Millimeter-Wave Dual-Band Dual-Polarized SIW Cavity-Fed Filtenna for 5G Applications

This article presents a millimeter-wave (mmWave) dual-band dual-polarized filtenna, which can achieve desirable out-of-band rejection for 5G applications. The dual-band dual-polarized antenna element consists of two fully-shielded quarter-mode substrate integrated waveguide (FSD-QMSIW) cavities and a dual-band stacked ring antenna. Two parts are coupled through the slot on the ground. The cavities are completely enclosed by the metal holes and copper cover to eliminate radiation loss. The loaded slots can tune the frequencies of the first two modes in the FSD-QMSIW cavity for dual-band operation. The inherent transmission null between the dual modes is generated to improve the stopband attenuation. To verify the proposed method, a dual-band dual-polarized filtenna with a three-order filtering function and four radiation nulls is designed and fabricated. The −10 dB impedance bandwidth can effectively cover 5G n258 (24.25–27.5 GHz) and n260 (37–40 GHz) bands in the measurement. The gains of two polarizations drop over 20 dB between the two bands. A four-element filtenna array is constructed to test its beam-scanning ability and further integrated with active beamformer integrated circuits (ICs). The measured results show that the fabricated filtenna array maintains satisfactory out-of-band rejection performance and can be one of the most promising 5G communication candidates.