Enhanced-Bandwidth Center-Fed Linear Slot Array and its Multibeam Application

In this letter, an enhanced-bandwidth multibeam antenna based on center-fed linear slot array is proposed. First, by placing the coupling slot in the center and inserting matching vias, the proposed center-fed method can enhance the bandwidth by exciting slots of linear slot array in phase in an enhanced bandwidth. To illustrate the operation principle, the electric fields of center-fed structure and the function equations among the phase, distance, and frequency are analyzed and presented. Then the multibeam application of the center-fed linear slot array with 4 × 4 Butler matrix beamforming network is fabricated and measured. The measured impedance and 3-dB gain bandwidths are 13.69% and 14.09%. When exciting different ports, the beam angles fluctuate around -38°, -20°, 20°, and 40°, with peak gains of 16.66, 17.65, 17.74, and 16.88 dBi