An apparatus includes a filter. The filter includes a metal structure forming a cavity and includes a ceramic block, which is suspended in the cavity. The ceramic block has two removed portions, the removed portions removed from two opposing sides of the ceramic block. The ceramic block further has one or more slots that that span a region of ceramic between the two removed portions and connects chambers formed by the two regions with chambers formed by the one or more slots, wherein a combined structure of the ceramic block, cavity, and metal structure supports multiple fundamental TM modes and one fundamental TE mode. The filter comprises multiple coupling structures to couple radio frequency signals into and out of the filter. The apparatus may include multi-cavity filters including one and typically multiple ones of the filters.

An RF filter includes: an electrical conductor defining an outer sphere; a dielectric material defining an inner sphere disposed within the conductor outer sphere; and at least a first electrical probe and a second electrical probe. Each probe extends through the conductor and is electrically insulated from it. A spherical shape of one or both of the inner and outer spheres is interrupted by: a) a first localized discontinuity in said spherical shape disposed along a first axis passing through a geometric center of the one or both of the inner and outer spheres; and b) a second localized discontinuity in said sphere form disposed along a second axis passing through the geometric center, the second axis perpendicular to the first axis. There can be more than these two discontinuities, implemented as chamfers, tuning screws, and the like. Series and parallel coupling of the spheres is detailed.

Targeting mass production, the present invention provides an advanced method of manufacturing pure niobium plate end-group components from pure niobium plate material for superconducting high frequency accelerator cavity by means of innovative shear-blanking followed by innovative forging procedures, wherein the invention is to convert the procedure/production method from the conventional machining or waterjet cutting followed by the conventional cold forging to the whole press-forming The invention gives the drastic effects on cost-effectiveness and press-performance.

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.

Disclosed is a tunable low-pass filter using a dual mode including a cylindrical cavity configured to trigger a resonant mode, a plurality of irises formed on a lateral face of the cylindrical cavity, and a dummy iris formed on the lateral face of the cylindrical cavity, wherein the resonant mode includes a plurality of modes having a plurality of resonant frequencies, and differences in resonance frequency between the plurality of modes are determined based on angles between the plurality of irises based on an axis of the cylindrical 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 triple-band bandpass filter with at least one cavity resonator. Each cavity resonator has the same three orthogonal resonances modes corresponding to three unique resonance frequencies. The three unique resonance frequencies define the passbands of the filter. The filter has an input probe coupled to an input cavity resonator. The filter has an output probe coupled to an output cavity resonator. The input and output probes are shaped to concurrently couple signal waveforms in each of the resonance modes. Coupling probes that can be used as input or output probes are also provided. An inter-cavity coupling operable to concurrently transmit signal waveforms in each of the resonance modes is also provided. The inter-cavity coupling can be used to transmit signals between adjacent cavity resonators in the filter.

A millimeter wave filter fine-tuning structure includes a resonant cavity, a fine-tuning cavity disposed at the edge of the resonant cavity, a fine-tuning cavity coupled to the resonant cavity, and plural adjusting screws disposed and inserted in the fine-tuning cavity, and the distance between the adjusting screws and the resonant cavity may be used to adjust the resonant frequency of the filter.

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 waveguide is provided, the waveguide configured to support at least two degenerate modes of electromagnetic fields. The waveguide comprises an input node configured to couple electromagnetic fields into the waveguide. An output node is configured to couple electromagnetic fields out of the waveguide. A perturbation is configured to couple the two degenerate modes within the waveguide. The input node and the output node are positioned such that coupled degenerate modes clockwise and counter-clockwise propagating waves within the waveguide with at least two transmission minima. A waveguide device comprising a plurality of such multi-mode waveguides is also provided, the waveguide device having a plurality of transmission minima.