A quasi-TEM design method for 3 dB hybrid couplers using a semi-reentrant coupling section

An effective quasi-TEM design method for 3-db hybrid couplers using a semi-reentrant coupling section is presented. The analysis is based on the use of the rectangular boundary division method for solving the boundary value problem, including thick-strip conductors in an inhomogeneous medium. A trial design of a microstrip 3-dB coupler using substrates of low dielectric constant has been carried out by adding a sequential optimisation algorithm to the analysis method. Measured parameters of the designed 3-dB hybrid coupler are compared with the theoretical ones.<
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