Calculation of tightly coupled transmission lines for MMIC/MHMIC technology

Analyses and calculations are performed to provide design equations for new tightly coupled transmission lines, compatible with MMIC/MHMIC technology. In this design, short subsections of different lines loaded by MIM capacitors are connected together to achieve the tight coupling needed. The design equations obtained are in good agreement with previous computer simulation results and experiments and will facilitate the design of the above transmission line to realise wide-band quadrature couplers and Schiffman phase shifters