A 64-Element and Dual-Polarized SICL-Based Slot Antenna Array Development Applied to TDD Massive MIMO

This letter reports the concept, design, fabrication, and characterization of a novel 64-element, slot-based and substrate-integrated coaxial line (SICL)-fed dual-polarized antenna array (SICL-SAA) for fully digital massive multiple-input–multiple-output (mMIMO) applications. The proposed array is composed of ±45° polarized elements based on half-wavelength slots. Each slot has its own back cavity, acting as an individual reflector for enabling boresight radiation. The slot is fed using a SICL feeding line for shielding the propagating mode in the feeding network, aiming at low mutual coupling levels. Experimental results in excellent agreement with full-wave numerical simulations demonstrate up to 2 GHz bandwidth from 24.5 GHz to 26.5 GHz for all array elements. Furthermore, the mutual coupling between adjacent elements is kept lower than −23 dB for the entire bandwidth, the radiating elements provide an 85° beamwidth in both planes (ϕ = 0° and ϕ = 90°) and 7.4 dBi gain.