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A two-octave 4×4 Butler matrix has been presented, for the first time in multilayer microstrip asymmetric coupledline technology. To achieve two-octave frequency band in terms of amplitude and phase responses a recently developed approach has been used in which multi-section coupled-line directional couplers and Schiffman C-sections are applied. A highperformance three-section coupled-line 3-dB microstrip directional coupler has been utilized as a basic element of the Butler matrix and two compensated microstripline Schiffman C-sections have been designed to provide appropriate differential phase characteristics. A very good performance has been achieved over two-octave frequency band in terms of amplitude and phase responses. The designed network can be easily applied in large microstrip networks as a surface mount element.
Date of Conference: 14-16 June 2010