On the Design of Linear Array with Steerable Beam Fed by Crossover-Free Butler Matrix

초록

There are various methods to produce steerable beam in array antenna, one of them is using a beamforming network. This paper focuses on the design of a linear array antenna with steerable beam which is fed by a crossover-free 8×8 Butler matrix. The proposed Beam-Steerable Linear Array (BSLA) comprises eight microstrip patch antennas configured in a 1×8 arrangement. In order to feed the input ports of Butler matrix using a common technique of microstrip feeding line, the crossover-free 8×8 Butler matrix is modified by rearranging some 90° hybrid couplers located in the center to the edge of matrix area. The Butler matrix and array antenna boards, deployed on FR4 Epoxy substrates, are then arranged in a stack manner, where both are connected one each other through 50 Ω coaxial cables. The characterization results of BSLA show good reflection coefficient responses and radiation patterns. The 10-dB reflection coefficient bandwidth is about 14.5%, while the main beams of linear array could be steered at ±8°, ±28°, ±46°, and ±72° at the frequency of 2.4 GHz. © 2025 IEEE.

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