Element-Level Decoupled-Beamforming Empowered Wideband MIMO Phased Array Antennas

This paper proposes wideband decoupled phased array antennas capable of pattern-preserved multi-beam generation and wide-angle beam-steering. Two novel element-level decoupled beamforming patch antennas with symmetrical configurations and feedings are developed, demonstrating over 25 dB port isolations across bandwidths of 28.2% and 27.3%, respectively. These antennas utilize a mixed-mode feeding strategy to produce broadside, tilted, and conical beams across the wideband. Combining the two antenna elements in the E-plane forms arrays that exhibit superior multi-path coupling suppression, with port isolations over 22 dB across a bandwidth of 26.2%. This ensures stable active reflection coefficients (ARCs) and prevents scanning blind spots during beam steering. The 2-element array with four ports supports beam scanning up to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${\theta}= {55^{\circ}}$</tex> across the operational band under a peak gain of 12.8 dBi, while scaling to a 1-by-8 array extends the scanning range to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${\theta}= {76}^{\circ}$</tex> under an 18.5 dBi peak gain. The antennas and arrays feature a single-layer, low-profile configuration, making them highly suitable for advanced MIMO phased array applications.