Wideband Circularly Polarized Substrate Integrated Dielectric Resonator Antenna Array for 5G Millimeter-Wave Applications

A wideband circularly polarized (CP) substrate-integrated dielectric resonator antenna (SIDRA) array is proposed for 5G communication applications. A dual-band CP SIDRA element operating at 28 GHz and 38 GHz is first designed, comprising a rectangular dielectric resonator (DR), a ring DR, a pair of asymmetric dielectric bridges, and a substrate-integrated waveguide (SIW) cavity. The antenna element is excited by a microstrip feed line through an unequal cross slot. In the lower band, the SIDRA resonates in the fundamental <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TE</i> 11δ mode and radiates a CP wave. In the upper band, the cross slot, together with four sequentially rotated slots, generates slot modes, while the entire DR resonates in the high-order <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TE</i> 31δ mode. The hybrid of slot modes and high-order DRA mode realizes CP performance. A 2 × 2 SIDRA array employing a sequentially rotated feeding network (SRFN) is further developed, which significantly enhances the impedance and axial ratio (AR) bandwidths. The proposed SIDRA array achieves an overlapped bandwidth of 27.92 GHz to 39.93 GHz (35.4%) where the reflection coefficient is lower than −10 dB and the AR is less than 3 dB simultaneously. The proposed SIDRA array could be a good candidate for 5G millimeter-wave communications.