Abstract: The array antenna includes a feed line, and a plurality of radiating element sections arranged at a predetermined arranging interval in a first direction, each of the radiating element sections including at least one radiating element fed a traveling wave through the feed line. The inter-element line length as a length of the feed line between each succeeding two of the radiating element sections is longer than the arranging interval in the first direction.

Abstract: In a FM-CW or CW radar apparatus, when interference components are contained in channel signals obtained as beat signals from array antenna elements of respective channels, and the interference components result from directly receiving transmitted CW radar waves from an external source, phase shifting is applied to each of the channel signals to shift respective phases of the interference components of the respective channels to a condition corresponding to reception of interference waves from a predetermined direction. The interference components are then eliminated, and reverse phase shifting is applied to restore remaining components of the channel signals to their original phase condition.

Abstract: The tunable impedance circuit comprises capacitors C1 and C2, an inductor L1, and an inductor L2 magnetically coupled with the inductor L1. The control current Icontrol with variable phase and amplitude from the control circuit 13 flows in the inductor L2. The impedance of the inductor L1 is changed by changing the phase and amplitude of the control current Icontrol. The output impedance is set to an optimum level by setting an effective inductance and an effective quality factor of the tunable impedance circuit 12a to be optimum by means of the phase and amplitude of the control current Icontrol relative to output current IRF of RF PA 11.

Abstract: A FMCW-type radar device generates snapshot data from a beat signal that represents a received condition of the radar device every modulation period. Auto-correlation matrices generated by the snapshot data every modulation period are averaged every set of plural periods. The radar device calculates the target azimuth of a target object such as a preceding vehicle based on the averaged auto-correlation matrix based on MUSIC (MUltiple SIgnal Classification) method. This averaging is performed by weighting average based on an amount of mixed noise (or an interference amount) contained in the snapshot data in each modulation period. A weighting coefficient to be applied to the auto-correlation matrix in each modulation period is set to a value corresponding to the amount of mixed noise, namely, the interference amount of this modulation period. The weighting coefficient becomes large when the interference amount is small, and on the other hand, becomes small when it is large.

Abstract: A sampled beat signal RD is split into a plurality of short-time data SD in the time direction, for each of antenna elements. Interference component frequency of an interference wave is detected from a frequency spectrum of the short-time data SD. A digital beam forming process is performed for the interference component frequency of the interference wave to extract a peak of the electrical power of an azimuth direction and estimate an absolute value of an incoming direction of interference components. Based on the absolute value of the incoming direction of the estimated interference components, a filter for suppressing the interference components is operated to suppress the interference components.

Abstract: In a FM-CW or CW radar apparatus, when interference components are Contained in channel signals obtained as beat signals from array antenna elements of respective channels, and the interference components result from directly receiving transmitted CW radar waves from an external source, phase shifting is applied to each of the channel signals to shift respective phases of the interference components of the respective channels to a condition corresponding to reception of interference waves from a predetermined direction. The interference components are then eliminated, and reverse phase shifting is applied to restore remaining components of the channel signals to their original phase condition.

Abstract: A sampled beat signal is cut out into two or more short time data in a time direction concerning each antenna component. From a frequency spectrum of the short time data, an interference element frequency of an interference wave is detected. From the interference element frequency of the interference wave, two or more candidates of the frequency before aliasing of the interference wave are produced, and phase correction is executed on each candidate. Digital Beamforming is executed on the corrected frequency so as to extract maximum peaks of the power of an azimuth direction, and the frequency candidate showing the maximum peak power is selected and the arrival azimuth of the interference element is estimated. A filter for suppressing the interference element is applied on the short time data from the estimated arrival azimuth of the interference element so as to suppress the interference element.

Abstract: A radar system mounted on a vehicle includes a first radar and a second radar, each having a transmitter-receiver and a signal processor. The transmitter-receiver transmits radar waves to detect objects such as another vehicle or other obstacles. An operating cycle period T1, T2 and a transmission time X1, X2 during which the radar waves are transmitted are set in both radars to satisfy the formula: K·T2+X2+X1?T1?(K+1)·T2?X2?X1 under a condition that T1>T2, where K is a positive integer. By setting both radars in this manner, interference between two radars is avoided without using additional devices in the radar system, and a high detection accuracy is realized.

Abstract: An FMCW radar device executes a frequency analysis for a beat signal in a frequency increase interval and a frequency decrease interval, to obtain frequency components in a predetermined high frequency range exceeding a frequency range corresponding to a target detection frequency range within which a target object for detection should be detected. Then the FMCW radar device calculates a value related to a sum of intensities of frequency components within the high frequency range respectively for each of the frequency increase interval and the frequency decrease interval. In the case that one of the calculated integrals is larger than a threshold, the FMCW radar device determines that the FMCW radar device is interfered with by a nearby radar device.

Abstract: A sampled beat signal is cut out into two or more short time data in a time direction concerning each antenna component. From a frequency spectrum of the short time data, an interference element frequency of an interference wave is detected. From the interference element frequency of the interference wave, two or more candidates of the frequency before aliasing of the interference wave are produced, and phase correction is executed on each candidate. Digital Beamforming is executed on the corrected frequency so as to extract maximum peaks of the power of an azimuth direction, and the frequency candidate showing the maximum peak power is selected and the arrival azimuth of the interference element is estimated. A filter for suppressing the interference element is applied on the short time data from the estimated arrival azimuth of the interference element so as to suppress the interference element.

Abstract: Occurrence of interference is detected using sampled amplitude data obtained by oversampling a beat signal. It is detected by comparing the absolute value (|VD|) of variation in the sampled data with a threshold value (TH). When interference occurs, a wideband signal is superposed on the beat signal, and this disturbs the signal waveform of the beat signal to drastically varies its amplitude. Therefore, occurrence of interference can be detected without fail regardless of the scheme on which a radar as the source of an interference wave is based and even when the amplitude of the interference wave is low. In addition, when low-frequency noise is superposed on the beat signal, erroneous detection of occurrence of interference can be prevented.

Abstract: Occurrence of interference is detected using sampled amplitude data obtained by oversampling a beat signal. It is detected by comparing the absolute value (|VD|) of variation in the sampled data with a threshold value (TH). When interference occurs, a wideband signal is superposed on the beat signal, and this disturbs the signal waveform of the beat signal to drastically varies its amplitude. Therefore, occurrence of interference can be detected without fail regardless of the scheme on which a radar as the source of an interference wave is based and even when the amplitude of the interference wave is low. In addition, when low-frequency noise is superposed on the beat signal, erroneous detection of occurrence of interference can be prevented.

Abstract: A radar system mounted on a vehicle includes a first radar and a second radar, each having a transmitter-receiver and a signal processor. The transmitter-receiver transmits radar waves to detect objects such as another vehicle or other obstacles. An operating cycle period T1, T2 and a transmission time X1, X2 during which the radar waves are transmitted are set in both radars to satisfy the formula: K·T2+X2+X1?T1?(K+1)·T2?X2?X1 under a condition that T1>T2, where K is a positive integer. By setting both radars in this manner, interference between two radars is avoided without using additional devices in the radar system, and a high detection accuracy is realized.

Abstract: An FMCW radar device executes a frequency analysis for a beat signal in a frequency increase interval and a frequency decrease interval, to obtain frequency components in a predetermined high frequency range exceeding a frequency range corresponding to a target detection frequency range within which a target object for detection should be detected. Then the FMCW radar device calculates a value related to a sum of intensities of frequency components within the high frequency range respectively for each of the frequency increase interval and the frequency decrease interval. In the case that one of the calculated integrals is larger than a threshold, the FMCW radar device determines that the FMCW radar device is interfered with by a nearby radar device.

Abstract: A semiconductor triode comprises a gate electrode provided on a channel layer, wherein there is interposed an insulating metal oxide layer between a top surface of the channel layer and the gate electrode.

Abstract: A gate electrode rectangular in section is formed by patterning on a GaAs substrate as a compound substrate having a channel layer. Subsequently, a specific metal, e.g., Ti is deposited. A solid-phase reaction layer to serve as source/drain is formed in a self-alignment manner with the gate electrode by a thermal treatment. The part of the Ti film which has not been reacted is then removed. Thus the source/drain (or at least one of them) are very easily formed to a shallow junction depth without using any ion implantation process. Realized is a semiconductor device showing an excellent device characteristics, capable of suppressing occurrence of short-channel effect even in its shortened gate length for reducing the device size.

Abstract: A semiconductor triode comprises a gate electrode provided on a channel layer, wherein there is interposed an insulating metal oxide layer between a top surface of the channel layer and the gate electrode.

Abstract: A gate electrode rectangular in section is formed by patterning on a GaAs substrate as a compound substrate having a channel layer. Subsequently, a specific metal, e.g., Ti is deposited. A solid-phase reaction layer to serve as source/drain is formed in a self-alignment manner with the gate electrode by a thermal treatment. The part of the Ti film which has not been reacted is then removed. Thus the source/drain (or at least one of them) are very easily formed to a shallow junction depth without using any ion implantation process. Realized is a semiconductor device showing an excellent device characteristics, capable of suppressing occurrence of short-channel effect even in its shortened gate length for reducing the device size.

Abstract: A semiconductor memory device including a plurality of bit lines and a plurality of word lines which intersect to form a matrix of cross points. A respective memory cell is disposed at each cross point and corresponds to the respective word line and respective bit line intersecting at the respective cross point. Each memory cell includes a transfer gate having a first current terminal connected to the corresponding bit line and a control terminal connected to the corresponding word line. Each memory cell also includes a pair of serially connected negative differential resistance memory elements having an interconnection node therebetween. The interconnection node is connected to the second current terminal of the transfer gate.

Abstract: A method of producing a semiconductor device (MESFET) which includes the following steps (a) to (h): (a) forming a trapezium dummy gate, which is made of a first insulating material (SiO.sub.2) and has two normal slopes, on a semiconductor substrate (of a compound semiconductor); (b) selectively forming ohmic electrodes, coming in contact with the dummy gate, on the semiconductor substrate; (c) forming an element isolation region in the semiconductor substrate; (d) forming an insulating film of a second insulating material (Si.sub.3 N.sub.4), different from the first insulating material, over the entire surface; (e) selectively removing projected portions of the dummy gate and insulating film to make a flat portion composed of the remaining dummy gate and insulating film; (f) removing the dummy gate to form an opening having two reverse slopes; (g) forming a sidewall portion of a third insulating material (SiO.sub.