A Compact Broadband 4×4 Butler Matrix With 360° Continuous Progressive Phase Shift
- Resource Type
- Periodical
- Authors
- Wang, X.; Chen, F.; Chu, Q.
- Source
- IEEE Transactions on Microwave Theory and Techniques IEEE Trans. Microwave Theory Techn. Microwave Theory and Techniques, IEEE Transactions on. 71(9):3906-3914 Sep, 2023
- Subject
- Fields, Waves and Electromagnetics
Butler matrices
Couplers
Broadband communication
Wideband
Transmission line matrix methods
Transmission line measurements
Power transmission lines
Butler matrix
continuous tunability
phase shifter (PS)
single layer
size miniaturization
wideband operation
- Language
- ISSN
- 0018-9480
1557-9670
This article presents a novel compact broadband $4\times 4$ Butler matrix with 360° continuous progressive phase shift. The tunable Butler matrix is composed of a typical $4\times 4$ Butler matrix and four wideband continuously tunable phase shifters (PSs). To realize the size miniaturization, the right-handed transmission line (RHTL) is employed to construct the compact branch-line couplers and crossovers, which performs well over the operating bandwidth. The size of the proposed Butler matrix utilizing the compact coupler and crossover is reduced about 50% compared with the traditional design. A novel coupled-resonant PS is proposed to realize $135^{\circ }\pm 10^{\circ }$ continuous phase shift over a wide fractional bandwidth (FBW) of 33.3% (2.0–2.8 GHz). By cascading the miniaturized $4\times 4$ Butler matrix and the 135° continuously tunable PSs, 360° continuous progressive phase shift between four outputs can be obtained. The measured results verify the feasibility of the design.