Design of Shared-Aperture Multi-Band MIMO Antenna Array by Scattering Minimization

A novel low-scattering antenna (LSA) is proposed for suppressing the strong scattering and mutual coupling in the shared-aperture dual-band dual-polarized base station MIMO antenna array. The LSA geometry is obtained by first discretizing a solid metal into multiple small meta-atoms and then strategically connecting them to realize the triple functions, including restoration of the radiation pattern, low scattering, and excellent matching in the antenna impedance. We have proposed a thorough and general LSA inverse design method that combines both electromagnetic scattering and RF circuit theories. The method can simultaneously consider S-parameters, radiation patterns and scattering fields in a shared-aperture dual-band antenna array. To verify the proposed design method, a prototype with two lower-band (0.88-1.16 GHz, 27.5%) LSA elements positioned above eight higher-band (1.45-2.65 GHz, 58.5%) antenna elements has been fabricated and tested. The results show that the shared-aperture dual-band dual-polarized antenna array with the proposed LSA has stable and symmetrical radiation pattern, while keeping high antenna-port isolation in both bands. The method’s generality and high performance (58.5% low-scattering bandwidth) make it valuable for 5G and beyond wireless systems, particularly for base station applications.