Abstract: A power circuit of a coil, includes two power or transmission line segments that are each connected to one of two ends of this coil, the line segments forming with the coil an oscillating circuit exhibiting a determined resonance frequency. The circuit has two line segments each including at least two conductors, of which one is connected to coil, and between them exhibit identical structures and identical lengths of connected conductors, whereby this common length is essentially a multiple of half of the resonance wavelength of the oscillating circuit. The conductors which are connected to coil at one of their ends are connected to one another at their other end by an adjustable symmetrical tuning component that completes this oscillating circuit, which with symmetrical structure is powered by a primary power circuit.

Abstract: A multifrequency power circuit of an NMR coil, includes two power or transmission line segments called principal line segments, each including a segment of a conductor that is attached to the coil, which attached segments together with the coil constitute a first oscillating circuit that exhibits a determined resonance frequency. The principal line segments consist of controlled-impedance multiconductor line segments, each including at least one other conductor segment that is not attached to coil and that extends into the principal line segment beside corresponding respectively attached conductor segment and that exhibits with the latter a capacitive coupling that is distributed along segments located beside or opposite the conductors.

Abstract: A power circuit of a coil, includes two power or transmission line segments that are each connected to one of two ends of this coil, the line segments forming with the coil an oscillating circuit exhibiting a determined resonance frequency. The circuit has two line segments each including at least two conductors, of which one is connected to coil, and between them exhibit identical structures and identical lengths of connected conductors, whereby this common length is essentially a multiple of half of the resonance wavelength of the oscillating circuit. The conductors which are connected to coil at one of their ends are connected to one another at their other end by an adjustable symmetrical tuning component that completes this oscillating circuit, which with symmetrical structure is powered by a primary power circuit.

Abstract: A multifrequency power circuit of an NMR coil, includes two power or transmission line segments called principal line segments, each including a segment of a conductor that is attached to the coil, which attached segments together with the coil constitute a first oscillating circuit that exhibits a determined resonance frequency. The principal line segments consist of controlled-impedance multiconductor line segments, each including at least one other conductor segment that is not attached to coil and that extends into the principal line segment beside corresponding respectively attached conductor segment and that exhibits with the latter a capacitive coupling that is distributed along segments located beside or opposite the conductors.

Abstract: A device for generating a radio frequency electrical signals, delivering at least two separate signals having different frequencies, in the form of signals delivered by different primary sources and amplified with a predetermined gain. The device comprises a combining circuit (3), combining the signals delivered by the primary sources (2), a single channel power amplifier (4) and a multi-channel selection and routing unit (5) with a parallel structure. Each channel delivers at the output an amplified signal (S) at a frequency (F) characteristic of one of the primary sources (2) and comprises a filter circuit (6) adjusted to be passing for one of the different characteristic frequencies (F) of the different primary sources (2), an impedance adaptation circuit (7) and a rejection circuit (8) for frequencies other than the passing frequency of the filter circuit (6) of the channel in question.

Abstract: An excitation circuit of a probe for measuring and recovering the signal emitted in return by this latter in an NMR spectrometric apparatus, connecting the probe under conditions defined by switching elements forming a portion of the circuit, to a high frequency excitation signal generator by a portion of the line or emission line, and by a portion of the line or reception line, to a receiver for acquiring and using signals emitted by the probe as a function of the specimen to be analyzed which it contains, a device being provided to carry out or verify the tuning of the measuring probe with the excitation signal generator, associated with the circuit. The device includes a directive coupler, mounted to the portion of the emission line.

Abstract: An excitation circuit of a probe for measuring and recovering the signal emitted in return by this latter in an NMR spectrometric apparatus, connecting the probe under conditions defined by switching elements forming a portion of the circuit, to a high frequency excitation signal generator by a portion of the line or emission line, and by a portion of the line or reception line, to a receiver for acquiring and using signals emitted by the probe as a function of the specimen to be analyzed which it contains, a device being provided to carry out or verify the tuning of the measuring probe with the excitation signal generator, associated with the circuit. The device includes a directive coupler, mounted to the portion of the emission line.

Abstract: A device for generating a radio frequency electrical signals, delivering at least two separate signals having different frequencies, in the form of signals delivered by different primary sources and amplified with a predetermined gain. The device comprises a combining circuit (3), combining the signals delivered by the primary sources (2), a single channel power amplifier (4) and a multi-channel selection and routing unit (5) with a parallel structure. Each channel delivers at the output an amplified signal (S) at a frequency (F) characteristic of one of the primary sources (2) and comprises a filter circuit (6) adjusted to be passing for one of the different characteristic frequencies (F) of the different primary sources (2), an impedance adaptation circuit (7) and a rejection circuit (8) for frequencies other than the passing frequency of the filter circuit (6) of the channel in question.

Abstract: A method for determining a temperature of a body by measuring emitted thermal noise includes measurement of thermal noise with a double radiofrequency signal amplification chain, one of whose branches continuously measures a thermal noise signal generated by a predetermined reference source. The heterodyne frequency transposition of the radiofrequency signal frequencies of the thermal noise processed in the two branches is changed with two converter circuits whose continuous signals are transmitted to a unit for control, processing and evaluation to determine in real time a temperature of a body.

Abstract: Radiometer for the determination of a temperature of a body by measuring emitted thermal noise and measurement process using this radiometer. The radiometer includes a double radiofrequency signal amplification chain (1) for thermal noises, one of whose branches (2') continuously measures a thermal noise signal generated by a predetermined reference source (3), two converter circuits (5, 5', 6, 6') whose continuous signals are transmitted to a unit (8) for control, processing and evaluation, and means (9, 10, 11) for changing the heterodyne frequency transposition of the radiofrequency signal frequencies of the thermal noise processed in the two branches (2 and 2').

Abstract: A process for frequency tuning microwave bridges and a device for practicing such a process. The process is characterized in that it consists in subjecting a resonator (3) to the radiation delivered by a secondary microwave source (10) sweeping a wide band of frequencies comprising particularly the frequency (F) of radiation delivered by the principal microwave source (1). The radiation reflected by the resonator (3) is displayed and the relative positions are marked along the frequency spectrum, of the frequency (F) and of the frequency of resonance (Fr) of the resonator (3). The frequency (F) of radiation delivered by the principal microwave source (1) is varied while controlling in real time the effect of this variation on the relative positions of the frequencies (F and Fr).

Abstract: A hyperfrequency generator comprising a source element (5) of negative resistance adjacent to a cylindrical resonant cavity (2) closed at opposite ends by two transversal closure plates (4, 7) for the purpose of tuning over a frequency band. The source element (5) is installed directly in the resonant cavity (2) such that there is a direct coupling between the source element (5) and the resonant cavity (2). One of the closure plates (7) is movable toward and away from the other for rough tuning.