Abstract: There is provided a negative differential resistance amplifier comprising a negative differential resistance transistor having negative input conductance by utilizing resonant tunneling effect. The transistor is electrically connected to a signal source circuit in cascade, and the following relation is established in the negative differential resistance amplifier:0<gs-gi<Gwherein gs (gs>0) indicates a conductance measured when viewed from an interface between the negative differential resistance transistor and the signal source circuit to the signal source circuit, -gi (gi>0) indicates a conductance of the negative differential resistance transistor, and G (G<gs) indicates a predetermined conductance. The above mentioned negative differential resistance amplifier provides not only excellent signal unilaterality, but also higher gain, lower noise and wider band by setting certain matching conditions between the negative differential resistance transistor and the signal source circuit.

Abstract: An amplifier including an in phase feedback signal to therefore exhibit negative resistance is receptive of an input alternating signal which includes a frequency F. The output of the amplifier is coupled to a resonator adjusted to a center frequency F and having undesirable resistance which is offset by the negative resistance of the amplifier. The resonator includes an inductor and adjustable capacitor arranged either in series or in parallel with the amplifier to therefore change the value of F.

Abstract: An electronically adjustable capacitor (varactor), an active element such as a Field Effect Transistor arranged to exhibit negative resistance, and an inductor are arranged as a frequency tunable resonator suitable for use at microwave frequencies. The negative resistance of the active element may be adjusted to compensate for the resistance of the other resonator components such that the resonator exhibits very high Q and therefore high selectivity and low loss. The resonator may be used as a filter element in a tunable filter. Alternatively the negative resistance of the active element may be adjusted such that the resonator exhibits net negative resistance and may be incorporated in a tunable reflection type amplifier.

Abstract: A modular microwave power combiner having a plurality of identical microwave diode amplifier circuits grouped in sets within the body of a modular unit which are electrically coupled in parallel to a central cavity sized to be resonant at a single frequency to minimize mismoding thereby enhancing combiner efficiency. A number of waveguides are provided for coupling of the microwave diode in each amplifier circuit to the resonant cavity, and the waveguides are situated on one side of a PC board at the top of each modular unit. Since each of the modular units is essentially identical in physical size and shape, the overall power output of the power combiner can be increased by merely adding additional modular units. The individual modular units are sized to fit top-to-bottom such that the respective resonant cavities are spaced apart by one-half wavelength (.lambda./2) for the parallel electrical coupling of all of the resonating cavities.

Abstract: A transmission line is disclosed which comprises a conductive layer, a resistive semiconductor layer disposed on the conductive layer and a blocking electrode disposed on the resistive semiconductor layer. By applying a biasing voltage between the blocking electrode and the conductive layer, a depletion layer is produced in the resistive semiconductor layer, the depletion layer formed in the semiconductor layer being used as a medium for transmission of electromagnetic wave.

Abstract: A millimeter wave amplifier having broadband characteristics in which a G diode or other two terminal negative resistance device having an integral heat sink is center mounted in a reduced height waveguide. The heat sink is attached to a mechanism for selectively adjusting its penetration into the waveguide cavity. The introduction of the heat sink into the waveguide cavity creates a discontinuity to the propagation of energy which causes localized waveguide modes other than the dominant mode to exist. The adjustable position of the heat sink allows the reactance due to the introduction of these modes to be variable, proper adjustment resulting in the cancellation of the parasitic reactances inherent in the packaged negative resistance device.

Abstract: A microwave amplifier is disclosed using a nonreciprocal three port junction circulator. The amplifier uses a ferrite circulator having an input port, an output port and a third electrical port. A semiconductor device such as an IMPATT diode having negative resistance is located adjacent and electrically coupled to the third electrical port. The negative resistance of the IMPATT diode combines with the output response of the third electrical port of the circulator to provide power amplification of microwave signals received on the input port.

Abstract: A network characterized at a reference terminal pair by a negative resistance at a frequency near nf.sub.o, where n is an integer greater than one. The network comprises a circuit element characterized by a negative resistance at frequencies in the range f.sub.1 to f.sub.2 where f.sub.1 < f.sub.o < f.sub.2, a passive non-linear network and a filter network for coupling the negative resistance element to the passive non-linear network only at frequencies near f.sub.o and to the reference terminal pair only at frequencies near nf.sub.o. The negative resistance network may be configured with suitable components as a negative resistance amplifier and as an injection locked oscillator.

Abstract: A broad-band microwave amplifier including a semiconductor TRAPATT diode generating a microwave signal at its fundamental, second and third harmonic frequencies. Energy is extracted at the second harmonic frequency and a certain impedance loading is provided at the fundamental and third harmonic frequencies by an open-ended tapered microstrip idler circuit connected in parallel with the diode. The tapered idler circuit also provides a predetermined relatively small rate of change of impedance with respect to frequency changes to obtain a wide instantaneous bandwidth of the amplifier.

Abstract: A Microwave reflection amplifier having improved gain, bandwidth and noise characteristics, uses two negative-resistance diodes, such as Gunn-effect diodes, connected in series across the terminals. The diodes are series resonated by inductance in their leads. The gain and bandwidth are higher than in amplifiers using a single diode. A shunt-resonant circuit is connected across one diode to improve the gain-bandwidth. A second shunt-resonant circuit may be connected across the terminals. At very high frequencies, the amplifier uses strip-line or microstrip circuitry and the shunt resonators are half-wavelength transmission lines.

Abstract: A frequency tunable microwave apparatus including a semiconductor TRAPATT diode generating a microwave signal at its fundamental, second and third harmonic frequencies. Energy is extracted at the second harmonic frequency and a certain impedance loading is provided at the fundamental frequency and third harmonic by a variable impedance hybrid idler circuit. The hybrid idler circuit comprises a distributed transmission line serially connected to a lumped variable capacitor. Variations in the capacitance of the variable capacitor tune the fundamental frequency without substantially varying the impedance loading conditions of the diode allowing energy to be extracted at the second harmonic frequency throughout the tunable frequency range.

Abstract: Disclosed is a millimeter wave waveguide structure adapted for operation with negative resistance devices, such as solid state avalanche breakdown diodes, at frequencies up to about 170 GHz or higher. A central portion of the structure is formed by a cylindrical metallic impedance transformer and bias pin which has a major face thereof substantially parallel to a common lower waveguide wall of the structure. A negative resistance device is DC coupled between this common waveguide wall and one edge of the impedance transformer, so that the impedance transformer also provides the required DC bias to the negative resistance device. Other portions of the waveguide structure include a first upper waveguide wall, immediately adjacent one side of the impedance transformer, and this wall, together with the common lower waveguide wall, forms a tuning cavity into which a sliding tuning short is positioned.

Abstract: This microwave circuit incorporates a transistor structure that provides either a two port amplifier or an injection frequency locked oscillator. This circuit eliminates circulators employed with Gunn and Impatt diode amplifiers and injection frequency locked oscillators. The collector-base junction is reverse biased so that the collector region functions either in the Impatt mode or in the transferred electron mode. An RF input signal is applied across the forward biased emitter-base junction. With a load across the collector-base junction having a conductance equal to the absolute value of the negative conductance generated by the collector region, the circuit functions as an oscillator at a frequency which is injection locked to the frequency of the input signal. With a load of increased conductance to suppress oscillations, i.e. overload the collector region, the circuit functions as an amplifier.