A multi-resonator filter has a signal input terminal, a signal output terminal, and a plurality of resonator components. The plurality of resonator components include an input resonator component coupled to the signal input terminal, an output resonator component coupled to the signal output terminal, and at least one intermediate resonator component coupled between the input resonator component and the output resonator component. The input resonator component, output resonator component and the at least one intermediate resonator component are arranged in a sequence to define a signal path between the signal input terminal and the signal output terminal. The at least one intermediate resonator component includes at least one multiple resonator component, where each multiple resonator component includes a pair of individual resonators coupled in parallel where each individual resonator in a given pair of individual resonators has the same resonant frequency.

The invention discloses a cavity-based dual-band filtering balun, which includes a first cavity resonator and a second cavity resonator which are connected by a metal plate, the first cavity resonator is provided with an input PCB board, a metal ground layer of the input PCB board is provided with an input trough line, the other side of the input PCB board is provided with an input microstrip line, and the first cavity resonator is provided with an input slot corresponding to a position of the input trough line; and two opposite outside surfaces of the second cavity resonator which are adjacent to the metal plate are each provided with an output PCB board, metal ground layers of the two output PCB boards are respectively provided with an output trough line, the other sides of the two output PCB boards are each provided with an output microstrip line, and the second cavity resonator is provided with an output slot corresponding to a position of the output trough line and communicated with the output trough line. A main body of the dual-band filtering balun includes two cavity resonators, its structure is high in quality factor and low in insertion loss, and meanwhile, the requirement of two passbands is realized by using two fundamental modes of the cavity resonators, thus reducing a size of a circuit.

The invention discloses a cavity-based dual-band filtering balun, which includes a first cavity resonator and a second cavity resonator which are connected by a metal plate, the first cavity resonator is provided with an input PCB board, a metal ground layer of the input PCB board is provided with an input trough line, the other side of the input PCB board is provided with an input microstrip line, and the first cavity resonator is provided with an input slot corresponding to a position of the input trough line; and two opposite outside surfaces of the second cavity resonator which are adjacent to the metal plate are each provided with an output PCB board, metal ground layers of the two output PCB boards are respectively provided with an output trough line, the other sides of the two output PCB boards are each provided with an output microstrip line, and the second cavity resonator is provided with an output slot corresponding to a position of the output trough line and communicated with the output trough line. A main body of the dual-band filtering balun includes two cavity resonators, its structure is high in quality factor and low in insertion loss, and meanwhile, the requirement of two passbands is realized by using two fundamental modes of the cavity resonators, thus reducing a size of a circuit.

Disclosed herein is a radio frequency filter having a notch structure. The radio frequency filter includes a hollow housing having a plurality of partition walls defining a plurality of cavities and an open surface formed on one side, a cover configured to shield the open surface of the housing, a plurality of resonance elements positioned in the cavities of the housing, a coupling substrate arranged to cross a partition wall between at least two of the plurality of resonance elements, and a tuning screw inserted into the housing through the cover. The partition wall crossed by the coupling substrate includes a support window formed to have a first depth from the open surface, the coupling substrate being arranged through the support window, and a tuning window formed to have a second depth greater than the first depth from the open surface, the tuning screw being inserted into the tuning window.

Disclosed herein is a radio frequency filter having a notch structure. The radio frequency filter includes a hollow housing having a plurality of partition walls defining a plurality of cavities and an open surface formed on one side, a cover configured to shield the open surface of the housing, a plurality of resonance elements positioned in the cavities of the housing, a coupling substrate arranged to cross a partition wall between at least two of the plurality of resonance elements, and a tuning screw inserted into the housing through the cover. The partition wall crossed by the coupling substrate includes a support window formed to have a first depth from the open surface, the coupling substrate being arranged through the support window, and a tuning window formed to have a second depth greater than the first depth from the open surface, the tuning screw being inserted into the tuning window.

A filter device having desired characteristics is easily designed. The filter device includes a post-wall waveguide functioning as a resonator group including five congruent resonators (R.sub.1 to R.sub.5). The resonators (R.sub.1, R.sub.2) include therein respective control posts (CP.sub.1, CP.sub.2), and a shortest distance (d.sub.i) from the control post (CP.sub.i) to a narrow wall of the resonator (R.sub.i) satisfies d.sub.1>d.sub.2. The resonators (R.sub.4, R.sub.5) include therein respective control posts (CP.sub.4, CP.sub.5), and a shortest distance (d.sub.j) from the control post (CP.sub.j) to a narrow wall of the resonator (R.sub.j) satisfies d.sub.4<d.sub.5.

A filter arrangement having three or more stacked metallization layers separated by printed circuit board, PCB, layers. Each metallization layer includes an aperture. The filter arrangement has a plurality of via-holes extending though the stacked metallization layers and through the separating Dielectric material layers, whereby the via-holes and the metallization layers delimit a cavity in each Dielectric material layer. The cavities in two consecutive Dielectric material layers being coupled by the aperture in the single metallization layer separating the two consecutive Dielectric material layers. The aperture of a topmost metallization layer being arranged as antenna element. The filter arrangement having a signal interface arranged as a conduit connecting at least one dielectric material layer to an exterior of the filter arrangement.

A filter arrangement having three or more stacked metallization layers separated by printed circuit board, PCB, layers. Each metallization layer includes an aperture. The filter arrangement has a plurality of via-holes extending though the stacked metallization layers and through the separating Dielectric material layers, whereby the via-holes and the metallization layers delimit a cavity in each Dielectric material layer. The cavities in two consecutive Dielectric material layers being coupled by the aperture in the single metallization layer separating the two consecutive Dielectric material layers. The aperture of a topmost metallization layer being arranged as antenna element. The filter arrangement having a signal interface arranged as a conduit connecting at least one dielectric material layer to an exterior of the filter arrangement.

A cross-coupled filter includes a minimum resonant structure including four resonators. In the minimum resonant structure, two resonators in the same row form a group, and two resonators in the same row are capacitively mainly coupled or inductively mainly coupled; two resonators in the same column are electrically and magnetically hybrid coupled; and the coupling polarities of the two groups of resonators in the two rows of resonant units are opposite to each other and form at least a cross-coupling. The invention realizes miniaturization and light weight in structural characteristics, and realizes low loss and good harmonic characteristics in electrical performance.

A cross-coupled filter includes a minimum resonant structure including four resonators. In the minimum resonant structure, two resonators in the same row form a group, and two resonators in the same row are capacitively mainly coupled or inductively mainly coupled; two resonators in the same column are electrically and magnetically hybrid coupled; and the coupling polarities of the two groups of resonators in the two rows of resonant units are opposite to each other and form at least a cross-coupling. The invention realizes miniaturization and light weight in structural characteristics, and realizes low loss and good harmonic characteristics in electrical performance.