Analysis and Design of Broadband Dual-Polarized Filtenna Array for 5G Millimeter-Wave Application

This letter presents a broadband dual-polarized filtering antenna (filtenna) designed for 5G millimeter-wave (mm-wave) applications. The antenna comprises three fundamental components: radiating elements, filtering circuits, and impedance matching structures. First, the radiation characteristics of the bandpass-type filtenna are optimized through structural modifications without increasing the overall size. Second, innovative impedance matching techniques are introduced. A coupled cross-patch structure is adopted to rectify pattern distortion, while a ring-slot configuration is utilized to enhance in-band return loss and achieve broad bandwidth. For validation, a 4×4 filtenna array prototype targeting the 5G n261/n258/n257 bands was fabricated and tested. Measured results demonstrate an impedance bandwidth of 31.5% (21.4–29.8 GHz for S₁₁ & S₂₂ < –10 dB), an average realized gain of 15.7 dBi, and out-of-band suppression greater than 20 dB.