Abstract: A surface acoustic wave (SAW) sensing device for remotely sensing structu integrity of a physical structure. The sensing device includes a piezoelectric substrate with a notch formed part way in the bottom of the substrate and along the width thereof. The substrate is mounted to a physical structure of interest. An antenna is coupled to the RF circuit on the substrate and is capable of receiving and transmitting a RF signal. Interdigital input and output transducers are disposed on the upper surface of the substrate. The input transducer is located adjacent one end of the substrate and the output transducer is located adjacent an opposing end of the substrate. Bus bars connect the input and output transducers. The input transducer provides a complementary first response upon receipt of an RF expanded linear/nonlinear FM signal from the antenna and transmits this compressed pulse to the output transducer.

Abstract: An X-band (8-12.5 GHz) amplifier comprises a bipolar junction transistor (BJT) arranged for receiving an X-band signal, amplifying the signal and providing the amplified signal to further circuitry. Input and output matching networks are advantageously provided for the BJT. Each network may have a first end for connection to a BJT and a second end for connection to a terminal, and may comprise a series connection of a first inductor, a first capacitor and a second inductor extending from the first end to the second end in that order; a third inductor connected between ground and the connection point of the first capacitor and the second inductor; and a second capacitor connected between ground and the second end. The various reactance components may be implemented on a dielectric board, for example by microstriplines and/or shaped cladding portions. An X-band oscillator may comprise the X-band amplifier described above, and a feedback circuit interconnecting an output and an input of the amplifier.

Abstract: A dual channel flexural device is fabricated on a gallium arsenide (GaAs) bstrate that includes a pair of elongated active vibrating (GaAs) bars formed in the substrate that serve as acoustic waveguides. One of the bars serves as a reference channel, while the other bar is covered with a chemically sensitive coating and operates as a sensing channel. A pair of pseudo-surface acoustic wave (SAW) transducers serving as input and output transducers are located at each end of the bars. Each of the transducers is comprised of discontinuous U-shaped elements having dimensions and mutual separations of one half the acoustic operating wavelength formed on one side of the substrate while ground electrodes are formed thereunder on the opposite side of the substrate. When the transducers are energized, a flexural motion in the bars is set up, causing the bars to vibrate.

Abstract: A dielectric resonator oscillator having a resonant structure connected to an amplifier the output of which is fed back to the input of the resonant structure. The resonant structure includes a metal cavity in which a dielectric disk is centrally mounted by a low-loss dielectric post. A pair of microstrip transmission lines extend into the cavity to provide energy outputs and inputs. Dielectric and conductive tuning screws are mounted on the cavity walls. Electrical tuning is provided via a varactor diode whose bias is adjustable. The diode may be connected in series or parallel with the microstrip transmission line.