Abstract: An electronic magnetometer and a method for measuring a magnetic field are provided. A Gunn diode with magnetic shielding and a Gunn diode without magnetic shielding generate different induced high-frequency oscillating currents in various environments. The high-frequency oscillating current of the Gunn diode with magnetic shielding and the high-frequency oscillating current of the Gunn diode without magnetic shielding are processed by circuits and subsequently compared. The difference of frequencies in the two currents is proportional to the magnitude of magnetic field, and the magnitude of magnetic field is obtained.

Abstract: A modulation-signal generating circuit includes a temperature monitoring unit that detects a casing temperature of the circuit, a voltage control oscillator including two variable impedance circuits that independently control oscillation frequency based on an input control voltage, a frequency-correction-voltage generating unit that outputs a voltage for compensating for a temperature drift of an oscillation frequency according to the casing temperature detected by the temperature monitoring unit, to one of the variable impedance circuits, and an FM-modulation-voltage generating unit that outputs a modulation voltage containing a constant DC component not depending on temperature and a predetermined AC component, to the other variable impedance circuit, under a temperature drift compensation condition of the frequency-correction-voltage generating unit.

Abstract: A voltage controlled oscillator having a reduced oscillation frequency-modulation sensitivity variation and having a positive modulation function is designed to: (a) reduce the modulation variation by making the rate of change in oscillation frequency with a certain change in a modulation signal generally constant with respect to a wide range of oscillation frequencies; (b) reduce the manufacturing cost by using only one varactor diode; and (c) reduce the cost of a system using the voltage controlled oscillator by eliminating the need for correction of the modulation variation on the side of a system using the oscillator. In a variable capacitance circuit of the voltage controlled oscillator, the cathode of a varactor diode is connected to a control voltage terminal and is also connected to a modulation signal input terminal by a coupling resistor and a voltage dividing resistor.

Abstract: A broadcast transmitter for generating low power modulated signals, especially for a wireless speaker system. A signal source such as a source of composite audio signals including left and right audio signals and a pilot signal are applied to a radio frequency signal oscillator. The radio frequency signal oscillator includes a bipolar transistor connected in a common base configuration, and having a stripline element as a frequency determinative component in the collector circuit of the bipolar transistor. The modulating signal is applied to the base of the bipolar transistor which modulates the collector junction capacitance of the transistor thereby frequency modulating the signal produced by the oscillator. Varactor tuning is provided for setting a nominal frequency of oscillation.

Abstract: The observation of self-sustained pulsation and transient self-pulsation in laser diodes at 1300 nm is described with the effects of optoelectronic feedback on the pulsations. Transient self-pulsation has a lifetime of a few minutes with frequencies up to 7 GHz. The linewidth of self-pulsation is on the order of 0.5 GHz. With optoelectronic feedback, the transient self-pulsation can be stabilized and enhanced. The center frequency of feedback-sustained pulsation is dependent on the passband of the bandpass filter in the feedback loop. The linewidth of feedback-sustained pulsation is significantly reduced to about 20 kHz. The optical spectra of the laser diodes exhibit coherence collapse at weak optoelectronic feedback. The feedback sustained pulsation can be frequency modulated. Applications of the feedback-sustained pulsation include subcarrier multiplexing optical networks.

Abstract: The invention relates to a biased electronic circuit in which a voltage-controlled component has a characteristic with a non-linear portion and a substantially linear portion. The circuit is biased by a voltage being applied to one terminal of the component thereby shifting the operation of the component to the linear portion.

Abstract: A fundamental or subharmonic optically injection locked oscillator is coupled to a phase locked loop circuit. The injection locked oscillator has two single stage HEMT amplifiers with parallel feedback from the drain of a second transistor to a gate of a first transistor. A feedback resonant network controls the oscillator frequency. A microwave/millimeter wave source modulates a laser diode and the signal from the laser diode is then transmitted via an optical fiber to a PIN photodetector diode. The signal from the photodetector diode is injected into the oscillator at an nth subharmonic of the oscillator frequency. The feedback network may consist of a microstrip gap resonator with two tuning varactors at the ends of the resonator. The phase locked loop includes a balanced mixer used as a phase detector to compare the nth harmonic of the signal from the photodetector diode to the sampled output of the oscillator.

Abstract: For minimization of a microstrip line and improvement of a Q value, the line length and width of the microstrip line are minimized, and the high frequency trend of the resulting resonant frequency is lowered and corrected to the resonant frequency near the oscillation frequency of an oscillator by connecting an additional capacitance component to the microstrip line. Thereby, the minimization of the microstrip line or the minimization of an oscillation circuit and characteristics equivalent to a dielectric coaxial resonator may be readily obtained. The strip line and the additional capacitance component are made as one piece circuit elements. The microstrip line is connected with a stub such that the stub may be trimmed to adjust the oscillation frequency. A cascode connecting amplifier which lessens the oscillation frequency fluctuation due to load variations is used.

Abstract: For realizing a highly sensitive and favorably linear frequency modulator stably operating with a small-sized and readily manufactured arrangement, input and output strip electrodes are disposed in face on both ends of a ferri-magnetic film deposited on a magnetic substrate and applied with a DC magnetic field perpendicular thereto, a high frequency electro-magnetic wave being applied through the input electrode, so as to generate a magneto-static forward volume wave propagating through the magnetic film, the propagation phase of which is modulated in response to the intensity variation of the applied magnetic field modulated by a signal, so as to derive a frequency modulated electro-magnetic wave from the output electrode.