Dielectric resonator filter

A dielectric resonator filter comprising:

• at least one dielectric resonator;
• an enclosure enclosing the dielectric resonator to function as a shield against an electromagnetic field;
• resonance-frequency tuning means including a conductor plate disposed in a space enclosed by the enclosure to have a first surface opposed to a surface of the dielectric resonator and a second surface opposed to an inner surface of the enclosure, the resonance-frequency tuning means being capable of changing the separation between the conductor plate and the dielectric resonator;
• a plate spring for suppressing propagation of a spurious electromagnetic field mode produced in and around a space between the second surface of the conductor plate and the inner surface of the enclosure, said plate spring being disposed between the second surface of the conductor plate and the inner surface of the enclosure and said plate spring substantially preventing said conductor plate from affecting the reduction of spurious mode;
• and
• wherein said plate spring automatically adjusts to span the space between the second surface of the conductor plate and the inner surface of the enclosure and thereby controlling the suppression of the spurious electromagnetic field mode without detaching said resonance-frequency tuning means from the enclosure.

A dielectric resonator filter comprising:

• at least one dielectric resonator;
• an enclosure enclosing the dielectric resonator to function as a shield against an electromagnetic field;
• resonance-frequency tuning means including a conductor plate disposed in a space enclosed by the enclosure to have a first surface opposed to a surface of the dielectric resonator and a second surface opposed to an inner surface of the enclosure, the resonance-frequency tuning means being capable of changing the separation between the conductor plate and the dielectric resonator;
• and
• a divided ring for suppressing propagation of a spurious electromagnetic field mode produced in and around a space between the second surface of the conductor plate and the inner surface of the enclosure, said divided ring being disposed between the second surface of the conductor plate and the inner surface of the enclosure, said divided ring capable of being detached and attached without requiring said resonance frequency means to be detached from the enclosure.