Thomson-Csf

Narguise Mamodaly

Alain Bert

Didier Kaminsky

Pierre Guillon

Luis Bermudez

A microwave resonator for operation in the whispering-gallery mode is constituted by a resonant element included in a flat disk having a diameter (2a) which is considerably larger than its thickness (2d). An electromagnetic wave which propagates within the disk is confined between the periphery of this latter and a so-called caustic surface having a smaller radius (a.sub.c). The wave does not radiate to the exterior and the resonator can be placed on a dielectric or metallic substrate. The disk can be hollowed-out within the caustic surface. A resonator can be simulated within the thickness of a dielectric substrate by at least one metallic ring which forms a magnetic short-circuit with the ground plane. Excitation is produced by microstrips or by dielectric image waveguides.

Microwave resonator for operation in the whispering-gallery mode

A frequency-doubling voltage-controlled oscillator (VCO) for use in the microwave frequency range has two channels which operate in parallel. A transistor is mounted as an oscillating system in each channel and its energy is collected on the drain electrode. The two transistors are mounted with their output currents in opposite phase, thus reducing FM noise in the vicinity of the carrier. In accordance with the invention, phase opposition is obtained by means of a varactor connected between the gates of the two transistors. The varactor is decoupled in direct current by means of two capacitors. In order to increase the range of frequencies, two additional varactors can be mounted in like manner on the source circuits of the two transistors.

Frequency-doubling voltage-controlled oscillator

The invention concerns a negative resistance hyperfrequency oscillator, operating in the millimetric band, comprising a waveguide delimited on one side by an iris and a useful load and on the other side by a supplementary load, wherein a Gunn or Impatt diode is polarized and coupled to the waveguide by means of an aerial, the resonator cavity of this oscillator being delimited by the iris and by a dielectric resonator placed in the waveguide between the aerial and the supplementary load, and double coupling being provided between the resonator and the guide and between the diode to the guide to produce a stable and relatively noiseless oscillator. The invention can be applied to hyperfrequency systems, for synchronizing hyperfrequency sources and conjugating their power.

Hyperfrequency oscillator operating in the millimetric band

A metallic support supports a number of semi-conductor devices surrounded by an annular dielectric substrate which in turn supports a circuit including at least two microstrip lines and a metallic circular output element. The small thickness and high dielectric constant of the substrate are selected to permit a reduction in width and in length of the microstrip lines which are folded-back in a curvelinear fashion and placed on the substrate along circular arcs which are concentric with the output element.

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Paris, France

Narguise Mamodaly