A Geometrically Simple Compact Wideband Circularly Polarized Antenna

Abstract

A compact broadband wide-slot circular polarization (CP) antenna is proposed. An inverted L-shaped parasitic strip at the open end of a microstrip line extension and a slot modification is applied to attain wideband CP. The advantage of this technique is simplicity, which makes it readily redesignable for different frequency bands. To demonstrate the concept, three designs working at different frequencies are obtained. The redesign procedure is straightforward and only requires a recalculation of the selected physical dimensions followed by electromagnetic-based parameter tuning. A compact size of 0.09 λ 0 is achieved when measured at the lowest CP frequency. The optimized designs are validated experimentally in terms of | S 11|, axial ratio, realized gain, and radiation patterns. For the design corresponding to the lowest operating frequency, a total impedance bandwidth of ∼89% (3.2–8.4 GHz), axial-ratio bandwidth (ARBW) ≤3 dB of 82% (3.2–7.65 GHz), average in-band realized gain of 3.3 dBi, and a bidirectional radiation pattern with a dual sense of polarization are achieved. A thorough benchmarking indicates the superiority of the proposed antenna over the state-of-the-art designs in terms of all major performance figures.