Highly Isolated Dual Circularly Polarized Metallic ME-dipole Antenna Array Design

Abstract

A novel dual circularly polarized metallic magneto-electric dipole (D-CP-M-ME-dipole) for the 30 GHz band is presented. The D-CP-M-ME-dipole uses solid metallic aluminum bulk without surrounding it with metallic cavities. It is fed by crossed narrow slots coupled to air-filled microstrip lines packaged by a bed of printed periodic mushrooms, achieving a bandwidth of 26–41 GHz (46%). An 8×8 array is constructed and fed by a carefully designed dual-polarized cooperative feeding network, which is optimized considering the mutual coupling influence. Hence, the need for an external decoupling mechanism to isolate the two polarizations is eliminated. The feed network is on Printed gap waveguide (PGW) to prevent leakage. Furthermore, parasitic elements are added to the 8×8 array to realize a 9×9 element array that improves the overall gain over the bandwidth. The 9×9 dual CP metallic ME- dipole is fabricated and measured to verify this procedure, with an ultrawide impedance bandwidth of 26–42 GHz (47%), 26.6 dBic gain, and 90% total efficiency, with less than 40 dBi isolation between the two polarizations throughout the band.