Dual-Band Dual-Sense Polarization Reconfigurable Circularly Polarized Antenna

This letter presents a novel dual-band circularly polarized slot antenna. The far-field polarization of the antenna can be switched electronically between left-hand circular polarization and right-hand circular polarization. A 50 Ω microstrip feed line is divided into four arms those excite a ground plane slot. The p-i-n diodes are introduced in the arms for polarization switching. A prototype dual-band dual-sense antenna with f₀₁ = 2.4 GHz and f₀₂ = 5.2 GHz is fabricated using a 1.6 mm thick FR4 substrate. The measured 3 dB axial ratio bandwidths are more than 16.6% and 5.7% at the lower and upper bands, respectively. The measured return loss is more than 10 dB over the wireless local area network (LAN) bands.