Abstract: The watercut of fluid in a mulitphase flow is measured. Microwave energy in the 10 Ghz range is transmitted through a test call having flow passing therein through a known geometry. Attenuation and phase shift of the microwave energy is measured and used to derive the wave number of the microwaves in the unknown fluid. The water fraction of the unknown fluid is then determined from the wave number and the known geometry of the test all using Hannai's equation.

Abstract: Methods for rapidly adjusting the impedance of a variable impedance apparatus to match the impedance of a source to the impedance of a load, where the load impedance is a nonlinear function of the power delivered to the load, are described. In addition, an automatic impedance matching apparatus for matching the impedance of a source to the impedance of a load and for maintaining a stable plasma are described. The apparatus includes a variable impedance apparatus, a plurality of electric field sensors, a photosensitive detector, a data processor, and a memory.

Abstract: A method calibrates a network analyzer having two test ports and at least four measuring locations by successive measurement of the transmission and reflection parameters at three calibration standards successively connected in arbitrary sequence between the two test ports according to the seven-term principle. A first calibration measurement is implemented at an electrical line whose characteristic impedance is known and whose electrical propagation constant may be unknown and complex. Second and third calibration measurements are then respectively implemented at a two-port that is connected between the test ports and is constructed of concentrated components. The electrical propagation constant of the line and correction values that are taken into consideration in following object measurements are calculated from these measured values.

Abstract: A multistate electronic transfer standard provides electronic conditions to at least one of two ports of a vector network analyzer. One embodiment of the multistate electronic transfer standard includes a plurality of semiconductor interconnected by transmission lines. Each of the semiconductor devices are biased to generate different conditions at each of the two ports. A control computer controls the biasing of devices according to a predetermined procedure and compares impedance values measured for at least one of the two ports of the network analyzer to known values stored by the control computer. The control computer thereby derives calibration coefficients that are used by the network analyzer in performing further measurements.

Abstract: A multistate electronic transfer standard provides electronic conditions to at least one of two ports of a vector network analyzer. One embodiment of the multistate electronic transfer standard includes a plurality of semiconductor interconnected by transmission lines. Each of the semiconductor devices are biased to generate different conditions at each of the two ports. A control computer controls the biasing of devices according to a predetermined procedure and compares impedance values measured for at least one of the two ports of the network analyzer to known values stored by the control computer. The control computer thereby derives calibration coefficients that are used by the network analyzer in performing further measurements.

Abstract: A multistate electronic transfer standard provides electronic conditions to at least one of two ports of a vector network analyzer. One embodiment of the multistate electronic transfer standard includes a plurality of semiconductor interconnected by transmission lines. Each of the semiconductor devices are biased to generate different conditions at each of the two ports. A control computer controls the biasing of devices according to a predetermined procedure and compares impedance values measured for at least one of the two ports of the network analyzer to known values stored by the control computer. The control computer thereby derives calibration coefficients that are used by the network analyzer in performing further measurements.

Abstract: A method for completely characterizing coupled transmission lines by short-pulse propagation is described. The complex frequency-dependent propagation matrix, impedance matrix and admittance matrix for a set of n parallel transmission lines can be determined by comparing the properties of two sets of coupled transmission lines of different length. Each transmission line set has two conductors of unequal length and ground conductors to form a coupled transmission line system. Each transmission line set can have uncoupled ends. An input pulse is provided at at least one node of each transmission line set. The complex frequency dependent propagation matrix of each transmission line set is determined by a comparison of the output pulses at the remaining nodes of each transmission line set which involves ratioing to cancel out the effect of the pad-to-probe discontinuity and the uncoupled ends which make it unnecessary to do any embedding.

Abstract: The present invention relates to a device for the vector measurement of ultra-high frequency signals of the same angular frequency of the six port junction type, comprising a power divider (10) and a phase shifting circuit (11) two of the six ports of said device being measuring ports connectable to two sources of signals to be characterized, the four other ports being connected to four detectors, one of them being a matched detector (14) and the three others (12, 13, 15) being unmatched detectors.

Abstract: A method and apparatus is provided for characterizing a differential circuit. A measurement system (200) is used to introduce input signals to the differential circuit and to measure corresponding output signals. Particularly, an input differential wave is introduced into the differential circuit (1010) while correspondingly measuring a differential output wave (1020) and a first common mode output wave (1030). Similarly, an input common mode wave is introduced (1040) while measuring a second differential output wave (1050) and a second common mode output wave (1060).

Abstract: A multistate electronic transfer standard provides electronic conditions to at least one of two ports of a vector network analyzer. One embodiment of the multistate electronic transfer standard includes a plurality of semiconductor interconnected by transmission lines. Each of the semiconductor devices are biased to generate different conditions at each of the two ports. A control computer controls the biasing of devices according to a predetermined procedure and compares impedance values measured for at least one of the two ports of the network analyzer to known values stored by the control computer. The control computer thereby derives calibration coefficients that are used by the network analyzer in performing further measurements.

Abstract: For calibrating a network analyzer having two test ports by successive measurements of the transmission and the reflection parameters on a plurality of calibration standards in any desired order, from which correction values are then calculated that are taken into account in subsequent measurements of a device-under-test, at least five successive calibration measurements with predetermined calibration standards or calibration standards in the form of discrete components according to basic predetermined circuits are performed. A total of 15 correction values is then calculated from the measured values obtained with these calibration standards.

Abstract: For calibrating a network analyzer which has two test ports adapted to be connected to an object under test by means of lines or through free-space, the transmission and reflection parameters are measured in a first calibrating measurement either on a line which is connected in reflection-free fashion between the two test ports or on the free-space connection. Subsequently two or three further calibrating measurements are performed with the same free-space connection or the same line, respectively, on calibration standards which are implemented by reflection-symmetrical and reciprocal interfering objects or discontinuities inserted at two or three different positions in the free-space connection or the line, respectively.

Abstract: A method of facilitating construction of a microwave system which permits the evaluation of a variety of hardware construction options and subsequent evaluation of their effectiveness by measuring or otherwise determining appropriate physical parameters of selected components arranged in a selected order to predict the power response uses an iterative ladder network constructed according to a point discontinuity model for individual components of the system in which input and output reflection coefficients and an attenuation coefficient are calculated for each component based on measured or specified insertion loss and VSWR or return loss values, and the ladder is analyzed by processing the coefficients forward in the direction of power flow.

Abstract: An unknown impedance can be determined in an analytically exact way by measuring in succession the 3 complex transmission coefficients of a transmission path, in which a measurement cell with the unknown impedance or with one of two known impedances is inserted. This is a broad-band method which takes into account all mismatches of the transmission line and of the measurement cell. Dielectric and magnetic material parameters can be determined via these impedance measurements.

Abstract: In a microwave imaging system, a three dimensional profile of the dielectric permittivity of a target is obtained. A transmitter transmits microwaves toward a target, and the target scatters the microwaves. The scattered waves are received by an antenna and are converted into suitable data for application to a digital computer. The computer processes the data using either a scattering matrix algorithm or a Fourier transform algorithm. The computer then generates data representative of a three dimensional profile of dielectric permittivity which can be displayed on a suitable display device such as a CRT.

Abstract: A highly sensitive, direct-contact, in situ sensor for nondestructively measuring or monitoring the complex dielectric and conductive properties of solids, liquids, or gasses at microwave frequencies. A metal microstrip dipole resonator (11) is etched on the surface of a dielectric substrate (12) which is bonded to a copper ground plane (14). The dipole resonator is electromagnetically driven by mutual inductive coupling to a short nonresonant feed slot (13) formed in the ground plane (14). The slot (13) is driven by a coaxial feed line (7) or a microstrip feed line (16) extending from a swept microwave frequency source (2) which excites the incident wave (17). Alternatively, the metal resonator is omitted and the length of the slot (15) is increased so that it becomes the resonator. In use, the sensor is placed in close physical contact with the test material (9) having complex dielectric constant .epsilon.* (=.epsilon.'-j.epsilon.") or conductivity .sigma..

Abstract: A wideband detector having a substantially flat response is made by using the signal at the isolation port of a coupler. As the response or transfer characteristic at the isolation port is substantially linear, a matching network having the inverse opposite transfer characteristic with respect to frequency may be connected to the coupler. The addition of the matching network transfer characteristic to the transfer characteristic of the coupler in the isolation port produces a superposition. Accordingly, the matching network transfer characteristic compensates for the linear varying transfer characteristic at the coupler isolation port to produce a substantially flat output of the matching network. The detector connected to the matching network output will then produce a detector signal which is substantially flat over the frequency range of the bandspread of interest.

Abstract: A source of microwave power is connected to the first, input, port of a six-port device whose second, output, port is connected to a device under test. A variable impedance is connected between the source and the input port. Preferably, the variable impedance is a mechanical three stub tuner. The six-port device includes a first directional coupler whose first input comprises the input port and whose first output comprises the output port. First, second and third hybrid couplers have outputs which constitute the third, fourth, fifth and sixth outputs of the six-port device. A power divider connects the directional coupler to the hybrid couplers.

Abstract: The thickness of the layers of rubber covering the steel belts within a tire can be measured by transmitting a microwave signal toward the outer surface of the tire and measuring the phase shift of the signal reflected by the tire. In the preferred embodiment, a waveguide is used to direct the microwave signal toward the tire. A standing wave is created within the waveguide by interference between the transmitted microwave signal and the microwave signal reflected from the tire. A series of crystal detectors mounted along the length of the waveguide measure the standing wave. A processor calculates the phase of the reflection coefficient, and determines the thickness of the rubber layer as a predetermined function of the phase. By proper selection of the microwave frequency and the spacing between the waveguide and the tire, the rubber layer thickness can be uniquely determined as a function of phase for any range of rubber thicknesses likely to be encountered in a tire.

Abstract: Apparatus for measuring the noise parameters of a device under test (DUT), with full compensation for impedance mismatches between the DUT and the test apparatus. The apparatus includes an S-parameter measuring device, such as vector network analyzer (VNA), combined with a noise module. The noise module includes, among other things, a pair of test ports for the DUT, a noise source which can be turned on or off by an external controller, a receiver, and a switch for coupling the output of the DUT to selectably either the receiver or port 2 of the VNA.

Abstract: An apparatus and method for determining the noise parameters of a two-port electronic device under test includes a six-port passive correlation network having two input ports and four output ports. Two noise sources are used, with each noise source being connected to separate input ports of the network using microwave circulators. One noise source is injected at the input port of the device under test while the other noise source is injected to the output port of the device under test. A power meter is selectively connectable to individual output ports of the network to detect the power level at the selected output port in response to predetermined noise signals from the noise sources. In the operation of the apparatus, the noise output from one noise source is held constant while the noise output from the noise source is varied. During this variation, the power meter reads power levels at the network output ports.

Abstract: A full reversing millimeter test set comprising a pair of test head assemblies which are connected to an analyzer by means of coaxial cables enclosed within a sheath. Microwave signals are sent to the test head assemblies and therein frequency-multiplied so as to provide the necessary millimeter test signals required for testing microwave devices in the W band of 75-110 GHz. By placing the millimeter wave components in the test head assemblies, the phase distortions which would otherwise be encountered in flexing or movement of the interconnecting coaxial cables and the bulk, signal loss and phase distortions associated with long waveguide are eliminated.

Abstract: A method and apparatus for millimeter wave flow cytometry of a cell stream hydrodynamically focused in a zone of interaction with a millimeter wave source and complex ratiometric receiver. The cell stream is characterized by complex power wave scattering parameters as a function of frequency, scattering angle and polarization. These parameters train a signal processor to sort specimen cells into one of a plurality of predetermined reference groups in accordance with a minimum number of normal cell types and functional states.

Abstract: A floating sampler and directional bridge for use in characterizing the impedance of an integrated device under test from D.C. up to frequencies above 100 GHz. The directional bridge has the structure of a Wheatstone bridge with resistor values selected such that when the input impedance of the device under test matches the output impedance of the source, no voltage develops across two nodes of the bridge. When no impedance match exists, a floating diode/capacitor sampler comprised of two diode/capacitor pairs driven by local oscillator strobe pulses samples the voltage difference between the two nodes of the bridge and outputs an IF signal proportional to the difference. Another pair of diode/capacitor samplers outputs an IF signal proportional to the amplitude of the RF excitation waveform.

Abstract: An arrangement for determining on approximation the equivalent circuit diagram of an electrical or electronic element at high frequencies includes a measuring apparatus (4), to which the element to be represented as a two-port element (59) or a one-port element (1) is connected through connection members (2; 57, 58, 60) and which measures over a preselected frequency range the parameters of the stray matrix of the two-port element of the impedance or the reflection factor of the one-port element with the connection members. To the measuring apparatus (4) is connected an evaluation circuit (7), which corrects the measurement result by inclusion of two-port parameters of the connection member(s) determined before the measurement and which calculates for a preselected equivalent circuit diagram of the element from the corrected measurement result values of the equivalent circuit diagram elements by means of an optimization strategy.

Abstract: A method of inspecting an integrated circuit comprises the steps of supplying an alternating signal to a plurality of different circuits in the integrated circuit, and measuring a signal corresponding to the alternating signal, which is output from each of the circuits.

Abstract: Methods for establishing the complex measuring capability of homodyne operating network analyzers. Single port as well as two-port measuring devices are treated in which the signal detection takes place by means of a linear mixing process. It is possible to overcome the disadvantage of the homodyne detection process, which does not directly supply information relating to the amplitude and phase of the measurement signal, by measuring arbitrary unknown standards. The required number of different unknown standards depends, among other things, on the complexity of the measuring device used. One of the proposed methods operates without any standards at all. After weighting factors have been determined, complex measuring values can be ascertained and one can then proceed as in the case of a heterodyne network analyzer, i.e. with system error calibration measurements and finally with DUT (device under test) measurements.

Abstract: Display section displays, on a screen, a zone marker for indicating, on a wide-band spectrum display area, that part of a wide-band spectrum which corresponds to a selected narrow-band spectrum to be displayed, and the wide-band spectrum, as well as said narrow-band spectrum which has been enlarged. First setting section changes a center frequency or a band width of said displayed narrow-band spectrum, in accordance with the change of the position or width of the zone marker. Second setting section cooperating with the first setting section changes the position or width of the zone marker in accordance with the movement of the center frequency or band width of the displayed narrow-band spectrum. Control section for controlling a measurement resolution and a sweep time in accordance with the magnitude of the displayed spectrum, so as to satisfy the formula:sweep time.gtoreq.band width/(measurement resolution).sup.2 .multidot.Kwhere K=a constant.

Abstract: A low cost and portable scalar network analyzer for the simultaneous measurement of forward and reflected scalar scattering parameters of devices under test. Plural UHF oscillators of similar construction are mixed to produce a wideband test instrument having good stability characteristics. A dual-diode biased RF detector with feedback, including an in-loop adjustable gain buffer stage, provides enhanced linearity, over a wide dynamic range, and at low cost. The forward transfer parameter measurement arrangement further includes a selectable attenuation/gain PIN-diode switched stage to accommodate the widely varying gain/attenuation characteristics of devices under test.

Abstract: A vector network analyzer comprising a circuit for measuring the real and imaginary components of the central spectral line in an RF pulse from a device-under-test is provided. The circuit comprises a modulator in response to a profiling pulse for modulating the amplitude of the RF pulse, mixers for down-converting the frequency of the amplitude modulated RF pulse, a narrow band filter for filtering the RF pulse having a bandwidth of 500 Hz and a synchronous detector responsive to the output of the crystal filter for providing a pair of dc outputs, which correspond to the real and imaginary components of the output of the device under test as the profiling pulse is shifted in time relative to the RF pulse.

Abstract: A method for correcting inaccuracies in error factors of an error model used for vector-corrected, microwave-frequency measurements. Verifying de-embedded measurements are compared to known characteristics of at least one verification standard. At least one parameter of the calibration standards, or an error factor, or measuring network geometry, is changed and the error factors are recalculated to bring the verifying measurements into conformity with the known characteristics of the verification standard.

Abstract: For calibrating a network analyzer, calibration measurements are successively performed in any desired order on three different calibration standards connected between the two test ports; the first calibration standard is a two-port circuit all of whose complex scatter parameters are known and which is, for example, implemented by a direct connection of the two test ports; the second calibration standard is an attenuator of random transmission but known reflection; the third calibration standard preferably is a two-port circuit exhibiting random reflection which, however, is equal on both sides and different from the reflection of the second calibration standard.

Abstract: A test set for use in measuring S-parameters with a network analyzer includes a first directional bridge, a second directional bridge and a single balun with two outputs mounted in an RF housing. A test signal from an RF signal source is transmitted through the test set to a device under test. The first directional bridge separates a signal from the device under test and the test signal, and provides the signal from the device under test to a coupled port. The second directional bridge separates the test signal and the signal from the device under test and provides the test signal to a reference port. The balun includes a coaxial transmission line with its outer conductor grounded at an intermediate location to define first and second balun sections. Ferrite beads are mounted on each of the balun sections. The ends of the first and second balun sections are coupled to the first and second directional bridges, respectively.

Abstract: A method and apparatus for monitoring two components of an object, such as moisture content and density in a tobacco rod, using scattered electromagnetic radiation are provided. The invention relies on the fact that both the real imaginary parts of the dielectric constant of water vary greatly over frequencies in the gigahertz region while those of the remaining constitutents of tobacco do not, and particularly on the fact that, at frequencies approaching 100 GHz, the real part of the dielectric constant of water is much closer to that of many organic polymers, such as those making up tobacco, than it is at lower frequencies, and the imaginary part of the dielectric constant of water is much lower at frequencies approaching 100 GHz than it is in the region of 20 to 30 GHz. By comparing the scattering of electromagnetic radiation by the object--i.e.