MMIC BROAD-BAND BRAIDED MICROSTRIP COUPLER

This article presents a broadband quadrature coupler realized using a novel braided microstrip structure that consists of 64 air-bridge crossovers. The test results of the 2.5-8-GHz single-section coupler fabricated on a 125-mum-thick GaAs substrate are presented. This coupler achieved better than 17-dB return loss, 11 dB of isolation and +/- 0.75 of amplitude variation over the almost 2-octave bandwidth. This bandwidth and performance are the best reported for a braided microstrip coupler. (C) 1994 John Wiley & Sons, Inc.