In -band Mutual Coupling Suppression in Dual-band Shared-aperture Station Arrays Using Dielectric Block Loading

Dual-band base station antenna (BSA) arrays with shared aperture have attracted considerable attention for the fifth-generation (5G) communication. The focus is mainly on decoupling between lower-band (LB) and higher-band (HB) antennas (i.e., cross-band decoupling). The in-band BSA decoupling techniques are usually not applicable to broadband dual-band shared-aperture BSA arrays. HB BSAs’ elements usually are separated by more than half-wavelength to reduce the in-band mutual coupling, which increases the array aperture and causes grating lobes for beam steering. Here, a novel decoupling technique of dielectric blocks is proposed to suppress the in-band couplings in dual-band shared-aperture BSA arrays. The dielectric blocks are placed above the HB elements to neutralize the original coupling by creating partially reflected waves (an addition wave path). A compact interleaved dual-band BSA array with dielectric blocks is designed and manufactured. The LB operates between 1.9 – 2.5 GHz, and the HB covers the 5G band from 3.3 – 3.9 GHz. The HB coupling is effectively reduced below -25 dB while the impedance matching and radiation performance of the HB and LB elements are maintained. Moreover, the dielectric blocks are implemented for stacked and interleaved dual-band BSA arrays with suppressed cross-band interference. The proposed decoupling method has simple structures, easy to design and fabricate, and is compatible with the existing cross-band decoupling techniques for different dual-band BSA array configurations.