Abstract: Electromagnetic emission from a printed circuit board is monitored by energizing the board while it is located adjacent an array of electromagnetic emission measuring probes. The probes are successively addressed and currents induced in the probes are measured at a receiver. A memory map of the electromagnetic emission as a function of board position is generated and is displayed together with the circuit board layout so that regions of high emission level can be identified in the circuit. Each probe of the array is a series connected pair of wire loops, the planes of the loops being perpendicular to each other and to the plane of the array.

Abstract: A photographic film is adapted to provide visual record of the occurrence of a transient electrostatic or transient magnetic field by the inclusion of metallic patterns close to the film. The patterns are of a geometry to define gaps at which the fields are concentrated in a manner to interact with the film. The film exhibits a light spot at the gap, when it is developed, if a field of sufficient intensity is present during the test period. The film packet is intended primarily for inclusion in the shipping package for sensitive electronic devices to provide a visual record of exposures during shipment.

Abstract: Disclosed is a system for detecting and processing an abnormality in electromagnetic shielding for use in an intelligent building which is constructed using an electromagnetic shielding material for the skeleton and openings such as windows and doorways so that the whole of the building is formed into an electromagnetic shielding structure in order to carry out radio communication inside the building. The system has radio wave detecting means for detecting an external radio wave inside the building, level judging means for judging the level of an external radio wave detected by the radio wave detecting means, and processing means for detecting and processing an abnormality on the basis of an output from the level judging means, whereby an abnormality in the electromagnetic shielding performance is detected on the basis of the intensity level of a detected radio wave intruding into the building from the outside.

Abstract: Disclosed is a radio wave leakage diagnosing system for use in an intelligent building which is constructed using an electromagnetic shielding material for the skeleton and openings such as windows and doorways so that the whole of the building is formed into an electromagnetic shielding structure. The system has a radio wave detector disposed outside the building for detecting a predetermined radio wave transmitted from each floor of the building, so that a floor, togethere with a specific position, where there is a leakage of radio wave is detected on the basis of the intensity of the detected radio wave. With this arrangement, a predetermined radio wave is transmitted from each floor of the building and the transmitted radio wave is detected by the radio wave detector.

Abstract: A current detection device has an annular dielectric substrate with a thin (e.g., less than one skin depth at maximum frequency) resistive foil laid down on the substrate outer surface and extending completely thereabout. Annular metal rims are affixed to the substrate edges respectively contacting the metal foil or film. A conductive strip of appropriate dimensions is received onto the outer edges of the metal rims and extends about the complete circumference of the rims. A resistive material is used to secure the conductive strip to the edges of the rims so that the entire resistance of the strip and resistance material exceeds that of the sensing metal foil to prevent shorting out of the foil.

Abstract: In a power sensor for RF power measurments, comprising a thin-film absorbing resistor formed on the top surface of a support member and a thermocouple which is electrically isolated from the circuit of said absorbing resistor, the absorbing resistor is formed on an insulating film of a silicon support member so as to increase the sensitivity and to facilitate manufacture thereof, the silicon support member including an island formed beneath the absorbing resistor, a thermally conducting portion formed in spaced relationship thereto with a narrow bridge portion provided inbetween, and said thermocouple being constituted by the bridge portion and by mutually spaced contact zones formed thereon.

Abstract: An electric field sensitive probe capable of measuring both CW and pulsed signals with consistent efficiency using a diode detector connected to a dipole antenna in which a shunt capacitor is connected in parallel with the dipole and one or more resistive elements are connected in series between the diode and the dipole.

Abstract: A microwave power sensor utilizing a semiconductor power absorption element which is mounted on a fin-line structure within a waveguide channel. In order to check calibration of the sensor, a coaxial line is used to feed a relatively low frequency reference signal to the power sensor. The power element is positioned between the input port of the waveguide and a coaxial line input port at which the reference signal is applied. The use of a precise and accurate reference signal enables the power sensor to be used for microwave measurements.

Abstract: A current detection device has an annular dielectric substrate with a thin (e.g., less than one skin depth at maximum frequency) resistive foil laid down on the substrate outer surface and extending completely thereabout. Annular metal rims are affixed to the substrate edges respectively contacting the metal foil or film. A conductive strip of appropriate dimensions is received onto the outer edges of the metal rims and extends about the complete circumference of the rims. A resistive material is used to secure the conductive strip to the edges of the rims so that the entire resistance of the strip and resistance material exceeds that of the sensing metal foil to prevent shorting out of the foil.

Abstract: Apparatus for measuring the near-field radiation of an antenna such that its far-field radiation characteristics can be determined. The invention utilizes the principle of the Foucault pendulum. It uses a bob attached to a long pendulum arm that is free to rotate. Rotation of the earth causes an apparent rotation of the swing plane of the pendulum with a period of T=24/sin (latitude). By attaching a field sensing probe to the pendulum bob and mounting the antenna under the Foucault pendulum, the entire antenna aperture can be scanned without moving the antenna. The motion of the probe covers part of an external sphere centered at the pivot point of the pendulum and having a radius equal to the length of the pendulum. Appropriate transformation of the measured near-field data gives the far-field radiation pattern.

Abstract: A device for displaying forward and reflected power values simultaneously comprises a plurality of display segments which are switched on in a predetermined sequence to display the forward power and switched off in a predetermined sequence to display the reflected power.

Abstract: A small field probe is calibrated by selectively varying the field intens and frequency and recording the data in arrays with each incremental step. The arrays are built by selectively varying one parameter while maintaining another constant. In this way coefficients of the equation for the calibration of the probe is arrived.

Abstract: A method and apparatus adapted to be worn by a person for measuring radio frequency (RF) energy absorbed by a person's body in the frequency range of 10 KHz-42 MHz wherein the person's height is less than 1/4 of the free space wavelength of the radiation.

Abstract: A passive, integrating electromagnetic radiation power dosimeter. A radiofrequency or microwave antenna is combined with a diode detector/rectifier, a squaring circuit, and a electrochemical storage cell to provide an apparatus for determining the average energy of electromagnetic radiation incident on a surface. After a particular period of irradiation, the dosimeter can be interrogated electrically or visually, depending on the type of electrochemical cell employed, to yield the desired information. The apparatus has a substantially linear response to the electromagnetic power density over a wide range of electromagnetic field, and all of the energy required to record the incident energy is supplied by the electromagnetic field.

Abstract: A junction field effect transistor circuit is used to detect the power level contained in radio frequency signals over a wide range of frequencies and signal levels. The radio frequency signal is coupled to the drain of a junction field effect transistor, the gate of which is biased at a d.c. potential equal to the pinch off voltage. The radio frequency signal is also coupled to the gate. The resulting current from the source contains a d.c. term proportional to the square of the magnitude of the radio frequency signal, as well as time varying signal components. A low pass filter is employed to remove the time varying signal components from the resulting source current to produce a D.C. output current which is proportional to the power level of the input signal.

Abstract: A two dimensional portable double gap detected probe for measuring B fields n large test volumes which are remote from electrical power. The probe is small, portable, and constructed for minimum field perturbation. The output of the probe is read by an ordinary high impedance volt meter, which is easily portable, and does not require external power.

Abstract: An electromagnetic field measurement probe for measuring an electromagnetic field and providing a corresponding measurement signal to a measurement output. The electromagnetic field measurement probe comprises an antenna arrangement for detecting the electromagnetic field and producing a corresponding electrical output, and an output connector arrangement connected to the antenna arrangement for providing the corresponding electrical output to the measurement output of the probe. The output connector arrangement includes a lead structure comprising a dielectric having opposing faces on opposite sides thereof, and high resistivity lead material disposed on the opposing faces. The probe further comprises a diode rectifier disposed between and connecting two antenna elements forming the antenna arrangement, as well as two output connector bonding pads, each being electrically connected to the high resistivity material disposed on respective ones of the two opposing faces of the dielectric.

Abstract: An electric field probe array including several dipole probes, each including a diode connected between two conductors with the diodes being collectively connected to at least two probe terminals. Also disclosed is a system for heating a target with electromagnetic radiation that includes a central control unit, a source coupled to the control unit with the source generating the electromagnetic energy at a frequency and power in response to the control unit, a radiation apparatus coupled to the source for transferring the electromagnetic energy from the source to the target and input circuitry connected to the control unit for indicating the status of the target whereby the operation of the system is controlled by the control unit as a function of the target's status.

Abstract: A passive safety probe for placement in a time varying magnetic field to alert personnel when the power density of high intensity electromagnetic fields reach and exceed applicable personnel safety limits. The probe senses the magnetic field present with a loop antenna. The loop antenna produces a voltage output in response to the magnetic field. The output voltage is linearized by a frequency dependent filter and rectified to provide a direct current output which is subsequently coupled to an attention getting indicating means such as a light emitting diode and/or a horn. When detected field voltage exceeds the threshold of the indicating means, a visual or audible response occurs, indicating that safe field levels have been exceeded.

Abstract: A unique diode sensor adapted for responding with pre-established sensitivity over a range of relatively low frequencies. A diode is connected to a dipole antenna having both conductive and resistive portions. Lumped impedances are connected in parallel with the diode and the values of these impedances are selected in coordination with the characteristics of the diode and antenna to control the sensitivity of the sensor as a function of the frequency of the illuminating energy.

Abstract: A high frequency electromagnetic field detector for detecting high frequency electromagnetic fields comprises a micro antenna for mainly receiving the induction term of the electromagnetic field, an amplifier for amplifying a voltage induced on the antenna, a comparator circuit for comparing the output of the amplifier with a predetermined reference level to output a signal indicating that the output exceeds the reference level, and an indicator in response to the signal from the comparator circuit for indicating it.

Abstract: An antenna comprising orthogonal arrays of resistive thermocouple dipoles interconnected by transversely extending conductive elements of discrete length. The components are designed to create an additional response by a traveling wave effect on the dipoles along the Poynting vector to offset the fall-off in dipole sensitivity experienced as frequency rises.

Abstract: An improved meter for measuring RF power. The RF power is applied to thermocouple means which transforms the RF power into a low level d.c. signal which then passes through a chopper stage that is driven by a clamped sinusoidal input. The output of the chopper stage includes periodic pulses with a prescribed pulse spacing: pulse duration ratio, the pulses being passed through a band-pass filter at a harmonic of the chopper drive signal. The filtered signal, which is also amplified, undergoes synchronous detection with a tri-level square-wave signal which is centered in phase relative to the amplified, filtered signal when the two signals are in phase. The power meter measurements adjusted for zero drift and calibration drift by a microprocessor; based on zero measurements and calibration measurements made before and after an RF measurement is made. Measurements are stored and processed digitally to enhance accuracy.

Abstract: An electromagnetic field detector adapted to display potential hazard to humans and other animals arising from illuminating electromagnetic energy over the frequency range determined to be hazardous by the American National Standards Institute; the detector being designed with various sensing means to create a sensitivity vs. frequency response that is the inverse of the A.N.S.I. protection guides.

Abstract: A spectrum analyzer for analyzing electromagnetic radiation which may be utilized to determine the radiation wavelength and power. The analyzer includes a gas filled chamber which has a collimating lens through which radiation is injected, and a reflective plate that reflects the radiation back toward the lens. A standing wave is created within the chamber having spatially periodic peaks. The chamber gas pressure is regulated to a pressure such that gas breakdown occurs, thereby generating a light pattern at each standing wave peak. The patterns are then photographed, and the patterns' diameters and spacing are measured from the resulting photograph. From the spacing and diameter obtained, wavelength and power may be calculated.

Abstract: Method and apparatus for testing microwave oven cavities during the oven fabrication process after the cavity forming operation is complete. The cavity to be tested is positioned front frame resting on a test plate containing a non-protruding microwave power source and choke/ferrite attenuators. The power source radiates into the interior of the cavity and microwave leakage is measured at the cavity exterior.

Abstract: A method and apparatus for testing microwave ovens to determine if exterior radiation levels exceed permissible maxima. The leakage levels are sensed by a sensor moved along a preselected path accurately spaced from the oven cabinet. The probe is moved automatically at high speed along the path until a leakage level above a preselected value is sensed. A control associated with the apparatus automatically causes the sensor to move subsequently at a reduced speed to determine the maximum leakage at that position. The control causes a repeated traverse of the questioned position at the slow speed to provide an accurate maximum leakage determination. The control includes reference information indicating acceptable levels of leakage along the path of movement of the sensor which are continuously compared with actual sensed values.

Abstract: An RF wattmeter is disclosed of the type using an "insertion-type" pick-up element to produce a voltage wave signal corresponding to the measured power in the coaxial transmission line. The induction loop in the pick-up element is connected to a principal detector, and a secondary detector is connected in opposition to the principal detector. Both detectors are located in close proximity to each other and are subject to the same thermal environment. A sine wave generator supplies a wave signal to the secondary detector in opposition to the wave signal supplied to the principal detector from the inductive loop. The d.c. portion of the resulting signal representing the difference between the opposed signals is integrated, and the integrated output is used as the amplitude in the generated sine wave. When the circuit is in balance, the integrated output matches the amplitude of the inductive wave form and can be used as an output indicating measured power in the coaxial transmission line.

Abstract: A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

Abstract: A radiation detector utilizing thin film thermocouples serially connected in an array and substantially disposed within a plane, said thermocouples being selectively mounted for non-perturbing introduction into the near-field region of an electric field.This application is a continuation of copending application Ser. No. 678,901 filed Apr. 21, 1976, now abandoned, which prior application was a continuation of previously copending application Ser. No. 423,754 filed Dec. 11, 1973, now abandoned, which latter application was a divisional of copending application Ser. No. 200,536, filed Nov. 19, 1971, now U.S. Pat. No. 3,794,914, which latter application was a continuation-in-part of copending application Ser. No. 848,620 filed Aug. 8, 1969, now U.S. Pat. No. 3,641,439.

Abstract: A radiation measurement means is shown which has the capability of detect radiation in both the millimeter wave, and the infrared, frequency regions. A basic self-oscillating Gunn diode is enclosed in a donut shaped silicon ring. The presence of infrared energy will create holes and electrons in the silicon material, altering its conductivity, and lower the power of oscillation. The realized drop in oscillating power identifies the infrared. Millimeter wave radiation is detected because an intermediate frequency is generated as the Gunn diode operates as a self-oscillating mixer of the new different frequency with its own oscillating frequency. Thus it is possible to detect signals from both ranges, in a single device.

Abstract: Disclosed is a method of measuring the effective power absorbed by a resistive device such as an electroexplosive (or substitute) device due to radio-frequency (rf) energy induced in an electrical line connected to the device. The method comprises calibrating a device by passing dc currents of known value through it and measuring the voltage across it. Knowing the voltage and current, one can calculate resistance and power dissipation. By then connecting the device to an electrical line, one can measure the power dissipation and resistance and subtract the power dissipation due to the dc current to obtain the power dissipation due to rf power on the electrical line.

Abstract: A compact power detector apparatus comprises a unique adjustable directional coupler and a power detector circuit integrated therewith. The adjustable coupler comprises a pair of stripline conductors, one of which is carried on a turntable. The coupling distance between the conductors varies as the turntable rotates. The power detector circuit is also carried on the turntable, thus avoiding the need for flexible interconnections. The output from the detector circuit is taken from a connector substantially in the center of the turntable.

Abstract: A liquid crystal film pack for detecting leakage from a microwave oven by passing the moist film pack adjacent the joints and seams of the oven to produce a color change in the liquid crystal material in response to a microwave radiation leak.

Abstract: A capacitively coupled inductive shunt current sensor which utilizes capacitive coupling between flanges having an annular inductive channel formed therein. A voltage dividing capacitor is connected between the coupling capacitor and ground to provide immediate capacitive division of the output signal so as to provide a high frequency response of the current pulse to be detected. The present invention can be used in any desired outer conductor such as the outer conductor of a coaxial transmission line, the outer conductor of an electron beam transmission line, etc.

Abstract: This portable microwave radiation monitor utilizes an antenna formed in a dual Archimedean spiral. The power density of the electric field is indicated on a meter coupled to diode means connected across the inner terminals of the antenna by inductance means selected to resonate with the variable capacitance of the diode, substantially at the frequency of the field being monitored.

Abstract: A sampler is constituted by a section of a rectangular waveguide in which are mounted two diodes connected in series by means of a conductor which is placed at equal distance from the two large faces of the waveguide, one end of the conductor being connected to the input of the sampler and the other end being connected to a matched load.

Abstract: This portable microwave radiation monitor utilizes an antenna formed in a dual Archimedean spiral. The ellipse ratio of the spiral is minimized by selective placement of resistive means over a portion of the antenna and the power density of the electric field is indicated on a meter connected via diode means to the inner terminals of the antenna.

Abstract: A radiation detector for free space microwave radiation uses thin film resistive strips, having an equivalent surface resistivity that is large compared to the characteristic impedance of free space, and diode circuits in series with the strips for deriving d-c signals monitoring the radiation intensity over a broad frequency range. In part of that range, the strips operate like a short dipole antenna. The diode circuits are constructed to operate with a uniform response over the entire frequency range.

Abstract: An improved broad band microwave detector of the type including a detector diode, a by-pass capacitor, and a resistive termination wherein fabrication using coplanar transmission line techniques results in a substantial increase in the frequency response of the detector.

Abstract: A stationary microwave leakage detector and method for testing microwave ovens for the maximum power density of microwaves leaking through the oven's door seals. The leakage detector is composed of an array of antennae arranged in a line generally circumscribing the circumference of the door at a fixed distance therefrom. The antennae are spaced apart a predetermined maximum distance thus insuring that a given antennae will sense at least a portion of the narrowest possible beam of microwaves emitting from the periphery of the door. Furthermore, the spacing and arrangement of the array vis-a-vis the oven door insure that the minimum power density observed by an antenna is a known ratio of the maximum power density of a narrowest beam possibly incident thereon, thus providing a means to guarantee from the measured power density levels that there are no microwaves leaking from the oven under test greater than a certain maximum power density.

Abstract: A power level measurement system includes a power level sensor having a linear response to power level variations for power levels below a predetermined level and a non-linear response above the predetermined level, a DC amplifier and linearity compensator for measuring power and amplitude levels above the predetermined power level, a switched amplifier circuit containing a DC to AC converter circuit, an AC amplifier and a detector for measuring power levels below the predetermined level, means for determining whether the power level of the high frequency signal is above or below the predetermined power level and for accordingly selecting either the DC amplifier or the switched amplifier system in accordance with this power level, and display means for displaying the output from the selected amplifier system.

Abstract: The electromagnetic energy is captured by the antenna and changes the reftivity of a Liquid Crystal Display (LCD) proportional to the field being measured. The LCD is illuminated by a fiber optic and this light is reflected from LCD proportional to the electromagnetic field. This field proportional light is captured by a fiber optic and transmitted to a photodetector where it is converted to an electrical signal proportional to the electric field. This electrical signal may then be displayed, recorded or processed with other information.

Abstract: Picosecond duration microwave pulses are generated used a laser activated semiconductor switch. High voltages are switched with picosecond rise time and result in the establishment of microwave pulses of frequency spectrum commensurate with the rise time of the voltage and wave guide parameters of a wave guide in which the switch is disposed. The activating light pulse is synchronous with the microwave pulse. A system, including an antenna and radar receiver, is responsive to the light pulse and return signals from a target on which the microwave pulse is incident. Reflection measurements of the microwave pulses from a body of semiconductor material which is optically excited by the light pulses relatively delayed between the generation of successive microwave pulses, indicate the duration of the microwave pulses.

Abstract: A device for warning a person carrying or wearing it of the presence of dangerous microwave radiation is fully powered by the radiations being detected. A very low-wattage gas-discharge lamp is energized by a broadly or a sharply tuned receiver circuit including dipole antennas or one antenna and a "grounding" casing element. The casing may be largely and uniformly transparent or have different areas gradedly light-transmissive to indicate varying radiation intensities. The casing can be made in the shape of a pocket watch, fountain pen, bracelet or finger ring, etc.

Abstract: Electrically conducting magnetic recording tape having a coating of .gamma.-Fe.sub.2 O.sub.3 particles on a polyester substrate is used as leads for probes in oven cavities and other microwave fields. The tape leads are flexible, have a high resistance per unit length, and are nearly transparent to electromagnetic waves. Electric diode-dipole probes with such leads are uniquely electric and a magnetic loop detector is uniquely magnetic.

Abstract: This invention relates to a microwave leakage detector of the kind suitable for use in a domestic environment for testing leakage from appliances such as microwave ovens by moving the detector along joins or seals of the appliance. The circuitry of the detector is generally known per se. In order to facilitate testing of the detector in the domestic environment the circuitry and associated dipoles are fully encased in a solid block of material in a container having a head portion for accommodating the circuitry and a handle for convenience in use. The container is a clear plastics material enabling a visual warning device associated with said circuitry to be viewed externally and the container has a specific gravity greater than that of water whereby said device is adapted to sink when placed in water. Thus testing of the detector may be readily effected by placing it in a container of water within an oven such that the warning device may be viewed externally of the oven.

Abstract: An electronic instrument is disclosed for measuring directional RF power levels and power function levels on a coaxial transmission line. The instrument includes an inductive sensing loop for sensing the RF voltage level on the transmission line and producing a voltage level proportional thereto. An analog-to-digital conversion means is connected to the sensing loop for converting the voltage level from the sensing loop to binary voltage data. A microcomputer means is associated with the conversion means for performing arithmetic operations upon the binary voltage data to calculate power data and power function data. Means connected to the microcomputer means are also provided for displaying the calculated power data and power function data. The instrument provides a direct readout in digital form of RF power data and data for various power and voltage functions such as VSWR.

Abstract: A device for measuring the power in a microwave transmission and for providing a measuring port at the output of a microwave signal generator or transmitter. First and second quarter wavelength transmission line sections, coupled in series with one another and having characteristic impedances Z.sub.2 and Z.sub.1 respectively, where Z.sub.2 >>Z.sub.1, are coupled at the first section to a predetermined point on a transmission line to be monitored. A port at the free end of the second section allows for the connection of two independent measuring circuits to the transmission line.

Abstract: A radio wave power measuring apparatus is disclosed, which includes a thel load confined in a reference temperature housing, a wave absorber disposed in the load for absorbing radio waves supplied thereto, a heater for heating the load, a thermoelectric cooler element provided between the housing and the load for the load, a temperature difference detector having a thermoelectric sensor element provided between the housing and the load for detecting the difference in temperature between the housing and the load, a heater controller for feeding to the heater the power corresponding to the temperature difference detected by the detector so as to maintain the load and the housing at the same temperature, and a measuring member for measuring the power fed to the heater.