A MW/MMW Shared-Aperture Antenna With Enhanced Dual-Band Performance Based on Structural Reutilization for Vehicular Applications

This paper proposes a dual-band shared-aperture antenna, consisting of a two-element microwave (MW) multiple-input multiple-output antenna and a four-element millimeter-wave (MMW) beam-steerable antenna array. Unlike general shared-aperture antennas, the proposed one not only realizes integration of two types of antennas, but also achieves dual-band mutual enhancement by leveraging the specific electromagnetic characteristic and structures of its sub-antennas. In the MMW frequency band, a column of quasi-mushroom shaped structures builds a compact array, and obtains improved gain and well beam scanning performance by reusing the natural metallic walls of the adjacent MW elements. Meanwhile, in the MW frequency band, the central independent MMW array also skillfully serves as a decoupling electromagnetic band-gap (EBG), suppresses the strong coupling between two planar inverted-F shaped antenna (PIFA) elements. More importantly, the MW decoupling frequency and MMW array operating frequency can be controlled independently, giving the design a certain degree of freedom. Experimental results show that the introduction of MMW antenna decreases the mutual coupling level of two MW elements from -9 dB to -18.2 dB, within bandwidth of 4.79-5.1 GHz (6.2%), satisfy the application in n79 frequency band. Simultaneously, MMW antenna array itself operating range from 25.9 GHz to 29.8 GHz (14%), covers n257 band, with a peak gain of 12.9 dBi and supports ±40° beam scanning. Hence, the proposed approach may be a good choice for designing a 5G vehicle communication antenna.