Adaptable resonator filter
View Patent ↗An adaptable filter made up of cavity resonators. The adaptation takes place by adjusting the connection from the input connector (CN 1 ) of the filter to the input resonator and from the output resonator to the output connector. For adjusting the connection there is a coaxial transfer line (TL 1 ), the outer conductor (OC 1 ) of which is connected by its one end to the wall of the filter casing and by its other end to the outer conductor of the connector (CN 1 ) and the inner conductor of which extends from the middle conductor of the connector to the cavity of the resonator and there into the internal connecting member of the resonator. A middle rod belonging to the inner conductor is surrounded over a certain distance by a cylindrical conductive tuning element, which can be moved by sliding it along the middle rod.
1. An adaptable resonator filter, comprising a filter casing made up of a bottom, a plurality of walls including an end wall and a lid, which filter casing functions as a ground for a transfer path and is divided with conductive partitions into resonator cavities, an input connector with a middle conductor, an input resonator, an output resonator and an output connector with a middle conductor, wherein for adaptation of the filter;
the filter further comprises a first coaxial transfer line for adapting input impedance of the filter, which first transfer line comprises an outer conductor and a middle conductor including a middle rod and a moveable conductive tuning element through which the middle rod passes, wherein the first transfer line is connected between the input connector and the input resonator of the filter,
the filter further comprises a second coaxial transfer line for adapting output impedance of the filter, which second transfer line comprises an outer conductor and a middle conductor including a middle rod and a moveable conductive tuning element through which the middle rod passes, wherein the second coaxial transfer line is connected between the output connector and the output resonator;
wherein the outer conductor of the first coaxial transfer line is connected by one end thereof to an outer conductor of the input connector and by another end thereof to the end wall of the filter casing, wherein a starting end of the middle rod of the first coaxial transfer line is connected to the middle conductor of the input connector and an opposing end of the middle rod connects to an internal connecting member of the input resonator;
wherein the outer conductor of the second coaxial transfer line is connected by one end thereof to an outer conductor of the output connector and by another end thereof to the end wall of the filter casing, wherein a starting end of the middle rod of the second coaxial transfer line is connected to the middle conductor of the output connector and an opposing end of the middle rod connects to an internal connecting member of the output resonator;
wherein each of the tuning elements of the first coaxial transfer line and the second coaxial transfer line is supported in an insulated manner on the middle rods of the first coaxial transfer line and the second coaxial transfer line and is configured so that the tuning element can be slid along the middle rod;
wherein the middle rods of each of the first coaxial transfer line and the second coaxial transfer line are smaller in diameter than a diameter of the middle conductors of the input connector and the output connector respectively, and wherein the tuning elements of each of the first coaxial line and the second coaxial line are larger in diameter than the diameter of the middle conductors of the input connector and the output connector, respectively; and
wherein each of the first coaxial transfer line and the second coaxial transfer line includes a dielectric control pin that extends from the tuning elements thereof and is arranged for moving the respective tuning elements.
2. The resonator filter according to claim 1 , wherein both said first and second transfer lines are dimensioned so that moving the respective tuning elements thereof along the middle rods thereof toward the respective input resonator and output resonator is arranged to cause a strengthening of a connection between the respective input or output resonator and the respective input or output connector of the filter.
3. The resonator filter according to claim 1 , wherein an electrically controllable actuator is attached to said outer conductor of each of the first coaxial transfer line and the second coaxial transfer line for moving the respective tuning elements thereof, whereby said control pin is mechanically connected to said actuator.
4. The resonator filter according to claim 3 , further comprising an adjustment apparatus having an actuator for moving the pass band of the filter and wherein the actuator associated with the adjustment apparatus and the actuators associated with said transfer lines have a shared control for correcting the adaptation of the filter at the same time as the pass band of the filter is moved.
5. The adjustable resonator filter according to claim 1 , wherein said input and output resonators are coaxial quarter-wave resonators, whereby each resonator cavity has an inner conductor that is connected at a lower end thereof in a conductive manner to the bottom of the filter casing.
6. The adjustable resonator filter according to claim 1 , wherein said input and output resonators are dielectric cavity resonators.