Communications: directive radio wave systems and devices (e.g. – Directive – Beacon or receiver
Reexamination Certificate
1999-03-15
2001-06-12
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Beacon or receiver
C342S074000, C342S075000, C342S080000, C342S149000, C342S195000, C342S196000, C342S417000, C342S422000
Reexamination Certificate
active
06246365
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radar apparatus for electrically carrying out scanning and, more particularly, to a radar apparatus suited for on-vehicle use.
2. Related Background Art
The on-vehicle radar apparatus is often utilized for recognition of cars etc. running ahead of a car and in that case, it is necessary to discriminate a preceding car from objects that cannot be obstacles because of their high altitudes from the road surface, such as road signs, information boards, and so on.
The invention to meet this demand is the on-vehicle monopulse radar apparatus for detecting a target by mechanically carrying out horizontal scanning and detecting an altitudinal bearing of the target by the monopulse method, as disclosed in Japanese Laid-open Patent Application No. 9-288178.
Since this on-vehicle monopulse radar apparatus can detect the altitudinal bearing of the target by the monopulse method, it can discriminate the cars from the road signs, information boards, etc. whose distances from the road surface are greater than those of the cars.
In this prior art, however, a plurality of receiving antennas of the mechanical scanning type are arrayed vertically, so that there are limitations on narrowing the space between the vertical receiving antennas. On the other hand, the monopulse method has a feature that the angular detection range becomes narrower as the antenna space increases. Therefore, the prior art described above had the problem that the angular range of detection in elevation was not assured sufficiently.
SUMMARY OF THE INVENTION
The radar apparatus of the present invention has been accomplished in order to solve the above problem and one thereof is a radar apparatus comprising: a receiving antenna having an array antenna in which a plurality of antenna elements are arrayed in a horizontal direction; and a signal processing section for carrying out recognition of a target existing in a predetermined horizontal bearing range from receive signals received by the receiving antenna, by electrically carrying out horizontal scanning of an antenna pattern of the receiving antenna, wherein at least one of the antenna elements is placed with a shift in a vertical direction, and wherein the signal processing section detects an altitudinal bearing of the target by a monopulse method by use of a receive signal from the antenna element with the shift in the vertical direction.
The vertical shift amount of the antenna element can be properly designed according to the purpose and there are no specific restrictions as to the arrangement on the extent of decrease of the shift amount. As this shift amount becomes smaller, the angular detection range becomes wider on in elevation.
There are a variety of vertical shift ways of the antenna elements; for example, they may be shifted alternately or only necessary antenna elements may be selectively shifted in the vertical direction.
In the case of the horizontal, electrical scanning of the antenna beam using the receive signals from the respective antenna elements, it is desirable to effect correction according to the shift amount on the receive signal from the antenna element with the shift in the vertical direction.
Another radar apparatus of the present invention is a radar apparatus comprising: a first receiving antenna having an array antenna in which a plurality of antenna elements are arrayed in a horizontal direction; a second receiving antenna having an array antenna in which a plurality of antenna elements are arrayed in a vertical direction; and a signal processing section for carrying out recognition of a target, based on receive signals from the first and second receiving antennas; wherein said signal processing section is arranged to carry out recognition of said target existing in a predetermined horizontal bearing range by electrically carrying out horizontal scanning of an antenna pattern of said first receiving antenna, to carry out recognition of said target existing in a predetermined altitudinal bearing range by electrically carrying out vertical scanning of an antenna pattern of said second receiving antenna, and, in the case of a plurality of targets being detected, to carry out identification of targets detected by the horizontal scanning and targets detected by the vertical scanning, based on intensities of receive signals.
Since this radar apparatus comprises the receiving antenna (the second receiving antenna) for vertical scanning, separate from the receiving antenna (the first receiving antenna) for horizontal scanning, the angular detection range can be set freely in elevation.
The scanning throughput is smaller and the size of the apparatus is also smaller than those of the radar apparatus for detecting the two-dimensional position of the target by using a two-dimensional array of antenna elements and electrically carrying out the vertical and horizontal scannings.
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 2929056 (1960-03-01), Page
patent: 2950474 (1960-08-01), Page
patent: 3274590 (1966-09-01), Page
patent: 4103304 (1978-07-01), Burnham et al.
patent: 4768034 (1988-08-01), Preikschat et al.
patent: 5248984 (1993-09-01), Sezai
patent: 5600326 (1997-02-01), Yu et al.
patent: 6087974 (2000-07-01), Yu
patent: 9-288178 (1997-11-01), None
patent: WO 95/04943 (1995-02-01), None
Database WPI, Section PQ, Week 9803, Derwent Publications Ltd., London, Great Britain; AN 98029288 XP002900495 and abstract of JP 09 288178.
Communication dated Jul. 30, 1999 (1 page) with.
European Search Report dated Jun. 22, 1999 (2 pages).
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Gregory Bernarr E.
Toyota Jidosha & Kabushiki Kaisha
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