Analysis and Design of Dual-Polarized Millimeter-Wave Filtering Magneto-Electric Dipole Antenna

Abstract

A wideband dual-polarized millimeter-wave (mm-wave) filtering magneto-electric dipole (ME-dipole) antenna design is proposed based on a transmission line model with multiple open-circuited loads. Based on the transmission line theory, the input impedance of a quarter-wavelength open-circuited transmission line is zero. Thus, a transmission line terminated with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> open-circuited loads has <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> transmission zeros. Inspired by this conclusion, the proposed antenna structure is developed which consists of three parts: the microstrip feedlines, the ME-dipole radiator, and a printed branch structure. The former three parts can be regarded as three open-circuited loads of an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -stub-loaded transmission line model while the last part is utilized for bandwidth improvement. By optimizing the length parameters of these three parts, three antenna radiation nulls can be generated as predicted. For verification, a dual-polarized antenna is implemented. Measurement results show that the proposed antenna has an operation bandwidth of 42.1% and an average realized gain of 7.5 dBi. In addition, it has three controllable radiation nulls and a better than 16-dB out-of-band suppression level. The above features make the proposed antenna a good candidate for 5G mm-wave applications.