Transmission-Line Identities for a Class of Interconnected Coupled-Line Sections with Application to Adjustable Microstrip and Stripline Tuners

Transmission-line identities are developed for a class of interconnected coupled-line sections. The identities, which may be used in several applications, are employed to synthesize adjustable microstrip and stripline tuners consisting of parallel, coupled or uncoupled strips with movable bridging wires. The tuners, which are analogous to waveguide and coaxial-line multistub tuners, can be used, in principle, to match any impedance falling within the Smith Chart. An experiment on a 12-GHz adjustable microstrip tuner is described, and the results are found to agree favorably with the theory.