Wideband X-Band Microstrip Butler Matrix

Abstract

This paper presents the design of a wideband X-band microstrip 4×4 Butler matrix. The wideband performance of the Butler matrix means that it possesses equal coupling and difference of phases throughout the operating band. Design of the wideband components such as 3-branch branch line hybrid, crossover and Schiffman line phase shifter are presented in this paper. A final design of the Butler matrix is proposed. The Butler matrix exhibits couplings and phase errors within −6.7 ± 0.7 dB and 10 • over a 20% bandwidth with a center frequency at 10 GHz.

Compact Planar Microstrip Crossover for Beamforming Networks

“…Butler matrix is the key component of those beamforming networks that are widely applied in smart antennas [1,2]. It is a passive microwave network consisting of N input and N output ports.…”

“…In the literature, a few fully planar structures are proposed, such as the conventional approach of cascading hybrid and symmetric fourport junctions [2,[8][9][10][11][12]. The cascaded structures utilized in [2,8] result in a large size, whereas the use of very thin lines [9] limits the power handling capability, which is crucial factor in the beamforming networks of microwave transmitters.…”

“…The cascaded structures utilized in [2,8] result in a large size, whereas the use of very thin lines [9] limits the power handling capability, which is crucial factor in the beamforming networks of microwave transmitters. The structures presented in [10][11][12] uses slotted grounds and thus they are not perfectly compatible with uniplanar microstrip circuits.…”

DESIGN AND IMPLEMENTATION OF A COMPACT PLANAR 4 x 4 MICROSTRIP BUTLER MATRIX FOR WIDEBAND APPLICATION

“…One method is using multilayer technology, such as two-layer substrate integrated waveguide (SIW) [1], multilayer coplanar waveguide (CPW) [2] and stripline coupled line [3]. The other method is based on planar printed circuit technology such as SIW [4] and microstrip lines [5,6].…”

“…In addition, the processing requirements are more rigorous than the single-layer planar circuits. In the study of planar wideband matrices, some researchers adopted SIW technology to design a Butler matrix for wideband applications [4], and some other researchers use disk hybrids [5] or wideband branch-line couplers [6] to compose wideband Butler matrices. These Butler matrices own their superiorities in some aspects as well as some disadvantages in other aspects.…”