Single‐Layer Dual‐Polarized Millimeter Wave Slot Antenna Using Nested Radiators Under Four Resonance Modes

ABSTRACT This letter proposes a novel single‐layer dual‐polarized (DP) millimeter wave (mmWave) low‐profile antenna. This antenna is based on a circular substrate integrated waveguide (SIW) resonant cavity. Two different resonant cavities are created by incorporating via fences internally: a conventional circular resonant cavity and a circular ring resonant cavity. The bandwidth is expanded by introducing a central via in the internal resonant cavity, which generates the TM 010 and TM 110 resonant modes. On the other hand, the external annular resonant cavity introduces the TM 410 and TM 510 resonant modes by carefully adjusting the size of the radiation slot. The radiation slots within the external annular resonant cavity and the inner circular resonant cavity are positioned orthogonally, enabling dual‐polarized (DP) operation. It is shown that the DP antenna can achieve the measured −10 dB impedance bandwidths (FBW) of 11.82% (26.26–29.56 GHz) and 11.15% (26.09–29.17 GHz) for port 1 and port 2, respectively. The antenna features stable radiation patterns with an average gain of 5.1 dBi and a high isolation exceeding 20 dB within the passband. The antenna exhibits a single‐layer structure, low profile, high‐isolation, and low‐cost advantages, which can be a good candidate for 5G mmWave indoor applications.