Quasi-Optical Beamforming Network for Millimeter-Wave Electronically Scanned Array Antennas with 1-Bit Phase Resolution

State-of-the-art design solutions for electronically scanned array antennas are mostly limited to microwave to low mm-wave frequency bands, while the demand for new designs at higher frequencies (i.e. frequencies beyond 100 GHz) is rapidly growing. We attempt to fill in this knowledge gap by presenting a new linear array antenna architecture as a building block of 2D arrays that can enable efficient beam steering and a simplified array design. This concept is based on the combination of a low-loss quasi-optical (QO) feed, providing predefined antenna port excitation, with 1-bit phase shifters which are co-integrated with the array antenna elements. In this study, we formulate the array design problem as minimization of the sidelobe level (SLL) through an optimum quasi-randomization of phase errors. An analytical expression for the optimum focal ratio of the QO feed has been derived to establish the relationships between the key design parameters. These results are validated through numerical simulations revealing that the optimum focal ratio leads to the minimum SLL.