Abstract: The present invention relates to the variable wave impedance generator (VWIF) which is used for the electric field intensity measuring instructor calibration, the magnetic field intensity measuring instructor calibration, the antenna calibration, and the unnecessary electronic wave interference and tolerance (EMI/EMS) measurement of the electric and electronic equipment using the features to generate the low impedance electronic wave (or, magnetic field) at the point meeting in phase, and the high impedance electronic wave (or electric wave) at the point meeting out of phase, when the power transmits in the coupled transmission line inside in the opposite direction from each other.

Abstract: The invention relates to a method of detecting a shielding defect of a shielded cable mounted in a building which defines between an instrument and the shielding of the cable, a first stray capacitance; the method steps are:placing measurement apparatus in such a manner as to define a second stray capacitance between itself and the building;injecting a high frequency signal into the shielding of the cable, by means of the measurement apparatus, the signal circulating back to the apparatus via the first and second stray capacitances; andmeasuring on the core of the cable, a signal that appears by radiation due to the injection of the high frequency signal, and representative of a defect in the shielding of the cable.

Abstract: The invention describes a method and an apparatus for generating and receiving electromagnetic waves for test purposes and is applicable particularly for measurements, investigations and tests of electromagnetic compatibility. For testing the immunity, the test piece is acted upon with defined field parameters and, during the emission measurement, the electromagnetic radiation emitted by the test piece is measured. It is an important distinguishing feature of the invention that a cell, constructed as a TEM waveguide, is rotated about the test piece. The apparatus is characterized in that the lid and bottom of the pyramidal cell are constructed so as to be electrically conducting and in that two-dimensional septa, which consist of individual wires of equal length, are disposed in each case symmetrically at a small distance from the lid and the bottom.

Abstract: The degree of variation in the normalized site attenuation of an RF test chamber may be reduced by adjusting the properties of the RF absorbers lining the walls of the RF test chamber such that for the frequencies of greatest variation the ground screen formed by the conductive floor of the chamber appears to be much greater than its actual finite size. This may be done by progressively reducing the degree of chamber wall absorption (for the frequencies of interest) for locations on the walls closer to the floor. The reduction begins at a height above the floor equal to the height of the device under test above the floor, and proceeds to some maximum reduction in absorption at the level of the floor. The reduction in absorption has the effect of making the ground screen appear to be much larger than it really is, and may be obtained either by spacing the absorbing tiles apart by increasing amounts nearer to the floor, or by using less absorptive tiles closer to the floor, or both.

Abstract: A system and a method for moving a measuring device (4, 30) to a plurality of positions above a test object (12), e.g. an electrically or electronically equipped printed board, at which the EMC, of the test object (12) is measured and later stored in a memory together with the position of the measuring device. The system includes a computer (18) and a measuring device (4, 30). The positioning device (8) moves the measuring device (3, 30) across the test object (12) from one position to another, wherein the number of positions and their coordinates are preselected and stored in a computer (18) for a later repetition of the measurement. Each position is assigned with a measurement value which is stored in the memory of the computer (18) together with the coordinates of the measuring device (4, 30). At each position, the power to the control devices is shut-off, in order to minimize interference with the measurements.

Abstract: A system and method for continuously monitoring the shielding effectiveness f an electromagnetically shielded enclosure is disclosed including an RF transmitter positioned remote from the shielded enclosure. RF signals emitted from the remotely positioned transmitter are received by both an enclosure receiver positioned inside of the enclosure and simultaneously by a reference receiver having its antenna positioned outside of the shielded enclosure. These two received signals are mixed so as to produce IF signals which are subsequently forwarded to a synchronous detector which determines the ratio of the two signal levels by comparing their strengths. This ratio is indicative of the enclosure's electromagnetic shielding effectiveness. If the effectiveness drops below a predetermined or threshold limit, such is determined by a comparator positioned within the enclosure and an alarm may be sounded so as to indicate that the shield is failing.

Abstract: A method for measuring a common mode current (Icm) in an outer conductor of a device comprising also at least one inner conductor which includes the steps of interconnecting the one inner conductor and the outer conductor at a junction point to a power source and supplying a current (Icm) to the junction point draining substantially all common mode current (Icm) from the outer conductor at the opposite side of the device by means of a low impedance drain; and sensing the drained common mode current (Icm) with a current sensor.

Abstract: A 6 port TEM cell for measuring garbage EMI/EMS of an electrical and electronic equipment which can form an electromagnetic field of horizontal/vertical polarization using characteristic that internal electric field polarization is changed according to feeder line selection inside a multi-transmission line, and coupling amount among internal conductors is reduced by positioning the spherical internal conductors at corners of external conductors, thereby widening a test area.

Abstract: An automatic broadband electromagnetic generator is disclosed including a coaxial connector joint portion for maintaining impedance matching; a taper area placed between an object tested and the coaxial connector joint portion, and in which a force transmitting member for rotating an internal conductor is installed to enable external driving; a rotating table for performing bearing variation to the rotation of the object tested; and a terminal portion in which a radio wave absorber terminates high-band electromagnetic waves, a distribution resistor absorbs low-band electromagnetic wave, and a radio wave absorbing ferrite terminates their intermediate band.

Abstract: A method for operating a TEM cell to determine the characteristics of a radiation source in a circuit. The circuit is placed in the TEM cell such that the relative orientation of the circuit and the TEM cell is measurable. The TEM cell provides an output signal indicative of the energy radiated by the circuit when the circuit is operated in the TEM cell. The output signal of the TEM cell is measured for at least 6 different relative orientations of the circuit and the TEM cell. The electric and magnetic dipole moments of a radiation source having an orientation and physical dimension associated therewith are determined from the measured output signals. The electric and magnetic dipole moments determined from the measured output values are compared to moments predicted by each of a plurality of antenna types to provide an estimate of the orientation of the radiation source relative to the circuit.

Abstract: Apparatus and method for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The probe may include a plurality of detector diodes mounted on a printed circuit board in a shielded structure that is directly connected to the test wire of the circuit to be monitored.

Abstract: Apparatus and method for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The system under test can then be removed from the electromagnetic field and, for each frequency at which the system failed, a voltage can be injected, using a voltage injection probe, into the system at another point to recreate the detected level of signal at the test point that was coupled into the system from the electromagnetic field.

Abstract: A device for injecting current at radio frequency into electric wiring, comprises a guiding structure (10) of an electrically conductive material consisting of a tapered shell (12) wherein a central vertical wall (20) is suspended determining two half-spaces (S, D) within the shell (12). At the tapered end, the shell (12) and the central vertical wall (20) are respectively connected to the braiding and the central wire of a coaxial cable (17) supplying radio frequency electric current. At the end opposite to said tapered end, a wiring (19) is disposed through the structure (10) perpendicular to the vertical central wall (20) and rests on a base (11) of dissipating material. In one of the two half-spaces, the wiring (19) is protected by a shield (23) integral with the shell (12).

Abstract: Apparatus for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The system under test can then be removed from the electromagnetic field and, for each frequency at which the system failed, a voltage can be injected, using a voltage injection probe, into the system at another point to recreate the detected level of signal at the test point that was coupled into the system from the electromagnetic field.

Abstract: Development of worst case operating environment, interfering parameters of a test item, is effected by a decoupling device. The device includes a series of resonators configured and interconnected in a particular manner along with a shunt capacitance. Each resonator has a torroidal core formed from a ferrite composition. When connected between the test item and its support system, the device provides such an impedance to signals other than those needed for normal operation, that the highest noise voltage levels emit from the test item. These levels permit developing repeatable worst case interference parameters which provide a guide for modifying the test item circuit components and connectors so as to minimize the effects of generating EMI sources or to immunize susceptible receptors within the test item.

Abstract: A multi-channel electromagnetically transparent voltage probe transmission link system or method monitors a plurality of voltage signals at a plurality of test points of a device under test that is subject to a radiation field with at least two intensity levels. The system or method compares the monitored voltage signals at the first intensity level corresponding to the level at which the monitored voltage signals not being affected by the radiation field, and the second intensity level being greater than the first intensity level. The system or methods determines whether or not the device is affected by the radiation field by determining if the monitored voltage signals are affected by the radiation field at the second intensity level.

Abstract: In order to measure radiation emitted from or the influence of radiation on an individual circuit board, which in use normally is arranged in a rack in parallel to other circuit boards, all circuit boards being connected to a common backplane, the backplane is modified in such a way that the connection of a considered board will be located on the opposite side of said backplane compared to the connections of the others boards. The whole equipment is located in a shielded housing except the considered circuit board. Thus the radiation from the other circuit boards will be shielded or attenuated and only the radiation from the considered circuit board will contribute to the radiation field around the device. In the same way only this considered circuit board will be sensitive to electromagnetic radiation arriving from the outside. The power supply of the device is preferably provided by power equipment located inside the shielded housing, such as a battery as well as a direct voltage power adaption unit.

Abstract: An improved cable fault detection system which makes the fault detection independent of the ground shift between units coupled to the interface. This fault detection is based on differentially sensing the voltage on a wire pair, in a cable, and using the differential voltage applied to the wires to make a decision as to whether or not the cable is faulted. The disclosed differential sensing and fault checking scheme reviews both data states thus making the fault detection independent of the ground shift between machines on the interface and this is accomplished without reducing the load impedance presented to the cable by the differential receiver coupled thereto.

Abstract: A coupling network for electromagnetic pulsed testing arrangements includes three stacks of toroidal ferrite cores. Two of the stacks are of identical diameter, the third stack has a diameter approximately equal to the combined diameters of the first two stacks. A copper tube looped through the central aperture of the first two stacks forms a primary winding. An insulated wire looped twice through the first two apertures forms a secondary winding of a 1:2 step-up transformer. The winding is extended through the aperture of the third stack. The third stack is operable to permit the laying in of a cable connected to a device under test. The cable forms the secondary of an isolation transformer.

Abstract: A TEM mode cell having an internal TEM element and at least one port on the cell, the cell comprising a stepped transmission line transformer coupling the internal TEM element to the port. The stepped transmission line transformer of the TEM mode cell has transfer characteristics selected to give maximum cancellation of VSWR in the cell and thereby enable optimum cell bandwidth. The TEM mode test cell comprises a hollow metallic housing having an enlarged center section with opposite open ends, and a pair of end sections, each end section closing off a respective one of the center section open ends and tapering to a distal end of reduced cross sectional area. A connector is provided at the distal end of each end section, and a stepped septum is mounted within the housing and insulated therefrom, the septum coupled to and extending between the connectors.

Abstract: Apparatus and method for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The system under test can then be removed from the electromagnetic field and, for each frequency at which the system failed, a voltage can be injected, using a voltage injection probe, into the system at another point to recreate the detected level of signal at the test point that was coupled into the system from the electromagnetic field.

Abstract: Apparatus and method for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The system under test can then be removed from the electromagnetic field and, for each frequency at which the system failed, a voltage can be injected, using a voltage injection probe, into the system at another point to recreate the detected level of signal at the test point that was coupled into the system from the electromagnetic field.

Abstract: An improved correlation method that computes E field measurements from voltage measurements produced by a TEM cell. Twelve voltage measurements are taken of radiation emanating from a device under test (DUT) for respective frequencies. The measurements are taken for the six faces of a hypothetical cube enclosing the DUT in both polarizations. Using these 12 measurements, the method identifies the face and polarization of the DUT which produces the highest emanation of radiation at that respective frequency. The method obtains three input voltages from these measurements and determines if the assumption of a dipole gain is adequate. If not, the actual gain is calculated and is used in a 3-input correlation algorithm to obtain more correct data regarding the E field emission of the DUT.

Abstract: A method for non-intrusively measuring the shielding effectiveness of coaxial wiring by employing an inductive current probe which causes current to flow on the shield of the wiring. A second inductive current probe senses the current on the shield circuit and outputs a voltage which is a function of the shield current. The method employs loop self-impedance in contrast to transfer impedance.

Abstract: A method and apparatus for traveling wave attenuation measurement in the UHF and VHF frequency bands. The test set up comprises a ramp structure located in the quiet zone of a parallel plate set up. The RAM specimen to be tested is attached to the top ramp surface starting at the highest point of the ramp. The time domain signal is gated to reject all scattering except the contribution from the ramp surface. The inverse Fourier transform of the gated time data results in the frequency response of the ramp. The RCS from ramp with RAM material attached is normalized to that of the perfectly conducting surface to provide a relative attenuation of the surface traveling wave.

Abstract: A device under test is placed in a metallic reverberation chamber and test are run for various characteristics. An antenna positioned in the chamber radiates microwave energy into the chamber. There is disclosed a method of frequency stirring which uses band limited White Gaussian noise (WGN) up-converted by performing double sideband, suppressed carrier modulation with a microwave signal from a synthesized sweeper. The output is then amplified with a TWT amplifier to meet the higher power level requirements. The synthesized sweeper is used to generate the monochromatic signal which determines the center frequency of the output while the WGN source and low pass filters provide the frequency agility.

Abstract: A system for evaluating the performance of an electrical filter installed on an electrical power supply network passing through the screening of a Faraday enclosure, includes a transmit device for transmitting an inlet electrical pulse to the inlet of the filter. A receive and processing unit receives and processes the response electrical signal at the outlet of the filter corresponding to the pulse. A display displays the results obtained by processing the signal. The inlet electrical pulse is coupled to the power supply network and is conveyed thereby through the filter. The response is obtained from the outlet of the filter by decoupling.

Abstract: A multi-channel electromagnetically transparent voltage probe transmission link system for monitoring a plurality of voltage signals at a plurality of test points of a device under test that is subjected to a radiation field. Each channel includes two voltage probes, an electrical to optical signal transmitter, an optical signal transmission line and a receiver located out of the radiation field. The voltage probes contact and sense the voltage signals at the test point. The electrical to optical transmitters are removably mounted in a common base and are powered by either a common (or shared) power supply and/or by dedicated power supplies, such as rechargeable batteries. The receivers process the optical signals and provide display signals corresponding to the sensed voltage signal at the plurality of test points for evaluating the effect of the test radiation field.

Abstract: Apparatus for measuring electromagnetic radiation from an electronic component in which a transverse electromagnetic cell has a coaxial connector for receiving radiation, a septum extending from the connector to a facing wall of the apparatus, the facing wall having a flat surface and formed from ferrite particles dispersed through rigid material. The rigid material is ceramic and conveniently the facing wall is made from ceramic tiles incorporating the ferrite particles. With this wall structure, the apparatus may be of small size suitable for measuring radiation or electronic chips or connector assemblies.

Abstract: The device is of the type comprising a closed test cell the periphery of which is defined by an outer conductor of a TEM waveguide constituted by a tubular casing. An inner conductor of the waveguide extends within the cell. The casing has at least one intermediate portion of uniform rectangular cross-section, in which there is a test region for accommodating an object under test. At least in the intermediate portion, the inner conductor has a substantially arcuate transverse profile, the concave side of which faces the object under test. The inner conductor is preferably constituted by an array of transversely spaced-apart parallel wires arranged so that the array has the said arcuate profile.

Abstract: A method for determining the electromagnetic RF shielding effectiveness of a shielding enclosure including sequentially driving the four diagonally opposite corner pairs of the enclosure with a RF signal, measuring the RF energy leakage for each corner pair, and averaging the four measured RF leakage levels to obtain an average RF energy leakage level. This average RF energy leakage level may then be compared with prior (preferably immediately after manufacture) measured average RF energy leakage levels to obtain an indication of the RF energy shielding effectiveness lost, if any, during the time from the prior test to the current test.

Abstract: An emitter assembly of low-power electromagnetic signals with random or pseudo-random frequency variation is located inside an electromagnetic shield to be monitored. These signals are detected by at least one synchronous detection receiver located outside the shield, a second transmission channel, preferably constituted by an optic fiber, connecting the emitter and receiver assemblies to enable synchronous detection of signals transmitted via an electromagnetic channel through the shield. The amplitude of the electromagnetic signals received by the detector is significant of the quality of the shielding.

Abstract: A testing fixture for testing a transfer impedance of an electromagnetic wave shielding material including a pair of coaxial reducers opposed to each other, each of the coaxial reducers including a cylindrical outer conductor and an inner conductor disposed therein. Each of the outer conductors is provided with a flange at the outer side for engaging the pair of coaxial reducers. Contacting parts are positioned at an end of the opposing outer conductors. Outer connectors are positoned at the other end of the opposing outer conductors. Each of the inner conductors includes head parts positioned at the inside portions thereof and inner connectors positioned at the outside portions thereof. The contacting parts of the outer conductors and the head parts of the inner conductors support the electromagnetic wave shielding material. The outer connectors of the outer conductors and the inner connectors of the inner conductors couple coaxial cable to the testing fixture.

Abstract: A method for comparing the quality of RF absorbers uses a TEM cell which is provided with a low-reflection termination, in which cell the absorber wall (5) is equipped with reference absorbers (13). A steep-edged pulse wave is radiated in by means of a pulse generator (9) and a scattered wave reflected by the test absorber (14) is detected by means of a sensor (10). A reflection of the absorber wall is then determined by means of a first calibration measurement. The reference absorber is removed in a test area and a reflection of a metal wall (8) lying behind it is then determined by means of a second calibration measurement. Finally, a reflection of the test absorber (14) arranged in the test area is determined in a comparison measurement.

Abstract: A high-voltage measuring device includes a grounded, cylindrical outer electrode (1) and an inner coaxial electrode (2) which has an at least approximately cylindrical shape and carries a high-voltage potential. A non-flat high-voltage resistor (3) which is arranged coaxially with respect to the inner electrode and is connected thereto. This resistor extends at least as far as the vicinity of the outer electrode. The response bandwidth and the loadability of the device substantially improved in that the high-voltage resistor is a cone shape envelope of uniform thickness such that the potential variation in response to current flow through the resistor corresponds to the electrostatic potential variation at least at the area of the inner electrode.

Abstract: An apparatus for determining the electromagnetic compatibility of a system, including a wide-band frequency source 2, optionally subject to frequency and amplitude modulation, and coupled to a cable 9 of the system. Accuracy may be improved by the addition of a current measuring arrangement 11, 12. The two coupling devices may be split and assembled into hinged frames to facilitate use.

Abstract: A device for measuring electromagnetic wave leakage from power supply lines and digital equipment by a system of focused concave reflective plates, an antenna to disburse and detect radiation, and an instrument to measure the leaked radiation.

Abstract: An improved RF shielding integrity monitoring system is provided for monitoring the shielding integrity of a shielded enclosure that accurately identifies degraded shielding effectiveness and leakage areas in the shielded enclosure. The RF shielding integrity monitoring system performs self-testing and self-diagnostic routines to assure proper system operation prior to monitoring of the shielded enclosure. The RF shielding integrity monitoring system includes a transmitter for transmitting predetermined transmitted by the shielded enclosure for receiving the signals; a receiver separated from the transmitted predetermined signals and for identifying the shielding effectiveness of the shielded enclosure; and a cable connected to the transmitter and the receiver for communicating signals between the transmitter and the reciever.

Abstract: The performance of a device under test is observed with and without the presence of controlled EMI fields. Voltage signals from the device under test are transmitted to an oscilloscope by overdamped conductors, a hybrid electrical/optical transmitter, a fiber optic cable, a receiver and a conductor cable. The overdamped conductors are transparent to the EMI fields and the current in those conductors is kept very small by the use of a very high input impedance in the transmitter. The hybrid transmitter may be an analog or a digital transmitter.

Abstract: In an arrangement for measuring transfer impedances of coaxial systems (3), a generator (1) is connected via a coaxial, supplying system (2) to a conductor shield (6) of the coaxial system (3) at a first end of the coaxial system (3). A voltage measuring instrument is connected to the first end between the conductor shield (6) and the inner conductor (5) of the coaxial system (3). The electrical contact between the supplying system (2) and the conductor shield (6) is created by a gripping collet (12). The conductor shield (6) and the inner conductor (5) are short-circuited at a second end of the coaxial system (3).

Abstract: A method of determining radiated shielding effectiveness for a piece of epment under test (EUT) utilizing a mode-stirred chamber. Radio frequency (rf) fields are transmitted from a broad band noise source into the mode-stirred chamber. A first paddle wheel tuner uniformly distributes the rf fields throughout the chamber. The EUT is housed in the chamber such that it is exposed to the transmitted rf fields. A second paddle wheel tuner and receiving antenna are mounted within the EUT to isolate them from the transmitted rf fields. The second paddle wheel uniformly distributes any rf fields that leak into the EUT and the receiving antenna is used to detect the rf leakage.

Abstract: The performance of a device under test is observed with and without the presence of controlled EMI fields. Voltage signals from the device under test are transmitted to an oscilloscope by overdamped conductors, a hybrid electrical/optical transmitter, a fiber optic cable, a receiver and a conductor cable. The overdamped conductors are transparent to the EMI fields and the current in those conductors is kept very small by the use of a very high input impedance in the transmitter. The hybrid transmitter may be an analog or a digital transmitter.