Ultrabroadband 8 × 8 Butler matrix designed with the use of multisection directional couplers and phase correction networks

Abstract

AbstractAn innovative approach that allows for realization of ultrabroadband 8 × 8 Butler matrices has been proposed. It is shown that such a matrix can be divided into two pairs of identical 4 × 4 submatrices, which appropriately connected constitute an ultrabroadband 8 × 8 Butler matrix. To achieve broadband operation in terms of amplitude multisection symmetrical coupled‐line directional couplers are used. Moreover, it has been shown that all the required broadband phase shifters can be realized with the use of tandem connections of two 3‐dB/90° directional couplers in conjunction with Schiffman C‐sections. To achieve that, four intentionally selected crossovers have been realized as tandem connections of two 3‐dB/90° coupled‐line directional couplers and appropriate Schiffman C‐sections have been added to the outer channels within each 4 × 4 submatrix. The proposed concept has been used for the design of an 8 × 8 Butler matrix operating in the frequency range 1.8–12 GHz and the measurements of the manufactured network are shown. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1375–1380, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26805