Showing papers in "IEEE Transactions on Instrumentation and Measurement in 1968"
TL;DR: In this paper, a technique for the measurement of the transmission and reflection scattering coefficients of microwave networks by Fourier analysis of the sampled transient response of the network to impulsive or steplike waveforms is presented.
Abstract: A technique is presented for the measurement of the transmission and reflection scattering coefficients of microwave networks by Fourier analysis of the sampled transient response of the network to impulsive or steplike waveforms. It is demonstrated that the method can reduce errors due to mismatch of the components of the measurment system by sampling the response over a finite time domain window that excludes unwanted reflected components. A review is made of the errors introduced due to aliasing, truncation, and noiselike sources such as timing jitter and additive noise, and a description is then given of an experimental system to evaluate the technique, based on use of a 12-GHz sampling oscilloscope for measurement of the transient response and a suitable form of the fast Fourier transform algorithm. Measurements on some typical wide-band components are presented, and it is concluded that for very broad-band measurements with moderate resolution the method has a potential accuracy of about ±0.1 dB and ±1°, with a significant reduction in mismatch errors.
137 citations
TL;DR: The time division multiplier-type wattmeter is based on a new principle of operation as mentioned in this paper, where an operational amplifier operates as an integrator of the sum of Ez (one of the two inputs) and either +E8 or -E8, E8 being an internal standardized voltage.
Abstract: The time division multiplier-type wattmeter is based on a new principle of operation. An operational amplifier operates as an integrator of the sum of Ez (one of the two inputs) and either +E8, or -E8, E8 being an internal standardized voltage. A pulse-width modulation in the form of switch reversals is obtained which differs from balance condition by an amount proportional to Ex. Instantaneous multiplication provides a wattmeter with dc accuracy of ± 0.1 percent up to at least 10 kHz. The output voltage is ± 1 volt for a ± 1-volt input from Ex and Ey. To obtain the required flat frequency characteristics, a coupling transformer and an adjustable resistor are provided. A time constant of 6.8 X 10-9 seconds has been achieved. The voltage signal is readily provided by a precision ratiotran. Errors of ± 0.0001 percent in magnitude and 50 microradians in phase angle are reasonable.
48 citations
TL;DR: In this article, the HP computer-controlled network analyzer performs fully automatic rapid characterizations of passive and active networks through their scattering parameters, and is extremely flexible in both measurement capability and presentation results, and provides standards laboratory accuracy.
Abstract: The Hewlett-Packard computer-controlled network analyzer performs fully automatic rapid characterizations of passive and active networks through their scattering parameters. It is extremely flexible in both measurement capability and presentation results, and provides standards laboratory accuracy. System operation is discussed, and in particular, the sources of error involved in making such measurements are dealt with: imperfect standards used for calibration, instrumentation, and signal source accuracy and repeatability errors. Total system accuracies and some measurement results are given.
45 citations
TL;DR: In this paper, several techniques for calibration of an electrooptical (Kerr cell) high-voltage pulse measuring system are described, without reference to pulse divider measurements, without application of a direct bias voltage to the Kerr cell.
Abstract: Several techniques for calibration of an electrooptical (Kerr cell) high-voltage pulse measuring system are described. Independent calibrations, without reference to pulse divider measurements, are achieved by application of a direct bias voltage to the Kerr cell. After calibration, experiments with voltages as high as 100 kV demonstrate reasonable agreement (to within 1 percent) between simultaneous Kerr cell and calibrated pulse divider measurements.
21 citations
TL;DR: In this article, the causes of error in inductive voltage dividers are examined in detail, and equations are developed from which the voltage ratios may be predicted with an uncertainty not exceeding 1 part in 108.
Abstract: The causes of error in inductive voltage dividers are examined in detail, and equations are developed from which the voltage ratios may be predicted with an uncertainty not exceeding 1 part in 108. Experimental methods for measurement of the voltage ratios to an accuracy of 2 parts in 109 of the input voltage vector are fully described, together with techniques by which the constituent parts of the overall error may be isolated. An improved method of winding decade inductive dividers is also described and specifications are given for multidecade devices in which the errors predictably will not exceed 1 part in 108 at 400 Hz or 5 parts in 108 over the whole frequency range 40 to 1592 Hz.
21 citations
TL;DR: In this paper, the phaseplane method was used to calculate the number of atoms in the F = 1, mF = 0 state to be focused by a hexapolar magnet on the aperture of a storage bulb.
Abstract: An atomic hydrogen maser utilizes the hyperfine transition between states with F=1, mF= O and F= 0, mF= O, respectively. Conventionally, atoms in the F=1, mF=1 state, which do not take part in the clock transition, also are focused by a hexapolar magnet on the aperture of a storage bulb. A selector for eliminating the F = 1, mF= 1 atoms from the atomic beam utilizes a first hexapolar magnet, adiabatic rapid passage transition for converting the mF=1 state to the mF = -1 state, and a second hexapolar magnet; thus, only atoms in the F = 1, mF= 0 state penetrate into the cavity. Calculation by the phase-plane method, applicable to other multiple-focalization systems, is shown to be advantageous in achieving improved focalization efficiency.
21 citations
TL;DR: In this paper, the 3.39-μm He-Ne laser is tuned to the center of the absorption line of methane which is assigned to the F1(2) component of the P(7) branch of the v3 band.
Abstract: Theoretical and experimental studies on a primary standard of wavelength and frequency in the infrared are reported. The 3.39-μm He-Ne laser is tuned to the center of the absorption line of methane which is assigned to the F1(2) component of the P(7) branch of the v3 band. The absence of Stark and Zeeman effects under the highest fields tested, the strong absorption at 63.2°K as well as at 78°K, and the separation from other lines are excellent features for a high degree of absolute stability and reproducibility. A method of automatic frequency control of the He-Ne laser at the line-center of methane is described.
20 citations
TL;DR: In this article, a voltage divider with ratios of 2n to I or 6n dB is obtained by cascading n binary dividers, each having a voltage ratio of 2 to 1.
Abstract: A voltage divider with ratios of 2n to I or 6n dB is obtained by cascading n binary dividers, each having a voltage ratio of 2 to 1. A theoretical analysis results in an expression for the ratio error. Several techniques are given for reducing this error. A voltage comparator is described for eliminating errors due to external loading of the divider. An experimental cascaded binary divider with a total of 42 dB in seven 6-dB steps is described. The attenuation of the divider was measured with a precision waveguide-below-cutoff attenuator at 1 MHz. The divider and attenuator values agree within the uncertainty of the attenuator and measuring system at 1 MHz.
16 citations
TL;DR: In this article, a horizontal cross capacitance with a movable guard electrode was constructed and the capacitance was determined as 0.1 pF with an accuracy better than 1 ppm.
Abstract: A cross capacitor is a calculable one whose capacitance is ideally determinable from one length measurement of its electrodes. In the Electrotechnical Laboratory of Japan (ETL), a horizontal cross capacitor was constructed. In this model, ease of checking alignment of the horizontal electrode bars, and a simple driving mechanism to move the guard electrode, were emphasized. Because the movable guard electrode rests on, and is guided by, the horizontal electrode bars no special supporting mechanism is necessary. The displacement, which defines the length of the capacitor, is observed by interference fringes using a Hg198 source. The sensitivity obtained for electrical measurement is better than 0.01 aF and for length measurement better than 1/30 fringe. The errors of this capacitor are examined in detail and confirmed by experimental tests. The absolute capacitance was determined as 0.1 pF with an accuracy better than 1 ppm.
14 citations
TL;DR: In this article, one-way VHF timing signals were relayed to remote clocks from a reference clock by means of a transponder on a geostationary satellite, and the accuracy of predicting the radio propagation delay was 10 As or 60 Ms depending on the method used.
Abstract: An experiment performed in late 1967 is reported which investigated the synchronization of widely separated clocks. One-way VHF timing signals were relayed to remote clocks from a reference clock by means of a transponder on a geostationary satellite. The problem of synchronizing clocks using one-way transmission reduces to the problem of predicting the radio propagation delay. The accuracy of predicting the delay was 10 As or 60 Ms depending on the method used. This technique may offer an alternative to transporting atomic standards to geodetic and spacecraft tracking stations around the world in fulfillment of their clock synchronization requirements.
14 citations
TL;DR: In this article, a method for measuring dielectric loss tangents is described that combines coherent optical resonator techniques with conventional microwave techniques to yield very high measurement accuracies, and the equation relating the experimentally measurable quantities is an algebraic expression instead of a transcendental equation.
Abstract: A method for measuring dielectric loss tangents is described that combines coherent optical resonator techniques with conventional microwave techniques to yield very high measurement accuracies. A very important feature of the technique is that the equation relating tan ? to the experimentally measurable quantities is an algebraic expression instead of a transcendental equation. The method basically consists of perturbing a microwave confocal resonator with a dielectric sheet placed normal to the axis of the resonator. The change in Q and the change in cavitylength necessary to restore resonance can then be related to the loss tangent of the dielectric. For the general case, where the dielectric is placed at any location along the axis of the resonator, the working mathematical equation is a complex transcendental expression. However, if the dielectric sheet is constrained to be at the center of the resonator and each reflector is moved inward an equal amount to restore resonance, then the equation simplifies and is no longer transcendental. These constraints are easily satisfied experimentally. The technique has been used to measure the loss tangents of several common dielectrics at 35 GHz and the results are presented.
TL;DR: In this article, the design and construction of a self-balancing direct current comparator for use in a seven-decade potentiometer is described, where the comparator generates an output current whose value, as a proportion of a constant input current, is determined to a very high accuracy by the ratio of the number of turns of two windings on a magnetic core.
Abstract: The design and construction of a self-balancing direct current comparator for use in a seven-decade potentiometer is described The comparator generates an output current whose value, as a proportion of a constant input current, is determined to a very high accuracy by the ratio of the numbers of turns of two windings on a magnetic core A linear, adjustable voltage scale is obtained by passing this output current through a resistor whose value does not vary with current Since the voltage adjustment is made by varying turns on a magnetic core and not by means of a resistive divider, the usual problems of contact resistance and thermal electromotive forces associated with this adjustment in conventional potentiometers are avoided The main sources of error in the comparator and the design techniques used to keep the errors less than the smallest step of the output current are discussed A self-checking feature whereby the linearity of each step of the output current can be checked quickly and easily is described The performance of the prototype model is given The normal range of the potentiometer is from zero to 2 volts in steps of 01?V
TL;DR: In this article, the authors proposed a system using a sweep generator, a slotted line with a broad-band probe, a sliding load which can be coupled mechanically to the probe carriage, a logarithmic amplifier, and a read-out device which can measure the VSWR of coaxial components continuously versus frequency.
Abstract: A system is described using a sweep generator, a slotted line with a broad-band probe, a sliding load which can be coupled mechanically to the probe carriage, a logarithmic amplifier, and a read-out device which can measure the VSWR of coaxial components continuously versus frequency. The technique is especially effective for the measurement of the VSWR of low-loss two-port networks and of residual VSWR of a slotted line where the elimination of termination reflections is accomplished automatically without computation. The technique of making swept-frequency VSWR measurements using slotted lines is described in detail. The use of a logarithmic RF ratio meter and dual-channel arrangement enables the operator to read the VSWR continuously versus frequency directly from the X-Y plot or scope trace independent of frequency sensitivity of the probe or of the sweep generator output or amplitude instability of the sweep generator. It is shown that the mechanical coupling of a termination sliding in a reference line with the probe carriage provides the equivalent of a reflection-free termination and allows the measurement of the magnitude of the reflection scattering coefficients independent of the loss or phase shift within the microwave component. The heart of the measurement system is a slotted line having a dielectric support at the measurement end with a reflection coefficient below 0.005 up to 18 GHz. By connecting the reference airline with the sliding termination directly to the slotted line output the overall residual VSWR of the measurement system is determined directly and continuously versus frequency.
TL;DR: In this paper, the transition probability for a two-state atomic system subjected to a phase modulated oscillatory perturbation was derived and an analysis of a typical cesium beam atomic clock system utilizing a Ramsey (two cavity) beam tube was performed to determine optimum design parameters.
Abstract: A brief derivation of the transition probability for a two-state atomic system subjected to a phase modulated oscillatory perturbation is presented. This result is used to perform an analysis of a typical cesium beam atomic clock system utilizing a Ramsey (twin cavity) beam tube in order to determine optimum design parameters. It is shown theoretically and experimentally that the optimum modulation frequency for this type of system is higher than has previously been supposed. An additional feedback loop can be incorporated to nearly eliminate cavity phase error.
TL;DR: In this article, a two-varactor, double-sideband up-converter with a signal frequency of 104 rad/s was constructed at room temperature with an optimum source resistance of 105 ohms and a minimum noise figure of 001 dB.
Abstract: A two-varactor, double-sideband up-converter pumped at 30 MHz has been constructed Operated at room temperature with a signal frequency of 104 rad/s, the device has an optimum source resistance of 105 ohms and a minimum noise figure of 001 dB Immersed in liquid N2, minimum noise figures below 0001 dB referred to a room temperature source have been measured The device is particularly useful as a null detector for audio frequency capacitance bridges At 104 rad/s, a signal current of 10-14 amperes through a capacitance of 1000 pF can be detected in less than one second with this instrument Techniques for suppressing microphonics and other extraneous sources of noise are described
TL;DR: In this paper, the operation and performance of a new type of regenerative switch for square-wave generation is presented. But the operation of the switch is controlled by a single timing capacitor, and the frequency of oscillation can be continuously or in steps over a wide range of frequencies by changing one parameter only.
Abstract: The operation and performance of a new type of circuit for square-wave generation is presented. The circuit is based on the application of two identical regenerative switches using complementary transistors, the operation of which is controlled by a single timing capacitor. Rise and fall times of the output pulses can be made to depend almost entirely on the switching speed of the transistors, and are independent of the values of the elements used in the timing network. The frequency of oscillation can be varied continuously or in steps over a wide range of frequencies by changing one parameter only. With silicon planar transistors used in the regenerative switches, the temperature stability is quite satisfactory, but a simple method for further increase in temperature stability is also discussed. The capacitive (or resistive) loading of the output terminals does not affect the frequency of oscillation. These features make the circuit described very useful in many applications, and particularly in the design of wide-range square-wave generators. An experimental model of the circuit covering the frequency range from 1 Hz to 10 MHz has been built and some results of measurements are presented.
TL;DR: In this article, a numerical procedure called deconvolution, inverse convolution is presented for the removal of measurement distortions introduced by intervening systems whose input and output are connected by convolution.
Abstract: A numerical procedure (called deconvolution, inverse convolution) is presented for the removal of measurement distortions introduced by intervening systems whose input and output are connected by convolution. The system impulse response is assumed known. Rather than modify this impulse response to avoid calculating unreasonable inputs as is commonly done, the technique developed makes corrections to the given (usually noisy) measured output arrays. The correction is determined by requiring the calculated input to have minimal energy. The mathematical manipulations can be carried out entirely in the time domain, the greatest computational difficulty being matrix inversion. The features of the procedure are conceptual simplicity and the need for only rudimentary subjective judgments from the investigator.
TL;DR: In this paper, an automatic data acquisition system was designed and fabricated from both commercially available and proprietary special-purpose equipment to obtain the large quantities of accurate voltage versus current data needed to define and study the voltage-current characteristics of semiconductor devices exposed to neutron bombardment.
Abstract: An automatic data acquisition system was designed and fabricated from both commercially available and proprietary special-purpose equipment to obtain the large quantities of accurate voltage versus current data needed to define and study the voltage-current characteristics of semiconductor devices exposed to neutron bombardment. The operation of the system in tracing out the entire current-voltage characteristic, per preprogrammed instructions, requires only a start command from the operator. The system is capable of measuring currents in the range of 10-10 to 2×10-1 amperes with an absolute accuracy of ±1 percent of reading and a precision (repeatability) of ±0.3 percent of reading, with a maximum voltage drop across the current sampling element of only 5 mV. This low value of voltage drop across the sampling element is made possible by the use of an autoranging technique, which selects discrete values of resistance for sampling the current being measured. The system is capable of programming input voltages from 0 to 50 V in 0.1-mV increments, or input currents from 0 to 2 amperes in increments of 0.01 to 10 ?A, depending on current range. The currents are sampled by the current sampler, whose output voltage is amplified by low-noise amplifiers, and measured by a Dymec 2401C-M31 digital voltmeter. The voltmeter readings, along with resistor identification information in digital form from the current sampler, are serialized by a Dymec 2540B coupler and recorded on a Friden Model SFD Flexowriter in both typewritten form and on punched paper tape.
TL;DR: In this paper, the design and principle of operation of a transistorized dielectric spectrograph operating at a frequency of 1650 ± 1 MHz was presented, which can be used up to pressure ranges of 100 atm or better.
Abstract: The design and principle of operation of a transistorized dielectric spectrograph operating at a frequency of 1650 ±1 MHz are presented. The apparatus has high sensitivity and can measure the dielectric constant to a relative uncertainty of 1×10-7 and the loss tangent to about 2×10-7. It can be used up to pressure ranges of 100 atm or better. The apparatus is particularly useful for the quick measurement of very small dipole moments (less than 1 Debye) to an accuracy better than 1 percent. The results for mixtures of helium with 1) carbonylsulfide, a linear molecule, 2) carbontetrafluoride, a spherical top, and for 3) pure nitric oxide, a diatomic molecule, are briefly presented.
TL;DR: The benefits that have been realized by the inclusion of the computer in the measurement system are emphasized-increased speed, elimination of errors, flexibility of operation, data reduction and presentation, and self-testing.
Abstract: A description is given of the application of automation to a classical measurement problem-determining the capacitance parameters of multiconductor communication cables. These parameters are important in the manufacture of cables and determine such factors as transmission efficiency, crosstalk, and noise. Although the desirability of automating these measurements has long been recognized, the problem of controlling stray capacitance in the switching equipment and connecting leads has previously prevented such automation. This problem has now been overcome by the use of a three-terminal guarded automatic bridge to measure the individual direct capacitances between conductors and a digital computer to calculate the desired parameters from these measurements. The benefits that have been realized by the inclusion of the computer in the measurement system are emphasized-increased speed, elimination of errors, flexibility of operation, data reduction and presentation, and self-testing.
TL;DR: In this paper, a dual-dry-load calorimeter, incorporating automatically controlled reference dc input power, has been developed at the National Bureau of Standards, which is used as a reference standard at frequencies from dc to 4.0 GHz in the power range of 10 mW to 1 watt.
Abstract: A new dual-dry-load calorimeter, incorporating automatically controlled reference dc input power, has been developed at the National Bureau of Standards. The calorimeter will be used as a reference standard at frequencies from dc to 4.0 GHz in the power range of 10 mW to 1 watt. The maxmum measurement uncertainty is 0.26 percent at frequencies below 1 GHz and 0.35 percent at frequencies above 1 GHz. The time required for the measurement system to reach equilibrium is less than two minutes. Construction details and design of the calorimetric and feedback control system are given, along with an error analysis and results of intercomparisons with other standards.
TL;DR: In this article, the design and construction of a multiratio, 36 000-ampex e compensated current comparator and the technique by which it may be cascaded with a second multiiratio comparator to calibrate, with a single balance, power frequency current transformers at ratios up to 7200/1 are described.
Abstract: The design and construction of a multiratio, 36 000-ampex e compensated current comparator and the technique by which it may be cascaded with a second multiratio comparator to calibrate, with a single balance, power frequency current transformers at ratios up to 7200/1 are described. The first comparator has a distributed, single-turn primary winding and a sectionalized 1200-turn secondary winding that may be series-paralleled to obtain eight ratios from 120/1 to 1200/1. A 300-kVA 1100-volt transformer is included in the single primary turn to provide the power required for the calibrations. In size the device is 40 inches in diameter and 20 inches in height, and its weight is 2700 lb. The two comparators are cascaded at nominal currents up to 30 amperes by connecting the secondary winding of the first comparator to the primary winding of the second and by making corresponding interconnections between the two compensation windings. At balance, the actual current ratio of the standard composed of the two comparators in cascade, or the first comparator alone, differs from the corresponding turns ratio by no more than a part per million (ppm).
TL;DR: The design of a system for the synthesis of one frequency from another is discussed in terms of mathematical methods of approximating real numbers, the ratio of the frequencies being the number approximated.
Abstract: The design of a system for the synthesis of one frequency from another is discussed in terms of mathematical methods of approximating real numbers, the ratio of the frequencies being the number approximated. A general equation describing the frequency synthesis process is derived and it is shown, using charts, how block diagrams for a frequency synthesizer can be developed from the solutions of this equation. Examples are given for a synthesizer which compares the frequency of an ammonia N15H3 maser with a standard frequency of 5 MHz, and for a synthesizer which offsets a standard frequency of 100 kHz by steps of 1×10-5 Hz.
TL;DR: In this paper, a directional coupler technique is described that obtains the mismatch factor directly from the complex reflection coefficients of the generator, load, and power meter, instead of measuring the individual reflection coefficients, which usually calls for the use of a slotted line.
Abstract: With the increasing demands for accuracy in microwave measurements, mismatch corrections are assuming an increased importance. In the application of a terminating-type power meter, the appropriate mismatch factor involves the complex reflection coefficients of the generator, load, and power meter. Instead of measuring the individual reflection coefficients, which usually calls for the use of a slotted line, a directional coupler technique is described that obtains the mismatch factor directly.
TL;DR: In this paper, one form of a predictable step generator is discussed that is useful in the subnanosecond to tens of nanoseconds time region after the step edge.
Abstract: Determination of the response of a time domain instrument to a voltage step is preferable to determination in terms of its response to sine waves. Unfortunately the output waveshape of a voltage or current step generator cannot be evaluated as easily as that of a sine wave source. Consequently, investigators rely (or should rely) upon waveform predictability rather than waveform measurement when employing step generators in system characterization. One form of a predictable step generator is discussed that is useful in the subnanosecond to tens of nanoseconds time region after the step edge. A practical realization of this form is given that has predictability to within 1 percent in that time region from 350 picoseconds to 6 nanoseconds after an 80-picosecond rise-time step edge.
TL;DR: In this paper, the authors used simple visual receiving equipment to determine the consistency of the apparent times of arrival of Loran-C sky-wave signals at ranges from 1000 to 6000 km.
Abstract: Operational tests were conducted using simple visual receiving equipment to determine the consistency of the apparent times of arrival of Loran-C sky-wave signals at ranges from 1000 to 6000 km. Measurements were made from St. Thomas, Bermuda, and the Boston area, and comparison with ground-wave times of arrival were made using automatic receivers where available. Time-of-arrival consistency was observed to be within ±20 ?s. The predictability of propagation delays, based on U.S. Naval Observatory estimated ground-wave delays, modified by sky-wave corrections published by the U. S. Naval Hydrographic Office, is discussed in connection with precise long-range clock synchronization using visual Loran-C equipment.
TL;DR: In this article, the design and calibration of three-terminal wye (Y) network standards in the teraohm (1012 ohms), and multitera-ohms (1014 ohms) ranges are described.
Abstract: Accompanying the improvement of electrical insulating materials, reflected in higher and higher resistivities, is the need for greater confidence in bridge performance with respect to precision and accuracy. To establish such assurance, standards extending to the upper limit of the bridge are required. This paper describes the design and calibration of three-terminal wye (Y) network standards in the teraohm (1012 ohms), and multiteraohm (1014 ohms) ranges which qualify for this purpose. The Y configuration consists of a geometric arrangement of three resistive components in which one end of each component is connected to a common terminal, while the other ends of the branches constitute the independent terminals of the network. A particular feature is that no solid insulation is used within the assembly to provide mechanical and electrical isolation of the resistance elements. The burden of providing this isolation rests with the insulation of the terminal block of the bridge to which the standard is secured. A further desirable feature is that the resistance elements, none of which exceeds 109 ohms, can be calibrated individually without removing, exposing or in any way handling, or disturbing the Y structure. These standards, developed at the Bell Telephone Laboratories and manufactured and calibrated by the Leeds and Northrup Co., have been calibrated also by the National Bureau of Standards. Both organizations report results with a precision of at least one part in one thousand and with an uncertainty not exceeding three parts in one thousand for the 1012-ohm standard.
TL;DR: In this paper, an experimental evaluation of five-terminal 10-kilohm hermetically sealed standard resistors as interlaboratory (transport) standards indicates that the typical drift is +0.4 ppm per year.
Abstract: An experimental evaluation of five-terminal 10-kilohm hermetically sealed standard resistors as interlaboratory (transport) standards indicates that the typical drift is +0.4 ppm per year; the effects of mechanical shock to 100 G and of vibration up to 10 G at 80 Hz, less than 0.1 ppm; the effect of hot shock to 65° C, less than 0.1 ppm after five days recovery; the effect of cold shock to -20° C, less than 0.1 ppm; the effect of temperature, applying corrections, 0.06 ppm over the range 18 to 280°C, and ignoring corrections, 0.92 ppm over the range 20 to 260°C. Greater precision of comparison can be achieved at the 10-kilohm than at the 1-ohm level. Incidental to the test, agreement among the values of the ohm as derived from the computable capacitor at NSL, Australia, and from the national standards at NBS (USA) and NRC (Canada) were found to be within 0.3 ppm of the expected values from data published by the International Bureau of Weights and Measures.
TL;DR: In this article, a voltage pulse in the form of a fast-rising ramp is applied to the sample and the current waveform is simultaneously observed, which is used for measuring the characteristics of materials with values of negative dielectric relaxation time in the -50-picosecond region.
Abstract: Semiconductors that show current instabilities usually have an associated negative conductivity for a certain range of electric field. Information about this region may be obtained from direct two-terminal measurements on the material. A direct method of measurement is described in which a voltage pulse, in the form of a fast-rising ramp, is applied to the sample and the current waveform is simultaneously observed. Also described are techniques for generating suitable driving waveforms, and for measuring and separating the conduction and displacement current components. The method has been used for measuring the characteristics of materials with values of negative dielectric relaxation time in the -50-picosecond region.
TL;DR: In this article, a description of a microwave oscillator of monotron type using a superconducting cavity is given, and a brief survey of theoretical properties shows that this type of oscillator can have good short-term frequency stability (10-14 for r=1 ms) and spectral purity (2?f/f=10-17).
Abstract: A description is given of a microwave oscillator of monotron type using a superconducting cavity. A brief survey of theoretical properties shows that this type of oscillator can have good short-term frequency stability (10-14 for r=1 ms) and spectral purity (2?f/f=10-17). After a brief description of the oscillator, experimental results on threshold current are given for starting oscillation and frequency stability; it is shown that it is possible to realize an S-band oscillator with a frequency stability better than 10-10 and capable of delivering continuous power of the order of 100 mW.