초록 ▼

Reception antenna elements are formed so that the reception beam axis in the vertical direction of at least one reception antenna element of a transmission/reception unit is displaced from the reception beam axes of the other antenna elements. Therefore, the amplitude (intensity) of the reception si

Reception antenna elements are formed so that the reception beam axis in the vertical direction of at least one reception antenna element of a transmission/reception unit is displaced from the reception beam axes of the other antenna elements. Therefore, the amplitude (intensity) of the reception signals of the reception antennas which are caused by a target is different from the amplitude (intensity) of the reception signal of the reception antenna element, and the amplitude difference is varied depending on the orientations of the reception beam axes in the vertical direction of the reception antenna elements. Accordingly, the amplitude difference when the reception beam axes of the reception antenna elements are correctly oriented to a desired direction is measured in advance, and the amplitude difference thus measured is set as a target amplitude difference, whereby the mount angle of the transmission/reception unit can be easily and accurately adjusted.

대표청구항 ▼

What is claimed is: 1. A radar device for a vehicle, comprising: a reception antenna having plural reception antenna elements arranged along the width direction of the vehicle so that a beam axis of at least one of plural reception beams in the vertical direction is displaced from beam axes of the

What is claimed is: 1. A radar device for a vehicle, comprising: a reception antenna having plural reception antenna elements arranged along the width direction of the vehicle so that a beam axis of at least one of plural reception beams in the vertical direction is displaced from beam axes of the other reception beams in the vertical direction; a transmission antenna having a transmission beam area that covers areas of the reception beams of the plural reception antenna elements; and an amplitude difference calculator for making the transmission antenna transmit a transmission signal to a target disposed at a predetermined position when the mount angle for mounting the radar device on the vehicle is adjusted, making the plural reception antenna elements receive a reflection wave of the transmission signal from the target to generate reception signals, and then calculating the amplitude difference between the amplitude of the reception signal of the reception antenna element having the displaced reception beam axis and the amplitude of the reception signal of the reception antenna elements having the non-displaced reception beam axes. 2. The radar device according to claim 1, further comprising a storage unit for storing in advance the relationship between the amplitude difference and the orientation of the reception beam axes of the reception antenna elements having the non-displaced reception beam axes in the vertical direction. 3. The vehicle radar device according to claim 1, wherein the transmission signal is subjected to frequency modulation so that the frequency varies continuously, wherein the amplitude difference calculator is equipped with a beat signal generator for generating beat signals each of which corresponds to the frequency difference between the transmission signal and each of the plural reception signals occurring in the plural reception antenna elements and a frequency spectrum calculator for calculating a frequency spectrum representing the magnitude of each frequency component contained in each of the beat signals generated by the beat signal generator, the amplitude difference being calculated while the peak of the frequency spectrum calculated by the frequency spectrum calculator is set as the amplitude of each reception signal. 4. The vehicle radar device according to claim 3, further comprising a reflection object detector for detecting the distance to a reflection object reflecting the transmission signal and the relative speed between the vehicle concerned and the reflection object on the basis of the peak of the frequency spectrum calculated by the frequency spectrum calculator. 5. The vehicle radar device according to claim 3, further comprising a direction detecting unit for detecting the direction to the reflection object in the vehicle width direction on the basis of the phase difference at the peak frequency of the frequency spectrum calculated by the frequency spectrum calculator. 6. The vehicle radar device according to claim 1, wherein the amplitude of the reception signals of the reception antenna elements having the non-displaced reception beam axes is calculated by averaging the reception signals of the reception antenna elements. 7. The vehicle radar device according to claim 6, wherein when the reception signals of the plural reception antenna elements are averaged, the reception signal of the reception antenna element having the displaced reception beam axis is contained in the plural reception antenna elements. 8. The vehicle radar device according to claim 1, wherein the reception beam axis of a reception antenna element disposed at an end portion of the vehicle in the vehicle width direction is displaced among the plural reception antenna elements. 9. The vehicle radar device according to claim 4, wherein the reception beam axis is displaced so as to direct to the ground surface, and the reflection object detector may use the reception signals of the reception antenna elements having the non-displaced reception beam axes in order to detect reflection objects spaced from the vehicle concerned at a predetermined distance or more and use the reception signal of the reception antenna element having the displaced reception beam axis in order to detect reflection objects existing within a predetermined distance from the vehicle concerned. 10. A method of adjusting a mount angle at which a vehicle radar device is mounted on a vehicle, the vehicle radar device containing a transmission antenna and a reception antenna comprising plural reception antenna elements disposed along a vehicle width direction so that the beam axis in the vertical direction of at least one reception beam in plural beam axes is displaced from the beam axes in the vertical direction of the remaining beam axes, the method comprising: transmitting a transmission signal to a target disposed at a predetermined position; receiving a reflection wave of the transmission signal from the target through plural reception antenna elements and generating reception signals; and calculating the amplitude difference between the amplitude of a reception signal of a reception antenna element having a displaced reception beam axis and the amplitude of reception signals of reception antenna elements having non-displaced reception beam axes. 11. The method according to claim 10, wherein the relationship between the amplitude difference and the direction of the reception beam axis of the reception antenna elements having the non-displaced reception beam axes is determined in advance, and the mount angle of the reception antenna in the vehicle vertical direction is adjusted on the basis of the relationship thus determined. 12. The method according to claim 10, wherein the transmission signal transmitted from the transmission antenna is frequency-modulated so that the frequency thereof varies continuously, and wherein a beat signal corresponding to the frequency difference from the transmission signal is generated from each of plural reception signals occurring in the plural reception antenna elements, a frequency spectrum indicating the magnitude of each frequency component contained in the beat signal is calculated for each beat signal, and the amplitude difference is calculated while the peak of the frequency spectrum concerned is set as the amplitude of the reception signal. 13. The mount angle adjusting method according to claim 10, wherein the amplitude of the reception signal of the reception antenna elements having the non-displaced reception beam axes is calculated by averaging the reception signals of the plural reception antenna elements. 14. The mount angle adjusting method according to claim 13, wherein the reception signal of the reception antenna element having the displaced reception beam axis is contained in the plural reception signals of the plural reception antenna elements when the reception signals of the plural reception antenna elements are averaged.