Communication Triple-Mode Planar Phased Arrays of Antennas Using Trifocal Rotman Lens as Switchable Mode-Former for Vehicular Radar Applications

A trimode phased array of antennas is presented for vehicular radar applications to provide both short- and long-distance coverages, which radiates various gains and beamwidths at different modes of coverage. The mode forming network is realized by applying the concept of a trifocal Rotman lens beamforming network (RL-BFN), where its beam ports serve as a mode selector. This approach first computes the required excitation phases for the desired radiation patterns at different modes. They are then used to design the trimode RL-BFN such that its outputs produce precisely the desired mode excitation phases. A practical transmitting (TX) antenna array at the 77 GHz band is presented with numerical simulations and measurements of an antenna prototype to validate the conceptual feasibility.