Abstract: A bulk wave acoustic resonant structure which is in accordance with the invention allows the difficulties encountered at high frequency, the impossibility of working at low frequency on simple structures and the absence of an adequate coupling level to be overcome. The invention therefore proposes the use of an additional layer of material which covers the upper electrode of a piezoelectric transducer in order to localize the position of maximum intensity of the dynamic stress close to the centre of the piezoelectric layer through the effect of propagation. The structure that is in accordance with the invention may be associated with Bragg mirrors and various uses are presented.

Abstract: The invention relates to a method for realizing surface acoustic wave filter arrangements of the kind comprising a piezo-electric substrate and on said substrate metallic strip elements constituting impedance filter elements arranged in a network scheme. In such an arrangement by electrostatic interaction between the network elements is produced a parasitic resonance at a frequency different from the operational resonance frequency. The method is characterized in that means are provided in the filter arrangement which produce a shifting of the parasitic resonance frequency to a frequency substantially equal to said operational resonance frequency. The invention can be used for filter arrangements.

Abstract: A bulk wave acoustic resonant structure which is in accordance with the invention allows the difficulties encountered at high frequency, the impossibility of working at low frequency on simple structures and the absence of an adequate coupling level to be overcome. The invention therefore proposes the use of an additional layer of material which covers the upper electrode of a piezoelectric transducer in order to localize the position of maximum intensity of the dynamic stress close to the centre of the piezoelectric layer through the effect of propagation. The structure that is in accordance with the invention may be associated with Bragg mirrors and various uses are presented.

Abstract: A filter or multicoupler has at least one resonator which can be electronically tuned by a tuning device, has at least one tuning element such as a tuning capacitor, a switching element for selectively connecting the tuning element electronically to the resonator, and a control device for the switching element. The resonator is a coaxial quarter-wave resonator with a central component having free surface perpendicular to the central axis for mounting of tuning devices.

Abstract: A method of controlling the amplitude of the microwave signal applied to an atomic clock comprising an atomic resonator and a device for interlocking an ultra-stable oscillator in follow-up relationship with the atomic resonance, adapted to produce the signal from which the microwave signal is derived, the method consisting in transforming the amplitude of the microwave signal before its application to the atomic jet resonator according to a law such that the shape of the curve of atomic response versus the amplitude of the microwave signal be symmetrical over a wide extent about the vertical line passing through the maximum of the response.