The present invention relates to a tuneable waveguide structure comprising a first, second, third and fourth electrically conducting inner wall. The first inner wall and the second inner wall are facing each other, and the third inner wall and the fourth inner wall are facing each other, the intended extension of the electrical field is parallel to the first inner wall and the second inner wall, and perpendicular to the third inner wall and the fourth inner wall. The waveguide structure comprises at least one tuning device that comprises a wall part that is movably arranged along an extension that is perpendicular to the intended extension of the electrical field. Each wall part is at least indirectly connected to support rods that are in sliding engagement with a corresponding sloped surface that is laterally adjustable in the extension of the slope. Each wall part may be constituted by an electrically conducting foil.

The present invention discloses a four-mode defected ground structure resonator, comprising a metal dielectric substrate and a defected ground unit which is etched in one surface of the metal dielectric substrate; the shape of the defected ground unit is axially symmetric about a first central axis of the defected ground unit, and also the shape of the defected ground unit is axially symmetric about a second central axis of the defected ground unit; the first defected ground unit is provided with H-shape or quasi H-shape, the second defected ground unit is provided with L-shape, quasi L-shape, U-shape or quasi U-shape. The four-mode defected ground structure resonator of the present invention is provided with four types of resonant modes, and the four types of resonant modes are provided with good tunability.

A waveguide transition includes a ridge waveguide section with a first ridge part running along a first wall having a first distance to an opposing second wall. The waveguide transition comprises a partial H-plane waveguide section with an electrically conducting foil that comprises a longitudinally running foil slot ending a certain edge distance before a foil edge that faces the ridge waveguide section. The ridge waveguide section and the partial H-plane waveguide section overlap during a transition section that has a first end at a transition between the second wall and a third wall. There is a second distance between the first wall and the third wall that exceeds the first distance. The transition section has a second end where the first ridge part ends by a transversely running second ridge part that crosses the foil slot and connects to a third wall.

This document describes techniques and systems relating to isolation slots for an antenna and printed circuit board (PCB) interface of a radar system. For example, isolation slots may be etched on a metal surface layer of a PCB for a radar control module on each side of each transmission line (e.g., microstrip line) that forms an array of channels (e.g., transmit channels, receive channels). When the PCB and an antenna structure are mated, a gap exists along the mating plane in which energy leakage between the channels can occur. The isolation slots create a stop band for a certain range of frequencies of interest and may reduce this energy leakage even when the gap is uneven along the mating plane. The isolation slots may be relatively easy and inexpensive to manufacture. The gap along the mating plane is not required to be constant, further simplifying the manufacturing process.

A notch filter includes a dielectric substrate; and a microstrip transmission line provided on the dielectric substrate and having an arrow-shaped embedded open-circuited stub.

The present invention relates to a filtering circuit comprising at least two slot line resonators arranged side by side and realized on a dielectric substrate having a first face equipped with a conductive layer and a second parallel face, each of said at least two resonators comprising a slot line etched in the conductive layer and folded according to a spiral pattern counting a plurality of turns, with a shape factor such that the slot line has parts noticeably parallel or concentric. According to embodiments of the invention, at least one turn of the spiral pattern of each of the resonators comprises at least one discontinuity, the discontinuities of said at least two slot line resonators being arranged in such a manner as to increase the electromagnetic coupling between said at least two slot line resonators.

A notch filter includes a dielectric substrate; and a microstrip transmission line provided on the dielectric substrate and having an arrow-shaped embedded open-circuited stub.

A band-pass filter having a body, a rectangular waveguide, and a dielectric insert, the dielectric insert has a dielectric plate and a high temperature superconductive film in line with a plurality of rectangular windows of the same height. The waveguide has ab cross-section, a being length of the long side walls and b the length of the short side walls. Each long side wall has a fixing groove at the central portion and a rectangular recess in the fixing groove. The dielectric plate has two ends in the fixing grooves and is symmetric with a perpendicular bisecting plane of the long side wall. The rectangular recess is symmetric to the perpendicular bisecting plane and has the same length as that of the waveguide, with its width w satisfying t<w<a/2, and depth d satisfying d</4, t being total thickness of the dielectric plate and the high temperature superconductive film, and the wavelength of the central frequency of the pass-band of the band-pass filter.