A multi-mode resonator includes: a housing having a cavity therein; and a plurality of resonance ribs which are arranged radially around a center of the cavity with a predetermined interval therebetween. Each of the plurality of resonance ribs includes a body having a lower end and an upper end. The lower end of each of the plurality of resonance ribs is fixed to a bottom surface of the housing, and the body of the each of the plurality of resonance ribs is bent so that the upper end of each of the plurality of resonance ribs points to the center of the cavity.

Waveguides in accordance with embodiments of the invention are disclosed. In one embodiment, a dual-mode circular waveguide includes a cavity, a first end wall including a first handedness-preserving metasurface positioned at a first end of the cavity, and a second end wall including a second handedness-preserving metasurface positioned at a second end of the cavity.

A multi-mode resonator includes: a housing having a cavity therein; and a plurality of resonance ribs which are arranged radially around a center of the cavity with a predetermined interval therebetween. Each of the plurality of resonance ribs includes a body having a lower end and an upper end. The lower end of each of the plurality of resonance ribs is fixed to a bottom surface of the housing, and the body of the each of the plurality of resonance ribs is bent so that the upper end of each of the plurality of resonance ribs points to the center of the cavity.

A resonator includes a housing having a cavity therein; a plurality of resonance plates which are arranged radially around a center of the cavity with a predetermined interval therebetween; and a plurality of legs each of which supports one of the plurality of resonance plates, respectively. A center of each of the plurality of legs is deviated from a center of a corresponding resonance plate.

A waveguide filter including a coupling window for generating negative coupling includes: a plurality of resonators including a substrate block; and the coupling window provided between the plurality of resonators for coupling, wherein a length of a dimension element of the coupling window is equal to or greater than half a working wavelength of the waveguide filter. The waveguide filter may reverse a coupling polarity between resonators to generate negative coupling.

A dual mode cavity filter installed aboard a satellite having a first and a second waveguide cavity, a first coupling waveguide iris having an input slot and followed by the first waveguide cavity, a second coupling waveguide iris having a coupling slot, following the first waveguide cavity and followed by the second waveguide cavity, and a third coupling waveguide iris having an output slot and following the second waveguide cavity. The dual mode cavity filter is associated with a plurality of devices having at least one respective commanded rod having a certain insertion length with respect of the waveguide cavities and of the slots. The devices are placed in predetermined positions of the cavities and/or of the irises and are arranged to perform a tuning modification and/or a coupling modification of the filter by controlling the insertion length of the rods in outer space.

A multi-mode resonator includes: a housing having a cavity therein; and a plurality of resonance ribs which are arranged radially around a center of the cavity with a predetermined interval therebetween. Each of the plurality of resonance ribs includes a body having a lower end and an upper end. The lower end of each of the plurality of resonance ribs is fixed to a bottom surface of the housing, and the body of the each of the plurality of resonance ribs is bent so that the upper end of each of the plurality of resonance ribs points to the center of the cavity.

Disclosed is a multimode microwave filter including a resonator in which a cavity is formed to generate a resonant mode and a plurality of irises formed on a side surface of the resonator, in which the cavity of the resonator has a rhombus-shaped cross section.

A multi-mode resonator includes: a housing having a cavity therein; and a plurality of resonance ribs which are arranged radially around a center of the cavity with a predetermined interval therebetween. Each of the plurality of resonance ribs includes a body having a lower end and an upper end. The lower end of each of the plurality of resonance ribs is fixed to a bottom surface of the housing, and the body of the each of the plurality of resonance ribs is bent so that the upper end of each of the plurality of resonance ribs points to the center of the cavity.

An apparatus includes a measurement structure for performing measurements of an RF device. The measurement structure includes an aperture in a conductive surface of the RF device and a conductive projecting region projecting into the aperture from a conductive perimeter of the aperture and electrically connected to that conductive perimeter. The aperture has a similar width in all dimensions. A combined shape of the aperture and the conductive projecting region does not possess even rotational symmetry about a point where a signal conductor will be placed on the conductive projecting region in order to conduct RF energy between the measurement structure and an external measurement instrument for performing the measurements. The measurement structure may be used for performing measurements of a multimode resonator, the measurements comprising one or more of resonant frequencies and quality factors of resonant modes of the resonator.