two novel broadband circularly polarized slot-microstrip antennas with circular and square structures. The circular SMPA utilizes parasitic elements to excite multiple CP resonant modes and improve the CP bandwidth. The proposed circular SMPA has a broad bandwidth suitable for various frequency applications.