Dual-Band Dual-Circularly Polarized Antenna Array With Printed Ridge Gap Waveguide

A dual-band dual-circularly polarized magneto-electric dipole antenna array for full-duplex communication systems is presented in this communication. The proposed array can simultaneously achieve left-hand circular polarization (LHCP) around 20 GHz and right-hand circular polarization (RHCP) around 30 GHz with a low-loss feed network using the printed ridge gap waveguide (PRGW). The antenna is composed of two sets of stacked interconnected short-circuit patches operating at different frequencies and fed by the same gap. The LHCP at the 20 GHz band and RHCP at the 30 GHz band are realized by exciting the corresponding orthogonal electric-dipole mode and magnetic-dipole mode with -90°/90° phase difference. A cylindrical cavity consists of a series of metalized vias with a top metal strip used for surface wave inhibition. Using the PRGW, a four-way power divider with a low transmission loss is designed. Finally, the simulated 2 ×2 array was fabricated and measured. The measurement results show that the impedance bandwidths are 18.85-20.8 and 29.5-30.9 GHz. The 3 dB axial ratio bandwidths are 19.4-20.4 and 28.5-31.4 GHz, with the peak gains of 13.2 and 11.5 dBic, respectively.