A Design of Triple-Wideband Triple-Sense Circularly Polarized Square Slot Antenna

In this letter, a microstrip-fed simple square slot antenna is proposed for triple-wideband triple-sense circularly polarized radiation. It consists of an L-shaped radiator and a frame lower ground structure with two rectangular strips at opposite corner. A rectangular slit, which is cut on the right side rectangular strip at the lower ground, is mainly used to broaden axial-ratio bandwidth (ARBW) at upper band. This antenna radiates righthand circularly polarized wave at lower and upper bands, and radiates left-hand circularly polarized wave at middle frequency band. The antenna has been fabricated andmeasured. Good agreement is achieved between the simulation and measurement. The measured impedance bandwidths are 44.0% (2.34-3.66 GHz) and 70.9% (4.55-9.55 GHz). The measured 3-dB ARBWs for the triple bands are 35.9% (2.40-3.45 GHz), 44.0% (4.65-7.27 GHz), and 6.3% (8.13-8.66 GHz), respectively. The measured peak gains within the 3-dB ARBWs are 4.2, 3.7, and 3.5 dBic, respectively.