A passive microwave component with constant impedance and electrically adjustable phase length utilizes a microstrip or stripline transmission line geometry incorporating a composite dielectric having both ferroelectric (FE) and ferromagnetic (FM) properties. These properties can be varied with externally applied electric and magnetic fields such that the phase length (or electrical length) of the line can be varied without varying the characteristic impedance of the transmission line. Thus, the component can be electrically tuned without adversely affecting the impedance match. The component can be used in microwave devices such as phase shifters, frequency filters, directional couplers, power dividers and combiners, and impedance-matching networks.
Tunable microwave components utilizing ferroelectric and ferromagnetic composite dielectrics and methods for making same
Joines, WT., & Palmer, WD. (2003). IPC No. U.S. Tunable microwave components utilizing ferroelectric and ferromagnetic composite dielectrics and methods for making same. (Patent No. 6593833).