Abstract: Disclosed is a microwave window comprising a circular strip mounted in a circular waveguide section connected, on either side, to a rectangular waveguide containing a matching transformer. The diameter of the circular waveguide is smaller than the diagonal of the rectangle. A wall provides for impervious sealing with respect to the exterior between the rectangular waveguide and the circular waveguide section. Each wall is provided with an aperture included in a portion of cross-section common to the rectangular waveguide and to the circular waveguide section. The area of the aperture is smaller than the area of the portion of cross-section. The disclosed device can be applied to wideband power microwave windows with improved mechanical and electrical behavior.

Abstract: The disclosure concerns microwave tubes and, more particularly, travelling wave tubes wherein the region under vacuum is isolated from the external HF input/output circuits by vacuum-tight windows. The disclosed window consists of a ceramic cylinder, the two ends of which bear metallic flexible rings. This window is brazed to the cylindrical chamber of the part under vacuum by means of a clearance machined in the chamber, so that the chamber and the window are integrated and coaxial. The HF transmission through the window is achieved by means of an antenna formed by a metallic strip mounted, at right angles, on a metallic cylinder that fits the chamber. The device can be applied to power microwave tubes and, notably, to travelling wave tubes.

Abstract: In a travelling wave tube, the delay line of which is coupled to a transmission line of an external microwave circuit by a coupling pin having a coupling surface that faces an end surface of the transmission line, a microwave window extends between the coupling surface of the coupling pin and the end surface of the transmission line. This window is permeable to the microwave energy and impermeable to the gases. It is fixed imperviously to the travelling wave tube.

Abstract: A travelling-wave tube has a cylindrical sleeve containing a delay line and a coupling device between the delay line and an external microwave circuit for removal or injection of microwave energy. This external circuit comprises a transmission line possessing a conductive internal core. A conductive part is placed at one end of the delay line. It has a coupling pin that projects inwards into the sleeve and is brazed to an end of the delay line. The conductive part is brazed to the sleeve. The coupling between the delay line and the external circuit is made between the part and the internal conductive core of the transmission line. This coupling is without contact, a narrow gap being prepared between the external surface of the part located on the side of the coupling pin and the internal conductive core.

Abstract: A thin waveguide window having a broad band of operating frequencies is composed of a metallic frame provided with an opening and a leak-tight closure plate of dielectric material. The frame permits a reduction in dimensions of the plate, with the result that any spurious frequencies introduced by the plate are rejected from the operating frequency band. By giving the plate an oblong shape, it is possible to balance its inductive components by means of its capacitive components at the mid-band frequency. A matching transformer formed by the ridges which are more closely spaced in the vicinity of the window than in the remainder of the waveguide permits matching throughout the frequency band.

Abstract: The present invention relates to a circular window for an ultra-high frequency waveguide. This window is constituted by a circular plate or wafer made from a dielectric material mounted in a waveguide section, connected on either side of a waveguide operating in a frequency band centered around the central frequency. The diameter of the circular plate is chosen so as to reject the ghost modes outside the frequency band. The length of the circular guide section is chosen so that the reactance of the assembly constituted by the plate and the circular guide is cancelled out for the central frequency. It also comprises a half-wave impedance transformer, whose height is chosen so as to bring about the matching in the operating frequency band. The window associated with rectangular waveguides is more particularly used with tubes for telecommunications.

Abstract: The microwave window is inserted in a rectangular waveguide and is constituted by a half-wave impedance transformer, the wavelength considered being such as to correspond to the central frequency F.sub.0 for which the window has been realized; a dielectric plate of small thickness is mounted above the transformer and two inductive shutters are located on each side of the plate. The dimensions of the window components are so determined that in the case of a matched waveguide, the standing-wave ratio of the window is substantially 1 in a frequency band of at least 35% of the central frequency around the central frequency.