A Millimeter-Wave Bidirectional Circularly Polarized Meta-Dielectric Resonator Antenna Array

In this paper, a millimeter-wave (mmWave) bidirectional circularly polarized (CP) meta-dielectric resonator antenna (MDRA) array is presented. The CP MDRA consists of upper and lower meta-dielectric resonator arrays, two dielectric substrates, and a metal plane with the coplanar waveguide (CPW) and the feeding slots. A one-to-four microstrip sequential feeding network (SFN) and four microstrip to CPW transition structures are designed to feed the 2×2 MDRA array to improve the axial ratio (AR) bandwidth and gain. Measured results show that the proposed 2×2 bidirectional CP MDRA array achieves a -10 dB impedance bandwidth of 43.35%, 3 dB AR bandwidths of 31.3% and 32.14% in the +z/-z directions, and peak gains of 9.53 dBic and 9.23 dBic in the +z/-z directions. The proposed MDRA array is particularly suitable for narrow and enclosed wireless communication environments, showing promising application prospects.