A Compact Antenna With Broad Bandwidth and Quad-Sense Circular Polarization

A new compact antenna design with broad bandwidth and quad-sense circular polarization (CP) is presented in this letter. The broadband property is achieved based on a compact monopole structure. Furthermore, the quad-sense CP wave is obtained by a ground plane embedded with a T-shaped slit (TSS) and an annular patch etched by an X-shaped slit (XSS). Good agreement is achieved between the simulation and measurement, which shows that the presented antenna covers the impedance operations from 3.1 to 22.2 GHz ( S₁₁ <; -10 dB), reaching the particularly broad bandwidth of 150%. Moreover, the design achieves good CP waves at Worldwide Interoperability for Microwave Access (WiMAX) (3.626-3.772 GHz) for left-hand CP (LHCP), the wireless local area network band (WLAN) (4.951-5.18 GHz) for right-hand CP (RHCP), X-band (10.9392-11.0456 GHz), and Ku-band (15.14-17.2 GHz) for LHCP. Simulated and measured results show that the CP 3-dB axial-ratio (AR) bandwidths are 4.02%, 4.51%, 1%, and 12.74% with a parasitic notch at the frequency of 17.75 GHz to realize good CP characteristics in quad bands.