ULTRABROADBAND 8 × 8 BUTLER MATRIX DESIGNED WITH THE USE OF MULTISECTION DIRECTIONAL COUPLERS AND PHASE CORRECTION NETWORKS

摘要

An 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.