An exemplary cavity resonator has a resonant frequency and includes a conductive body containing a cavity and a plate attached to the body enclosing the cavity. The position of a conductive tuning mechanism that protrudes into the cavity affects the tuning of the resonant frequency of the cavity resonator. A portion of the enclosed cavity is made of a shape memory alloy (SMA) material that has been trained to have a coefficient of thermal expansion that results in dimensional changes of the portion as the temperature varies so that the dimensional changes produce changes in the resonant frequency that counteract the combined change in the resonant frequency due to dimensional changes with temperature associated with the other portions of the enclosed cavity made of materials other than SMA material. This results in a stable resonant frequency versus temperature characteristic.

A mode converter which converts between a mode of a post-wall waveguide and a mode of a line in which a strip-shaped conductor is formed on another substrate different from a substrate of the post-wall waveguide, is less likely to cause a transmission failure resulting from a change in environmental temperature. A mode converter (10) includes: a post-wall waveguide (PW) in which an opening (121) is provided in a wide wall (conductor layer 12); a dielectric substrate (15) having a main surface on which a strip-shaped conductor (16) is formed; and a joining member (solder 18) joining the wide wall (conductor layer 12) and the substrate (15), wherein in a plan view, the opening (121) and the strip-shaped conductor (16) overlap each other.

A mode converter which converts between a mode of a post-wall waveguide and a mode of a line in which a strip-shaped conductor is formed on another substrate different from a substrate of the post-wall waveguide, is less likely to cause a transmission failure resulting from a change in environmental temperature. A mode converter (10) includes: a post-wall waveguide (PW) in which an opening (121) is provided in a wide wall (conductor layer 12); a dielectric substrate (15) having a main surface on which a strip-shaped conductor (16) is formed; and a joining member (solder 18) joining the wide wall (conductor layer 12) and the substrate (15), wherein in a plan view, the opening (121) and the strip-shaped conductor (16) overlap each other.

In some aspects, a flexible cable may comprise: a flexible strip with first and second parallel surfaces and first and second ends, said flexible strip being electrically insulating; a metal stripline within said flexible strip; first and second metallic grounding planes on said first and second surfaces, respectively; and a first circuit board mechanically attached to at least one of said first end of said flexible strip and said first and second metallic grounding planes at said first end, said first circuit board being mechanically stiff, said metal stripline being electrically connected to electrical circuitry on said first circuit board.

In some aspects, a flexible cable may comprise: a flexible strip with first and second parallel surfaces and first and second ends, said flexible strip being electrically insulating; a metal stripline within said flexible strip; first and second metallic grounding planes on said first and second surfaces, respectively; and a first circuit board mechanically attached to at least one of said first end of said flexible strip and said first and second metallic grounding planes at said first end, said first circuit board being mechanically stiff, said metal stripline being electrically connected to electrical circuitry on said first circuit board.

High power impedance tuners suffer from intense heating of the center conductor of the tuner airline (slabline), due to dissipated RF and DC power and, in addition to high electric field between the metallic tuning probe (slug) and the center conductor, also from associated thermal expansion causing sagging of the center conductor and possible electrical short. If the thermal expansion cannot be accommodated by structural means, the center conductor is cooled using forced air created by ventilators or re-circulating low loss dielectric liquid flowing through the slabline. Premature tuner aging through continuous airflow or cooling liquid circulation is avoided using real time monitoring of dissipated (heating) power and regulation of the cooling mechanism.

High power impedance tuners suffer from intense heating of the center conductor of the tuner airline (slabline), due to dissipated RF and DC power and, in addition to high electric field between the metallic tuning probe (slug) and the center conductor, also from associated thermal expansion causing sagging of the center conductor and possible electrical short. If the thermal expansion cannot be accommodated by structural means, the center conductor is cooled using forced air created by ventilators or re-circulating low loss dielectric liquid flowing through the slabline. Premature tuner aging through continuous airflow or cooling liquid circulation is avoided using real time monitoring of dissipated (heating) power and regulation of the cooling mechanism.

The technology described herein is directed towards a cryogenic-stripline microwave attenuator. A first high thermal conductivity substrate such as sapphire and a second high thermal conductivity substrate such as sapphire, along with a signal conductor comprising one or more attenuator lines between the substrates form a stripline. A compression component such as one or more screws, vias (plus clamps) and/or clamps presses the first high thermal conductivity substrate against one side of the signal conductor and presses the second high thermal conductivity substrate against another side of the signal conductor. The high thermal conductivity of the substrates facilitates improved thermalization, while the pressing of the substrates against the conductor reduces the thermal boundary (Kapitza) resistance and thereby, for example, improves thermalization and reduces thermal noise.

The technology described herein is directed towards a cryogenic-stripline microwave attenuator. A first high thermal conductivity substrate such as sapphire and a second high thermal conductivity substrate such as sapphire, along with a signal conductor comprising one or more attenuator lines between the substrates form a stripline. A compression component such as one or more screws, vias (plus clamps) and/or clamps presses the first high thermal conductivity substrate against one side of the signal conductor and presses the second high thermal conductivity substrate against another side of the signal conductor. The high thermal conductivity of the substrates facilitates improved thermalization, while the pressing of the substrates against the conductor reduces the thermal boundary (Kapitza) resistance and thereby, for example, improves thermalization and reduces thermal noise.

In a radar apparatus, a high-frequency integrated circuit is mounted to a board, and a shielding case encloses the high-frequency integrated circuit. A radio-absorbing and heat-dissipative gel is arranged to cover at least part of the high-frequency integrated circuit and to be in contact with the shielding case.