TECHNICAL FIELD

The present disclosure relates to a target detecting device for detecting the azimuth of a target and to an antenna device used in the target detecting device.

BACKGROUND ART

There are proposed various techniques of transmitting a radar wave signal, receiving, by a plurality of receiving antennas, waves that are based on reflection of the transmitted radar wave signal from a target, and detecting the azimuth of the target based on received signals obtained by the respective receiving antennas.

Patent Literature 1 (PTL 1) discloses an azimuth detecting device that detects a target in a wider angular range in a horizontal direction without increasing an area of each receiving antenna element.

Specifically, in the azimuth detecting device disclosed in PTL 1, a plurality of antenna elements is arranged at first intervals d1. The azimuth detecting device performs a first signal processing task based on a received signal from each of the antenna elements in a short-distance area detection mode, and performs a second signal processing task based on a received signal from each of the antenna elements in a long-distance area detection mode; the first and second signal processing tasks are different from each other.

CITATION LIST

Patent Literature

[PTL 1]

Japanese Patent Publication NO. 4715871B

SUMMARY OF THE INVENTION

Technical Problem

In order to make it possible to detect, in a wider angular range, the azimuth of a target existing in a short distance, it is sufficient to narrow the arrangement intervals between the receiving antennas.

However, simply narrowing the arrangement intervals between the receiving antennas while fixing and maintaining the number of channels in the azimuth detecting device lowers angle accuracy and angle resolution (hereinafter, collectively referred to also as angle performance).

In contrast, let us consider an azimuth detecting device in which the arrangement intervals between the receiving antennas is widened in view of the angle performance. In the azimuth detecting device, a so-called grating ghost due to phase reflection in a wide-angle region may increase the possibility of erroneously detecting a target, that is, erroneously detecting existence of a target in an azimuth in which no real targets exist.

The present disclosure has been made in view of the above problems and aims to provide an antenna device capable of preventing erroneous detection of a target due to a grating ghost while maintaining excellent angle performance, and a target detecting device using the antenna device.

Solution to Problem

An antenna device according to a first aspect of the present disclosure is an antenna device for receiving a radio wave signal. The antenna device includes a plurality of antenna groups, each of the antenna groups (41to44,51to53,61to64,71to74) including a plurality of unit antennas (5-1,5-2,5-3) arranged in a predetermined direction. The plurality of antenna groups are arranged in the predetermined direction at equal intervals. The plurality of unit antennas in each of the plurality of antenna groups are arranged at two or more different intervals in the predetermined direction in the antenna device.

The above configured antenna device includes the plurality of antenna groups arranged at equal intervals. This enables the antenna device according to the first aspect of the present disclosure to be applied as a receiving antenna of a device configured to receive a reflected wave of a search wave to thereby detect a target. Specifically, it is possible to detect, based on the received signal for each of the plurality of antenna groups, an azimuth of a target existing at a relatively long distance in a predetermined azimuth angle range.

In addition, all of the plurality of unit antennas of the antenna device according to the first aspect of the present disclosure are not arranged at equal intervals as the entire antenna device, and are arranged at the two or more different intervals.

Using the antenna device makes it possible to obtain, for a target in a distance at least closer than the long distance, an azimuth detection result in a wider angle range than the azimuth angle range in accordance with the individual received signals from the respective unit antennas while maintaining an angle performance; the azimuth detection result includes reduced erroneously detected targets due to grating ghosts.

A target detecting device according to a second aspect of the present disclosure includes a transmitting portion (2,3) configured to transmit a search wave, a receiving portion (4,50,60,70) configured to receive a reflected wave signal that is generated based on reflection of the search wave by a target, and an azimuth detecting section (6,8,10) configured to detect an azimuth of the target based on the reflected wave signal received by the receiving portion.

The receiving portion includes a plurality of antenna groups. Each of the antenna groups (41to44,51to53,61to64,71to74) includes a plurality of unit antennas (5-1,5-2,5-3) arranged in a predetermined direction. The plurality of antenna groups are arranged in the predetermined direction at equal intervals. The plurality of unit antennas in each of the plurality of antenna groups are arranged at two or more different intervals in the predetermined direction in an antenna device.

The azimuth detecting section includes a first detecting function of generating, for each of the antenna groups, reception information based on a received signal received by each of the unit antennas, and detecting an azimuth of the target based on the reception information for each of the antenna groups. The azimuth detecting section includes a second detecting function of

(1) Using one of the plurality of antenna groups or at least two adjacent antenna groups in the plurality of antenna groups as a target group to generate, individually for each of the unit antennas of the target group, reception information based on the received signal received by the corresponding one of the unit antennas

(2) Detecting an azimuth of the target based on the reception information for each of the unit antennas of the target group.

The target detecting device configured above uses the above-described antenna device as the receiving portion.

This obtains the same effects as the effects obtained by the antenna device.

Note that each of reference numerals in parentheses described in this [solution to problem] and claims described later represents a correspondence relation to a specific means described in embodiments described later as one aspect, and this does not limit the technical scope of the present invention.

