Abstract: A low-pass filter comprises input and output transmission lines, a high impedance, series transmission line coupling the input and output transmission lines, a first meandered transmission line having one or more pairs of coupled transmission lines and one or more transition transmission lines connecting respective pairs of coupled transmission lines together, wherein one of the coupled transmission lines is connected to the input transmission line, and a second meandered transmission line having one or more pairs of coupled transmission lines and one or more transition transmission lines connecting respective pairs of coupled transmission lines together, wherein one of the coupled transmission lines is connected to the output transmission line. A high-pass filter is similar to the low-pass filter, except it has a pair of series coupled transmission lines in place of the series transmission line. The transmission lines are formed on a dielectric subtrate.

Abstract: A temperature-compensating tuning device is disclosed for tuning and temperature stabilizing the resonant frequency of a dielectric resonator. The tuning device comprises a tuning element in the form of a cylindrical shaft, an inner sleeve coaxially around the tuning element and mating therewith by corresponding sets of threads, and an outer sleeve coaxially around the inner sleeve, and mating therewith by corresponding sets of threads. The outer surface of the outer sleeve may also include threads for mating with threads of a dielectric resonator enclosure. Rotation of the tuning element, inner sleeve and/or outer sleeve can move the tuning element in proximity to a dielectric resonator, which provides the resonant frequency tuning effect. The tuning element, inner and outer sleeves are made of temperature expanding material to cause the tuning element to move in proximity of the dielectric resonator with temperature changes to provide temperature stability to the resonant frequency.