A Simple Design of Compact Dual-Wideband Square Slot Antenna with Dual-Sense Circularly Polarized Radiation for WLAN/Wi-Fi Communications

A novel compact dual-wideband, dual-sense, circularly polarized (CP), square slot antenna with the simple structure is presented in this communication. The right-hand circular polarization in the +z-direction for the lower frequency is mainly realized by an inverted L-shaped strip, and the left-hand circular polarization in the +z-direction for the upper frequency is mainly achieved by an offset feed structure. A parasitic matching stub is helpful to improve the input impedance matching. The overall dimension of the prototype is only 50 × 50 × 1mm³. An optimized antenna is fabricated and measured. The measured 10 dB return loss bandwidth is 111% (1.82-6.36 GHz). Its measured 3 dB axial-ratio bandwidths in the broadside direction are 55% (1.91-3.36 GHz) at lower band and 29.3% (4.78-6.41 GHz) at upper band, which can fully cover all the wireless local area network and wireless fidelity bands. What is more, this antenna has stable antenna gain and good radiation patterns within these two CP bands.