91results about How to "Wide frequency response" patented technology

The invention relates to the technical field of radar, in particular to a millimeter-wave quasi-optical integrated dielectric lens antenna and an array thereof. The array consists of a microstrip integrated antenna, a dielectric lens, an objective lens, an array base, a reflecting mirror, a protective cover and a beam transfer switch; one end face of the dielectric lens is a hemisphere or an ellipsoid, while the other end face is a cylindrical section; the microstrip integrated antenna is generated by an dielectric substrate, the front surface of the dielectric substrate is closely adhered tothe cylindrical section of the dielectric lens and serves as a feed source, and the back surface is grounded; the hemispherical or ellipsoidal end face of the dielectric lens is an antenna radiating surface; the length of the cylindrical part of the dielectric lens can be changed; the antenna array is arranged into a linear array or an area array; the array base and the reflecting mirror have conical quasi-optical reflecting mirror surfaces; the focus of the objective lens of the linear array or the area array aligns with the central line of the dielectric lens; the protective cover is arranged outside; and the antenna array is controlled by the beam transfer switch. The antenna structure has strong shock resistance and dust prevention, and is suitable for millimeter-wave radars for planes, automobiles and ships, and receiving/emitting sensing of communication equipment.

An apparatus and method of detecting COPD and in particular, emphysema utilizes a change in acoustic transmission characteristics of a lung due to e.g. the appearance of fenestrae (perforations) in the alveoli of the lung. The use of acoustic signals may provide good sensitivity to the existence of alveolar fenestrae, even for microscopic emphysema, and the appearance and increase in fenestrae may be determined by monitoring acoustic transmission characteristics such as, for example, an increase in acoustic signal velocity and velocity dispersion, and/or a change in attenuation. A transmitter may be located in e.g. the supra-clavicular space and receivers may be mounted on the chest. Measurements may be correlated between pairs of receivers to determine acoustic transmission profiles.

The invention provides a production method of a high-power precision alloy SMD (surface mount device) resistor. The production method comprises the steps: respectively combining two oxygen-free copper strips with two sides of a resistor alloy strip to form an integrated strip-shaped resistor strip, and wrapping a high-heat-conductivity substrate with the integrated strip-shaped resistor strip; etching a basic resistor structure on a wrapping body; precisely adjusting the resistance value of the basic resistance structure; coating, terminal electroplating and printing a resistor body to form a high-power precision alloy SMD resistor. The material with high heat radiation capability and high heat conductivity such as a metal substrate, a high-heat-conductivity ceramic substrate is used as the substrate, so that the actual load capacity of the resistor is greatly increased; the oxygen-free copper strip is partially arranged on the side surface and below the substrate and used as an electrode lead, so that the contact area is increased, and the heat conductivity of the resistor body is also increased on the other hand.

The invention discloses a surface electromyographic electrode comprising a signal acquisition unit and having an amplifying function. After the acquisition unit acquires an electromyographic signal, the electromyographic signal is processed by a signal filter unit and a signal amplifying unit in turn, and an expected electromyographic signal is output from a signal output unit; the acquisition unit comprises a signal electrode, a grounding electrode and a reference electrode; the signal filter unit comprises a high-pass filter circuit; and the signal amplifying unit comprises an instrument amplifier. The electromyographic electrode has good anti-jamming capability, can accurately acquire the electromyographic signal, and can well meet the requirements of research and application on the aspect of clinical medicine.

Electronic circuitry for high-power, high-frequency excitation of electromagnetic acoustic transducers (EMAT) without the use of a matching transformer is described. This circuit contains a least 4 switching devices such as power Mosfet transistors, arranged in an H-Bridge configuration that are designed to drive various EMATs over a wide range of frequencies. The switching devices can be connected in parallel with respect to the H-Bridge and switched in sequence for greater power output and variety of wave forms. This circuit configuration can provide a many excitation waveforms including, Churp, Hemming window tone burst, rectangular tone burst and Barker Code wave forms.

An improved electronic pulser circuit based on the H-bridge topology is designed for driving the sensor coils of an electromagnetic acoustic transducer (EMAT) to correct the disadvantages of conventional H-bridge pulsers and pulsers that require the use of an output transformer. A plurality of switching devices, primarily power Mosfets, are connected in parallel and augmented with support circuitry to provide improved performance in terms of increased power output, stability, reduced noise and complex output wave forms. This improved design provides for the application of modulated pulses such as multi-pulse, multi-frequency tone bursts of peak power outputs in excess of 20 thousand watts and frequencies in excess of 10 thousand Hertz.

An acoustic device comprising a diaphragm (10) having an area and having an operating frequency range and the diaphragm (10) being such that it has resonant modes in the operating frequency range, an electromechanical transducer having a drive part coupled to the diaphragm (10) and adapted to exchange energy with the diaphragm, and at least one mechanical impedance means (20,22,24) coupled to or integral with the diaphragm, the positioning and mass of the drive part (26) of the transducer and of the at least one mechanical impedance means (20,22,24) being such that the net transverse modal velocity over the area of the diaphragm (10) tends to zero. A method of making an acoustic device having a diaphragm having an area and having an operating frequency range which includes the piston-to-modal transition, comprising choosing the diaphragm parameters such that it has resonant modes in the operating frequency range, coupling a drive part of an electro-mechanical transducer to the diaphragm to exchange energy with the diaphragm, adding at least one mechanical impedance means to the diaphragm, and selecting the positioning and mass of the drive part of the transducer and the positioning and parameters of the at least one mechanical impedance means so that the net transverse modal velocity over the area tends to zero.

An MR system features an intracavity probe and associated interface device. The probe includes a shaft, a balloon at one end thereof, and a coil loop within the balloon. The loop has two drive capacitors and a tuning capacitor, all of which in series. A junction node between the drive capacitors serves as a ground for electrically balancing the loop. Diametrically opposite the node, the tuning capacitor enables the loop to resonate at the operating frequency of the MR system. The interface allows the MR system to couple the loop to a port of the MR system during a receive cycle thereof and decouple it from the port during a transmit cycle thereof. With its balloon inserted and inflated within a cavity of a patient, the probe allows the MR system to generate images and/or spectra of the region of interest using the MR signals received by the loop.

The invention discloses an optical current sensor based on the Faraday magneto-optic effect. The optical current sensor comprises a laser generator which is used to generate polarized laser of a set wavelength, an integrated probe which comprises a magneto-optical medium, a photodetector which is used to convert an optical signal into an electrical signal, and a data analyzing and processing device which filters out noise through the combination of hardware filtering and software filtering to acquire a good response effect. A polarizer and an analyzer are arranged on two ends of the magneto-optical medium respectively, and are insulatedly packaged on both ends of the magneto-optical medium respectively. The laser generator and the polarizer are connected through an optical fiber path, andthe photodetector and the analyzer are connected through an optical fiber path. The invention further discloses a current measurement method of the optical current sensor based on the Faraday magneto-optic effect.

The invention discloses a shear stress sensor based on 1-3 type cement-based piezoelectric composites and a preparation method thereof. The shear stress sensor comprises a 1-3 type cement-based piezoelectric composite component; and a packaging layer and a shielding layer with which the 1-3 type cement-based piezoelectric composite component is wrapped in sequence. Positive and negative electrodesof the 1-3 type cement-based piezoelectric composite component are led out of the shielding layer through a wire to be connected with a shielding wire. The shielding wire is connected with the shielding layer. The component comprises a cement-based piezoelectric composite body and an electrode. The cement-based piezoelectric composite body is composed of a piezoelectric ceramic column array formed by piezoelectric ceramic columns and a cement base material filled among the piezoelectric ceramic columns. The piezoelectric ceramic column array is obtained by cutting a polarized piezoelectric ceramic block with the cutting direction perpendicular to the polarization direction of the piezoelectric ceramic block. The sensor of the invention has the advantages of high sensitivity, wide frequency response, good anti-interference effect and good compatibility with a concrete structure, and can be used for the health monitoring of the concrete structure.

The invention relates to a non-contact phase-difference type torque sensor which comprises an input sleeve, an output sleeve, a Hall sensor, a first involute gear and a second involute gear, wherein the input sleeve is connected with the output sleeve through a torsion bar, a hub bore of the first involute gear is in interference fit with the output sleeve, a hub bore of the second involute gear is in interference fit with the input sleeve, third sections of shaft segments of the input sleeve and the output sleeve are respectively matched with an inner ring of a corresponding bearing, an outer ring of the bearing is respectively matched with two groups of sensor shells which are arranged at two sides of the torsion bar, a magnetic circuit support is respectively fixed on the inner surface of each sensor shell, a magnetic circuit assembly and a circuit board are fixed on each magnetic circuit support, the Hall sensor is welded on the circuit board, and a detection surface of the Hall sensor is arranged in an air gap where the end surface of magnetic-conducting soft iron a just faces to a top addendum circle of the involute gear. The invention has the advantages of simple structure, accurate test, good stability, comparatively lower cost, and the like.

The invention provides non-contact measurement equipment and method of contact net voltage. The equipment comprises a non-contact electric field coupling sensor and a data acquisition and analysis device, wherein the non-contact electric field coupling sensor comprises vehicle top high voltage equipment and which is arranged on electrical locomotive high voltage equipment or a contact net detection vehicle and an electric field distribution uniform area which is arranged around a contact net line, and the non-contact electric field coupling sensor is used for conducting coupling sensing on anelectric field strength signal in the electric field distribution uniform area; the data acquisition and analysis device is connected with the non-contact electric field coupling sensor and is used for receiving the electric field strength signal subjected to coupling sensing by the non-contact electrical field coupling sensor, and determining the contact net voltage according to the electric field strength signal and the relation of the electric field strength signal and voltage. By means of the non-contact measurement equipment and method of the contact net voltage, the efficiency, safety and convenience of detection and maintenance of the contact net voltage are improved.

The invention discloses a pulse drive transformer assembly for a self-excited switching power supply converter. The pulse drive transformer assembly (3) provides a drive signal for a power electronic switch assembly (Sk) in the self-excited switching power supply converter. By adopting a magnetic amplifier technology or a quadrature transformer technology, the power electronic switch assembly (Sk) driven by the pulse drive transformer assembly can normally work under an extremely-high amplitude direct current pulse power supply, so that the self-excited switching power supply converter finishes the filtering of a power supply alternating current input side of a commercial power grid without an electrolytic capacitor and generally meets the requirement without a power factor compensation (PFC). With the magnetic coupling current negative feedback action, the performance of the power electronic switch assembly (Sk) driven by the pulse drive transformer assembly is remarkably improved and the reliability of the complete machine can be improved. The invention has the advantages of low cost and high reliability and especially has remarkable benefits to energy-saving lamps and electronic ballasts.