Hitachi, Ltd.

Toshiyuki Nagasaku

Hiroshi Kondoh

Hiroshi Shinoda

Naoyuki Kurita

Hideyuki Nagaishi

Yusuke Wachi

Mitsutoshi Morinaga

Kazuhiro Nagaoka

A transfer impedance from input terminals of a resonator to output terminals of the resonator is larger than a driving-point impedance of the input terminals of the resonator at an oscillation frequency. The input terminals of the resonator are connected with the drain terminals of transistors Qand Qthat are outputs of a differential amplifier, and the output terminals of the resonator are connected with gate terminals of the transistors Qand Qthat are inputs of the differential amplifier. With this configuration, during the oscillating operation, the oscillation voltage amplitude of the gate terminals of the transistors Qand Qbecomes larger than the oscillation voltage amplitude of the drain terminals. Therefore, it is possible to prevent the transistor, which is oscillating, from operating in a triode region, and suppress the deterioration of the Q-factor.

Oscillator and communication system using the same

There is provided a highly accurate velocity sensor having a reduced detection error. A sensor circuit unit generates an electromagnetic wave and emits it from a transmission antenna. Furthermore, a reception antenna receives a reflection wave from the ground and a mixer mixes it with a local signal, thereby generating a low-frequency signal. The electromagnetic wave emitted from the sensor circuit unit shapes a beam by a dielectric lens before emitting it toward the ground. Here, the beam shape is such that the beam width in the vicinity of the sensor is smaller than the beam width in the vicinity of the ground.

Velocity sensor and ground vehicle velocity sensor using the same

An inexpensive surveillance radar apparatus capable of identifying the kind of an object by using a monopulse radar that performs wide-angle two-dimensional surveillance. The radar apparatus receives reflected waves from a plurality of points on a moving object within a monitoring area, using a monopulse radar apparatus for measuring of angles, and determines the reflection point for each reflected wave, and then calculates the position and the width in the measuring angle of the surveillance radar of a moving object.

Radar apparatus

The present invention provides that a monopulse radar system to correct an amplitude error and a phase error developed between receiving channels and improve the accuracy of a detected angle. A part of a transmit signal is supplied to respective channels on the receiving side through a signal transmission line for calibration. At this time, the gains of a variable phase shifter and a variable gain amplifier are adjusted so that an azimuth angle of a pseudo target, based on a signal for calibration, which is calculated by signal processing means, reaches a predetermined angle. In the monopulse radar system of the present invention, calibration work is simplified and an angular correction can be automated. The present monopulse radar system of the present invention is capable of coping even with variations in characteristic after product shipment due to environmental variations and time variations in parts characteristic.

Monopulse radar system

The invention intends to provide a sensor module suitable for miniaturization and reduction in costs, in the radar sensor that uses a millimeter or sub-millimeter wave signal of which frequency is more than 20 GHz. To accomplish this problem, the radar sensor is integrated into a one chip MMIC, in which an active circuit including an oscillator and a mixer is formed with an antenna on one semiconductor substrate. Further, the MMIC is sealed with a resin package. A dielectric lens is formed on the resin package over the antenna to attain a desired beamwidth. Thereby, the lens and the resin package can integrally be formed by a metal mold, thus reducing the cost.

Radar sensor

An automotive radar which can process signals at high speed to detect a target in a wide angle range is provided. The automotive radar comprises a transmitting antenna which emits an electromagnetic wave, two receiving antennas which receive the electromagnetic wave reflected by a target, an antenna plate on which the transmitting antenna and two receiving antennas are arranged. It also includes a drive which rotates the antenna plate in an azimuth direction, which corresponds to the direction of arrangement of the two receiving antennas, to scan a detection angle formed by the two receiving antennas. The drive has rest time between scans to stop rotation. The automotive radar also includes a signal processor which detects the azimuth angle of the target with respect to a reference direction during the rest time according to received signals from the two receiving antennas and the rotation angle of the antenna plate at rest.

Automotive radar

The oscillator includes an active device, a substrate, a microstrip line formed on the substrate, and a dielectric block. The resonator is made up with the microstrip line and the dielectric block that is disposed so as to couple with the microstrip line. The active device produces a negative resistance in a desired oscillation frequency band. The dielectric block is set such that a resonance frequency of the lowest order mode of the dielectric block is lower than a desired oscillation frequency, and the resonance frequency of one of the higher order modes coincides with the desired oscillation frequency. The oscillator is generated with the higher order mode of the resonator. Thus, the invention provides at a low cost a millimeter wave band oscillator of a low phase noise by using this oscillator, and a transmitter-receiver module and a radar system applying this oscillator to the local signal generator.

Oscillator, transmitter/receiver module and radar system

A multiple PLL oscillator for oscillating and outputting a plurality of frequencies having a predetermined step frequency, comprising a first and a second reference frequency sources, a switch for selecting the ore of outputs of the first and the second reference frequency sources alternatively and at predetermined time interval, and a PLL frequency synthesizer generating a millimeter wave oscillation output corresponding to each of the first and second reference frequency sources.

Multiple PLL oscillator and multiple CW radar used therefore

A monopulse radar system aims to correct an amplitude error and a phase error developed between receiving channels and improve the accuracy of a detected angle. To achieve the above aim, part of a transmit signal is supplied to respective channels on the receiving side through a signal transmission line for calibration. At this time, the gains of a variable phase shifter and a variable gain amplifier are adjusted so that an azimuth angle of a pseudo target, based on a signal for calibration, which is calculated by signal processing means, reaches a predetermined angle. Therefore, calibration work is simplified and an angular correction can be automated. Therefore, the present monopulse radar system is capable of coping even with variations in characteristic after product shipment due to environmental variations and time variations in parts characteristic.

Growing community of inventors

Kokubunji, Japan

Toshiyuki Nagasaku