EP1969394A1

EP1969394A1 - Radar device

Info

Publication number: EP1969394A1
Application number: EP06819763A
Authority: EP
Inventors: Joerg Schoebel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-12-28
Filing date: 2006-11-24
Publication date: 2008-09-17
Also published as: DE102005062772A1; WO2007077062A1

Abstract

The radar device has a local oscillator and a plurality of monostatic transmitter devices and receiver devices. The local oscillator has the purpose of generating a radiofrequency signal and is coupled to the plurality of monostatic transmitter devices and receiver devices. Each monostatic transmitter device and each monostatic receiver device of the plurality of monostatic transmitter devices and receiver devices has an antenna element and a delay path. The antenna element has the purpose of transmitting the radiofrequency signal and of receiving reflected components of the radiofrequency signal. The first delay path for delaying the radiofrequency signal by an invariable period is connected between the antenna element and the local oscillator.

Description

description

Title radar device

State of the art

The present invention relates to a radar device, in particular a radar device for use in the automotive sector.

To increase driving safety, driver assistance systems should be used in the automotive sector. Here, e.g. Adaptive cruise control known, which are used for vehicle speeds in the range of 50 to 180 km / h. In addition, driver assistance systems should also be provided, which control the vehicle even in heavy traffic or in traffic jams the speed of the vehicle. Among other things, it is thought to decelerate the vehicle to a standstill, if the vehicle in front stops. Other auxiliary systems can be used to monitor areas that the driver can not or poorly see, as well as when reversing or when parking. An essential component of these driver assistance systems are radar devices which can determine the speed of preceding vehicles and the distance to them. In addition, an angle-resolved measurement of the distance and / or the speed is needed to distinguish a preceding vehicle from a vehicle, which may be e.g. parked in a parking bay next to the roadway.

One approach for achieving the angular resolution here is based on the so-called analog beam shaping. Lenses, mirrors or diaphragms emit and / or receive the radiation of high-frequency signals from a plurality of feed antennas in a plurality of partially partially overlapping directions. On the basis of signal amplitudes of the received reflected high-frequency signals, it can be determined in which direction the detected object is located. A disadvantage of the analog beam shaping is the relatively large mechanical structure of the antenna devices due to the lenses with a depth of several centimeters. Another method is based on the so-called digital beam forming. In this case, a high-frequency signal is emitted by an antenna and the reflected signal is received by a plurality of spatially mutually spaced receiving antennas. The distance of the individual receiving antennas to the object are slightly different. As a result, the transit times of the reflected signals differ from the object to the receiving antennas. The transit time differences are determined as the difference in the phase of the corresponding received reflected signals. The direction to the object can then be determined from the phase differences.

Due to the arrangement of the lenses for an analog beam shaping and the spatial arrangement of the receiving antennas for digital beam shaping, the angular range is predetermined, in which a clear direction determination is possible and at the same time predetermines the accuracy of the angular resolution. In different driving positions, however, the requirements for the angular range and the angular resolution are different. On the highway are usually only the vehicles of interest, which are located at a distance of 50 to 200 m (long range) in front of the vehicle on the same or on the adjacent lane. Detection of these objects and angle determination requires a high intensity density per angular volume to obtain a sufficient signal-to-noise ratio between received reflected signal components and signals from noise sources. However, as described, the entire angular range to be covered is relatively small. A parking aid, on the other hand, requires almost all-round visibility around the entire vehicle, but only a detection of objects at a distance of a few decimeters to meters (near range). For this latter application thus antennas are required with a broad emission characteristic, but no high signal intensity.

A use and installation of two independent radar devices is undesirable because of the considerable space required and for cost reasons.

Disclosure of the invention

The radar device according to the invention with the features of independent claim 1 can be realized compact with simple components and detect objects in a near area and objects in a long range.

The radar device comprises a local oscillator and a plurality of monostatic transmitting and receiving devices. The local oscillator is used to generate a high-frequency signal and is coupled to the plurality of monostatic transmitting and receiving devices. Each monostatic transmitting and receiving device of the plurality of monostatic transmitting and receiving devices has an antenna element and a first delay path. The Antenna element is used to transmit the high frequency signal and to receive reflected portions of the high frequency signal. The first delay path for delaying the high-frequency signal by an invariable duration is connected between the antenna element and the local oscillator.

The monostatic structure, which uses an antenna element for both transmission and reception, can be made very compact. In particular, the fact that the number of necessary antennas is approximately halved.

The radiation characteristic of the radar apparatus is determined by the individual delay of the high frequency signal before being radiated by the antenna elements. By selecting suitable signal delay paths with their fixed delay periods, a variety of emission characteristics can be formed by means of constructive and destructive interference of the radiated radio-frequency signals. With the aid of filter structures, both lagging and leading phase shifts of the high-frequency signal can be generated.

Further developments and refinements of the radar device according to the invention are specified in the subclaims.

In particular, the radar device may comprise a plurality of transmitting devices, each including an antenna element and a second signal delay line. The second signal delay path corresponds to the first signal delay paths. The antenna element, however, is set up exclusively for transmitting the high-frequency signal. In this way, it can be achieved that a more favorable shaping of the emission characteristics is achieved by the very simple to set up transmitter devices which require, inter alia, no mixer.

An embodiment of the present invention provides that the first and / or the second signal delay path is formed by a first line having a predetermined length. The line can in this case be rectilinear, wave-shaped or meander-shaped. Furthermore, at least one second line with its second end can be connected to the first line, wherein a first end of the second line is open or short-circuited.

An embodiment of the present invention provides that the first / or the second signal delay path is formed by a filter structure, which in turn consists of one or more series and / or parallel circuits of one or more substantially inductive or capacitive elements. These elements can be realized as discrete components or as (planar) line structures.

An embodiment provides that the monostatic transmitting and receiving device has a mixing device which is connected in series with the delay line and between the antenna element and the local oscillator. The mixing device may comprise a circulator, a directional coupler, a hybrid mixer or a transfer mixer, which couples a high-frequency signal to be transmitted from the local oscillator into the antenna element and which isolates the local oscillator from a received high-frequency signal.

The antenna elements may be formed as at least one patch antenna. The patch antennas of a transmitting element can be connected in series. An embodiment provides to realize the radar device planar on a support. The carrier may comprise a flexible or rigid substrate on which printed conductors are applied, which form the antenna elements and / or the delay lines.

The antenna elements may have a distance from one another which corresponds to half of a (free space) wavelength of the high-frequency signal. In another embodiment, the distance can also correspond to greater than half the wavelength of the high-frequency signals.

A power divider and / or an amplifying device can be connected between the local oscillator and the monostatic transmitting and receiving devices, whereby the power of the transmitted high-frequency signal of the individual transmitting and receiving devices for each transmitting and receiving device is set individually to a predetermined value. In particular, the power supply for transmitting and receiving devices, which are centered in the

Radar device are arranged, decrease to transmitting and receiving devices, which are arranged at the edge of the radar device.

Exemplary embodiments and embodiments are explained in more detail in the figures and the description below.

In the figures show:

FIG. 1 shows a block diagram of an exemplary embodiment of the radar device according to the invention. Figure 2: a second exemplary embodiment of the radar device according to the invention.

FIG. 3: schematic representation of a radiation characteristic of one of the

Embodiments as intensity distribution over a radiation angle.

Figures 4-7: Layout diagrams illustrating four embodiments.

Figures 8-12: Circuit diagrams of mixers for use in the previous ones

Embodiments.

In the figures, the same reference numerals designate the same or functionally identical components.

FIG. 1 shows the block diagram of a first exemplary embodiment of a radar device. A local oscillator 7 is connected to a plurality of monostatic transmitting and receiving devices 6a, 6b, ... for providing a high-frequency signal LO. The monostatic transmitting and receiving devices 6a, 6b, ... emit the high-frequency signal LO as a high-frequency signal Tx to be emitted. The signal portions of the emitted high-frequency signal reflected by an object are received as received high-frequency signals Rx.

Each of the monostatic transmitting and receiving devices 6a and 6b,... Comprises an antenna device Ia, Ib,..., A mixing device 4a, 4b,... And at least one signal delay path 2a, 2b,..., 3a, 3b, ..., on. The high-frequency signal LO provided by the local oscillator 7 is delayed in time by a first delay line 2a, and forwarded to the mixing device 4a, 4b,. The mixing device forwards a signal component to the antenna device Ia, Ib,... As a high-frequency signal Tx to be emitted. Between the

Mixing device 4a, 4b and the antenna device Ia, Ib, the signal can be delayed in time by the second signal delay line 3a, 3b, ....

The signal components of the emitted high-frequency signal Tx reflected by the object are received by the antenna devices 1a, 1b,... Of the transmitting and receiving device 6a, 6b as received high-frequency signals Rx. The received high-frequency signals Rx optionally pass through the second signal delay line 3a, 3b,... And are then demixed in the mixing device 4a, 4b,... With the local oscillator signal LO to form an intermediate frequency signal ZF. The intermediate frequency signal ZF is decoupled and fed to an evaluation device, which is not shown in FIG. The mixing device 4a, 4b, ... insulates the

Receiving area on the side of the antenna device Ia, Ib, ... of the local oscillator 7, so that only negligible small portions of the received high-frequency signal Rx in the local Oscillator 7 are fed. But it is also possible to manage with a lower isolation. This allows the use of particularly simple and inexpensive to implement transfer mixers.

Corresponding mixing devices 4a, 4b,... Are described below.

The embodiment illustrated in FIG. 1 permits emission of the emitted high-frequency signal Tx with an intensity distribution I, as represented in FIG. 2 by the angle θ. The direction θ = 0 denotes the vehicle direction. In an angle range between minus 15 degrees and plus 15 degrees, the emitted high frequency signal Tx has an intensity I about 10 dB higher than in the angle range between minus 60 degrees to minus 15 degrees and plus 15 degrees to plus 60 degrees. For angles inclined more than 60 degrees to the vehicle direction, the intensity I falls to negligible low values. This radiation profile corresponds to the requirements for vehicle assistance systems, which are intended to detect a long-range and a close range in parallel.

The following will explain the basic principles necessary for understanding the embodiment of FIG. 1 in order to adapt the signal delay paths 2a, 2b or 3a, 3b and to obtain the described intensity profile in FIG. The high-frequency signals Tx emitted by the individual antenna devices Ia, Ib,... Have a fixed phase relation to each other, since they are all from the same source, i. the local oscillator 7, are fed. In the radiation profile thus arise areas of destructive and constructive interference. The exact interference pattern depends on the spatial arrangement of the antenna devices Ia, Ib,... And the frequency of the high-frequency signal Tx. In addition, the duration of the high-frequency signal LO in the electronic circuits and line paths to the antenna devices Ia, Ib, ... has a decisive influence on the interference pattern. The signal delay lines 2a, 2b,..., 3a, 3b,... Enable the propagation delays to the corresponding antenna devices 1 a, 1 b,. Thus, a designer, the radar device shown in Fig. 1 is given the opportunity to realize different interference pattern and thus radiation characteristics. Conveniently, the procedure would be as follows: First, it sets a desired intensity profile I, e.g. from FIG. 2. Thereafter, it iteratively or by means of suitable adaptation algorithms adjusts the delay lines 2a, 2b, 3a, 3b,... in such a way that an interference pattern results, which agrees sufficiently with the desired intensity profile.

The delay lines 2a, 2b, 3a, 3b, ... are preferably simple line sections with a fixed length. The length is determined by the designer as described previously. To the To integrate delay lines 2a, 2b, 3a, 3b, ... in the circuit construction, it may be advantageous to arrange this view of the local oscillator 7 before and / or after the mixing device 4a, 4b,.

Other design possibilities of the signal delay lines 2a, 2b, 3a, 3b,... Are described below.

FIG. 3 shows a second exemplary embodiment of the radar device as a block diagram, in addition to the components and devices already described in FIG. 1, transmission devices 16e, 16f,... Are connected to the local oscillator 7. These transmission devices 16e, 16f,... Have only one antenna device 1ee, 1ff, and one signal delay path 12e, 12f,. The omission of a mixing device allows these transmitting devices 16e, 16f to build more compact and to arrange them more flexible.

In Fig. 4 is a plan view of an embodiment is shown, which corresponds to the block diagram of Fig. 3. The local oscillator 7 is connected via a distributor device 9 to the monostatic transmitting and receiving devices 6a, 6b,... And the transmitting devices 16e, 16f. In this embodiment, each monostatic transmitting and receiving device and each transmitting device 16e six patch antennas Ia, Ib, 1 Ie, ... on. Each of these patch antennas can be realized by a conductive surface, shown here as squares. The individual patch antennas Ia, Ie, ... are connected in series by interconnects. The signal delay lines 3a, 3b, 12e, ... connect the patch antennas connected in series with the distributor device 9. The signal delay devices 3a, 3b, 12e, ... have partially different lengths, as shown in FIG. The track has a deflection in this area, which is directed away from the direct and shortest connection. The size and number of excursions determines the length of the signal delay paths and thus the signal propagation delay caused by them. The mixing devices 4a,... Are shown schematically as T-shaped transfer mixers. Their structure and operation will be explained in more detail below. FIG. 5 shows an exemplary embodiment of a radar device which substantially corresponds to the block diagram of FIG. Here, the additional pure transmitting devices with respect to the embodiment of Fig. 4 is omitted. Otherwise, these embodiments do not differ.

FIG. 6 shows a further exemplary embodiment of the radar device. A plurality of monostatic transmitting and receiving devices 26a, 26b,... And transmitting devices 36e, 36f are connected via a distributor device 9 to a local oscillator 7. The monostatic transmitting and receiving devices 26a, 26b, ... have in this embodiment a Reinforcement means 30a, 30b, 30c. These amplifying devices 30a, 30b, 30c feed in pairs two parallel monostatic transmitting and receiving devices 26e, 26f with a different signal strength. The signal strength or intensity of each individually emitted by the monostatic transmitting and receiving devices 26a, 26b, ... high-frequency signal Tx affects the intensity profile I of the radiation of the entire radar device. By a suitable choice of gain, a designer thus receives an additional degree of freedom to obtain a desired intensity profile. A determination of the amplification takes place analogously to the necessary delays through the delay lines 3a, 3b, 12e,... By means of an iterative method or an adaptation algorithm.

In Fig. 7, a further embodiment is shown, which differs by the realization of the signal delay lines 23a, 23b, ... from the previous embodiment. Instead of wave-shaped or curved strip conductors as signal delay lines 3 a, 3 b, 12 e, ... are connected perpendicular to a straight conductor at least one conductor track with an open end. In the exemplary embodiment illustrated in FIG. 7, in each case two parallel interconnects with an open end are shown. A high-frequency signal fed from the local oscillator 7 into a monostatic transmitting and receiving device 46a, 46b branches at the T-shaped connections and is then at least partially reflected at the open end. The returning reflected wave interferes with the input high-frequency signal LO and results in a phase shift thereof. The length of the interconnects with an open end determines the phase delay experienced by the RF input signal LO.

In the figures 8 to 12, mixers are shown by way of example, which can be used for the mixing devices 4a. These are suitable to a high-frequency signal LO in one

Feeding antenna device and decouple a received signal RX from the antenna device. Figure 8 shows a circulator 42 which is placed between the antenna device and the local oscillator. A third output of the circulator 42 is connected to a mixer 43, which receives as a second input signal the high-frequency signal fθ of the local oscillator. Figure 9 shows a structure which uses a coupler 52 instead of the circulator.

Figure 10 shows a so-called transfer mixer which uses the nonlinearity of a diode 63 to demix the received high frequency signal Rx with the high frequency signal LO of the local oscillator. The connection of the diode 63 to the antenna device 4 and to the local oscillator via a coupler 62. A simplified structure with a T-shaped connection of the diode 74 to the local oscillator and the antenna device 4 is shown in Figure 11. FIG. 12 shows a transfer mixer with a diode 81 which is connected in series between the Antenna device 4 and the local oscillator is connected, such a structure is known inter alia from the published patent application DE 102 35 338 Al.

Although the present invention has been described in terms of several embodiments, it is not limited thereto. In particular, the number of patch antennas connected in series can be changed in any desired manner. Furthermore, various combinations of the signal delay paths shown, mixing devices, monostatic transmitting and receiving devices and pure transmission devices are possible.

Claims

claims

A radar apparatus comprising: a local oscillator (7) for generating a high-frequency signal; and a plurality of monostatic transmitting and receiving means (6a, 6b, ...) coupled to the local oscillator (7) and each having an antenna element (Ia, Ib, ...) for transmitting the high frequency signal (Tx ) and for receiving reflected portions of the high frequency signal (Rx), and wherein a first signal delay path (2a, 2b, ...; 3a, 3b, ...) for delaying the high frequency signal (Tx) by an invariable duration between the antenna element (Ia, Ib, ...) and the local oscillator (7) is connected.

2. Radar apparatus according to claim 1, comprising a plurality of transmitting devices (16e, 16f, ...), which is an antenna element (1 Ie, 1 If, ...), which is set up exclusively for transmitting the high-frequency signal (Tx) , and a second signal delay line (12e, 12f, ...) connected between the antenna element (1ee, 1ff, ...) and the local oscillator (7) and the high frequency signal (Tx) by a fixed one Duration delayed.

3. Radar device according to claim 1 or 2, in which the first signal delay path is formed by a series and / or parallel circuit discrete or realized in the form of line structures elements that are essentially capacitive or inductive in their effect and in their interconnection substantially form a filter structure and thus produce a fixed, positive or negative phase shift of the high-frequency signal.

A radar apparatus according to claim 1 to 3, wherein said first signal delay line (2a, 2b, ...; 3a, 3b, ...) is formed by a first line having a predetermined length.

A radar apparatus according to claim 4, wherein said first signal delay line (2a, 2b, ...; 3a, 3b, ...) comprises a second line having a predetermined length and an open or shorted first end, and a second end of second line is connected to the first line.

6. Radar device according to one of the preceding claims, in which the monostatic transmitting and receiving device (6a, 6b, ...) has a mixing device (4a, 4b, ...), which in series with the signal delay line (2a, 2b, ..., 3a, 3b, ...) between the antenna element (Ia, Ib, ...) and the local oscillator (7) is connected and the

Mixing device (4a, 4b, ...) has a circulator, a Richtkopp ler, a hybrid mixer or a transfer mixer, which is a high-frequency signal to be transmitted (Tx) from the local oscillator (7) in the antenna element (Ia, Ib , ...) and which simultaneously mixes the received high-frequency signal (Rx) with a local oscillator signal.

7. Radar device according to one of the preceding claims, whose antenna elements (Ia, Ib, ..., He, Hf, ...) are formed as at least one patch antenna.

8. Radar device according to one of the preceding claims, which is realized planar on a support.

A radar apparatus according to any one of the preceding claims, wherein the antenna elements (Ia, Ib, ...) are spaced from each other by approximately half the wavelength of the high frequency signals (Rx, Tx).

10. Radar device according to one of the preceding claims, with a power divider and / or an amplifying device, which is connected between the local oscillator (7) and the monostatic transmitting and receiving means (6a, 6b, ...), whereby the power of the sent High-frequency signal (Rx) of the individual transmitting and receiving devices (6a, 6b, ...) for each transmitting and receiving device (6a, 6b, ...) is set individually to a predetermined value.