Abstract
This paper proposes a new Butler matrix topology. The proposed Butler matrix consists of only four couplers without phase shifters and crossovers. The output phase difference is relatively flexible. Compared with the phase differences (±45° and ±135°) generated by the conventional Butler matrix, the proposed design can generate different sets of phase differences, which can be realized from −180° to 180°. The proposed new Butler matrix replaces the traditional 90° coupler with arbitrary phase-difference couplers. In this paper, closed-form design equations are derived and presented. A 4 × 4 Butler matrix with output phase differences of −30°, +150°, −120°, and +60° is designed according to equations. The 4 × 4 Butler is meant to operate at 2 GHz. The simulation results show that the amplitude unbalance is less than 0.1 dB, the phase mismatch is within 1°, the return loss is higher than 29 dB, and the isolation is higher than 32 dB.
Highlights
In recent years, multibeam antennas have been widely used in the military and civilian fields
By exciting one of the input ports, the equal-amplitude and progressive-phase distribution responses can be generated at the output ports. e traditional 4 × 4 Butler matrix consists of four 90° couplers, two crossovers and two 45° phase shifters
A flexible output phase difference of Butler matrix topology was established by using couplers with arbitrary phase differences [12]
Summary
Multibeam antennas have been widely used in the military and civilian fields. E traditional 4 × 4 Butler matrix consists of four 90° couplers, two crossovers and two 45° phase shifters. A flexible output phase difference of Butler matrix topology was established by using couplers with arbitrary phase differences [12].
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