87 results about "Electromagnetic testing" patented technology

The invention discloses an electromagnetic resonance-based nondestructive testing method for metal materials. According to the method, responding resonance signals of eddy current testing are obtained through multipled resonant capacitors in testing coils, comparative analysis of the responding resonance signals is carried out, and the relationships between a defect size and a signal amplitude and between defect depth and a signal phase are calibrated in advance, thereby enabling convenient nondestructive testing of metal materials. The electromagnetic resonance-based nondestructive testing method not only can produce same defect detection effects as a plurality of conventional electromagnetic testing methods like single-frequency eddy current and pulsed eddy current do, but also can effectively detect internal defects in a workpiece and detect workpieces with complicated surface conditions such as a casting surface, an unsmooth surface, a surface with oil stains, a rust-resisting paint, a corrosion layer or other pollutants, etc., without contact under the condition of a high liftoff value; according to the method, no cleaning is needed for test pieces, and particularly, no cumbersome processes like magnetization and demagnetization of magnetic metal materials are needed.

The present invention is an apparatus and method for determining the remaining service life of electrochemical energy generation and storage device including batteries, supercapacitors, DSSC solar cells and fuel cell. Measurements are performed by passing ultrasonic oscillations through the test object. The apparatus of the present invention comprises two arrays of transmitting and receiving ultrasonic probes between which the object being tested is affixed. Polyurethane tips are used for matching the acoustic resistance of the probes with the test object body. The apparatus includes means for positioning the transmitting and the receiving probe arrays relative to each other. The apparatus includes an electromagnetic means for measuring the test object thickness. The calibration characteristic for determining the remaining service life of a the test object are established from the signal values from the ultrasonic probes related to the number of charge-discharge cycles obtained at various charge values. A three-dimensional approximating dependence surface is constructed using the normalized signals from the receiving probes. The average value of this surface is determined. The remaining service life of the test object is determined using a calibration curve based on the average level of the surface

A non-contact printed circuit board (PCB) electromagnetic testing system comprises at least one high resolution transducer operative to induce multi-frequency, multi-amplitude eddy currents in a tested PCB, each such transducer including both a high frequency excitation coil that serves also as a sensing coil and a direct current (DC) bias coil operative to provide an optimal transducer operating regime; a multi-frequency generator for providing AC and DC bias signals to each transducer; and a control mechanism for driving the transducer. Optionally, the system further comprises an external ferrite concentrator that enhances a magnetic field flux focus and depth of focus on the inspected PCB. The multi-frequency, multi-amplitude methods enable three-dimensional mapping of various features in the PCB with both high sensitivity and high resolution in respective operating regimes.

A non-contact printed circuit board (PCB) electromagnetic testing system comprises at least one high resolution transducer operative to induce multi-frequency, multi-amplitude eddy currents in a tested PCB, each such transducer including both a high frequency excitation coil that serves also as a sensing coil and a direct current (DC) bias coil operative to provide an optimal transducer operating regime; a multi-frequency generator for providing AC and DC bias signals to each transducer; and a control mechanism for driving the transducer. Optionally, the system further comprises an external ferrite concentrator that enhances a magnetic field flux focus and depth of focus on the inspected PCB. The mutli-frequesncy, multi-amplitude methods enable three-dimensional mapping of various features in the PCB with both high sensitivity and high resolution in respective operating regimes.

The invention discloses an electromagnetic radiation parameter testing system. The system is composed of a receiving subsystem, a parameter testing subsystem, a signal processing and control subsystem and an auxiliary subsystem. The system can realize automatic testing by use of a lifting rotary turntable, a program-controlled attenuator and a microwave switch, and can automatically monitor and store multiple data; a power divider is used for providing multiple testing channels so as to test and monitor multiple radiation parameters in real time; and an amplitude limiter is used for performing key protection on an easily damaged testing element, thereby guaranteeing the safe work of the system. A wave detector is used for testing the pulse power so as to conveniently acquire the electric field waveform of the wideband time domain pulse; uncorrected envelope technology is used for measuring the pulse signal envelope, and the testing system structure is simplified; the automatic testing and storage of multiple dynamic data can be realized in real time, and a mater control computer and a comprehensive data post-processing software platform can realize seamless link. A powerful means is provided for the electromagnetic radiation testing of a complex electromagnetic environment.

Model human hands (902) for use in electromagnetic (e.g., microwave and RF) testing comprise a skeleton (1200, 104) of dielectric tubes (142, 148, 166, 170, 174, 178, 206, 208, 210, 1202, 1212, 1214, 1216, 1228, 1230, 1236, 1240, 1242, 194, 195, 196) inside a glove (908) that is filled with a fluid that has electrical properties that match that of a typical human hand at a particular frequency. According to certain embodiments the model hands comprise thumbs (193, 1236) that are located out of a plane of palms of the model hands. According to one embodiment the dielectric tubes are pivotally coupled to each other and biasing means (181,702) are provided to bias the hand into a gripping position so that the model human hand is able to grip different types of wireless communication devices (802) in different ways.

The invention discloses a method which realizes electromagnetic testing in different ways through changing motivation models. Wherein, a sensor is imposed with different motivation models: a sine wave motivation is imposed when carrying out eddy current testing, a square wave motivation is imposed when carrying out magnetic flux leakage, and a high duty ratio pulse motivation is imposed when carrying out magnetic memory testing, then the sensing signals obtained in different motivation models are carried out different analysis and processing so as to obtain different detection parameters, thereby the invention not only can respectively realize single eddy current testing or magnetic flux leakage or magnetic memory testing according to the requirements of different components to be detected, but also can obtain the detection parameters of eddy current testing, magnetic flux leakage, and magnetic memory testing through time-sharing detection according the requirement of the same component to be detected. Thus, the invention brings great convenience for people and greatly reduces the production cost of the detector.

The invention discloses a device and method for testing electromagnetic scattering of a jet pipe cavity of an aeroengine. A device body is wrapped in a pointed-cone-shaped absorbing material to carry out electromagnetic scattering test on the jet pipe cavity, the pointed-cone-shaped absorbing material at the outer wall can absorb most radar waves, electromagnetic wave reflection at the outer wall of a jet pipe model can be effectively shielded during electromagnetic test, electromagnetic reflection at the metal outer wall of the jet pipe model is eliminated, reliable electromagnetic scattering data of the jet pipe cavity is obtained, and the test data can accurately reflect the electromagnetic scattering characteristic of the jet pipe cavity. The test device is simple in structure, low in processing difficulty, low in cost and convenient to operate, can be used repeatedly, and greatly reduces the cost of electromagnetic scattering test of the jet pipe cavity; the test method can be used to obtain accurate and reliable test data; and the test method and device have great significance in researches on electromagnetic scattering of the jet pipe cavity.

The “discrete frequency stir” (DFS) method provides improved mode stir testing of electromagnetic characteristics of an enclosure / cavity. Adequate sampling of the electric field inside the enclosure / cavity is provided by electronic perturbation or “stirring” of the field with a short duration, continuous wave, radiated source where the wave frequency is stepped in small steps across a frequency range of interest. The frequency steps are selected to be at least slightly larger than the resonant mode bandwidth associated with the given enclosure / cavity in order to provide statistically independent measurements. A stirring bandwidth is selected to encompass a statistically significant number of these measurement samples while maintaining adequate frequency resolution. A statistical evaluation of the measured field is then performed over this stirring bandwidth. For example, the average field level at a given frequency is determined by averaging over the samples contained within the stirring bandwidth when centered on that frequency.

The invention relates to a vehicle semi-active suspension hardware-in-loop experimental platform based on an electromagnetic vibration table. The vehicle semi-active suspension hardware-in-loop experimental platform comprises a real-time simulation platform, an electromagnetic vibration testing system, an interface circuit and a magnetorheology damper driving power supply. The real-time simulation platform comprises a host machine, a target machine and a data collecting card. The electromagnetic vibration testing system comprises a vibration table base, an electromagnetic vibration generator, a guiding rod, an upper mounting base U-shaped clamp, a lower mounting base U-shaped clamp, a displacement sensor, a force sensor, an accelerator sensor, a magnetorheology damper, a horizontal beam, a screw rod and a power amplifier. The interface circuit comprises an SCSI100 needle connecting wire, a bent angle female base wiring plate, a displacement sensor output signal processing circuit, a force sensor output signal processing circuit and an amplitude limiting circuit. The magnetorheology damper driving power supply comprises a program control power supply and an RS232 serial port transmission line. The electromagnetic vibration testing system is used for simulating road excitation, and the testing platform is small in occupied space, low in operation noise, stable in operation and convenient to maintain.

The present invention relates to inspection of medical patients including, but not limited to, phonocardiography, auscultation and ultrasound medical imaging and other non-acoustical inspection techniques; and industrial non-destructive testing and evaluation of materials, structural components and machinery; and more particularly to the incorporation of cognitive artificial intelligence into an inspection system and method that utilizes cognitive mathematical techniques which emulate the cognitive processing abilities of the human brain including, but not limited to, symbolic cognitive architectures and inference process algebras, to analyze data collected from infrasound acoustical sensors (0.1 Hz-20 Hz), audible acoustical sensors (20 Hz to 20 kHz), ultrasound acoustical sensors and transmitters above 20 kHz, data collected from other non-acoustical inspection devices and systems including, but not limited to electrocardiography (EKG), computed-tomography (CT), single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), electromagnetic testing (ET), magnetic particle inspection (MT or MPI), magnetic flux leakage testing (MFL), liquid penetrant, radiographic (x-ray and gamma ray), eddy-current testing, low coherence interferometry, and combinations thereof (i.e., multi-modality inspection data); fuse this data resulting in the generation of new metadata; and then utilize cognitive mathematical techniques to interpret this data against inspection signatures that characterize conditions being diagnosed. The present invention has the ability to also identify and anticipate abnormal conditions that fall outside known inspection signature patterns; and communicate the inspection results to an operator thereby simplifying the initial inspection and diagnosis for medical patients and industrial objects; minimizing false negative and false positive initial inspection results and lowering costs.

The invention provides a low-scattering shell suitable for an external field wind environment electromagnetic test and used for an engine. The low-scattering shell is of a flat oval conical structureand comprises a front section and a rear section. The front section comprises a flat oval cavity part and four semi-spindle body parts; wherein one positioning bolt is arranged in each half spindle body part of the front section; the rear section comprises a tail cone matched with the front edge of the front section; wherein the front edge of the front section and the part, matched with the frontedge of the front section, of the rear-section cone of the rear section comprise sawtooth-shaped structures, and when an engine is placed in the front section to be subjected to an electromagnetic test, the tail portion exposes a spray pipe of the engine, and the size of the tail portion in the width direction is matched with that of the spray pipe.

First and second electrically conductive rods are provided inside a shielded electromagnetic test chamber. These rods are energized to radiate electromagnetic energy inside the chamber. The rods are mounted inside the chamber at right angles to one another, the first rod is movable through the interior volume in a first direction perpendicular to its long axis, and the second rod is movable through the chamber in a second direction perpendicular both to its own long axis and to the first rod's direction of motion. Energy is supplied to the two rods in a way that enhances the uniformity of the electromagnetic field applied to a working volume inside the chamber as the two rods move through the chamber.

The invention provides a microstrip nanometer film microwave electromagnetic parameter testing apparatus, which belongs to the technical field of electromagnetic parameter testing. The apparatus is provided with a microstrip clamp, a microwave vector network analyzer, a GPIB data acquisition card, and a computer. The microstrip clamp is composed of an L-shaped base, an upper conduction band, an adjustable short circuit piece, an SMA connector, a shield cover and a fixed platform. One end of the L-shaped base is provided with a circular hole; the other a step. The two ends of the adjustable short circuit piece are provided with grooves. The SMA connector is mounted on the L-shaped base and is connected to the coaxial cable of the microwave vector network analyzer; a nanometer film sample is placed at the center position of the input end and the adjustable short circuit piece. The microstrip clamp is fixed on the fixed platform, and the four corners of the fixed platform are equipped with height adjustable supporting rods. The fixed platform is evenly engraved with a set of horizontal lines marked with scales. Two spring clamp sheets are locked on the fixed platform and are placed on the end face and the face of the microstrip clamp respectively. The apparatus can achieve precise measurement, cause no damage and is convenient to operate.

A model hand (120, 700) for use in electromagnetic testing comprising a body (210, 710) and at least one digit (220, 780) extending from a side of the body. For one embodiment, the body (210) has an outer semi-cylinder surface (230) with an arcuate shape and an inner semi-cylinder surface (240) following the arcuate shape of the outer semi-cylinder surface. A digit (220) is coupled at a base end (260) coupled to the side (250) of the cylindrical body (210) to permit pivotal motion of the digit relative to the cylindrical body. For another embodiment, the body (710) has a palm-like shape with four static digits (740-770) affixed at one end to the palm-shaped body. In addition to the four static digits (740-770), a dynamic digit (780) extends from the body (710) and couples to the body to permit pivotal motion of the digit relative to the body.

The invention discloses a zero-magnetic-flux shallow transient electromagnetic test coil and a test method thereof. The test coil comprises a transmitting coil and a receiving coil, wherein the transmitting coil is embedded in the receiving coil and is arranged in a coplanar and coaxial manner; the receiving coil comprises an outer receiving coil and an inner receiving coil; the radius of the outer receiving coil is larger than that of the inner receiving coil; the radius of the inner receiving coil is equal to that of the transmitting coil; and meanwhile, the turns inside the transmitting coil and the receiving coil are connected with each other in series. By the test method provided by the invention, the primary fields in the inner receiving coil and the outer receiving coil are equal insize and opposite in direction, and mutually offset to enable the total magnetic flux in the receiving coil to be zero, so that the effective elimination of the primary fields is realized, a pure secondary field signal is obtained, the shallow detection blind area range is greatly reduced, and the transient electromagnetic shallow detection resolution is effectively improved.

The invention relates to a switch power supply which can filter the industrial frequency noise of floating system, wherein based on traditional switch power supply, the invention eliminate the Y capacitor, to realize pure coil induction couple between the first coil and the secondary coil of transformer, to eliminate the transmission path of industrial frequency noise at the alternative current end to the secondary end; each rectify diode of rectify bridge is parallel connected to one capacitor, to reduce the aberration of alternative signal generated at the start and end of diode. With said invention, the industrial frequency noise of floating system can be filtered, to confirm the electromagnetic test of switch power meets the EMC standard.

This invention relates to one electromagnetic testing system, which comprises testing platform, first level antenna, first vertical antenna and signal processing unit, wherein, the test plat is to put object; the first level antenna is located in wave dark room; the first vertical antenna is located in other place in the room; the first level antenna and first vertical antenna are to receive electromagnetic wave to generate one level wave and one vertical wave; the signal processing unit is coupled to the first level antenna and first vertical antenna; the signal processing unit is to convert and analyze the said level wave and vertical wave.

The invention discloses an experimental method of using a digital storage oscilloscope to observe an alternating current magnetic hysteresis loop, and belongs to the technical field of electromagnetic testing. The experimental method aims to reducing the distortion of testing the alternating current magnetic hysteresis loop, and improve the precision of testing dynamic magnetic parameters. According to the experimental method, firstly an alternating current triangular wave constant flow source circuit is designed, a magnet exciting coil is arranged as the load of the alternating current triangular wave constant flow source circuit, and the weave shape of magnetic field intensity H is enabled to be a triangular wave. The negative feedback sample resistance R1 of the alternating current triangular wave constant flow source circuit is the sample resistance of an exciting current, and the terminal voltage VH of the alternating current triangular wave constant flow source circuit is transmitted to the input end X of an oscilloscope. A test coil outputs voltage e2, and VB is obtained through the integration of an electronic integrator and is transmitted to the input end Y of the oscilloscope. The oscilloscope displays the alternating current magnetic hysteresis loop through XY scanning. In a measurement process, the rate of the change of H is enabled to be unchanged, the change rule of B is observed under the condition that H evenly changes, and the tested magnetic hysteresis loop is enabled be capable of reflecting the function relationship between the numerical values of B and H inside a sample better. The e2 replaces the VB to be sent to the input end Y of the oscilloscope, and a differential permeability mu d-H curve can be directly displayed.

A circuit architecture provides for the parallel supplying of power during electric or electromagnetic testing of electronic devices integrated on a same semiconductor wafer and bounded by scribe lines. The circuit architecture comprises a conductive grid interconnecting the electronic devices and having a portion external to the devices and a portion internal to the devices. The external portion extends along the scribe lines; and the internal portion extends within at least a part of the devices. The circuit architecture includes interconnection pads between the external portion and the internal portion of the conductive grid and provided on at least a part of the devices, the interconnection pads forming, along with the internal and external portions, power supply lines which are common to different electronic devices of the group.

The invention relates to an electromagnetic acoustic emission non-destructive testing method for a non-ferromagnetic metal sheet and a device adopting the testing method, and relates to the test for a metal material by utilizing an acoustic emission technology. The testing method comprises the following steps of: loading a pulse vortex generated by a vortex generator onto a to-be-tested non-ferromagnetic metal sheet; if the to-be-tested non-ferromagnetic metal sheet has a crack, arousing an acoustic emission signal; detecting and collecting the acoustic emission signal by four piezoelectric sensors; inputting into a preamplifier through a signal line; inputting into a PC (Personal Computer) machine after amplifying; performing two-dimensional time difference positioning by the PC machine according to the collected acoustic emission signal; and positioning and detecting the crack defect of the to-be-tested non-ferromagnetic metal sheet. The device comprises the vortex generator, four piezoelectric transducers, the preamplifier and the PC machine. The method and device provided by the invention are used for overcoming the defect that for the existing electromagnetic testing method, active state information of the material can not be detected to obtain, and solving the difficulty that for the existing acoustic emission detecting technology, a local defect weak signal of the material is difficult to extract from the whole signal.

The invention discloses a signal undisturbed test system for resisting strong electromagnetic interference, which comprises a test sensor, an electro-optical conversion module and a photoelectric conversion module. The test sensor is connected with the electro-optical conversion module; the electro-optical conversion module is integrated in a portable shielded cavity; a fiber-optic waveguide through-wall component is respectively arranged on the side wall of the portable shielded cavity and the cavity wall of the test shielded cavity; the electro-optical conversion module and the photoelectricconversion module are connected through an optical fiber; and the optical fiber penetrates through the fiber-optic waveguide through-wall components on the portable shielded cavity and the test shielded cavity, sequentially. The signal undisturbed test system for resisting strong electromagnetic interference in the invention adopts the test system and solves the problem that a cable coupling signal in a current strong electromagnetic test is too large to affect the accuracy of the test result.

The invention discloses an electromagnetic immunity testing system building method, which comprises a measurement system, a control system, two pulse high voltage sources and a bounded waveguide transmission line connected in sequence. The testing system building method comprises steps: 1, according to long pulse and short pulse in a theoretical electromagnetic pulse radiation field, technical parameters of a transient electromagnetic field are determined respectively; 2, according to the technical parameters, parameter setting on the bounded waveguide transmission line and the two pulse high voltage sources is carried out; 3, the two pulse high voltage sources are respectively connected with the bounded waveguide transmission line; and 4, whether deviation of technical parameters of an actual electromagnetic pulse radiation field meets design standards is verified. The service life and the environmental adaptability of a tested device can be improved, the cost is saved, the design accuracy is high, the actual system parameter reference value is large, various experimental environments can be configured flexibly, and practicability is strong.

The invention relates to an input device compatible with capacitance positioning and electromagnet positioning and an input method of the input device. The input device comprises an input induction unit, an oscillating unit, a data processing unit and a control unit, wherein the oscillating unit provides a first oscillating signal suitable for electromagnetic testing and capacitance testing for the input induction unit. The input induction unit comprises a first group of conductors extended along a first direction and a second group of conductors extended along a second direction, and is used for inducting input of an electromagnetic pen and inputting and outputting an electromagnetic signal and / or a touch control signal through a touch control manner. The data processing unit is used for determining the input positions according to an induction signal. When the electromagnetic signal and the touch control signal are output by the input induction unit, and the data processing unit is controlled by the control unit based on the electromagnetic signal or the touch control signal, and input positions can be ensured. Due to the adoption of the input device and the input method disclosed by the input device, so that signal interferences due to misoperation can be effectively avoided, input precision can be improved and input experience of uses can be improved.

Methods, tests systems and computers for controlling power delivered to a test volume are provided. According to one aspect, an electromagnetic test system has at least one operational path having a channel emulator output, an amplifier, an attenuator and an antenna. A method includes, for a given desired output power level, C, setting a channel emulator output power to a power level B, and setting the attenuator to a setting A, such that C is a function of B and A. In such embodiments, the attenuation A is calculated based on an upper limit output power of the channel emulator and the desired output power C.

The invention discloses an MEMS viscosity-density sensor chip based on in-plane resonance and a preparation method thereof. The MEMS viscosity-density sensor chip comprises a silicon substrate and a silicon micro resonant beam structure, wherein the silicon micro resonant beam structure comprises a middle oscillator, elastic connecting beams and elastic clamped beams; the elastic connecting beamsand the elastic clamped beams are arranged at two sides of the oscillator; two mutually vertical connecting beams at each side of the oscillator form a T-shaped beam structure; the oscillator, and theelastic connecting beams and elastic clamped beams at the two sides of the oscillator are respectively provided with two leads; the two leads are distributed along the length direction of the oscillator in parallel and are respectively used for circulating sinusoidal alternating current of a certain frequency and induced electromotive force generated by detection, obtaining a resonant frequency of the silicon micro resonant beam in measured fluid according to the output amplitude of the induced electromotive force when the silicon micro resonant beam is in a resonant state and realizing measurement of the viscosity and the density of the fluid through the resonant frequencies and quality factors of the silicon micro resonant beam in the different fluid. The MEMS viscosity-density sensor chip utilizes methods of electric magnetization and electromagnetic testing to realize accurate measurement of the viscosity and the density of the fluid based on an in-plane vibration principle.

The invention discloses an electromagnetic test probe, an electromagnetic test device and an electromagnetic test method. The electromagnetic test probe comprises: a hollow positive cylinder, whereinan induction coil is wound around the peripheral wall of the positive cylinder, a flat glass is arranged on the bottom surface of the positive cylinder, and a circular dial is drawn on the surface ofthe flat glass; and a holding rod, wherein the bottom of the holding rod is connected to the side surface of the positive cylinder, a laser generator and a test signal line are arranged inside the holding rod, the positive pole of the test signal line is connected with the first end of the induction coil, and the negative pole of the test signal line is connected with the second end of the coil. The bottom of the holding rod is provided with an opening, an inclined semi-transmissive mirror is arranged in one side wall of the positive cylinder at a position corresponding to the opening, and aninclined reflector is arranged in the other side wall of the positive cylinder and opposite to the semi-transmissive mirror. The invention can intuitively and conveniently measure the radiation statenear a mainboard to be tested, and provides a reliable reference for the layout and structural design of the mainboard component, thereby eliminating the noise generated by the common mode interference of the acoustic related product from the design.

The invention relates to an antenna leveling method and system. One embodiment of the system comprises at least three distance measuring units; each of the at least three distance measuring units is arranged at the edge of the bottom surface of an antenna platform, and the signal transmitting direction of each distance measuring unit points to the ground; each distance measuring unit is used for acquiring the distance between the distance measuring unit and the ground; the distances acquired by the at least three distance measuring units are used for comparison; when the comparison results arethe same, it is represented that the antenna scanning surface is parallel to the ground; and when the comparison results are different, the antenna attitude is adjusted until the comparison results are the same. According to the embodiment, the antenna leveling can be realized by using the distance measuring units, and the problem of different radiation gains on the target caused by different antenna scanning beginning and end heights in the existing near-field electromagnetic test is solved.

A circuit architecture provides for the parallel supplying of power during electric or electromagnetic testing of electronic devices integrated on a same semiconductor wafer and bounded by scribe lines. The circuit architecture comprises a conductive grid interconnecting the electronic devices and having a portion external to the devices and a portion internal to the devices. The external portion extends along the scribe lines; and the internal portion extends within at least a part of the devices. The circuit architecture includes interconnection pads between the external portion and the internal portion of the conductive grid and provided on at least a part of the devices, the interconnection pads forming, along with the internal and external portions, power supply lines which are common to different electronic devices of the group.

The invention discloses a low-scattering covering for external field testing and a preparation method thereof. The low-scattering covering comprises a wave absorbing layer, a conducting layer and a reinforcing layer; the wave absorbing layer comprises a plurality layers of wave absorbing material, and the wave absorbing material is formed by adding wave absorbing microparticles into a silicone rubber material; the conducting layer is formed by adding conducting fibers into a silicone rubber material; a built-in fiber mesh cloth structure is adopted by the reinforcing layer, and fiber mesh cloth is arranged between the two silicone rubber material layers. According to the low-scattering covering for external field testing and the preparation method thereof, multiple layers of wave absorbing material are prepared by mixing liquid rubber with the wave absorbing microparticles, the conducting fibers, a reinforcing material and the like in a multi-time pouring mode. A material prepared from the covering can be applied to electromagnetic scattering testing of a large target in an external field to achieve the good electromagnetic wave absorbing or shielding effect, has the advantages of being high in field arrangement speed, resistant to oxidization and corrosion, low in manufacturing cost and the like and is a complex wave absorbing or shielding electromagnetic product with the application prospect.