Abstract: A coaxial resonator for radio frequency, RF, signals, said resonator comprising a cavity, the cavity comprising a first wall, a second wall opposite the first wall, and at least one side wall, the resonator further comprising a first post extending with its longitudinal axis into the cavity from said first wall, wherein an outer diameter of at least a first axial section of said first post is, preferably reversibly, changeable.

Abstract: The invention relates to a dielectric double-mode resonator of a radio-frequency filter that comprises a block structure comprising at least two resonator structures having at least one resonance mode each. In addition, said block structure comprises a cavity wall that limits a cavity at least partly inside the block structure, the cavity affecting the resonance modes of the at least two resonator structures. The block structure comprises a first block and a second block set against each other and each comprising at least part of the at least two resonator structures and at least part of the cavity wall limiting the cavity.

Abstract: The invention relates to a dielectric double-mode resonator of a radio-frequency filter that comprises a block structure comprising at least two resonator structures having at least one resonance mode each. In addition, said block structure comprises a cavity wall that limits a cavity at least partly inside the block structure, the cavity affecting the resonance modes of the at least two resonator structures. The block structure comprises a first block and a second block set against each other and each comprising at least part of the at least two resonator structures and at least part of the cavity wall limiting the cavity.

Abstract: The invention relates to a resonator filter comprising a housing structure (10), at least one resonator conductor (20) in the housing structure, and a regulating means (30) for regulating the frequency band of the resonator filter. The regulating means (30) is substantially transverse with respect to the propagation direction of the resonator conductor so that the regulating means (30) forms at least one turn around the resonator conductor (20) transversely to the propagation direction of the resonator conductor.

Abstract: A filter has a shell construction including a connection surface and a bar-like resonator in the shell construction. The bar-like resonator has an initial section having one end region thereof connected to the connection surface of the shell construction and an opposite end region. A substantially straight and elogate intermediate section extends from the opposite end region of the initial section to an end and a turning-point section extends from the end of the intermediate section to an end. A substantially straight and elongate end section has one end connected to the end of the turning-point section so as to extend adjacent to the intermediate section and supporting means connect to the connection surface of the shell construction for supporting the bar-like reasonator at least at one of the end section and turning-point.