Series coupled filters where the first filter is a dielectric resonator filter with cross-coupling

A dielectric resonator filter having an input port which receives an electromagnetic signal and an output port at which is provided a filtered electromagnetic signal, the filter operating in a magnetic dipole mode and comprising:

• a multi-cavity housing having a plurality of vertical walls disposed at least partially between a base of the dielectric resonator filter and a cover of the dielectric resonator filter, defining a plurality of sequential dielectric resonator cavities that are sequentially oriented in first and second side-by-side rows;
• a plurality of cylindrically shaped dielectric resonators, each cylindrically shaped dielectric resonator respectively disposed in one of the plurality of sequential dielectric resonator cavities;
• means for coupling the electromagnetic signal between the respective resonators of the sequential dielectric resonator cavities so as to provide respective inter-resonator coupling factors;
• means for providing cross-coupling of the electromagnetic signal between respective dielectric resonators of a first dielectric resonator cavity and a second non-sequential dielectric resonator cavity of the plurality of sequential dielectric resonator cavities;
• and
• wherein in each of the cylindrically shaped dielectric resonators comprises a ZrSnTiO base material which is doped with a first dopant Ta in a range between 50 and 1,000 parts per million and a second dopant Sb in a range between 50 and 1,000 parts per million.

A method of providing a band pass filter which will meet in-band and out-of-band electrical performance requirements for insertion loss, return loss and attenuation comprising the steps of:

• providing a first band pass filter having a first pass-band width including a first center frequency, a first out-of-band suppression factor, and a first in-band insertion loss and return loss which meet the in-band electrical performance requirements of the bandpass filter;
• and
• providing a second band pass filter, disposed in series with the first band pass filter, having a second center frequency that is substantially the same as the first center frequency and a second pass-band width that is broader than the first pass-band width of the first bandpass filter so that the first pass-band of the first bandpass filter is included within the second pass band of second bandpass filter, and a second out-of-band suppression factor sufficient, in combination with the first out-of-band suppression factor of the first bandpass filter, to suppress any spurious signals from the first band pass filter and to comply with the out-of-band attenuation electrical performance requirements of the bandpass filter;
• wherein the first band pass filter is a dielectric resonator filter, comprising:
• a multi-cavity housing having a plurality of vertical walls disposed at least partially between a base of the dielectric resonator filter and a cover of the dielectric resonator filter, defining a plurality of sequential dielectric resonator cavities that are sequentially oriented in first and second side-by-side rows;
• a plurality of cylindrically shaped dielectric resonators, each cylindrically shaped dielectric resonator respectively disposed in one of the plurality of sequential dielectric resonator cavities;
• at least one coupling device, disposed in a first wall of each of the plurality of sequential dielectric resonator cavities, for coupling an electromagnetic field between the respective resonators of the sequential dielectric resonator cavities;
• and
• a cross-coupling device, disposed through a second wall of a first resonator cavity and a second non-sequential dielectric resonator cavity of the plurality of sequential dielectric resonator cavities, wherein the cross-coupling device providing cross-coupling of the electromagnetic field between the respective dielectric resonators of the first and second dielectric resonator cavities.