Abstract: The radiometric thermometer includes a microwave sensor and electronic means for processing the electrical signal delivered by the sensor. The electronic means includes means for preamplifying the electrical signal delivered by the microwave sensor; variable-gain amplification means with automatic gain control, which means amplify the signal delivered by the preamplification means, the amplification means having an automatic gain control signal that allows the gain to be automatically adjusted on the basis of the signal output by the amplification means, and electronic temperature measurement means for measuring temperature on the basis of the automatic gain control signal.

Abstract: The radiometric thermometer includes a microwave sensor and electronic means for processing the electrical signal delivered by the sensor. The electronic means includes means for preamplifying the electrical signal delivered by the microwave sensor; variable-gain amplification means with automatic gain control, which means amplify the signal delivered by the preamplification means, the amplification means having an automatic gain control signal that allows the gain to be automatically adjusted on the basis of the signal output by the amplification means, and electronic temperature measurement means for measuring temperature on the basis of the automatic gain control signal.

Abstract: The invention relates to a method and a device for measuring the temperature T.sub.x of any material or object, by using a microwave radiation, as well as to an application of said method for determining the coefficient of hyperfrequency reflection of any material or object. According to the method, the microwave radiation emitted through an antenna (1) is captured and the signals received are directed towards signal processing means (3). Additionally, between the antenna (1) and said means (3), a given impedance line (4) is intercalated whose impedance is a function of the input impedance of said means (3), and with a length L much bigger than the wave length of processed signals, so that the correlation factor of said means (3) is negligible. Furthermore, the output voltage is processed by calculation of all parameters by cylindrically modifying the structure of said processing means (3).

Abstract: The invention relates to an impedance adaptation control process in low noise reception chains and a miniature microwave thermometer of application of the said process. The process is used mainly in order to measure internal temperature by microwave thermography. The thermal radiation is picked up by means of an aerial (1) which provides a signal (2). This signal (2) is sent alternatively with a signal (5) coming from a standard source to a hyperfrequency amplifier (3) in order to compare the said signals (2,5) and to adjust the source (4) in consequence. According to the invention, in parallel, an additional impedance (15) is placed by intermittance in parallel to the input of the amplifier (3). By means of a synchronous detection (18) of the resulting signal (7), the impedance of the standard source (4) is adjusted so as to equal that of the aerial (1).

Abstract: To measure the temperature of a sub-surface volume of a body, for example, living tissue, in microwaves, at least two probes are placed on or near the surface of the body to pick up thermal noise in the microwave range. The two probes are positioned so that the volumes of the body from which the respective probes receive thermal noise signals overlap to provide a common volume from which both of the probes receive thermal noise signals. The signals received by the probes are processed so as to be amplified and to accentuate the signals emitted by the common volume relative to the signals omitted by the remainder of the volumes from which the probes receive thermal noise signals. In one form of apparatus, the two probes are connected in parallel to a correlator the output of which is connected to an amplifier-receiver. In another form of apparatus the probes are connected to an amplifier-receiver, one being connected through a phase shifter.