Abstract: A polarity reversal network is provided for a microwave filter that includes a plurality of resonators. The polarity reversal network has a magnetic coupling device that is positioned within an iris of the filter between a pair of the resonators. The coupling device is tunable to adjust its resonant frequency and is used to magnetically couple a signal from a first one of the pair of resonators to a second one of the pair of resonators. The coupling device also reverses the polarity of the magnetically-coupled signal upon the resonant frequency being tuned below a passband frequency of the microwave filter. As a result, the polarity of the signal resembles that of a capacitively-coupled signal.

Abstract: An inductive tuning disk for tuning a resonant frequency of a resonator of a microwave filter. The microwave filter includes a housing that encloses a cavity and a resonator therein. The resonator exhibits a magnetic field that appears in the cavity. The inductive tuning disk includes a dielectric base which is supported from a top wall of the housing by a support, and which is disposed within the cavity at an adjustable height above the resonator. The inductive tuning disk further includes an inductor ring which is disposed over a portion of a top surface of the dielectric base, and which is spaced apart from a center of the base. The inductor ring includes an electrically conductive material. The inductor ring interacts with the magnetic field to cause a resonant frequency of the resonator to vary as a function of the adjustable height. The disk may also be used to couple the magnetic energy between a pair of resonators of a filter.