Abstract: An apparatus for collecting RF signal measurement data at signal ports of an RF and microwave device-under-test (DUT). The apparatus comprises means for measuring incident and reflected RF signals at the signal ports of the DUT. Synthesizer means for generating RF signals at a fundamental frequency and higher harmonics. Tuner means arranged for loading the DUT under different impedance conditions for the fundamental frequency and higher harmonics, and means for feeding the RF signals of the synthesizer means to the signal ports of the DUT. The apparatus may form part of a Non-linear Network Measurement System (NNMS).

Abstract: A plasma processing system including a plasma chamber (120) having a substrate holder (128) and a monitoring system (130). The monitoring system (130) includes a microwave mirror (140) having a concave surface (142) located opposite the holder (128) and a power source (160) is coupled thereto that produces a microwave signal perpendicular to a wafer plane (129) of the holder (128). A detector (170) is coupled to the mirror (140) and measures a vacuum resonance voltage of the signal within the chamber (120). A control system (180) is provided that measures a first voltage during a vacuum condition and a second voltage during a plasma condition and determines an electron density from a difference between the second voltage and the first voltage. The processing system (110) can include a plurality of monitoring systems (130a, 130b, 130c) having mirrors (140a, 140b, 140c) provided in a spatial array located opposite the substrate holder (128).

Abstract: A method, apparatus and article of manufacture to aid in the characterization of a device establishes a device S-parameter matrix (SD) to represent electrical behavior of the device, an adapter T-parameter matrix (Ta) to represent all possible electrical paths through circuits to all device ports of the device, and a cascaded S-parameter matrix (Sc) to represent the circuits cascaded with the device. Values for the adapter T-parameter matrix are obtained either through measurement or modeling. The device cascaded with the circuits is measured to obtain values for the cascaded S-parameter matrix, permitting use of a general solution for the device S-parameter matrix as a function of the adapter T-parameter matrix and the cascaded S-parameter matrix.

Abstract: A method, apparatus and article of manufacture to aid in the characterization of a device establishes a device S-parameter matrix (SD) to represent electrical behavior of the device, an adapter T-parameter matrix (Ta) to represent all possible electrical paths through circuits to all device ports of the device, and a cascaded S-parameter matrix (Sc) to represent the circuits cascaded with the device. Values for the adapter T-parameter matrix are obtained either through measurement or modeling. The device cascaded with the circuits is measured to obtain values for the cascaded S-parameter matrix, permitting use of a general solution for the device S-parameter matrix as a function of the adapter T-parameter matrix and the cascaded S-parameter matrix.

Abstract: An instrument is provided for measuring a noise figure with significant flexibility. The instrument includes a noise source (306) and a vector network analyzer (VNA) (300). The VNA (300) includes an external connector port (302) for removable connection of the noise source (306). The noise source (306) can be connected to the VNA backplane port (302), or directly to a DUT (350). The DUT (350) can be connected to both VNA test ports (310,314) if the noise source (306) is connected to port (302), or only to test port (314) if the noise source (306) is directly connected to the DUT. A receiver connected to the test port (314) includes a downconverter (324) providing an IF signal through either a narrowband IF channel (350) or a wideband IF channel (352) for providing both wideband and narrowband power measurements enabling fast accurate measurement of a noise figure.

Abstract: A tunable ferroelectric component and a narrowband resonant circuit for measuring the loss of the ferroelectric component. The ferroelectric component may be a capacitor integrated in the resonant circuit. The testing method eliminates other sources of loss to isolate the loss due to the ferroelectric material and to demonstrate that this loss is low.

Abstract: A tuner (10) for a reverberation chamber is provided comprising a plurality of electrically conductive surfaces (12) attached to each other in a Z-fold configuration. Each lateral edge (15) of the tuner is contacted with a generally planar, laterally positioned substrate (16) which prevents lateral extension or medial compression of the Z-fold. Optionally, end substrates (18) are attached to each of the two leading edges (17). Also, a device minimizes electromagnetic radiation leakage along a shaft including: a bearing housing; a plurality of thrust bearings contacting the bearing housing and axially juxtaposed along the shaft so that at least two thrust bearings oppose each other; a radial bearing intermediate each thrust bearing; and a provision for adjustably moving the thrust bearings toward each other so as to compress the thrust bearings against the bearing housing.

Abstract: A probe for non-destructive determination of complex permittivity of a material and for near field optical microscopy is based on a balanced multi-conductor transmission line structure created on a dielectric substrate member which confines the probing field within a sharply defined sampling volume in the material under study.

Abstract: The present invention is an adaptable pre-matched tuner system and calibration method for measuring reflection factors above &Ggr;=0.85 for a DUT. The system includes a first and second large-band microwave tuners connected in series, the first and second large-band tuners being mechanically and electronically integrated; and a controller for controlling the two large-band tuners. The first tuner is adapted to act as a pre-matching tuner and the second tuner is adapted to investigate an area of a Smith Chart that is difficult to characterise with a single tuner, so that the combination of the first and second large-band tuners permits the measurement of reflection factors above &Ggr;=0.85. The pre-matched tuner system allows the generation of a very high reflection factor at any point of the reflection factor plane (Smith Chart).

Abstract: Methods are provided for virtually embedding and/or de-embedding balanced four-port networks into/from a device under test (DUT). For the methods, a set of scattering-parameters is acquired for the DUT. Additionally, a respective set of scatter-parameters is acquired for each of the balanced four-port networks to be embedded and/or de-embedded. A transfer-matrix is generating for the DUT based on its scattering parameters. Further, a respective transfer-matrix is generated for each of the networks to be embedded/de-embedded based on its respective set of scattering-parameters. The transfer-matrix for the DUT is then multiplied with the one or more transfer-matrices associated with the balanced four-port networks to be embedded and/or by an inverse of the transfer-matrices associated with the balanced four-port networks to be de-embedded. A composite transfer-matrix is thereby produced. Finally, a set of composite scattering-parameters is then generated based on the composite transfer-matrix.

Abstract: A method and apparatus for characterizing a device under test (“DUT”) calibrates a multiport test set and measures S-parameters [S] of the DUT. The method and apparatus further involves determining elements of a scalar orthogonal matrix [M] corresponding to terminals of the DUT and DUT modes of operation. The scalar orthogonal matrix [M] comprises a row of elements representing a single-ended terminal of the DUT, and four rows of elements representing a balanced terminal of the DUT. The S-parameters of the DUT are then transformed into mixed-mode S-parameters [Smm] according to Smm=MSM−1. A method of and apparatus for characterizing a DUT involves calibrating a multiport test set, coupling the DUT to the multiport test set, and measuring S-parameters of the DUT. The S-parameters are converted to a time domain representation and at least one of the S-parameters is convolved with a simulated input signal to generate an output response.

Abstract: Methods are provided for characterizing N interface devices (e.g., adapters or test fixture arms) using a vector network analyzer (VNA). These N interface devices are useful for connecting an N-port device under test (DUT) to the VNA. A first step of includes performing an N-port calibration at each of N outer reference planes. A second step includes performing an N-port calibration at each of N inner reference planes. A set of scattering-parameters (S-parameters) is then determined for each of the N interface devices based on results of the calibrations performed at the first step and results of the calibrations performed at the second step. Each set of S-parameters characterizes a respective one of the N interface devices.

Abstract: A method for correcting reciprocity error in two port network measurements, in which an iterative algorithm is used to obtain an optimal symmetric matrix approximation to a measured 2×2 reciprocal network. The algorithm smooths measured data to obtain a low noise floor on measurements related to mode conversion in cables and connecting hardware. A geometric interpretation is used to approximate a measured data vector with the closest vector which satisfies the reciprocity constraint. An initial point in the constraint surface (reciprocity manifold) is located, and another point which is a better approximation of the measured data vector which satisfies the reciprocity constraint is generated. By repeating this process, the closest point in the manifold is quickly located. This closest point defines a reciprocal matrix which can be used to estimate the actual device under test (DUT) parameters.

Abstract: According to one embodiment of the invention, there is provided a method of calibrating an N-port multiport test system for measurement of a DUT. The method consists of coupling each port of an N-port automatic calibration device to a respective port of the N-port multiport test system, and presenting three reflection standards with the automatic calibration device to each port of the N-port multiport test system. The method also consists of providing with the automatic calibration device, N−1 through conditions of a possible N(N−1)/2 possible through conditions, between corresponding ports of the N-port multiport test system, and making measurements with the N-port multiport test system of the three reflection standards at each port and the N−1 through conditions between the corresponding ports. The method further consists of determining all of systematic error coefficients for all of the ports of N-port multiport test system.

Abstract: A probe for non-destructive determination of complex permittivity of a material and for near field optical microscopy is based on a balanced multi-conductor transmission line structure created on a dielectric substrate member which confines the probing field within a sharply defined sampling volume in the material under study. A method for manufacturing dielectric support member based probes includes anisotropically depositing a 50-100 Å thick underlayer of Cr, Ni, W or Ta onto the dielectric support member, anisotropically depositing conductive material onto the Cr, Ni, W or Ta underlayer, and removing the unwanted conductive material at the sides of the dielectric support member to electrically isolate the created conductive strips.

Abstract: An apparatus for localized measurements of complex permittivity of a material is provided. A probe (10) analyzes the complex permittivity of a sample (11), the probe (10) having a balanced two conductor transmission line (12) formed of conductive segments (13 and 14). A probing end (15) of the transmission line (12) is brought within close proximity of sample (11) and an opposite end (16) of the transmission line is connected to a terminating plate (17) to form a resonator structure (18) for measurement of the complex permittivity of sample (11).

Abstract: A circuit analyzing device comprises a wiring model information extracting section for generating wiring model information for each wiring of a circuit, a circuit simulation section for analyzing waveform propagation characteristics of each wiring model information that has been extracted by the wiring model information extracting section, a spectrum characteristic information calculating section, a linear simulation section, and an S parameter information calculating section.

Abstract: A parameter extraction technique for an electrical structure is based on a definition of network parameters that isolates pure mode responses of the electrical structure, and that makes mode conversion responses of the electrical structure negligible. A set of network parameters is obtained that represents pure mode responses for the electrical structure (410). These network parameters are processed to obtain model parameters that characterize each pure mode response (422, 424, 426, 428, 432, 434, 436, 438). Preferably, the mode specific parameters to combined to obtain mode independent parameters, such as coupling factor, propagation constant, and characteristic impedance values (440, 450).

Abstract: A probe for non-destructive determination of complex permittivity of a material and for near field optical microscopy is based on a balanced multi-conductor transmission line structure created on a dielectric substrate member which confines the probing field within a sharply defined sampling volume in the material under study. A method for manufacturing dielectric support member based probes includes anisotropically depositing a 50-100 Å thick underlayer of Cr, Ni, W or Ta onto the dielectric support member, anisotropically depositing conductive material onto the Cr, Ni, W or Ta underlayer, and removing the unwanted conductive material at the sides of the dielectric support member to electrically isolate the created conductive strips.

Abstract: The electromagnetic wave generating source searching method includes the steps of calculating a first electric field strength at a measuring point based upon a current distribution owned by an object to be measured; calculating a second electric field strength at said measuring point by employing such a current distribution at a preselected position on said measuring object, which corresponds to a portion of the current distribution of said measuring object; and calculating a relative ratio of said first electric field strength with respect to said second electric field strength, thereby judging a source for generating a remote electric field.

Abstract: The electromagnetic wave generating source searching method includes the steps of calculating a first electric field strength at a measuring point based upon a current distribution owned by an object to be measured; calculating a second electric field strength at said measuring point by employing such a current distribution at a preselected position on said measuring object, which corresponds to a portion of the current distribution of said measuring object; and calculating a relative ratio of said first electric field strength with respect to said second electric field strength, thereby judging a source for generating a remote electric field.

Abstract: A method and apparatus for measuring complex permittivity of dielectric materials in solid, liquid, or gas form. The apparatus is includes a TEM or quasi-TEM transmission line test fixture, which contains the dielectric material under test, a set of unique reflective load assemblies for inducing reflections in the fixture, an analyzer that measures magnitude and phase, a custom calibration kit, and a computer with computational software. The method begins by sequentially placing the set of load assemblies at the input of the analyzer. One port s-parameters are then obtained. Next, the set of load assemblies is sequentially placed at one end of the test fixture while the other end of the fixture is placed at the input of the analyzer and one port s-parameters are then obtained. Connectors are coupled to both ends of the fixture. A computer then executes a program to solve a set of equations constructed from the s-parameter data for computing input reflection coefficients.

Abstract: A fully differential analogue circuit is tested by monitoring the currents in two branches when a common mode signal is applied and indicating correct operation if the two currents are correlated. A part of the circuit (T20,T21,S1,S2,S3,S4) is modified during test and currents through transistors (T20,T21) are monitored by means of a current mirror and current subtractor arrangement (T213,T214,T215,T216). A voltage (VRL) is produced that, with correlation of the currents, will be approximately mid way between the power supply rails and when mis-correlation occurs will tend to one of the supply rails. The voltage (VRL) is applied to a first amplifier (T219,T221) and to a second amplifier (T222,T223) having a different threshold value from the first amplifier. The outputs of the amplifiers will have opposite logic values if the voltage (VRL) lies between their threshold voltages and the EXOR gate 9 will give a logic 1 output indicating proper circuit function.

Abstract: A non-invasive method to detect vascularization associated with one or more malignant tumors in living tissue of a living organism, where dielectric properties of the vascularization are different than dielectric properties of normal living tissue. In one embodiment, a non-ionizing input wave within a wide band frequency range is generated, and the input wave is applied to a field excitation antenna to illuminate a discrete volume within the living tissue of the living organism and to develop scattered power returns from the discrete volume. A receiving antenna then collects at least a portion of the scattered power returns. The scattered power returns are detected and then applied to a signal processor to develop a segregated signal, which is then processed in order to identify the vascularization associated with one or more malignant tumors.

Abstract: A multi-port device analysis apparatus is capable of analyzing a multi-port device having three or more with improved efficiency and accuracy.

Abstract: Method and apparatus to determine scattering coefficients for a device under test (DUT) using a vector network analyzer (VNA) is disclosed. Traditionally, for a DUT having P ports, all combinations of reflective and transmission coefficients are measured and calculated. This is true even for reciprocal devices where SijA=SjiA because, during the measurement, the source and load matches vary. However, the present invention teaches that, for reciprocal devices, only one of the two transmission coefficients between a first port and a second port need be measured. Under the inventive technique, error terms are removed from the measured scattering coefficients. Then, the source and the load matches may be normalized to a normalization match value. The normalization process removes the differences of the source and the load matches.

Abstract: A system and method of calibrating an S parameter measurement instrument (such as a vector network analyzer) in which the number of calibrations required to fully characterize the error model of an n-port system is n/2 calibrations for an even number of ports and (n+1)/2 calibrations for an odd number of ports. Each test port in the system is involved in at least one full calibration, thus n/2 test paths are fully calibrated. For each measured test path, the error terms of the applicable error model are calculated. These error terms are then decoupled from the associated test path into error parameters that are localized to the individual test ports of the test path. Having localized the error parameters, the error model for each test port can then be treated independently from the other test ports. The error terms for the test paths that are not calibrated are then constructed using the localized error parameters for the individual test ports.

Abstract: An automatic test system for microwave components. The test system includes internally switchable calibration references. As part of a calibration routine, incident power from a source is measured. During the measurement, calibration references are switched to change the amount of power reflected back to the source. Changes in the incident power are measured continuously while this change occurs. The resulting measurements allow the source match term to be determined. Correction is made to the source amplitude to adjust for the source match.

Abstract: A self calibrating method and apparatus for measuring butterfat and protein content based on measuring the microwave absorption of a sample of milk at several microwave frequencies. A microwave energy source injects microwave energy into the resonant cavity for absorption and reflection by the sample undergoing evaluation. A sample tube is centrally located in the resonant cavity passing therethrough and exposing the sample to the microwave energy. A portion of the energy is absorbed by the sample while another portion of the microwave energy is reflected back to an evaluation device such as a network analyzer. The frequency at which the reflected radiation is at a minimum within the cavity is combined with the scatter coefficient S.sub.11 as well as a phase change to calculate the butterfat content in the sample. The protein located within the sample may also be calculated in a likewise manner using the frequency, S.sub.11 and phase variables.

Abstract: A measuring method for equivalent circuitry is disclosed herein to characterize the interconnects using time-domain reflectometry measurement. By combining the layer peeling algorithm for transmission lines and the matrix-pencil approach for discontinuities, the technique yields a simple equivalent circuit model which consists of distributed transmission lines and networks of lumped elements. With element values being independent of frequency, the model is well suited to model nonlinear broadband circuit simulation for electrical performance of the interconnects.

Abstract: Method and apparatus for three-phase fluid flow measurement that operates reliably and accurately over a wide range of gas cut. The system uses a fluid conditioner to separate the three-phase fluid flow into a liquid rich component and a gas rich component. The gas flow rate of the gas rich component is controlled by a valve to maintain the gas cut at a predetermined level. The valve is responsive to control signals generated by a measurement apparatus that measures oil, gas, and water cuts. The system configuration includes a pipeline for carrying the liquid rich component, a gas line for carrying the gas rich component, and a measurement line in parallel with the pipeline.

Abstract: A parameter extraction technique for an electrical structure is based on a definition of network parameters that isolates pure mode responses of the electrical structure, and that makes mode conversion responses of the electrical structure negligible. A set of network parameters is obtained that represents pure mode responses for the electrical structure (410). These network parameters are processed to obtain model parameters that characterize each pure mode response (422, 424, 426, 428, 432, 434, 436, 438). Preferably, the mode specific parameters to combined to obtain mode independent parameters, such as coupling factor, propagation constant, and characteristic impedance values (440, 450).

Abstract: The present invention relates to a calibration method for step attenuator that is utilized in wide-band RF instruments, wherein the step attenuator comprises a plurality of single-stage attenuators connected in series. Use of the method disclosed in this invention allows one to obtain attenuation of the attenuator under various circumstances by computing measurements of single-stage attenuation. As opposed to the conventional calibration method, this invention is advantageous in reducing time for taking measurements, in elevating total attenuation of the object to be tested, and in simplifying the method of calibration and testing.

Abstract: In a network analyzer having one or two test ports each of which is connected via fourports to measuring points the measured values of which are analyzed in an evaluation means that includes a memory for storing system errors which have been determined during a calibration operation and must be taken into account for the object measurement, there is provided a calibration twoport between at least one of said test ports and said fourport of the associated measuring points, said calibration twoport being adapted to be switched from a basic state to two further switching states, and said calibration twoport differs in one of said further switching states from the basic switching state at least in transmission and in the other one of said further switching states differs at least in reflection from the basic switching state.

Abstract: A system for and method of electromagnetically detecting an embedded dielectric region within a target object are provided. The method includes the steps of: (i) selecting a target object including a plurality of discrete scattering mediums, wherein the plurality of discrete scattering mediums include the embedded dielectric region and an adjacent dielectric region, and wherein the plurality of discrete scattering mediums define at least one dielectric interface between the embedded dielectric region and the adjacent dielectric region; (ii) directing electromagnetic radiation at the target object, wherein the electromagnetic radiation is characterized by a diagnostic frequency that is varied incrementally over a diagnostic frequency band; (iii) detecting electromagnetic radiation reflected by the target object over the predetermined frequency band such that there are M measurements of a reflected electromagnetic signal at frequencies f.sub.1, f.sub.2, . . . , f.sub.

Abstract: An error correction method improves measurement accuracy of a vector network analyzer by reducing reflection measurement errors for a broad class of devices, such as filters, switches, cables, couplers, attenuators, and other passive devices tested by vector network analyzers (VNAs) that are reciprocal, having a forward transmission coefficient S.sub.21 and a reverse transmission coefficient S.sub.12 that are equal. Errors due to impedance mismatches at the load port of a transmission/reflection (T/R) test set are corrected without impacting the measurement speed of the VNA. The source port of the T/R test set is calibrated and a reflection measurement is performed while an impedance matched thruline standard of known electrical length is coupled between the source port and load port of the T/R test set. The reflection measurement is corrected for the electrical length of the thruline standard to obtain a reflection measurement of the load port of the T/R test set.

Abstract: A variable termination load switch (102) is provided to enable transmission and group delay measurements to be made of a device under test (DUT) (103) using only one port of a vector network analyzer (VNA) (100). The variable termination load switch (102) selectively provides an open or a short based upon a signal provided to its control input (106). The variable termination load switch (102) has a load port (113) for connecting to one port of the DUT and the VNA port is connected to another port of the DUT during testing. The variable termination load switch (102) includes a diode (143) connected by a resistor (149) to the control input (106). The diode (143) has connected parallel transistors (141, 142) and a series transistor (140) to provide a load impedance matching the DUT impedance when the load is functioning either as a short or an open. Isolation capacitors (145) and (146) reduce the affect of AC signals from the control input (106).

Abstract: A measurement method adjusts the IF bandwidth of a network analyzer to increase measurement speed for high dynamic range devices. According to the first preferred embodiment of the present invention, the bandwidth of the IF filter is adjusted for each corresponding measurement sweep of the network analyzer. The forward transmission and reflection characteristics of the device under test are measured using a first IF bandwidth, and the reverse transmission and reflection characteristics of the device are measured using a second IF bandwidth. When high measurement sensitivity of the forward transmission parameter of the high dynamic range device is sought, the first IF bandwidth is selected to be narrower than the second IF bandwidth. When high measurement sensitivity of the reverse transmission parameter of the high dynamic range device is sought, the first IF bandwidth is selected to be wider than the second IF bandwidth.

Abstract: A vector network analyzer (VNA) has a first harmonic generator multiplying an RF signal by an odd number M1 to produce incident and reflected test signals received at inputs of mixers providing IF signals. A second harmonic generator multiplies an LO signal by an odd number M2 offset by 2 from M1 to provide signals to additional inputs of the mixers providing IF signals. With the harmonic generators providing odd harmonics separated by 2, a single filter removes remaining harmonics from IF signals provided from each mixer. Each harmonic generator includes two step recovery diodes (SRDs) with opposing ends connecting the signal path to ground, the SRDs functioning to cancel even harmonics. A first coupler provides the output of the first harmonic generator to the mixers, the first coupler having a minimal size enabling its output power to increase with frequency.

Abstract: A method and system for detecting an incipient tumor in living tissue such as that of a human breast in accordance with differences in relative dielectric characteristics. A generator produces a non-ionizing electromagnetic input wave of preselected frequency, usually exceeding three gigahertz, and that input wave is used to irradiate the living tissue, being effectively focused into a minute, discrete volume within the tissue to develop a non-ionizing electromagnetic wave at that position. The illumination location is shifted over a portion of the living tissue in a predetermined scanning pattern. Backscatter signal returns from the living tissue are collected to develop a backscatter return signal wave.

Abstract: A method for updating automatic calibration to provide a perfect through connection during the calibration of the VNA. After the VNA is initially calibrated, a user may assess the calibration of the through connection to determine if the quality is sufficient. If the quality is insufficient, the user is able to replace the calibration parameters for the through connection used during initial calibration with parameters for a currently used through connection to create a perceived "perfect" through connection calibration.

Abstract: A calibration standard (204) provides interconnection between measurement ports (212, 214, 216) of a network analyzer (202) having at least three measurement ports. Once the measurement ports (212, 214, 216) of the network analyzer (202) are interconnected, a non-zero signal transfer is generated between each of the measurement ports and at least one other measurement port as part of the calibration process. Interconnecting all of the measurement ports (212, 214, 216) together and generating non-zero signal transfers characterizes the relative relationship between the ports during the calibration process. The calibration standard (204) can also provide a desired level of mode conversion.

Abstract: A computer-aided method and system are provided for obtaining a measurement of the capacitance value of a device under test (DUT). The complex impedance of a device under test (DUT) is measured at two nearby frequencies using an RLC meter. The two complex impedance values are then stored in a computer readable medium. The DUT is modeled by a programmed computer as a four element RLC model circuit including a resistor and inductor in series with a parallel RC circuit having a single capacitor which represents the capacitance of the DUT. Four equations which describe the electrical characteristics of the four element RLC model circuit are stored in a computer readable medium. The four measured values of complex impedance are substituted by the computer into the four stored equations. Values are obtained for the four individual RLC circuit elements by solving the four equations. The four unknown values are obtained by use of an optimization routine and then stored to a computer readable medium.

Abstract: An apparatus for characterizing transmission coefficient and group delay for a bi-directional two port device under test (DUT) using only one port of a measurement device, such as a vector network analyzer (VNA). The apparatus in one embodiment includes a programmable switch for coupling to one DUT port to selectively provide an open or a short. The measurement device is controlled to measure a reflection coefficient with the open at the DUT port and another reflection coefficient with a short at the DUT port. The measurement device then calculates a transmission coefficient magnitude value and a transmission coefficient phase angle for the DUT using the open reflection coefficient and the short reflection coefficient measurements. Group delay can then also be calculated using phase angle measurements at different frequencies.

Abstract: A lubricating/hydraulic fluid condition monitor in which a coaxial microwave resonator is placed in a fluid conduit to determine changes in the chemical properties and debris concentration is disclosed. Microwave radiation is applied to the resonator for measuring the resonant frequency and resonator Q. An externally powered electric or magnetic field is used to alternately align and misalign debris in the fluid while the resonator properties are being measured. A logic unit automatically generates tables of resonant frequency and Q versus resonator mode and external field strength. This set of tables constitutes a fingerprint of the fluid condition. By matching the fingerprint against a set of fingerprints taken under known conditions, the condition of the fluid is determined.

Abstract: An apparatus (310) for characterizing a multiport circuit (390) includes a signal generator (320) and a circuit interface apparatus (330, 340, 350). The signal generator (320) has an output (329) selectable from among a set of composite signals that are linearly independent. The circuit interface apparatus (330, 340, 350) is coupled to the signal generator (320) and has an output (319) of a set of circuit stimulus signals derived from the set of composite signals, which set of circuit stimulus signals are linearly independent, and which together form a complete basis for describing any response for the multiport circuit (390). The circuit interface apparatus (330, 340, 350) has measurement circuitry for measuring circuit response of the multiport circuit (390). Preferably, the circuit interface apparatus (330, 340, 350) is formed from multiple two-port test sets.

Abstract: An error correction method reduces transmission measurement errors and improves measurement accuracy of vector network analyzers. A reflection measurement made using a thruline standard connected between a source port and load port of a transmission/reflection (T/R) test set characterizes the impedance match of the load port while a reflection calibration characterizes the source port. The source port characterization and the load port characterization are then processed to correct a transmission tracking error in subsequent transmission measurements made on a device under test (DUT), without impacting the measurement speed of the VNA. A reflection measurement made with the DUT connected between the source and load port provides a measurement of the DUT's input reflection coefficient, including the effect of the impedance mismatch of the load port. This reflection measurement and the source port characterization are processed to correct a DUT input mismatch error.

Abstract: A calibration technique (200) uses a set of calibration standards to solve for unknown network parameters of calibration standards as well as error correction terms. A set of standards provides an over-determined system of calibration equations having more calibration equations than unknown error terms (202). The additional calibration equations are used to solve for the unknown network parameters of the calibration standards (210). Once solved, the network parameters of the calibration standards provide a more accurate determination of error terms for a network analyzer (214).

Abstract: In a method for calibrating a network analyzer having two test ports and at least four measuring locations according to the fifteen-term principle, correction values that are taken into consideration in the following subject measurements are calculated by successive measurement of the transmission and reflection parameters at five calibration standards that are successively connected in arbitrary sequence between the two test ports. A one-port network having a known impedance or open circuit is used as a calibration standard for the first calibration measurement. It is being successively connected to the two test ports (MM or OO double one-port network calibration) and four calibration standards are used for the other four calibration methods. Only eleven of the total of sixteen scatter parameters of these four calibration standards are known, whereas the remaining, five unknown scatter parameters are subsequently calculated from the total of measured values.

Abstract: The purpose of a through calibration is to correct errors in transmission coefficients in both the forward and reverse directions between two measurement ports of a circuit network measurement device having many ports. If there are N measurement ports, error corrections of the transmission coefficients are necessary for all combinations of two measurement ports selected from N ports. The calibration method of this invention is one in which the calibration measurements are performed with n combinations, rather than all combinations, and calibration values for all combinations are obtained by calculation. The n combinations and their measurements may be performed by any combination that satisfies the following conditions: (A) there are triangular combinations of connected ports; (B) all of the other combinations of ports are linked with the triangular combination; and (C) in one combination among the triangular combinations, a measurement of the transmission coefficient in only one direction is sufficient.