73 results about "Electric field amplitude" patented technology

A method for determining whether the relative position of electrodes used by a neurostimulation system has changed within a patient comprises determining the amplitude of a field potential at each of at least one of the electrodes, determining if a change in each of the determined electric field amplitudes has occurred, and analyzing the change in each of the determined electric field amplitudes to determine whether a change in the relative position of the electrodes has occurred. Another method comprises measuring a first monopolar impedance between a first electrode and a reference electrode, measuring a second monopolar impedance between second electrode and the reference electrode, measuring a bipolar impedance between the first and second electrodes, and estimating an amplitude of a field potential at the second electrode based on the first and second monopolar impedances and the bipolar impedance.

A marine electromagnetic sensor cable includes a plurality of sensor modules disposed at spaced apart locations along a cable. Each module includes at least one pair of electrodes associated with the module. The electrodes are arranged to measure electric field in a direction along the direction of the cable. The cable is arranged to form a closed pattern. Another marine electromagnetic sensor cable includes a plurality of sensor modules disposed at spaced apart locations along a cable. Each module includes at least one pair of electrodes associated therewith. The electrodes are arranged to measure electric field in a direction along the direction of the cable. A plurality of spaced apart magnetic field sensors is associated with each module and arranged to enable determining an electric field amplitude in a direction transverse to the direction of the cable from magnetic field gradient.

A method for sensing an electric field includes processing digitized electric field signals, e.g., from an electric field sensing probe. The processing may include performing a Fast Fourier Transform of the digitized electric field signals to provide an indication of the magnitude of the electric field, and may include processing the digitized electric field signals at a rate that is related to the speed at which a movable sensing probe is moving. The method may include performing unweighted and/or weighted averaging in relation to processing electric field data, setting a comparison threshold, providing a human perceivable indication, or a combination of the foregoing.

The invention discloses a terahertz time-domain spectrograph capable of entering at a fixed angle and simultaneously detecting transmission and reflection and belongs to the technical field of spectrums. The spectrograph is characterized in that a femtosecond laser device is used as an excitation source, and a beam splitter arranged at the output end of the femtosecond laser device is used for splitting one beam of laser into two beams, wherein one beam is detection light; the other beam is further split into two beams through a beam splitting prism, wherein one beam is used as pumping light and the other beam is also used as the detection light; the pumping light is gathered on a terahertz transmitter and pulse terahertz waves are generated by radiation; the generated terahertz waves are used for irradiating a sample; the terahertz waves transmitting the sample are focused on one path of terahertz detector, and the terahertz waves reflected by the sample are focused on the other path of terahertz detector; the two paths of detection light are also focused on the two terahertz detectors at the same time, and pulse terahertz wave electric field amplitude values of transmission and reflection are calibrated. In the system, a relative position between a reflecting mirror and the sample is fixed, and a transmission spectrum and a reflection spectrum of the sample can be obtained at the same time, so that the transmittance and the reflectivity of the sample are accurately obtained, the reliability of data is guaranteed and experiment efficiency is also improved.

The invention relates to an MT denoising device which comprises an electromagnetic receiver, a magnetic induction sensor and a non-polarizable electrode group, wherein the electromagnetic receiver is placed on the ground; the magnetic induction sensor is placed on the ground in a direction parallel to an x axis or a y axis and connected with the electromagnetic receiver through a cable; the non-polarizable electrode group takes a coordinate system origin as a central point, is placed symmetrically along the y axis or the x axis and grounded, and comprises a first long pole pitch electric dipole and a first short pole pitch electric dipole; the first long pole pitch electric dipole is used for measuring amplitude data of a long pole pitch electric field, and the first short pole pitch electric dipole is used for measuring amplitude data of a short pole pitch electric field; and all non-polarizable electrodes are connected with the electromagnetic receiver through wires. The device is used for calculating the correlation coefficient and the standard deviation between the amplitude data of the long pole pitch electric field and the short pole pitch electric field, when the correlation coefficient is smaller than a set correlation threshold, electric field amplitude data with largest standard deviation are removed, the correlation coefficient is calculated repeatedly until the correlation coefficient is larger than or equal to the set correlation threshold, and near field interference data are effectively removed.

The invention discloses a terahertz time-domain spectrometer capable of variable-angle incidence and simultaneous measurement of transmission and reflection, and belongs to the technical field of spectrum. The spectrometer is characterized in that an output beam of a femtosecond laser is divided into two beams by a beam splitter, one beam is probe light, the other beam is divided into two beams through the beam splitter, one beam is pump light, the other beam is also probe light, the pump light is collected to a terahertz emitter to generate terahertz waves, the terahertz waves respectively reach two terahertz detectors through sample transmission and reflection, two channels of probe light are respectively collected to the two terahertz detectors, and transmission and reflection terahertz wave electric field amplitudes are calibrated; the terahertz emitter and the two terahertz detectors are both arranged on a circular rail with scales, and the positions of the terahertz emitter and the terahertz detectors are adjustable; and a sample frame is fixed at the position of the center of circle of the rail so that transmission and reflection spectrums of a sample in different angle incident conditions can be measured through adjustment of relative positions of the terahertz emitter and the terahertz detectors with the sample.

The application relates to a lightning forecasting method and system. The method comprises the steps of reading the latest electric field station observation data and radar observation data of an electric field station, and establishing a lightning proximity prediction model according to the electric field station observation data and the radar observation data; the establishing of the lightning proximity prediction model comprises the following steps: step a: setting an electric field amplitude threshold and an electric field difference threshold; step b: judging whether the read electric field station observation data reaches the set electric field amplitude threshold or the electric field difference threshold, and if the electric field station observation data reaches the set electric field amplitude threshold or the electric field difference threshold, performing step c; step c: determining whether the radar observation data before the current time reaches the preset threshold, ifthe radar observation data reaches the preset threshold, performing step d; and step d: generating a lightning warning graphic product and issuing lightning warning. The application realizes the beforehand release of thunderstorm early warning, and raises the capability and level of lightning forecast.

A method for accurately solving wind turbine blade echoes is provided, in order to obtain accurate blade echoes. The method mainly comprises three parts: firstly, solving two-dimensional backscattering field data of wind turbine blades within a range of a certain frequency band and a certain corner angle; secondly, according to the obtained two-dimensional backscattering field data of the blades,calculating an autocorrelation covariance matrix, and solving electromagnetic scattering electric field amplitudes and space coordinate parameters of the blades; and thirdly, establishing a blade equivalent model according to the obtained electric field amplitudes and space coordinate parameters, and deriving an equivalent model-based blade echo expression, so as to solve the blade echoes. The method provided by the present invention can be used to accurately solve the blade echoes and to realize the blade echo filtering on the radar side in actual engineering, and has significance to solve the passive interference of the wind turbine to the adjacent radar station.

The invention discloses an antenna radiation characteristic acquisition method based on phase-free near-field measurement. The method comprises the following steps: firstly, acquiring electric field amplitude information of all sampling points on a closed curved surface in a near-field region which is not far away from an antenna to be measured, and then establishing two nonlinear relationships between electric field distribution on a certain spherical surface of the near-field region and amplitude data on a measurement surface through a spherical wave expansion theory; and finally, speculating electric field distribution on the target spherical surface of the near-field region by using a genetic algorithm; when the algorithm stops iterative optimization, the tangential electric field distribution of the spherical surface to be guessed being basically close to an ideal result, at the moment, calculating a weighting coefficient on the spherical surface to be optimized by utilizing a spherical wave mode expansion theory, and obtaining a far field through spherical surface near-far field transformation. The invention provides a technology suitable for measuring antennas of various specifications.

The invention discloses an antenna near-field no-phase measurement method, wherein multiple near fields of a to-be-measured antenna can be accurately reconstructed through measuring an electric field amplitude value of a near-field scanning surface without direct measurement of phase information, and furthermore a far field directional diaphragm characteristic of the to-be-measured antenna is obtained. The antenna near-field no-phase measurement method aims to overcome the influence of the phase error to a measurement result in traditional near-field amplitude and phase measurement in a high-frequency working condition, and is a low-cost high-precision solution for near field measurement and aperture field diagnosis of high-frequency working antennae such as millimeter wave/submillimeter wave antenna and tera-hertz antenna.

The invention provides a terahertz spectrum analyzer which comprises a laser, three optical fiber couplers which are a first optical fiber coupler, a third optical fiber coupler and a fourth optical fiber coupler, an optical switch, a frequency shift ring, three optical delay lines which are a second optical delay line, a third optical delay line and a fourth optical delay line, a photoelectric detector, two photoelectric converters with terahertz detection antennas, two terahertz focusing elements and a terahertz optical splitter. In the acceleration of a terahertz electric field, photon-generated carriers are in accelerated motion to generate current which is proportional to the electric field amplitude of a terahertz wave, current is measured respectively, then square and sum are calculated, the radiation power of the terahertz wave is obtained, the frequency of the terahertz wave is obtained from the time sequence of the current, and the spectrum of the terahertz wave can be obtained. The terahertz spectrum analyzer has the advantages of wide spectral range, high spectral resolution and important scientific significance and application value and works at a room temperature.

The invention discloses an antenna near-field measurement method using an interpolation algorithm. The method comprises the steps: S10, collecting and recording electric field amplitude and phase information on a near-field scanning surface of the antenna to be measured, wherein the near-field scanning surface is in any curved surface shape and needs to meet the following three conditions at the same time. S20, interpolating the electric field amplitude on the near-field scanning surface of the antenna to be measured through cubic spline interpolation. S30, interpolating the electric field phase on the near-field scanning surface of the antenna to be measured through bilinear interpolation. S40, calculating a far-field electric field of the to-be-tested antenna according to a Huygens equivalence principle based on the near-field electric field amplitude and phase value of the to-be-tested antenna obtained by interpolation. and S50, based on the calculated far-field electric field of the to-be-tested antenna, calculating a far-field normalized directional diagram of the to-be-tested antenna. The near-field scanning surface in the method is not limited to a plane, a cylindrical surface and a spherical surface, and can be changed into any curved surface according to the actual measurement environment change.

A method of examining a configuration of a sample includes the step of irradiating a terahertz pulsed light, which possesses a wavelength to transmit through the sample, to at least two different portions of the sample, the step of detecting at least two electric field amplitude-time resolved waveforms of the terahertz pulsed light transmitted through the first and second portions of the object to be examined, and the step of examining the configuration of the sample based upon phase information obtained from the electric field amplitude-time resolved waveforms detected.

The embodiment of the invention discloses a nonlinear nanoantenna scattering directivity control method, device and equipment, and a computer readable storage medium. The method comprises the steps: adding a plane electromagnetic wave to a dimer nanoantenna which is formed in a manner that first dielectric material particles and nonlinear graphene wrap second dielectric material particles, and calculating dynamical nonlinear equations for describing the electric dipole moment of the dimer nanoantenna; calculating the dipole scattering intensity of the dimer nanoantenna according to the nonlinear equations; Adjusting the geometric parameters of the dimer nanoantenna and the conductivity parameter of graphene to enable the dipole scattering of the dimer nanoantenna to be in a bistable stateunder the preset frequency of the plane electromagnetic wave, adjusting the electric field amplitude of the plane electromagnetic wave applied to the dimer nanoantenna, so as to enable the scatteringstate of the dimer nanoantenna to be switched between a first directional scattering state and a second directional scattering state. According to the invention, the method achieves the controllable operation of the scattering direction of a nonlinear optical nanoantenna in a time evolution process.

The invention discloses a satellite-borne four slot feeding four-arm helical antenna comprising four helical antennas, a Balun electrically connected with the four helical antennas and a metal bottomboard used for supporting the Balun, wherein the Balun comprises an external conductor of a hollow structure, and an inner conductor coaxially arranged in the outer conductor; four slots are formed inthe top of the external conductor along axis directions, used for achieving equal electric field amplitude on the four helical antennas, and phases which sequentially differ by 90 DEG from one another, the external conductor is divided into four external conductor units by the four slots, and the internal conductor is electrically connected with the first external conductor unit in the four external conductor units; a data receiving port is arranged at the bottom of the external conductor, the metal bottom board is provided with a through hole, the position of the through hole is corresponding to the data receiving port, and the through hole is used for holding a data receiving device. The four arms of the four-arm helical antenna only forms an antenna pattern, without performing phase control; the Balun generates the phase difference needed by the four arms of the antenna, and the design difficulty of the four-arm helical antenna is reduced.

The invention discloses a device and method for simultaneously measuring the topological charge size and positive and negative values of a vortex light beam. The device comprises an angular gradual-change attenuation piece which is used for the angular modulation of the amplitude of an electric field of a to-be-measured vortex light beam; a focusing lens which is used for focusing the modulated vortex light beam; and a CCD camera that is used for recording the focusing light intensity and obtaining the size and positive and negative information of the topological charge of the vortex beam to be measured through the distribution of the focusing light intensity. By means of the technical scheme, simultaneous measurement of the topological charge and the positive and negative values of the vortex beam to be measured is realized.