1586 results about "Microwave frequency" patented technology

A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 OMEGA-cm at room temperature and a concentration of deep level trapping elements that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.

Printed antenna devices are provided, which can operate at RF and microwave frequencies, for example, while simultaneously providing antenna performance characteristics such as high gain / directivity / radiation efficiency, high bandwidth, hemispherical radiation patterns, impedance, etc., that render the antennas suitable for voice communication, data communication or radar applications, for example. Further, apparatus are provided for integrally packaging such printed antenna devices with IC (integrated circuit) chips (e.g., transceiver) to construct IC packages for, e.g., wireless communications applications.

Apparatus for minimally invasively measuring concentrations of constituents contained within a biological tissue structure includes a microwave energy source arranged generate a range of microwave frequencies, a first antenna coupled to the microwave energy source and arranged to transmit at least a portion of the microwave energy into the tissue structure, a second antenna arranged to receive at least a portion of the microwave energy transmitted through the tissue structure, a signal processor arranged to determine the resonant frequency of the received microwave energy, and a data processor arranged to provide an output of the concentration of constituents within the biological tissue structure according to the determined resonant frequency.

A method and system for examining biological tissue includes the steps of radiating a tissue region with a plurality of microwave radiation pulses. The microwave pulses are swept across a range of microwave frequencies. In response to the swept frequency microwave pulses, the tissue region emits a plurality of thermoacoustic signals. At least one image of the tissue region is formed from the plurality of thermoacoustic signals. The signals can be ultrawideband signals.

A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 OMEGA-cm at room temperature and a concentration of trapping elements that create states at least 700 meV from the valence or conduction band that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.

The invention discloses an online microwave frequency detector and a detecting method thereof based on a cantilever beam and a direct-type power sensor. The detector is prepared on a GaAs substrate and comprises coplanar waveguide (CPW) transmission lines, four micro-electromechanical system (MEMS) cantilever beam structures of the completely same structure, a power combiner and three MEMS direct-type microwave power sensors of the completely same structure. The micro-electronic mechanical online microwave frequency detector provided by the invention not only has the advantages of being novel in structure and smaller in size, but also can realize online detection on a microwave signal frequency, and can be compatible with a GaAs single wafer microwave integrated circuit.

The invention relates to glass articles suitable for use as electronic device housing / enclosure or protective cover which comprise a glass material. Particularly, a housing / enclosure / cover comprising an ion-exchanged glass exhibits the following attributes: (1) radio, and microwave frequency transparency, as defined by a loss tangent of less than 0.03 and at a frequency range of between 15 MHz to 3.0 GHz; (2) infrared transparency; (3) a fracture toughness of greater than 0.6 MPa*m<1 / 2>; (4) a 4-point bend strength of greater than 350 MPa; (5) a Vickers hardness of at least 450 kgf / mm<2> and a Vickers median / radial crack initiation threshold of at least 5 kgf; (6) a Young's Modulus ranging between about 50 to 100 GPa; (7) a thermal conductivity of less than 2.0 W / m DEG C; and (9) at least one of the following attributes: (i) a compressive surface layer having a depth of layer (DOL) greater and a compressive stress greater than 400 MPa, or, (ii) a central tension of more than 20 MPa.

A method of obtaining a material property of a pavement material from a microwave field generally includes generating a microwave frequency electromagnetic field of a first mode about the pavement material. The frequency response of the pavement material in the electromagnetic field can be measured, such as by a network analyzer. The measurement of the frequency response permits correlating the frequency response to a material property of the pavement material sample, such as the density. A method of correcting for the roughness of a pavement material divides the pavement into a shallow layer and a deep layer. Two planar microwave circuits measure the permittivity of the shallow and deep layer. The permittivities are correlated to correct for roughness. An apparatus for obtaining the density of a pavement sample includes a microwave circuit and a network analyzer. The network analyzer measures the frequency response to determine the density of the pavement material.

An RMS-to-DC converter implements the difference-of-squares function by utilizing two identical squaring cells operating in opposition to generate two signals. An error amplifier nulls the difference between the signals. When used in a measurement mode, one of the squaring cells receives the signal to be measured, and the output of the error amplifier, which provides a measure of the RMS value of the input signal, is connected to the input of the second squaring cell, thereby closing the feedback loop around the second squaring cell. When used in a control mode, a set-point signal is applied to the second squaring cell, and the output of the error amplifier is used to control a variable-gain device such as a power amplifier which provides the input to the first squaring cell, thereby closing the feedback loop around the first squaring cell. Accurate square law approximation at microwave frequencies can be achieved by implementing the squaring cells as series-connected three-transistor multi-tanh transconductance cells. By using carefully balanced squaring cells and a well-balanced error amplifier, approximation errors are cancelled and accurate RMS measurement is realized at high frequencies. A feedforward bootstrapping feature uses an op amp to balance the voltages at the common nodes of the transconductance squaring cells and also provides a balanced differential input drive to one of the squaring cells. A base current compensation circuit for providing accurate base compensation current to both of the squaring cells prevents errors due to DC offset voltages.