Abstract: A universal electromagnetic resonance system is aimed at detecting and measuring local non-uniformities in objects made from conductive or non-conductive materials. The system comprises a composite measuring unit composed of two identical and symmetrically arranged individual oscillation circuits with measurement elements in the form of identical and symmetrically arranged inductive coils or capacitor chips. The unit is connected to an impedance analyzer for supplying RF current and for measuring the voltage signal in the oscillation circuit. Since all the elements of individual oscillation circuits are identical, in the case of non-uniformity of the object on the scanned area, the parameters of the resonance will hanged. This change will violate the symmetry in the operation of the individual oscillation circuits. The variation in measured signal can be calibrated in terms of the target parameter or characteristic of the object.

Abstract: A method and a device for analyzing a sensor device, in which the sensor device forms an electric resonator in an oscillating circuit energized with an external energization voltage. The current in the oscillating circuit is detected in the range of the resonant frequency, and then the current thus detected is multiplied by the external excitation voltage. Finally, the signal obtained by this multiplication is averaged.

Abstract: A resonator device for testing a material quantity in the tobacco-processing industry for existence of at least one foreign substance and/or for detecting at least one of weight, density and humidity level of the material includes a resonator housing having a through opening for the material to pass through and a testing region located inside the resonator housing to which the material can be moved at least in part. The device has at least one element that increases energy density of electromagnetic waves for increasing the energy density in at least a portion of the testing region.

Abstract: In one embodiment, a radio frequency (RF) configuration in a plasma processing system includes an RF electrode driven by an RF signal source and a non-RF electrode coupled to an electronic module. A filter coupled to the non-RF electrode is configured to provide maximum attenuation at or near an RF signal frequency, while allowing signals associated with the electronic module to pass. The filter may be placed as close to the non-RF electrode as possible. The filter may be, for example, a band stop filter such as a parallel resonant circuit having a resonant frequency at or near an RF signal frequency.

Abstract: Soot content in Diesel engine lubrication oil is determined using electrical resistance measurements of the oil at high frequency. A sensor in the form of a capacitor is immersed in the oil, wherein the oil serves as a dielectric between the plates. The capacitance and resistance between the plates change as a function of engine oil condition. An inductor is placed in series with the sensor, and high frequencies are sweeped over a range to find resonance where the capacitive and inductive reactances cancel. At this frequency, the resistance of the oil is measured and the condition of the oil thereby determined.

Abstract: In the method and system for non-contact measurements of microwave capacitance of test structures patterned on wafers used for production of modern integrated circuits, a near-field balanced two-conductor probe is brought into close proximity to a test structure, and the resonant frequency of the probe for the test structure is measured. The probe is then positioned at the same distance from the uniform metallic pad, and the resonance frequency of the probe for the uniform metallic pad is measured. A shear force distance control mechanism maintains the distance between the tip of the probe and the metallic pad equal to the distance between the tip of the probe and the test structure. The microwave capacitance of the test structure is then calculated in accordance with a predefined formula. The obtained microwave capacitance may be further used for determining possible defects of the test structure.

Abstract: A non-contact probe for determining the conductivity of coating materials is disclosed. The probe includes a free running oscillator operating at a selected frequency, a sensor made up of an LC circuit, a detector for detecting a change in the LC circuit in response to change in the sensor coil induction, and a processor for converting the detected changes in the signal to surface conductivity data. The detector may be a frequency detector that detects changes in the resonant frequency of the LC circuit or the detector may be a magnitude detector that detects changes in the signal magnitude of the LC oscillator. The sensor is the coil inductor of the LC circuit. Inductance of the sensor coil is variable depending on conductivity of the material near the sensor coil.

Abstract: A resonant sensor for determining structural property changes, in particular for detecting the presence of chemical or biological species, comprises a structure (2) mounted to be capable of resonating and having a cyclically symmetrical configuration with two independent degenerative modes of vibration of a common natural frequency (f), and means (24,26,28,30,32,34,36,38) for exciting the structure (2) to resonate according to the two degenerative modes, regions (8,12,16,20) of the structure (2) being modified such that, on changes in the structural properties of the modified regions (8,12,16,20), for example by the addition or subtraction of mass, the natural frequencies (f1, f2) of the two modes of vibration become different, the difference in frequencies (?f) being proportional to the change in structural properties.

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: The device for testing the quality of rope-like materials in the form of yarns, rollings, fiber bands and the like by means of a measuring device which has a microwave resonator and devices for determining the displacement of the resonant frequency and the widening of the resonance curve due to the rope-like material and mechanical devices for transporting the rope-like materials through the measuring volume of the microwave resonator is distinguished by the fact that the microwave field is homogeneous in the measuring volume and that the measuring device is a microwave generator which is constructed for measuring the mass per length and the moisture of the rope-like materials.

Abstract: A method for measuring a material's complex permittivity is provided where a near-field microwave probe is positioned a predetermined distance from a first and a second standard sample for measuring a relative resonant frequency shift of the near-field microwave probe for standard samples. Based on measurements, calibration coefficients are calculated. A relative resonant frequency shift of the near-field microwave probe for a sample under study is measured by fast frequency sweep technique while the distance between the tip of the probe and the sample under the study is maintained nominally at the distance between the tip of the probe and each standard sample during a calibration procedure by a shear-force based distance control mechanism. Also, the change in the quality factor of the probe for unloaded and loaded resonator is measured.

Abstract: The effects of electromigration have been shown to lead to damage of metal electrodes of electronic devices such as thin film resonator (TFR) devices in only a few hours, for a test input power that is within the operational range of these devices. It has been determined that this failure is sensitive to the frequency of the input power. The present invention provides a method and apparatus for determining high power reliability in electronic devices, so as to enable an accurate determination of the failure time of the electronic device, and hence projected lifetime. This determination is independent from the frequency of an input power applied to the electronic device as part of the method for testing the device. Based on the above results, a TFR device has been developed, which includes a protective or electromigration-reducing layer such as titanium being deposited atop an electrode of the device.

Abstract: A method and apparatus for measurement of mass of small sample sizes. The method and apparatus is particularly adapted for providing microbalance measurement of solid materials as part of a combinatorial research program. The method and apparatus contemplate monitoring the response of a resonator holding a sample and correlating the response with mass change in the samples.

Abstract: Systems, methods, and probe devices for electronic monitoring and characterization using absorbent media confined by a metallic mesh. The mesh allows a stream of liquid or gas to pass through the structure, so that the media will adsorb the material to which it is specific. This changes the permittivity of the media in which the electromagnetic field is propagating. This change in permittivity can be seen through the use of classical microwave methods such as phase shift, amplitude changes, frequency changes in a cavity or the frequency of an unbuffered oscillator. Some embodiments use a two cylinder structure, where an outer cylinder contains a material which selectively removes a chemical which may be in conflict with or would contaminate the sensing of the desired chemical. This outer cylinder does not play a part in the measurement because it is outside the metal shield which contains the measurement adsorbent, and is thus outside the electromagnetic field.

Abstract: First and second electrically conductive rods are provided inside a shielded electromagnetic test chamber. These rods are energized to radiate electromagnetic energy inside the chamber. The rods are mounted inside the chamber at right angles to one another, the first rod is movable through the interior volume in a first direction perpendicular to its long axis, and the second rod is movable through the chamber in a second direction perpendicular both to its own long axis and to the first rod's direction of motion. Energy is supplied to the two rods in a way that enhances the uniformity of the electromagnetic field applied to a working volume inside the chamber as the two rods move through the chamber.

Abstract: A sensor unit is formed by a single integral body obtained by coupling a resiliently deforming portion with a base portion without interposing a soft material therebetween, and a force applied to a probe secured to a front end of the resiliently deforming portion is measured as a change in capacitance of a capacitor constituted by electrodes secured to opposing surfaces of the resiliently deforming portion and base portion. These electrodes are connected to a resonance circuit of a high frequency oscillation circuit, and in order to measure a change in a resonance frequency which is varied in accordance with the applied force, an output signal from the high frequency oscillation circuit is counted by a digital frequency counter for a predetermined time period. It is possible to provide the electrocapacitive type force measuring apparatus which can measure a very small force with an extremely high precision without being affected by temperature variation, humidity variation and secular variation.

Abstract: An electromagnetic wave source detecting apparatus may include a plurality of probes for measuring intensities of an electric field or magnetic field generated from an object to be measured at each measuring position. Calculation means may calculate a phase difference or time difference between electric fields or magnetic fields associated with the probes from the electric field or magnetic field intensities measured by the individual plural probes. A position of an electromagnetic wave source existing in the measured object may be calculated and identified by using the phase difference or time difference thus calculated. A magnitude of a current existing in the electromagnetic wave source at the position thus calculated may be identified on the basis of the electric field or magnetic field intensities thus measured.

Abstract: In a quasi-hemispherical Fabry-Perot resonator for the non-destructive determination of the surface resistance Rs of electrically conductive thin material films, spherical and planar mirrors are disposed opposite each other in a double shielded cooled resonator space structure supported on individual base plates and the planar mirror, on which a wafer with the thin material film is supported, is mounted on a support arm which extends through the double shield structure. Shield sections through which the support arm extends are supported on pivot arms which are pivotally mounted in the center of the base plates and the shield sections are engaged by the support arm so that they move along with the support arm when the support arm is moved sidewardly for a positioning change of the planar mirror thereby preventing radiation leakage from the resonator space.

Abstract: The method of detecting foreign bodies in continuous mass streams of fibrous material, strand-like material or material similar to bulk goods with the aid of microwaves, in which the mass flow is led through the field of a microwave resonator and in which the change (A) in the resonant frequency, effected by the material, and the change (B) in the width of the resonance curve of the microwave resonator is determined, is distinguished in that the ratio (B/A) of the changes is evaluated and compared with corresponding averages, and the presence of a foreign body is reported when the ratio differs from the averages by more than a predefined value.

Abstract: In a method of detecting and eliminating foreign bodies in tobacco, a flow of tobacco advances first through a preparation zone where it is gathered into a continuous ribbon of tobacco filler, then through a forming station at which the filler is used to fashion a continuous cigarette rod, and finally through a cutter device that divides the rod into cigarette sticks; the advancing flow is directed at a given point through a detection device and exposed to electromagnetic radiation of microwave frequency emitted and received in such a way as to generate output signals reflecting any variations in moisture content along the flow of tobacco, caused by the inclusion of foreign bodies and associated with given portions of the flow each coinciding with a singly identifiable cigarette stick.

Abstract: Systems, methods, and probe devices for electronic monitoring and characterization using single-ended coupling of a load-pulled oscillator to a system under test.

Abstract: The measuring arrangement contains a measuring cell and a reference cell (9, 10), respectively, and microphones (11 and 12) assigned to these cells, to which microphones an electronic evaluation circuit (7, 8) is connected and in which a subtraction of the signals of the microphones (11 and 12) takes place, as well as a radiation source (5) for applying a modulated signal to the measuring cell (9). The modulation frequency of the radiation source (5) coincides with the resonant frequency of the measuring cell (9), and the measuring cell and the reference cell (9 and 10) are open at at least one end to the gas and/or aerosol to be detected.

Abstract: A load pull circuit with a monitoring port which provides a constant VSWR throughout a phase variation in excess of 360°. The fundamental circuit comprises a fixed resistor of fifty ohms placed in series with an external fifty ohm load monitoring port resistor to ground. In parallel with the two series resistors, which total 100 ohms, is placed a 33.3 ohm resistor that is connected to ground through a series L-C circuit. The capacitance in the L-C circuit is adjustable and can be varied to cause the L-C circuit to change in net value from being inductive, to being resonant, and finally being capacitive. This causes the 33.3 ohm resistor to be connected to ground through an inductor, then through a short, and finally through a capacitor, making the load pull circuit present a load that vary through 360 degree in phase, while still remaining at a VSWR of 2:1. The inductor in the L-C circuit is a varactor, making the sweep through all 360° totally electronically controllable and simple to automate.

Abstract: A new method and apparatus for detecting and measuring the level of metal present on the surface of a substrate is achieved. Energy, in the form of rf or light or microwave energy, is directed at the surface of a wafer, the reflected energy or the energy that passes through the semiconductor substrate is captured and analyzed for energy level and/or frequency content. Based on this analysis conclusions can be drawn regarding presence and type of metal on the surface of the wafer. Furthermore, by inclusion of metal within the resonating circuit of an rf generator changes the frequency of the vibration and therefore detects the presence of metal.

Abstract: There are provided electromagnetic wave source detecting apparatus and method as well as electromagnetic wave source analyzing system and method which can detect and analyze a source of (electromagnetic disturbing wave) representing a main factor in generating an electromagnetic field remotely of the apparatus in order to suppress the electromagnetic field intensity at the remote distance from the apparatus to below a regulated value.

Abstract: At least one characteristic, such as the mass/density and/or moisture content and/or dielectric constant, of a substance (such as the rod-like tobacco filler of a continuously advancing cigarette rod or a continuously advancing rod-like filler of filter material for tobacco smoke) is ascertained by an evaluating circuit receiving high-frequency signals from a resonator arrangement which receives microwave signals at least at two different frequencies from one or more microwave generators. The substance is caused to advance through a dielectric resonator of the resonator arrangement, and the high-frequency signals are influenced by the substance. For example, the circuit can compare first and second curves of high-frequency signals which respectively are and are not influenced by a selected substance; the curves can have sloping flanks and each of the two frequencies can be allocated to a sloping flank of a curve.

Abstract: A filter has a plurality of resonators formed regularly on a substrate and made of a superconducting material. In measuring resonance frequency of the resonators, the filter and a conductive metal plate having an opening are placed in a vacuum chamber so that all the resonators other than one resonator which faces the opening are covered with the metal plate. The metal plate has an input probe and an output probe at the opening of the metal plate. The resonance frequency of each resonator is measured in sequence while rotating the metal plate. Each resonator is adjusted in shape by a laser trimming or providing a dielectric film in correspondence with the measured resonance frequency so that all the resonators have a fixed resonance frequency.

Abstract: There are provided electromagnetic wave source detecting apparatus and method as well as electromagnetic wave source analyzing system and method which can detect and analyze a source of (electromagnetic disturbing wave) representing a main factor in generating an electromagnetic field remotely of the apparatus in order to suppress the electromagnetic field intensity at the remote distance from the apparatus to below a regulated value.

Abstract: An embodiment of the present invention includes the use of a single connection to measure the resonance frequency of main cells or side cells of a resonant structure, such as a linear accelerator cavity structure. Only one antenna is require to perform both the tasks of exciting a cavity structure and picking up the resonant frequency signal. According to an embodiment of the present invention, a first antenna probe is inserted into the main cells of a linear accelerator cavity structure. The first antenna probe includes an antenna window which may be positioned approximately in the center of a main cell adjacent to a target side cell in order to measure the resonance frequency of a target side cell. All non-target side cells adjacent to the main cell aligned with the window antenna are then shorted. For example, the non-target cells may be shorted by metal surrounding the first antenna probe at locations other than the antenna window. A signal is sent and a resonance frequency is noted.

Abstract: An apparatus and method for accurately estimating the absolute value of surface resistances and penetration depths of metallic films and bulk samples. The apparatus carries out measurements using two nominally identical samples with flat sample surfaces which are brought together with a thin dielectric separation of variable thickness sandwiched between the samples in order to form a two-conductor parallel plate transmission line resonator which carries an electromagnetic wave. A liquid or gas of unknown dielectric properties fills the dielectric spacer. A resonant condition of the microwave signal is established and the resonant frequency and the quality factor Q are measured while the spacing between the sample plates is varied. The variation of the resonant frequency and Q with spacer thickness is then analyzed to yield absolute values of the sample surface resistance and penetration depth which are then further used for determination of absolute complex conductivity and surface impedance of the samples.

Abstract: The microwave sensor produces an electrical output signal according to a position or displacement of a movable mechanical part (2), especially a valve needle in an injector valve for injecting fuel into an internal combustion engine. This position or displacement sensor includes a cavity resonator (40,70) provided with walls bounding a cavity (4,7) dimensioned for microwaves of a predetermined frequency and an antenna (8,14) for reception of the microwaves in the cavity. The end (3) of the movable mechanical part (2) protrudes into the cavity. A hybrid evaluating circuit (9) is connected with the antenna, which detects changes in the microwave radiation fed into and coupled out of the cavity, e.g. phase relationships, which depend on the position of the mechanical part (2), so that small position changes in very tight spaces are accurately determined.

Abstract: A resonant sensing apparatus for operative arrangement within a test environment to sense an analyte. A sensing structure is included having an antenna in electrical communication with a resonant circuit and a structural element made of a material that selectively responds to the analyte. This sensing structure will resonate at a particular characteristic resonant frequency in the presence of an applied interrogation electromagnetic field and the analyte upon the occurrence of the selective response. A receiver is used for remotely identifying a value for the characteristic resonant frequency by measuring a plurality of values for electromagnetic emission intensity of the sensing structure taken over an operating range of frequencies. A length of a conductive segment of any component of the resonant circuit may also function as the antenna.

Abstract: A filter is composed of plural resonators formed on one surface of a dielectric substrate and a ground plane formed on the other surface. A resonant frequency of each resonator is accurately measured individually and independently from other resonators. Other resonators not selected for measurement are all short-circuited or covered with a conductive member to shift their resonant frequency to a region that does not interfere with the resonant frequency of the resonator under measurement. Also, a coupling coefficient of an arbitrary pair of resonators is accurately measured under no interference from other resonators in the similar manner.

Abstract: While a high-frequency pulse is introduced at one end of a parallel conductor which is simulated as in an impedance equivalent state, an impedance mismatch generator is mounted to an intermediate region of the parallel conductor. As the impedance mismatch generator has produced a reflected wave of the pulse, a duration before the reflected wave is received at the one end is measured and multiplied by the propagation speed of voltage to calculate the distance from the pulse introducing point at the one end of the parallel conductor to the impedance mismatch generator.

Abstract: A method and apparatus for measuring the frequency of a desired resonant mode of a crystal arrangement, or other two-port device, during an automated operation. The crystal arrangement, or other two-port device, is placed into a test circuit and subjected to a sinusoidal test signal of known frequency. Based upon the output response of the crystal arrangement to the test signal, the frequency of the test signal is changed such that the test signal rapidly converges on a desired mode of operation of the crystal arrangement. This is accomplished by first noting a desired increase in amplitude of the output response of the crystal arrangement, followed by measuring an error signal related to the desired crystal arrangement mode of operation. When the error equals a predetermined value the frequency of the sinusoidal test signal is the frequency of the desired mode.

Abstract: An embodiment of the present invention includes the use of a single connection to measure the resonance frequency of main cells or side cells of a resonant structure, such as a linear accelerator cavity structure. Only one antenna is require to perform both the tasks of exciting a cavity structure and picking up the resonant frequency signal. According to an embodiment of the present invention, a first antenna probe is inserted into the main cells of a linear accelerator cavity structure. The first antenna probe includes an antenna window which may be positioned approximately in the center of a main cell adjacent to a target side cell in order to measure the resonance frequency of a target side cell. All non-target side cells adjacent to the main cell aligned with the window antenna are then shorted. For example, the non-target cells may be shorted by metal surrounding the first antenna probe at locations other than the antenna window. A signal is sent and a resonance frequency is noted.

Abstract: A circuit measures a signal propagation delay through a series of memory elements. In one embodiment the memory elements are configured in series so that together they form a delay circuit. In another embodiment the memory elements are configured in a loop to form a ring oscillator. Each memory element propagates a signal to a subsequent memory element so that the time the signal takes to traverse all of the memory elements is proportional to the average delay induced by the individual elements. This proportionality provides an effective means for measuring the delays of those components. Various embodiments of the invention measure the speeds at which memory elements can be preset, cleared, written to, read from, or clock enabled.

Abstract: At least one characteristic, such as the mass/density and/or moisture content and/or dielectric constant, of a substance (such as the rod-like tobacco filler of a continuously advancing cigarette rod or a continuously advancing rod-like filler of filter material for tobacco smoke) is ascertained by an evaluating circuit receiving high-frequency signals from a resonator arrangement which receives microwave signals at least at two different frequencies from one or more microwave generators. The substance is caused to advance through a dielectric resonator of the resonator arrangement, and the high-frequency signals are influenced by the substance. For example, the circuit can compare first and second curves of high-frequency signals which respectively are and are not influenced by a selected substance; the curves can have sloping flanks and each of the two frequencies can be allocated to a sloping flank of a curve.

Abstract: A circuit measures a signal propagation delay through a series of memory elements on a programmable logic device. In one embodiment, a number of latches are configured in series. Each latch is initialized to store a logic zero. The first latch is then clock-enabled so that the output of the latch rises to a logic one. The logic one from the first latch clock-enables the second latch in the series so that the output of the second latch rises to a logic one, which in turn enables the next latch in the series. The time required for a rising edge to traverse the entire sequence of latches is the cumulative time required for the output of each latch to change in response to a clock-enable signal. Consequently, the delay through the series of latches provides a measure of the time required for one of the latches to respond to a clock-enable signal.

Abstract: A system for testing interconnects in multi-chip modules including a radio frequency resonator having a resonant circuit with a relatively high quality factor, the output of the resonant circuit being attached to a probe. Electrically coupled to the resonant circuit output is an apparatus to analyze the voltage signal output. The probe is applied to one end of an interconnect. When the probe is applied, the resonant frequency of the resonant circuit and the magnitude of the frequency response are altered due to the additional loading created by the interconnect. Due to the relatively high quality factor of the resonant circuit, the magnitude of the frequency response of the altered resonant circuit is measurably distinct from a predetermined reference magnitude at a predetermined reference frequency, thus indicating the existence of a defect.

Abstract: A microwave microscope for measuring electrical characteristics of a sample, such as a semiconductor wafer, with fine resolution. A probe includes a microwave waveguide capable of supporting the two lowest orthogonal modes from a microwave source, e.g. of millimeter radiation. The probe tip includes a thin conductive wall formed at the probe end of the probe. Two perpendicularly arranged slits, that is cross slits, are formed in the conductive wall, each slit having a length nearly resonant with the microwave radiation and a width substantially smaller, e.g. of the order of 100 .mu.m, and of a size such that the radiation of the proper polarization nearly transparently passes through that slit. The sample to be tested is placed in the near field of the probe tip and scanned relative to the probe. Probing microwave radiation having the polarization which passes through one slit is launched in the waveguide. A non-rotated polarization component is reflected back from the sample through the same slit.

Abstract: A method and apparatus for determination of orientation of fibers in a material such as a paper or paperboard web comprised of elongated fibers of high moisture content. The material is subjected to an alternating electric field (E) of the RF or microwave frequency range lying in the plane of the material and the change caused by the presence of the material in the alternating electric field (E) is measured. The direction of the alternating electric field (E) is altered during the measurement, whereby the material need not be rotated with respect to the resonator for the measurement.

Abstract: A stochastic resonator signal detector comprises a multi-stable nonlinear device for coupling to an input signal and a control signal coupled to the multi-stable nonlinear device for varying asymmetry among stable states of the multi-stable nonlinear device. The interaction of the input signal with the control signal in the multi-stable nonlinear device generates an output signal having an amplitude responsive to the input signal amplitude and a frequency range that comprises harmonics of products of the control signal and the input signal.

Abstract: The identification of and compensation for changes in the dielectric properties of a hydraulic fluid in hydraulic apparatus is achieved by continuously sampling a hydraulic fluid in a resonant chamber with a central conductor that is both inductively and capacitively coupled to an oscillator. The output frequency changes of the oscillator is an indicator of changes of the dielectric properties of the hydraulic fluid and their magnitude. The invention is of particular value in hydraulic cylinder piston position determining systems.

Abstract: An apparatus for contactlessly measuring the electrical resistance per unit ength of a low-resistance test conductor (e.g., wire or cable) at a selected measurement frequency, which includes a coaxial cavity structure having a central cavity region defined by opposed first and second outer conductor sections, and a center conductor, wherein the test conductor comprises the center conductor. An input probe disposed adjacent to the first one of the outer conductor sections launches a standing wave on the center conductor, and an output probe disposed adjacent to the second one of the outer conductor sections senses the Q of the central cavity region. A detector coupled to the output probe measures the sensed Q of the central cavity region. The electrical resistance per unit length of the test conductor at the selected measurement frequency can be determined from the measured cavity Q.

Abstract: A convenient, non-optical method for scanning probe microscopy tip-to-sample distance control based on the impedance change in a shear-force dither piezo. This is accomplished by determining the tip-sample distance by measuring the impedance change in a shear-force piezo-member. A Wheatstone type bridge can be utilized to regulate the tip-sample separation. Alternatively, an electrical bridge, having an output, regulates the tip-sample separation relative to the bridge output by driving the piezo/tip with a sine wave and combining said sine wave with a phase-referenced wave of equal amplitude at a 180.degree. phase shift. The electronic bridge detects impedance changes of about -100 dB across loads with impedance phases between -90.degree. to +90. Power dissipation is determined by measuring changes in electric impedance that a dither piezo presents to an oscillator.

Abstract: The instant invention relates to an apparatus for measuring a powder mass flow in a powder/gas mixture during the conveyance thereof through a feed pipe, the apparatus comprising a velocity measuring device for the powder/gas mixture, a mass measuring device for the powder mass per volume unit, and a calculating device to calculate the powder mass flow based on the velocity measured, the powder mass per volume unit measured, and the dimensions of the feed pipe. The mass measuring device comprises a microwave resonator and means for sensing the resonant frequency and/or the microwave amplitude of the microwave resonator. The microwave resonator is embodied by a coil which is applied on the outside of the feed pipe.

Abstract: A piston position sensing system with improved accuracy and reliability is achieved by electromagnetic wave coupling using the combination of: a mechanical structure that in addition to supporting the rod, provides an extension of the resonance cavity, supports the electromagnetic wave couplers and a hydraulic fluid input-output port into the extended cavity and a piston travel stop; an electronic circuitry shielded package having a high frequency section with coaxial shielded input and output conductors on opposing package sides and a lower frequency counting section having a piston position output shielded conductor and a fluid dielectric property change monitor input conductor separated from the high frequency section conductors; and, the positioning of the electronic package on the mechanical structure with the coaxial shielded input and output conductors respectively adjacent to the input and output couplers and with the hydraulic fluid input-output port positioned elsewhere around the periphery of the c

Abstract: A highly compact, portable, pulsed-molecular-beam Fabry-Perot cavity Fourier transform microwave spectrometer which incorporates ultra-fine Fabry-Perot mirror surface finishes has been developed for trace gas analysis. The mirrors, having a surface finish of less than or equal to 0.25 microns rms, are coated with nickel and then with either gold or silver. In a further embodiment, one or more fixed-tuned Fabry-Perot cavities are incorporated within a single vacuum chamber to monitor one or more chemical species of interest.

Abstract: The ability to be able to identify, distinguish and verify a lock onto harmonic frequency signals in the oil of a hydraulic cylinder using a ratio between consecutively detected harmonics. The identification is useful in providing early and reliable harmonic resonance "lock on" and the ability to "lock on" to a particular order harmonic resonance.