Beam-Reconfigurable Antenna Based on Vector Modulator and Rotman Lens on LTCC

Abstract

A beam-switching array is designed using a $4\times 6$ Rotman lens as a beam-forming network to switch the beam towards -30°, -10°, 10°, and 30°. Six substrate integrated waveguide fed $1\times 4$ microstrip patch arrays are used as the radiating elements. The beam-switching array is designed on the LTCC substrate to operate at 71-76 GHz. In this work, the feasibility of implementing a beam-switching network with a vector modulator (VM) integrated circuit as switching element is studied for the first time. The measured radiation pattern of the beam-switching array with the VM is in line with the simulated radiation pattern. The measured peak realized gain of the beam port 1, 2, 3, and 4 with 3-dB backoff gain of the VM are 17, 17, 17.8, 16.9 dBi at 75 GHz, respectively. In addition, the work demonstrates the possibility of beam-reconfigurability in beam-switching array by simultaneous excitation of the beam ports in optimum phase using the VM. The simultaneous excitation of the adjacent two ports, 1-2, 2-3, and 3-4, steer the beam towards -19°, 0°, and 19°, respectively, which improves the beam cross-over level. With various combinations of simultaneous excitation, the half power beam-width of the beam-switching array is varied from 17.8° to 75°.