Millimeter-Wave Wide-angle Scanning Array Antennas for 5G/6G Communication

Doctoral thesis, 2024

The advancement of 5G wireless communication brings fast speeds, high data volume, ultra-low latency, and broad bandwidth. 5G millimeter-wave (mmWave) bands enable data rates of ∼1 Gbps and latency as low as 1 millisecond. Future 6G aims for Tbps-level throughput over distances up to 1 km. W- and D-bands (92–175 GHz) are widely considered for this purpose.
     Phased array antennas (PAAs) with electronic beam-steering are expected to enable efficient, wide-coverage wireless communication systems for 5G and beyond. Conventional PAA architectures face challenges at 100 GHz due to high dissipation losses, component costs, and stringent manufacturing tolerances. Integrating beamforming electronics is particularly difficult, as component size approaches the antenna element size. To address these limitations, we introduce a novel antenna array element design based on the open-ended ridge gap waveguide (RGW), which eliminates the need for galvanic contact, easing manufacturing complexity and enhancing electronic integration. The E-and H-plane grooves are added to effectively suppress mutual coupling effects between the array elements, thereby achieving a wide-angle beam-steering range of 50◦ with 89% radiation efficiency. Furthermore, we propose a hybrid beam-steering PAA architecture that employs a low-loss Gap Waveguide (GWG)-based quasi-optical (QO) feeding network, providing nearly uniform amplitude excitation of the array elements, along with on-chip 1- and 2-bit integrated phase shifters for precise beam-steering. The hybrid QO PAA is optimized for the best trade-off between the maximum available gain and minimum sidelobe levels through numerical system performance analysis. 
     A novel design of a 28 GHz dual-polarized (DP) dielectric resonator antenna (DRA) in a two-dimensional (2-D) beam-steerable PAA is presented for 5G Antenna-in-Package (AiP) applications, utilizing low-temperature cofired ceramic (LTCC) technology. The radiating element consists of a DRA loaded with a two-layer metasurface, which acts as a wide-angle impedance matching (WAIM) layer. An 8×8 AiP array prototype is implemented on a PCB carrier to evaluate practical scenarios. Electromagnetic bandgap (EBG) structures are incorporated into the PCB to preserve radiating characteristics in the presence of array truncation effects. Measurements confirm that the proposed design achieves a scan range of ±60◦ (with a scan loss of 3–4.5 dB) and ±55◦ (with a scan loss of 2.5–4 dB) for 27.5–29.5 GHz.