Arrangement and method for testing waveguide antennas for radar sensors

Abstract

The invention relates to an arrangement for testing waveguide antennas (22) for radar sensors, comprising a transmitting and receiving device and an electronic evaluation device (26) for determining transmission and / or reflection properties of the antennas, characterised in that the arrangement has a reflector (14) which is arranged at a distance from the antenna (22) to be tested, and in that the transmitting and receiving device is a high-frequency assembly (16) of a radar sensor, said high-frequency assembly having a high-frequency interface (20) to the antenna (22) to be tested and a digital interface (28) to the evaluation device (26).

Description

[0001] R.415850

[0002] - 1 -

[0003] Description

[0004] title

[0005] Arrangement and method for testing waveguide antennas for radar sensors

[0006] Description

[0007] The invention relates to an arrangement and a method for testing waveguide antennas for radar sensors, comprising a transmitting and receiving device and an electronic evaluation device for determining the transmission and / or reflection properties of the antennas.

[0008] State of the art

[0009] In radar sensors used in driver assistance systems for motor vehicles to detect the traffic environment, the antenna arrangement for transmitting radar signals and receiving radar echoes is often formed entirely or partially by waveguide structures. Antenna arrangements of this type are collectively referred to here as waveguide antennas or simply antennas. The waveguide antennas, or at least their waveguide structures, can be manufactured, for example, by injection molding a base body from plastic, which is then subsequently metallized. The resulting waveguide antenna is then attached to a circuit board that carries the radar sensor's high-frequency assembly by gluing, welding, press joining, or similar methods. It is advisable to subject the antennas to a functional test before permanently attaching them to the circuit board.

[0010] To test the antennas, a vector network analyzer (VNA) is usually used, which is a signal generator (transmitter) for generating radar signals R.415850.

[0011] - 2 - and sensors (receivers) for measuring the high-frequency field coupled into and influenced by the waveguide antennas. However, these VMAs are bulky and expensive, and the analysis method is time-consuming. Disclosure of the invention

[0012] The object of the invention is to create a cost-effective test setup that enables fast and accurate testing of waveguide antennas.

[0013] This problem is solved according to the invention in that the arrangement has a reflector which is arranged at a distance from the antenna to be tested, and that the transmitting and receiving device is a high-frequency assembly of a radar sensor which has a high-frequency interface to the antenna to be tested and a digital interface to the evaluation device.

[0014] The high-frequency assembly may be a product that is mass-produced cost-effectively during the manufacturing of radar sensors. It is possible, but not necessarily the case, that the high-frequency assembly used in the measurement setup is identical in construction to the high-frequency assemblies of the radar sensors that are to be equipped with the antennas under test.

[0015] Advantageous embodiments and further developments of the invention are described in the dependent claims. The evaluation device can be configured to compare the signal reflected at the reflector and received again by the antenna arrangement with a predetermined target signal. The antenna passes the test if the deviations between the received signal and the target signal are within certain limits.

[0016] To generate the target signal, a sample antenna can be used whose properties have been carefully tested using a conventional test procedure. The sample antenna may be a prototype that does not conform to the specifications for R.415850.

[0017] - 3 - the other antennas were not manufactured using conventional methods, but rather, for example, by machining metallic materials with very low manufacturing tolerances. During the test, the antenna under test is mechanically attached to the radar sensor circuit board in such a way that it is positioned relative to the high-frequency signal source(s) of the high-frequency assembly exactly as the reference antenna was positioned when receiving the target signal. Certain positioning aids, such as stops or similar devices, may be provided on the circuit board for this purpose.

[0018] If the high-frequency assembly used in the test setup is not of the same type as the high-frequency assemblies of the radar sensors for which the antennas are to be used, an adapter can be provided between the signal source(s) on the circuit board and the waveguide antenna under test, which couples the signal generated by the high-frequency assembly into the waveguide antenna in the desired manner.

[0019] An exemplary embodiment is explained in more detail below with reference to the drawing. Figure 1 shows a front view of a test setup according to an embodiment of the invention; and

[0020] Fig. 2 shows a side view of the test setup according to Fig. 1. The test setup shown in Figures 1 and 2 has a base 10 to which a support 12 for a standardized reflector 14, for example a triple mirror, is rigidly attached. In the example shown, the support 12 projects vertically from the base 10. A high-frequency assembly 16 of a radar sensor is attached to the base 10 by means of positioning aids 18 such that it has a precisely defined spatial relationship to the reflector 14. In the example shown, only the side edge of a circuit board is visible, which carries the electronic components of the high-frequency assembly 16.

[0021] - 4 -

[0022] The components of the high-frequency assembly are mounted on the circuit board. These components themselves are, however, concealed by an adapter mounted on the circuit board, which forms a high-frequency interface 20 to the antennas to be tested and onto which a waveguide antenna 22 to be tested is detachably mounted. Positioning aids 24 of the adapter ensure that the antenna 22 assumes a precisely defined position relative to the high-frequency interface 20, which in turn is precisely positioned relative to the components on the circuit board. The high-frequency interface 20 has high-frequency lines through which the signals generated by the signal sources of the high-frequency assembly 16 are coupled into the waveguide antenna 22 in a defined and reproducible manner.

[0023] The high-frequency module 16 has its own high-frequency interface through which the signal is coupled into the adapter. If the high-frequency module 16 is identical in construction to the high-frequency modules of the radar sensors for which the antennas to be tested are intended, the adapter can be omitted. The signal is then coupled directly into the antenna from the high-frequency module's own high-frequency interface.

[0024] During the test procedure, the waveguide antenna 22 transmits the signals from the high-frequency assembly 16 to the reflector 14, which reflects these signals in a reproducible manner so that they are received again by the waveguide antenna 22 and then forwarded to the high-frequency signal inputs of the high-frequency assembly 16. The entire test setup is located in a reflection-free environment so that the received signals are not distorted by interfering reflections. For example, the test setup can be housed in an enclosure (not shown) whose walls effectively absorb radar waves in the frequency range used by the high-frequency assembly 16.

[0025] In the example shown, an electronic evaluation unit 26 is housed in the base 10 and connected to the high-frequency module 16 via a digital interface 28. The evaluation unit 26 can transmit commands to the high-frequency module 16 via the interface 28 and process the digital signals R.415850 generated by the high-frequency module 16 based on the received radar signals.

[0026] - 5 - receive and evaluate. The function of the evaluation unit 26 is analogous to the function of the digital control and evaluation electronics of a radar sensor. However, the evaluation unit 26 of the test setup also has the function of comparing the digital signals received from the high-frequency assembly 16 with a target signal stored in a memory of the evaluation unit 26. This target signal was previously recorded in a process in which, instead of the waveguide antenna 22, a prototype antenna with precisely known radar-optical properties was mounted on the high-frequency interface 20, and the same measurements were performed on the prototype antenna as on the waveguide antennas 22 to be tested.

[0027] The evaluation unit 26 has an output 30, via which the test result is output after a test has been performed. If the signals transmitted by the high-frequency assembly 16 during the test of the waveguide antenna 22 correspond to the target signal within certain tolerance limits, the tested antenna is rated as "flawless". Otherwise, it is rejected as defective.

[0028] The test setup described here has the advantage that it can test the radar-optical properties of the antennas with sufficient accuracy in a very short time, for example, about one second per antenna, while requiring very little space. In a practical example, the distance between the base 10 and the reflector 14 is approximately 1.5 meters.

Claims

R.415850 - 6 - Claims 1. Arrangement for testing waveguide antennas (22) for radar sensors, comprising a transmitting and receiving device and an electronic evaluation device (26) for determining the transmission and / or reflection properties of the antennas, characterized in that the arrangement has a reflector (14) which is arranged at a distance from the antenna (22) to be tested, and that the transmitting and receiving device is a high-frequency assembly (16) of a radar sensor which has a high-frequency interface (20) to the antenna (22) to be tested and a digital interface (28) to the evaluation device (26).

2. Arrangement according to claim 1, wherein the high-frequency interface (20) is an adapter configured to forward at least one high-frequency signal from the high-frequency assembly (16) to the antenna (22) to be tested.

3. Arrangement according to claim 1 or 2, wherein the high-frequency interface (20) has positioning aids (24) by means of which the antenna (22) to be tested can be detachably placed on the high-frequency interface (20) in a defined position.

4. Arrangement according to any one of the preceding claims, comprising a base (10) on which the high-frequency assembly (16) is mounted and to which a support (12) for the reflector (14) is rigidly attached.

5. Arrangement according to claim 4, wherein the support (12) extends vertically from the base. (10) rises.

6. Arrangement according to one of the preceding claims, wherein the evaluation device (26) is configured to compare the digital signal supplied by the high-frequency assembly (16) with a target signal during a test.

7. Method for testing waveguide antennas (22) for radar sensors using an arrangement according to claim 6, characterized in that the target- R.415850 - 7 - The signal is recorded by performing the same measurements on a sample antenna with known properties as on the waveguide antennas (22) to be tested.

8. The method of claim 7, wherein the sample antenna is manufactured using a manufacturing process that has lower manufacturing tolerances than the manufacturing process for the antennas (22) to be tested.

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