A Circularly Polarized Magneto-Electric Dipole Antenna Array With Wide AR and Impedance Bandwidth for Millimeter-Wave Applications

This letter presents a wideband circularly polarized (CP) magneto-electric (ME) dipole antenna array for millimeter-wave (mmW) applications. According to the design evolution, the proposed antenna element comes from a linearly polarized ME-dipole fed by an H-shaped slot, in which the microstrip patches work as electric dipoles, and the widths of the patches are first tuned to achieve an elliptically polarized wave. Then the L-shaped strips are loaded on the patches to further deflect currents, and two CP ME-dipole modes are generated by electric and magnetic currents in parallel. Next, some perturbations, including the conversion of L-shaped strips to F-shaped strips and the partial truncation of a pair of patches, are adopted to further improve the AR performance. The proposed CP ME-dipole antenna finally achieves an overlapped operating bandwidth of 32%. For verification, a 1-to-64 microstrip feeding network is designed to build a corporate-fed 8 x 8 array. The measured results indicate that the proposed CP array achieves an overall bandwidth of 31.7% covering 30.2-41.6 GHz, a peak gain of 22 dBic, and a radiation efficiency of greater than 64%. With outstanding CP performance and compact size, the proposed CP array is an attractive candidate for mmW and satellite communications.