Abstract: An electromagnetic, reflective type, active proximity sensor includes a transmitter, the transmitter including a voltage controlled oscillator circuit, a transmitter circular waveguide and a transmitter polarization circuit. The voltage controlled oscillator circuit generates an output signal which is modulated such that the frequency of the output signal varies over time between a range of frequencies. The frequency varying, output signal is provided to the transmitter circular waveguide and propagated to the transmitter polarization circuit where it is circularly polarized in a first circular direction. The circularly polarized, frequency varying, output signal is radiated by the transmitter to the target, where it strikes the target and reflects back toward the sensor to form return signals. The return signals, upon being reflected, rotate in a second circular direction opposite to the first circular direction.

Abstract: A low power, low cost, millimeter wave (MMW) proximity sensor that provides over a 6:1 increase in minimum detection range (55 mm minimum) compared to standard 18 mm inductive proximity sensors preferably includes a low cost MMW Gunn oscillator, MMW detector and analog processing/driver circuitry. The sensor is preferably designed for 3-wire operation and will fit in a standard 18 mm tube.

Abstract: A direct digitally synthesizer-based, injection locked oscillator includes a direct digital synthesizer for generating a digitally synthesized signal at frequency f.sub.0, an analog oscillator circuit for generating an analog signal at frequency f.sub.1 and a filter coupled to the direct digital synthesizer for filtering the digitally synthesized signal to provide a signal at frequency Nf.sub.0. N may be an integer from 1 to 10. Also included is a coupler to couple the filtered, digitally synthesized signal into the analog oscillator to lock the frequency of the analog output signal to the frequency of the digitally synthesized signal such that the frequency f.sub.1 is equal to the frequency Nf.sub.0. The coupler also electrically couples the analog signal from the analog oscillator circuit to a second filter to filter the analog signal. An amplifier electrically coupled to the second filter amplifies the filtered signal to provide an analog oscillator output signal.

Abstract: A Q enhanced dielectric resonator circuit includes a metal enclosure having interior walls defining a chamber. Secured to at least two interior walls is a dielectric substrate. Flatly mounted to at least one side of the dielectric substrate is a substrate stripline. A dielectric resonator is secured to the dielectric substrate at a selected distance from the substrate stripline. The dielectric substrate is positioned a sufficient distance from a ground plane such that the magnetic field lines of the dielectric resonator do not significantly interact with the ground plane. The dielectric resonator is also positioned such that there is substantial coupling of the magnetic field lines of the dielectric resonator with the magnetic field lines of the substrate stripline.

Abstract: An oscillator operational in the millimeter wave and microwave range, including frequencies greater than 60 GHz, is provided with reduced phase noise by enhancing Q of the resonant circuitry by reactively terminating fundamental frequency oscillation and increasing stored fundamental frequency energy in the resonant circuitry. A two frequency system is provided with constructive reflection of energy at fundamental frequency back to the resonant circuitry, and with isolation of fundamental frequency energy from the output load. Energy to the output load is obtained from the in-situ generated second harmonic of the active element. Phase noise is reduced by enhancing Q by more than an order of magnitude.

Abstract: Flicker (1/f) noise is suppressed in an oscillator by reducing oscillator voltage-frequency pushing to zero. A varactor (56) is incorporated in the resonator circuit and is biased with a tuning voltage setting the varactor to a capacitance value providing the zero oscillator pushing at a given frequency. A common bias connection (62) is provided between the varactor and the active element (64) such that a random perturbation voltage change across the active element also causes a change in voltage across the varactor, to compensate a change in oscillator frequency otherwise caused thereby. The varactor capacitance versus voltage characteristic is shaped such that a change in active element voltage provides a change in varactor voltage, and the combination of these voltage changes results in a zero change in oscillator frequency. The tuning slope of the oscillator provided by the varactor is opposite the tuning slope of the oscillator resulting from a change in active element voltage.

Abstract: A varactor tuned oscillator (10), VCO, operational in the millimeter wave range including frequencies greater than 30 GHz, includes a lumped element active circuit (12) with a negative resistance, a lumped element tuning circuit (16) coupled to the active circuit and providing resonant circuitry in combination therewith, and a VCO output (26) reactively terminated at the fundamental frequency of oscillation and generating a higher order output harmonic at least as high as the second order. The reactive termination at fundamental frequency eliminates the intrinsic diminishing effect on tuning range of resistive loading, to extend tuning range and provide an ultrabroadband VCO. The VCO output (26) is resistively loaded at the higher order harmonic. The output is obtained from the higher order harmonic generated in-situ in the active element (14). Measured performance included continuous tuning from 46 to 66 GHz, a 20 GHz tuning range, with a maximum power output of +6 dBm.

Abstract: An oscillator (10) operational in the millimeter wave range including frequencies greater than 30 GHz includes a lumped element active circuit (12) including an active element (14) with a negative resistance, a lumped element resonator circuit (16) in parallel therewith, and an antenna (18) extending directly from the oscillator without an intermediate impedance matching section therebetween and without an isolation element therebetween. The antenna has a length of nominally a quarter wavelength at the desired fundamental frequency, and has zero connection length from the oscillator. The antenna serves a dual function of radiating the energy generated by the oscillator and also transforming the output impedance of the oscillator to the impedance of transmission media providing a load, such as free space or a wave guide.

Abstract: Frequency/temperature compensation of millimeter wave lumped active element oscillators is disclosed by use of a simple capacitive compensating element, and including printed circuit versions in which the temperature compensating capacitor is printed in-situ with the circuit elements.

Abstract: A combined phase shifter and signal source are formed by injection locking a variable frequency oscillator. The free running frequency control of the oscillator operates as a phase control when the oscillator is injection locked. The invention functions as a phase shifter which exhibits gain, permitting its use in a unique phased array antenna system.

Abstract: A tunable millimeter wave frequency Gunn oscillator operates efficiently beyond the normal Gunn oscillator frequency range through the use of a second harmonic enhancement circuit. The enhancement circuit is tuned to the fundamental frequency of the oscillator and is tracked with a second harmonic circuit to provide a wide tuning range. Lumped element circuitry is used to aid in providing the wide tuning range and to facilitate adjustment and fabrication.

Abstract: A tuning compensation device to reduce post-tuning frequency drift in voltage controlled oscillators, comprising a thermoelectric element, such as a wafer of doped semiconductor material, in contact with the junction of a tuning element, such as a varactor diode, to produce a correction to the control voltage and thereby compensate for thermally induced frequency drift.

Abstract: Microwave devices for power conversion between harmonically related frequencies, using an oversized cavity and antenna means to provide the required coupling to a varactor therein.