Abstract: Methods and instrumentation for pulse scattering estimation and imaging of scattering parameters in a material object by transmitting a pulse along a transmit beam and directing a receive beam that crosses at least one transmit beam at an angle <45 deg. The receive beam is at least in an azimuth direction at the transmit beam, and records scattered receive signal from the overlap region. A receive interval of the receive signal is gated for further processing to form measurement and/or image signals from cross-beam observation cells.

Abstract: The present disclosure provides methods and systems for the characterization of a microtexture of a sample, component, or the like. The methods may include methods of determining a service life limiting region of a component, determining a treatment method for a component, and/or selecting components from a batch of components for use in production. The characterization may include calculating a microtexture level indicator from ultrasonic C-scan images for various samples, regions, components, or the like. The microtexture level indicator may include at least one of an average peak factor, a standard deviation of peak amplitude, and/or a baseband bandwidth.

Abstract: A method for detecting an obstacle utilizing reflected ultrasonic waves, comprises transmitting an ultrasonic burst transmission signal by an ultrasonic transmitter to a detection area to be observed and receiving an ultrasonic signal reflected by an obstacle in the detection area by an ultrasonic receiver as an ultrasonic reception signal. In the ultrasonic reception signal at least one echo is detected resulting from an obstacle. The echo section of the ultrasonic reception signal belonging to the echo is transformed from the time domain into the frequency domain. The frequency spectrum of the echo section is then examined for the presence of at least one of a plurality of predetermined spectral characteristics, wherein each spectral characteristic is representative of a predetermined obstacle type or a plurality of predetermined obstacle types. The echo section is allocated to a predetermined obstacle type based on the examination.

Abstract: An ultrasonic diagnostic system includes elements disposed around a subject to transmit and/or receive ultrasonic waves. A controller controls the elements so that some of the elements disposed in a first region transmit ultrasonic waves at a first angle to a diagnosis target in the subject, some of the elements disposed in a second region receive reflected waves of the ultrasonic waves, which are reflected from the diagnosis target at a second angle, and some of the elements disposed in a third region receive reflected waves of the ultrasonic waves, which are reflected from the diagnosis target at a third angle distinct from the second angle. An operator calculates a velocity vector of the diagnosis target using the reflected waves received by the some of the elements disposed in the second region and the reflected waves received by the some of the elements disposed in the third region.

Abstract: Techniques, systems, and devices are described for implementing for implementing computation devices and artificial neurons based on nanoelectromechanical (NEMS) systems. In one aspect, a nanoelectromechanical system (NEMS) based computing element includes: a substrate; two electrodes configured as a first beam structure and a second beam structure positioned in close proximity with each other without contact, wherein the first beam structure is fixed to the substrate and the second beam structure is attached to the substrate while being free to bend under electrostatic force. The first beam structure is kept at a constant voltage while the other voltage varies based on an input signal applied to the NEMS based computing element.

Abstract: Systems and methods for measuring the thermal crown of rolls in-situ (e.g., at high temperature) either inside or outside the rolling mill can include sensors that measure propagation times of mechanical waves through the rolls. In some embodiments, one or more sensors are used to measure the propagation times of ultrasonic waves traveling inside the roll and normal to the roll's axis. These measurements can be taken when the roll is still hot and can be used to determine in real-time the thermal expansion at various points along the roll.

Abstract: According to an embodiment, a structure evaluation system includes a plurality of AE sensors, a signal processor, a position locator, and an evaluator. The AE sensors detect an elastic wave generated from a structure. The signal processor performs signal processing on the elastic wave detected by the AE sensors and outputs an AE signal including information on the elastic wave. The position locator derives a source distribution indicating the distribution of sources of the elastic wave generated in the structure, using an AE signal caused by an impact on the structure. The evaluator evaluates a state of deterioration of a predetermined region of the structure from a density of the sources of the elastic wave obtained on the basis of the source distribution.

Abstract: An arrangement for transmitting and/or receiving an ultrasonic, wanted signal in a measured medium, comprising a vibration decoupling element for securing at least one ultrasonic transducer in a containment, characterized in that the vibration decoupling element has a platform for securing the vibration decoupling element to a sensor nozzle or to the containment and a second interface for securing an ultrasonic transducer. Between the second interface and the platform a vibration decoupling structural element is arranged, which structural element is embodied as a solid body, which has one or more interfaces with other elements of the vibration decoupling element, especially with the second interface for securing the ultrasonic transducer and/or the platform, and wherein the structural element (11, 39, 55, 75) has an as much as possible spherical-, ellipsoidal-, toroidal- or polyhedral shape.

Abstract: An inspection tool for inspection of a hole of a metallic lug, including, a first arm, a second arm, a third arm, and a housing element, wherein the first arm, the third arm and the housing element may vary their position independently of each other in relation to the second arm. Also, the present invention discloses an inspection device for inspection of a metallic lug that comprises an inspection tool and a probe housed in the housing element, and a method for detecting cracks around metallic lug.

Abstract: Ultrasound signal processing circuitry and related apparatus and methods are described. Signal samples received from an ultrasound transducer array in an ultrasound transducer based imaging system may be processed, or conditioned, by application of one or more weighting functions. In some embodiments, one or more weighting functions may be applied to the signal samples in the time domain. In other embodiments, the signal samples may be converted to the frequency domain and one or more weighting functions may be applied in the frequency domain. In further embodiments, one or more weighting functions may be applied in the time domain and one or more weighting functions may be applied in the frequency domain. The weighting functions may be channel dependent and/or channel independent. The processed data can be provided to an image formation processor.

Abstract: Optical microphone, laser-based microphone, and laser microphone having reduced-noise components of low-noise components. A laser microphone comprises a laser-diode associated with a low-noise laser driver TX; and a photo-diode associated with a low-noise photo-diode receiver RX. The low-noise laser driver TX supplies a drive current which is a combination of a Direct Current component having a first bandwidth, and an attenuated version of an Alternating Current component having a second, different, bandwidth. Additionally or alternatively, the low-noise photo-diode receiver RX utilizes hardware-based demodulation of the analog signal, and operates to remove a Direct Current component of its output signal prior to digitization.

Abstract: A deformation detecting device comprises a vibration module configured to vibrate a first point of a measuring plane of a measured object in a non-contact manner; a transmission time measurement module configured to measure transmission time of vibration from the first point to a second point of the measuring plane in a non-contact manner; an inclination measurement module configured to measure an inclination of the measuring plane to a reference surface in a non-contact manner; and a determination module configured to determine presence/absence of deformation in the measured object by comparing the transmission time with reference transmission time serving as transmission time of vibration from the first point to the second point in a case in which there is no inclination of the measuring plane and corrects the reference transmission time in response to the inclination of the measuring plane.

Abstract: A system is provided that includes a gateway node and terminal node. The gateway node may be configured to produce a continuous acoustic wave for propagation through a fluid such as water, and detect an echo thereof. The terminal node may be configured to control a piezoelectric layer to switchably reflect or transmit the acoustic wave incident thereon to produce and modulate the echo with a data stream to thereby convey the data stream within the echo, which the sensor of the gateway node may detect. The terminal node may be further configured to capture and store energy produced by the piezoelectric layer while the piezoelectric layer is controlled to transmit the incident acoustic wave. And at least a portion of the terminal node may be powerable from the stored energy.

Abstract: A method of inspecting a structure is disclosed. The method generally comprises selecting a search region of a dispersion curve of the structure corresponding to one or more inspection parameters. The search region comprises at least one guided wave mode activation point not located on the dispersion curve. The method further comprises activating, using an inspection system comprising at least one transducer, a plurality of activation points located within the search region of the dispersion curve and identifying an optimal activation point for the one or more inspection parameters. The optimal activation point comprises at least one of the plurality of activation points producing an optimal response for the one or more inspection parameters.

Abstract: Porosity of aluminum ingot can be evaluated using focused beam ultrasonic testing and/or florescent dye penetrant testing. The aluminum ingot can be machine cut to form an aluminum ingot slice prior to testing. The machine cut can be performed using a polycrystalline cutting material in a “fly cutter” configuration. The polycrystalline cutting material can comprise a diamond material. The insert can cut an aluminum ingot slice to a surface roughness finish in the range of about 7-9 micro inches.

Abstract: An ultrasonic measuring method for measuring an inside of a measured object by using ultrasonic waves propagating through air includes attaching a sheet having an acoustic impedance higher than the air as well as lower than the measured object to the measured object and measuring the inside of the measured object to which the sheet is attached by using a sensor.

Abstract: Provided are an ultrasonic probe capable of forming an image without degradation even when the frequency band of a photoacoustic wave and the frequency band of an ultrasonic wave used in ultrasonography are separated from each other, and an inspection object imaging apparatus including the ultrasonic probe. The ultrasonic probe includes a first array device capable of transmitting and receiving an ultrasonic wave; and a second array device capable of receiving a photoacoustic wave. The first array device includes plural electromechanical transducers arranged in a direction perpendicular to a scanning direction, the second array device includes plural electromechanical transducers arranged in a two-dimensional manner, and the first array device and the second array device are provided on the same plane and in the scanning direction.

Abstract: A grammage detection sensor which detects a grammage of a recording medium using an ultrasonic wave includes a transmitting unit configured to transmit the ultrasonic wave and a receiving unit including a first vibration member configured to receive the ultrasonic wave that is transmitted from the transmitting unit and passes through the recording medium. The receiving unit includes a guide member configured to guide the ultrasonic wave that passes through the recording medium to the first vibration member. A length from a surface of the first vibration member to a plane including an end plane of the guide member along a line that passes through a center of the first vibration member and is perpendicular to the first vibration member is approximately n times of one-half wavelength of the ultrasonic wave transmitted from the transmitting unit where n is an integer of one or greater.

Abstract: Frequency-steerable acoustic transducers (FSATs) that allow directional generation or sensing of waves propagating in two-dimensional domains. Directionality is the result of the spatial filtering effect produced by the characteristic shape of the sensing surface. A wavenumber spiral FSAT (WS-FSAT) maps the direction of wave sensing in the [0°, 180°] range to a specific frequency component in the spectrum of the received signal. The use of a wavenumber spiral FSAT operating in sensing mode can be used for the localization of broadband acoustic events. One configuration includes a broadband source generating guided elastic waves in an isotropic plate. The WS-FSAT records the plate response and defines the source location through a time-frequency analysis of the received signal. The frequency selective response of the WS-FSAT directly maps the dominant component of the received signal to the direction of arrival of the incoming wave, thus greatly facilitating the source localization procedure.

Abstract: A method is for examining a sheet-shaped or card-shaped value document with a security feature having one or more cavities configured in the value document. The width of the cavity or cavities is in at least one respectively specified direction exceeding 10 ?m. Transmission values are established in a locally resolved manner for the transmission of ultrasound in a specified frequency range. In employing the transmission values, it is checked whether a specified number of transmission values is greater than a specified transmission threshold value.

Abstract: A radar wave sensing apparatus including a rotation element, a nanosecond pulse near-field sensor and a control unit is provided. The nanosecond pulse near-field sensor emits an incident radar wave and receives a reflection radar wave of the incident radar wave hitting on a surface of the rotation element to obtain a repetition frequency variation of the reflection radar wave corresponding to the incident radar wave. The control unit calculates a vibration of the rotation element according to the repetition frequency variation.

Abstract: Solid contents verification systems and methods are provided. The system includes a contents sensor unit, a container-carrying unit and a control unit. The contents sensor unit has at least one contents sensor configured to send and receive sonic pulses to determine a state of contents in a container. The contents sensor unit is configured to send a signal communicating a state of the contents in a container. The container-carrying unit is configured to hold a container in substantial alignment with the contents sensors to expose the contents to the sonic pulses. The control unit is operatively connected to the contents sensor unit. The control unit is configured to receive the signal communicating the state of the contents and to compare the state of the contents with a desired state of the contents.

Abstract: The objective of the present invention is to provide an unexpected detecting apparatus enabled to evaluate an evenness of a compound coated on an electrode of a battery. The detecting apparatus (1) detects an evenness of a compound (12) coated on an electrode (10) of a battery, and includes a first sensor (20) for measuring a mass per unit area of the compound (12) in any points thereof, a second sensor (30, 50) for measuring a thickness of the compound (12) in the any points, and a holder (40, 60) for holding the first and second sensors (20, 30, 50), in which the first and second sensors (20, 30, 50) measure the mass and thickness at the same time, and the evenness is evaluated on the basis of the measured mass and thickness.

Abstract: A conformable medical data acquisition pad and configurable imaging system. The conformable pad may comprise a carrier base having a plurality of transceivers in operative association with an interconnection network that communicates with a computer system. The data acquisition pad may be constructed with a flex circuit and at least one ultrasound data collection device to carry out a variety of medical procedures. Different types of signal transmitting and receiving elements can be selected to provide ultrasound systems, including scalable capacitive micromachined ultrasound transducers arranged in a variety of configurations in combination with controlling electronics which interface with a translator board and software for signal processing. The resulting ultrasound data, such as a three-dimensional model, can be transmitted via an industry standard high speed bus to standard interfaces on various ultrasound systems.

Abstract: Solid contents verification systems and methods are provided. The system includes a contents sensor unit, a container-carrying unit and a control unit. The contents sensor unit has at least one contents sensor configured to send and receive sonic pulses to determine a state of contents in a container. The contents sensor unit is configured to send a signal communicating a state of the contents in a container. The container-carrying unit is configured to hold a container in substantial alignment with the contents sensors to expose the contents to the sonic pulses. The control unit is operatively connected to the contents sensor unit. The control unit is configured to receive the signal communicating the state of the contents and to compare the state of the contents with a desired state of the contents.

Abstract: An ultrasonic detection assembly detects a characteristic in a test object. The ultrasonic detection assembly includes a phased array probe positioned in proximity to a peripheral surface of the test object. The phased array probe includes a plurality of transducer elements. The transducer elements of the phased array probe transmit a sound beam into the test object. The sound beam is movable by the phased array probe within the test object to detect the characteristic. A method of detecting a characteristic in the test object with the ultrasonic detection assembly is also provided.

Abstract: Measurement or imaging of elastic wave nonlinear scatterers with a memory of scattering parameters comprises selecting LF pulses having characteristics to change the scattering parameters of nonlinear scatterers. A transmit time relation is selected so that the incident HF pulse propagates sufficiently close to the LF pulse that the effect of the incident LF pulse on its scatterer parameters is observed by the HF pulse. At least two elastic wave pulse complexes comprising a high frequency (HF) pulse and a selected low frequency (LF) pulse are transmitted towards the region. Received HF signals are combined to form nonlinear HF signals representing the scatterers with memory, with suppression of received HF signals from other scatterers. At least one of the received HF signals may be corrected by time delay correction and/or speckle correction with a speckle correction filter, determined by movement of the scattering object. Systems are also disclosed.

Abstract: [Problem to be Solved] To provide a property measuring device for measuring a measurement object, which can highly reliably extract an electric signal serving as the measurement object from an electromagnetic field noise or the like generated by an acoustic wave generating source even if the acoustic wave is a continuous wave, while a high spatial resolution is maintained, by using an acoustic wave as a properly measuring means for measuring an object and method thereof.

Abstract: Disclosed is an ultrasonic device optimized with both averaging and dithery pulsing techniques. The averaging technique significantly removes white noise; on the other hand, the dithery pulsing significantly removes acoustic noise, which is otherwise accumulated during conventional averaging processes.

Abstract: The present application provides a rotary testing apparatus for use with a work piece. The rotary testing apparatus may include a rotor, a probe, and a lifting unit for maneuvering the probe about the work piece. The lifting unit may include a hydraulic lifting mechanism and a counterweight mechanism.

Abstract: The rotary transformer 5 includes a plate-shaped stator 51 having a coil arranged on one surface thereof, and a plate-shaped rotator 52 having a coil arranged on one surface thereof, in which the respective coil-arranged surfaces are disposed to face with each other so that signal transmission in a frequency range of 1 to 10 MHz is performed between the coils. The stator includes a substrate 512 on which a plurality of one-turn coils are formed into a concentric shape, and a supporting member 513. The rotator includes a substrate 522 on which one-turn coils 521 of same number are formed into a concentric shape, and a supporting member 523. Air or a material M which is an insulator and has a relative magnetic permeability substantially equal to 1 is lying between the substrate 512 and the supporting member 513, and between the substrate 522 and the supporting member 523.

Abstract: A sensing assemblage (1) for capturing a transit time, phase, or frequency of energy waves propagating through a medium is disclosed to measure a parameter of the muscular-skeletal system. The sensing assemblage (1) comprises a transducer (2) and a waveguide (3). The transducer (2) is coupled to the waveguide (3) at a first location. A second transducer (11) can be coupled to the waveguide (3) at a second location. An interface material that is transmissive to acoustic energy waves can be placed between transducers (402, 404) and a waveguide (414) to improve transfer. The interface material (408, 410) can affix the transducers (402, 404) to the waveguide (414). Alternatively, a reflecting feature (5) can be placed at a second location of the waveguide (3) to reflect acoustic waves back to the transducer (2) where transducer (2) emits energy waves into the medium and detects propagated energy waves.

Abstract: Provided are devices, systems, and methods for the testing of materials and structures. For example, the devices, systems, and methods are optionally used for the non-destructive testing of a material or structure. Furthermore, the devices, systems, and methods may optionally use a high-amplitude, air-coupled acoustic source for non-destructive testing of materials and structures.

Abstract: Methods and systems for inspecting a component within an assembled turbomachine are disclosed. At least one miniature robotic device having a non-destructive testing structure attached thereto is configured to travel around a surface of the component. The non-destructive testing structure gathers data related to the surface, and sends the data to a computing device connected to the at least one miniature robotic device. In one embodiment, the non-destructive testing structure comprises an image capture device and an infrared (IR) heat source.

Abstract: A laser vibrometer makes non-contact measurements of vibrations of a target. A laser produces a laser beam, and a beamsplitter splits the laser beam into a reference beam and a first target beam. A first frequency shifter/splitter splits the first target beam into a pair of target beams each having a frequency different than a frequency of the other target beams. The target beams are reflected from the target to a detector, and the reference beam is combined with the target beams such that the detector receives the target beams and reference beam together.

Abstract: A photoacoustic multipass cell includes a light source, an acoustic resonator and a reflecting arrangement configured in a concentrating manner for reflecting light into the acoustic resonator. Additionally, the light source is arranged at least partially within the reflecting arrangement.

Abstract: The present invention provides a photoacoustic measuring device and a method by which the presence of an object can be easily identifyied in a relatively short time in photoacoustic measurement while holding an object by a holding plate. The photoacoustic measuring device has a irradiating unit with which the object is irradiated with light, a holding unit holding the object by the holding plate, a detecting unit detecting the photoacoustic wave generated by irradiating light and an analyzing unit analyzing photoacoustic signal of the photoacoustic wave. The analyzing unit analyzes a photoacoustic signal to acquire information concerning change of a signal intensity of a component of the photoacoustic signal of produced in an interface between the detecting unit and the holding plate and an interface between the holding plate and the object, to identify the presence of the object.

Abstract: In a method for assessing a condition of at least one value document with regard to limpness, there is determined from transmission values representing the ultrasound transmission at different places on the value document a condition value which depends on a variation of the transmission values and characterizes the condition of the value document with regard to limpness. A condition of the value document is determined for the condition value using a preset criterion.

Abstract: Both a method and apparatus for determining internal discontinuities or inhomogeneities in a green or fired ceramic honeycomb structure is provided. In the method of the invention, an ultrasonic transmitter is positioned adjacent to, but not in contact with, the honeycomb structure. The transmitter propagates an ultrasonic wave, of preferably less than 5 MHz, through the honeycomb structure which is received, filtered and analyzed to determine the presence or absence of internal discontinuities or inhomogenieties. The ultrasonic transmitter generates an ultrasonic wave of less than five megahertz to provide a relatively high signal-to-noise ratio in the ultrasonic wave propagated through the structure.

Abstract: Embodiments contemplate methods and devices for conducting ultrasound interrogation of a medium. An ultrasound echo wave may be received at a first transducer element of a transducer array in a handheld probe. The ultrasound echo wave may also be received at a second transducer element of the transducer array. The ultrasound echo wave may also be received at a third transducer element of the transducer array. The handheld probe may process into digital data the ultrasound echo wave received at the first transducer element and the ultrasound echo wave received at the second transducer element. The processing may preclude data representative of the ultrasound echo wave received at the third transducer element from being included in the digital data. The processing may include reducing the digital data and the reduced digital data may be transmitted to a location relatively remote from the handheld probe.

Abstract: A sensor for examining a document of value in a detection range of the sensor has at least one electrical component for converting electrical energy into sound waves and/or electromagnetic fields, in particular optical radiation, for examining the document of value and/or for detecting sound waves and/or magnetic or electromagnetic fields, in particular optical radiation, from the document of value to generate detection signals. Additionally, the sensor has a holder for the component, having a recess or a hole for at least partially accommodating the component, in which the electrical component is held, and on or in which at least one conductive path extends to contact with at least one electrical contact of the electrical component.

Abstract: Methods are provided for analyzing characteristics of fluids in the context of an acoustic ejection system. Such a system has a controller, an acoustic radiation generator, and a coupling medium coupling the radiation to a reservoir holding fluid. The methods can use acoustic radiation to both perturb a surface of the fluid in the reservoir and analyze the effect of the perturbation. The methods may use information about prior fluids. The methods of the invention can determine physical characteristics such as speed of sound and viscosity. The methods also include ways to determine a level of acoustic energy suitable to eject a droplet. Preferably the methods are executed automatically under control of programming of a controller of an acoustic ejection system.

Abstract: A photoacoustic apparatus includes an acoustic lens configured to collect a acoustic wave, an acoustic detector configured to detect the acoustic wave collected by the acoustic lens, a driver configured to move at least one of the acoustic detector and the acoustic lens so as to measure the acoustic wave generated from an object to be measured due to a photoacoustic effect, and a controller configured to output a first measurement signal resulting from the acoustic wave that is generated from a first position in the object, and to eliminate a second measurement signal resulting from the acoustic wave that is generated from a second position different from the first position in the object.

Abstract: An ultrasonic transducer (100) includes a substrate (1) having a first electrode therein or on a surface thereof and a diaphragm (5) having a second electrode therein or on a surface thereof, with a cavity (4) therebetween. Further, at least one beam (7) is provided on a surface or inside of the diaphragm (5) or the second electrode.

Abstract: Porosity of aluminum ingot can be evaluated using focused beam ultrasonic testing and/or florescent dye penetrant testing. The aluminum ingot can be machine cut to form an aluminum ingot slice prior to testing. The machine cut can be performed using a polycrystalline cutting material in a “fly cutter” configuration. The polycrystalline cutting material can comprise a diamond material. The insert can cut an aluminum ingot slice to a surface roughness finish in the range of about 7-9 micro inches.

Abstract: Disclosed is a photoacoustic measurement apparatus that irradiates a light beam onto a subject, from a same side as that of an acoustic wave detector, and that measures photoacoustic waves. The photoacoustic measurement apparatus has: an acoustic wave detector; a diffraction grating member provided in front of a detection surface of the detector; a light source that generates a light beam; and an optical system that guides the light beam from the light source towards the diffraction grating member. The diffraction grating member is configured such that the light beam led to the diffraction grating member is outputted by the diffraction grating member towards a subject surface that opposes the detection surface of the detector. As a result, light beams can strike a biological body in a near-perpendicular angle. This affords greater illumination efficiency, and allows light of substantial light energy to be irradiated deep inside biological structures.

Abstract: An ultrasonic sensor, including a diaphragm cup, a housing and a decoupling element, the diaphragm cup and housing having a lateral surface, the decoupling element being at least partially made from an elastic material and having a continuous recess bounded by an inner wall of the decoupling element, the diaphragm cup and/or the housing being at least partially situated in the recess.

Abstract: A high spatial resolution phase-sensitive technique employs a scanning near field ultrasound holography (SNFUH) methodology for imaging elastic as well as viscoelastic variations across a sample surface. SNFUH uses a near-field approach to measure time-resolved variations in ultrasonic oscillations at a sample surface. As such, it overcomes the spatial resolution limitations of conventional phase-resolved acoustic microscopy (i.e. holography) by eliminating the need for far-field acoustic lenses.

Abstract: An apparatus and a method that achieve physical separation of sound sources by pointing directly a beam of coherent electromagnetic waves (i.e. laser). Analyzing the physical properties of a beam reflected from the vibrations generating sound source enable the reconstruction of the sound signal generated by the sound source, eliminating the noise component added to the original sound signal. In addition, the use of multiple electromagnetic waves beams or a beam that rapidly skips from one sound source to another allows the physical separation of these sound sources. Aiming each beam to a different sound source ensures the independence of the sound signals sources and therefore provides full sources separation.

Abstract: Systems and related methods for structural health monitoring are provided. In this regard, a representative array system includes: a component to be monitored; and an array system mounted to the component, the array system has multiple array components exhibiting spatial periodicity, the array components being operative to produce waves with frequency dependent directional characteristics, which propagate through the component, responsive to simultaneous activation of the array components.