Abstract: A module board comprised of a microstrip transmission line, terminating resistors and detectors is mounted over two coupling apertures spaced one quarter guide wavelength along a rectangular waveguide. The microstrip line has a length of five quarters of a wavelength as measured in the secondary line system. Output signals representing forward and reflected power flow in the waveguide are developed by the two detectors. This power sensor is low cost and compact and is suitable for a microwave oven.

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 signals monitoring the radiation intensity over a broad frequency range. The diode circuits are constructed to operate with a uniform response over that frequency range.

Abstract: It is known to measure the frequency of microwave signals by heterodyne conversion or by transfer oscillator techniques. Heterodyne conversion frequency counters are limited in their ability to measure the frequency of pulsed microwave signals. On the other hand, while transfer oscillator frequency counters can measure the frequency of pulsed microwave signals they have limitations in measuring signals with large frequency modulation components. The present invention utilizes analog microwave frequency dividing devices to virtually instantaneously convert the signal to be measured in octave steps into the frequency regimes associated with digital frequency counters. The apparatus disclosed comprises an antenna or other device for receiving a microwave frequency signal and feeding it to an analog frequency divider system having n stages, where n is an integer, each stage dividing frequencies applied to it by a factor of 2.

Abstract: A microwave hazard alarm that indicates the presence of microwave radiation from microwave ovens or other transmitting sources by means of a light indicator. The alarm comprises a handheld microwave receiver including an antenna, a detector, a battery powered amplifier, a light emitting diode and a unique circuit connecting the components on a small printed circuit board. The indicating light emitting diode (LED) blinks on and off periodically when the detected microwave power level is safe and below a predetermined power level. At greater power levels the LED stops blinking and glows continuously.

Abstract: A method and apparatus for the generation of an ionized gas or plasma for measurement of ultra-high frequency electromagnetic radiation utilizing a casing containing an ionizable gas, an oscillating circuit comprising an inductor and a capacitor in the casing, the oscillating circuit being adapted to resonate at a predetermined resonance frequency in the ultra-high frequency range and to have a Q factor in a vacuum of greater than 1 in order to render the circuit capable of producing a firing voltage across the capacitor for ionizing the gas when the inductor receives electromagnetic radiation near the resonance frequency, the casing further including optical conducting means having one end attached to the casing near the capacitor and means attached to the other end of the optical conducting means for analyzing the light transmitted from the conductor as a function of the power of the electromagnetic radiation.

Abstract: An yttrium-iron-garnet (YIG) tuned reflection filter is placed in the magnetic field adjacent a High Voltage Direct Current Transmission Line. A YIG filter receives a microwave signal from a remote transmitter and the same signal is modified by the YIG filter and returned to a remote receiver wherein the current in the transmission line is evaluated.

Abstract: The circuit includes a receiving circularly polarized crossed slot waveguide antenna having a longitudinal axis and spaced crossed slots disposed on a selected side of said axis spaced therefrom; and a broadband matched magic "TEE" hybrid having an output difference port, an output sum port, a first input port coupled to the receiving antenna to receive therefrom left-hand circularly polarized waves and a second input port coupled to the receiving antenna to receive therefrom right-hand circularly polarized waves. A microwave meter is coupled to the difference port to detect the value of the difference (.DELTA.) of the waves coupled to the first and second input ports and another microwave meter coupled to the sum port to detect the value of the sum (.SIGMA.) of the waves coupled to the first and second input ports to enable solving the equation R = 20 log .SIGMA./.DELTA. to obtain the value R of the radiation axial ratio.

Abstract: A highly sensitive method and system for making absolute measurements of er at all radio frequencies is described. This method surmounts the primary shortcoming of the other existing methods in that it permits absolute measurement of power at all radio frequencies, whereas all other methods except one, viz, the so-called incremental method, (described in our co-pending application), are inherently frequency limited, with the current upper limit being about 75 GHz. This major advantage stems from the fact that this method utilizes a direct comparison of the unknown rf power with a primary standard, whereas the other methods (with the exception of the incremental method) require a conversion of the power to heat before making the comparison. The main advantage of this method over the incremental method is that it has much higher sensitivity, permitting absolute measurement of rf power to be made down to about -100 dBm, as compared with only about -10 dBm for the incremental method.

Abstract: A six-port measuring circuit includes only four hybrids coupling two input orts to four power measuring ports. A first hybrid is connected to one input port and to second and third hybrids; a second input port is connected to the second hybrid; the second and third hybrids are connected to a fourth hybrid; first and second measuring ports are connected respectively to the second and third hybrids; and third and fourth measuring ports are connected to the fourth hybrid. In one embodiment, the first hybrid is a 180.degree. hybrid; and the second, third and fourth hybrids are quadrature hybrids. In a second embodiment, the first three hybrids are 180.degree. hybrids and the fourth a quadrature hybrid. Another embodiment includes three quadrature hybrids as the first three hybrids and a 180.degree. hybrid as the fourth hybrid. A fourth embodiment employs four quadrature hybrids. The basic six-port circuit is useful as a vector voltmeter and may be coupled to a transmission line by means of a directional coupler.

Abstract: The herein disclosed test instrument includes an arrangement for measuring the standing wave ratio of a transmitter, antenna combination which comprises a printed circuit board having a first conductive path thereon adapted for connection in series with the energy flowing between a transmitter and its associated antenna, a second conductive path contiguously disposed on the printed circuit board such that energy is electro-magnetically coupled from the first to the second conductive paths; circuit means for sequentially measuring the energy flowing in opposite directions along the second conductive path; and meter means for displaying the ratio of the measured energy. The test instrument further includes a circuit for measuring the transmitter's output power wherein the "loading" of the metering circuit on the transmitter is substantially reduced.

Abstract: A broadband active isotropic receiving antenna for use with a conventional lectromagnetic interference receiver to measure weak near-zone electric fields of unknown polarization. The antenna consists of three mutually orthogonal active dipoles, including RF amplifier circuitry and light emitting diode means, located therein coupled to fiber optic waveguide means. The frequency range of each of the three field components is amplified and used to modulate respective light emitting diodes whose modulated infrared or visible signals are guided through the fiber optic waveguide means to photo-detectors at the far end of the fiber optic guides. These photo-detectors recover the RF modulation from the IR carrier which is then time multiplexed for input to the electromagnetic interference receiver. The DC output from the receiver is processed to provide an output voltage proportional to the square root of the sum of the squares, i.e. the Hermitian magnitude of the three mutually orthogonal electric field components.

Abstract: Apparatus for monitoring the voltage, current, and phase of an RF signal in a transmission line. A current measuring section having a low input impedance is coupled to the transmission line and employs an isolation amplifier stage of two bipolar transistors in push-pull to produce an output signal representing the current in the RF signal. A voltage measuring section having a high input impedance is coupled to the transmission line and employs an isolation amplifier stage of two field effect transistors in a series cascade arrangement to produce an output signal representing the voltage of the RF signal. The sections include coaxial delay lines of different lengths to compensate for different internal propagation delays so that the phase relationship between the output signals representing voltage and current is the same as in the RF signal being monitored.

Abstract: An electronic instrument module for detecting and measuring the forward and reflected RF voltage wave signals on a coaxial transmission line. The instrument is integral with a coaxial line section adapted to be electrically inserted in a tubular transmission line, the line section having an elongated conductive metal body with a central cylindrical opening with a coaxial center conductor therein electrically insulated from the metal body. The metal body also has a transverse opening communicating with the central cylindrical opening and adapted to receive an inductive pick-up coil mounted on the body for rotation in the opening about an axis normal to the axis of the line section. The pick-up coil is responsive to the voltage wave signal on the transmission line.

Abstract: A VSWR meter circuit using a variable RF attenuator for use in an electronic instrument for detecting and measuring the forward and reflected RF voltage wave signals on a coaxial transmission line. The instrument is integral with a coaxial line section adapted to be electrically inserted in a tubular transmission line, the line section having an outer conductor with a coaxial center conductor therein. An inductive pick-up coil is mounted in the field surrounding the center conductor for rotation about an axis normal to the axis of the line section and is responsive to the voltage wave signal on the transmission line. A D'Arsonval meter movement is connected to the pick-up coil through a meter circuit designed so that the meter provides an indication of the level of either the forward voltage wave signal or the reflected wave signal depending on the orientation of the inductive pick-up coil.

Abstract: The detector is primarily useful in detecting RF leaks due to defects in the shielding in a CATV coaxial cable distribution network. RF leaks are detected by transmitting a unique signal and using a very narrow band receiver to detect the unique signal to thereby detect small amounts of RF leakage from the CATV coaxial cable distribution network at the locations of defects in the shielding. The leakage from the CATV coaxial cable distribution network is due to defects in the shielding such as small cracks in the cable, loose fittings or other non-RF tight conditions. The detector is a three-part system including a transmitter, a remote cable powered preamp and antenna assembly, and a narrow band receiver providing an audio output. The transmitter is designed to be permanently installed at the head end location and is modulated with a unique audio tone. An RF leak is detected by moving the remote preamp and antenna assembly along the coaxial cable distribution network of the CATV system.

Abstract: A VSWR meter unit for detecting and measuring the forward and reflected RF voltage wave signals on a coaxial transmission line. The unit is adapted to be electrically inserted in a tubular or coaxial transmission line, having an outer conductor with a coaxial center conductor therein. A microstrip circuit board is provided within the meter unit and comprises a dielectric board with a ground plane conductor printed on one side and inserted across the outer conductor, and a specially designed conductive path printed on the other side and inserted across the inner conductor. Also printed on the other side of the microstrip board is an inductive sensing loop located within and concentric with a circular loop portion of the conductive path. The sensing loop is closely spaced to the loop portion of the conductive path so as to be responsive to the voltage wave signal on the transmission line. A D'Arsonval meter movement is connected to the conductive loop through a specially designed 180.degree.

Abstract: A wideband, passive detector of electromagnetic fields in free space is disclosed. The apparatus is especially designed to minimize amplitude perturbations of the electromagnetic field being monitored. The apparatus includes an electro-optic modulator having first and second surfaces with electrodes attached thereto and a third and fourth surfaces intersecting an optical path. An electrically small dipole or loop antenna has a first electrode connected to the first electrode of the modulator and a second electrode connected to the second electrode of the modulator, for converting electromagnetic fields intercepted in free space to a voltage signal to be applied to the first and second electrodes of the modulator. A loading resistor may be added in parallel with the electrodes to improve system bandwidth. A light source is located along the optical path, for transmitting light into the modulator through the third surface.

Abstract: Liquid crystals having color play centered at different temperatures are arranged in a similar pattern on metal coated and non-metal coated disks which are used to monitor electromagnetic radiation. An embodiment which measures radiation in the range of 1 to 15 mW/cm.sup.2 at 2.45 GHz is described. The monitor uses the temperature-dependent light scattering properties of liquid crystals as the measuring and indicating mechanism. While both disks will respond equally to changes in ambient temperature, the metal coated disk also responds to induced temperature changes caused by incident radiation. Thus the difference between the temperature indications of the two disks is a measure of the radiation present.

Abstract: A microwave or other r.f. radiation detector in which a tunnel diode or other negative resistance device exhibiting the proper I-V (current-voltage) characteristics is biased in the positive resistance region near the voltage point at which the peak current occurs. Microwave or any other r.f. signal is picked up and detected by the tunnel diode such that an oscillation circuit connected thereto is caused to oscillate. The frequency of oscillation varies in accordance with the amplitude of the detected r.f. and is monitored with an earphone and/or a meter.

Abstract: A current probe for coaxial conductors including a coaxial coupling having transformer surrounding the central conductor and a coaxial passive load assembly within the coupling connected between the central and outer conductors. The transformer and passive-load components are interchangeable with others of different characteristics.

Abstract: The coupler inserts in an RF transmission line and produces a pair of DC signals whose level is representative of the magnitude of forward or reverse power flow therethrough.Power flow is sensed via a pair of non resonant loops, each of which is terminated and oriented such that AC signals, whose amplitudes correspond to the forward or reverse power flow magnitude, are produced. Since the RF signals produced by the loops are dependent on the RF power flow frequency, unique circuitry processes the RF signals and compensates for this frequency dependence whereby the processed AC signals are substantially frequency independent.Also disclosed are improved rectification circuitry, and a means to compensate the coupler against error due to thermal drift of coupler components.

Abstract: This is a probe for detecting the magnetic field component of low frequency electro-magnetic fields. Loop antennas utilizing thermocouples are tuned to resonate at a frequency below the lower frequency of the range being detected and a plurality of these loop antennas are arranged orthogonally to one another in order to obtain isotropic performance.

Abstract: A method and apparatus is disclosed for controlling the temperature rise of a material placed in a microwave oven in which use is made of a correlation between the power delivered to the load and the residual field within the oven at a position spaced away from the load. By sensing the strength of the electromagnetic field, electronic circuitry is provided for evaluating the time required to achieve a given temperature rise of the material being heated.

Abstract: A self-balancing D.C.-substitution R.F. power measuring system includes ft and second high gain differential operational amplifiers, a bolometer element, and a reference resistor element. The amplifiers and the two elements are connected in a current loop with one of the elements connected between the output terminals from the differential amplifiers and the other of the elements connected between center points of isolated dual power supplies associated with each of the amplifiers. The inputs to one amplifier are connected from an adjacent end of one of the elements and the far end of the other element, while the inputs to the second amplifier are connected to the far end of the one element and the adjacent end of the other element. Current flows out of one amplifier and into the other.

Abstract: A current shunt, for measuring rapidly changing values of current, providing a voltage indicative of the current wave that is free of any inductive effects of the shunt is provided by forming the shunt from two dimensionally identical elements but each having a different electrical resistivity and adding the voltage drops across the elements. The elements have equal and cancelling induced electrical voltages leaving an electrical voltage free of inductive effects and that is proportional to the current flowing through the shunt.

Abstract: A microstrip instantaneous frequency discriminator operable at frequencies bove 18GHz. A first power divider divides the input signal into equal power outputs which are used as the inputs to second and third power dividers. One of the outputs from each of the second and third power dividers is used as the input to a 180.degree. hybrid and the other output from each of the second and third power dividers is used as the inputs to a 90.degree. hybrid. The outputs of the 90.degree. hybrid and the 180.degree. hybrid are subsequently processed to provide signals suitable for a visual polar display of the instantaneous frequency and power level of the input signal.

Abstract: A power meter having a remote power transducer is provided with a circuit for measuring the value of a resistor in the transducer to indicate and automatically adjust the power measuring circuitry for the sensitivity of the transducer used.

Abstract: Apparatus for effecting relative positioning between two mechanical members in accordance with digital (or analog) commands includes a standing wave supporting, electrical wave propagating structure terminated other than by its iterative impedance. The wave structure is mechanically fixed to one mechanical member, and a probe is coupled to the wave structure and fixed for translation with the other mechanical member.A voltage controlled oscillator excites the wave structure developing a standing electrical wave therein -- the wave pattern node positioning being determined by the input digital command. Feedback servomechanism apparatus then responds to the potential induced in the probe (or, by superposition, that on the wave structure) for positioning the probe at the requisite standing wave null point.In accordance with one aspect of the present invention, the wave propagating structure is sealed, and the probe disposed external thereto, to preserve measuring accuracy.

Abstract: A detection device for electromagnetic radiation uses strips of thin resistive films connected in electrically conductive paths with the area of spacing between adjacent ones of the strips being greater than the area of the strips to achieve an impedance which is largely resistive over a broad band of radio frequencies. The strips are mounted in dielectric material and exposed to free space radiation. A radiation hazard meter is produced with thermally sinked thermocouple elements forming the resistive strips.