Broadband Dual Polarized Filtenna for 5G Millimeter Wave Application

This paper introduces a broadband dual-polarized filtering antenna (filtenna) for 5G mm-wave applications. It consists of a planar radiation patch with integrating four through holes, a hoop, a cross patch and the feeding network. By investigating the antenna's equivalent circuit, we achieve a bandpass radiation response featuring four controllable radiation nulls. Additionally, eight L-shaped slots are etched into the radiation patch to generate an upper radiation null, ensuring a wide upper stopband. However, the impedance matching response within the working band is poor due to the limitations of the millimeter wave processing technology. Therefore, two circular ring slots are loaded at the ground for achieving the good impedance matching. For demonstration, a 4×4 filtering antenna array for 5G mm-wave applications is implemented and tested. Measured results show that the proposed antenna array has an operated bandwidth of about 31.5% (S11 < -10 dB within 21.4-29.8 GHz), an average realized gain of 17.1 dBi and better than 24 dB out-of-band suppression level. Above features make the proposed antenna a good candidate for 5G mm-wave applications.