METHOD AND DEVICE FOR RADAR ACCURACY MEASUREMENTS

Description

TECHNICAL FIELD

[0001] The invention relates to a use of a test setup for evaluating the impact of radar antenna covers on radar waves. The test setup comprises a test antenna, a radar sensor antenna and a radar sensor antenna cover.BACKGROUND ART

[0002] Generally, radar antennas are covered with a weatherproof enclosure, called a radome or bumper to protect the antenna. Even though the radome / bumper is constructed of material that minimally influences the radar waves, the angular accuracy of a radar sensor is affected and the antenna beam pattern is distored. Thus is a need for a measurement method and setup to measure the effects on the radar wave caused by the radome / bumper.

[0003] WO 2015 / 043935 A1 discloses a method for monitoring a cover of a Doppler radar sensor of a rail vehicle, using two adjacent antenna arrays, wherein a first radio signal is transmitted by a first antenna array, the said radio signal is at least partly reflected by the cover to be monitored and measured by a second antenna array. On the basis of the reflected signal, measured by the second antenna, dirt present on the cover is automatically detected. However, said document does not show a test antenna comprising several antenna elements in elevation and / or azimuth direction to evaluate the effect of radar waves caused by a radome or bumper. WO 2015 / 043935 A1 only detects dirt on a cover based on reflection measurements, wherein the transmitting antenna array and the receiving antenna array are located at the same side of the cover and since said document does not disclose the measurement of the influence on the radome / bumper material on radar waves with a test antenna. There is a need to provide a system and method with a test antenna, a radar sensor antenna, a radar sensor antenna cover.

[0004] EP3115804A1 discloses a test rig for testing a distance radar device for determining distance and speed of obstacles.

[0005] JP 2011 122892A discloses a test apparatus and a test method for testing a radome boresight error.

[0006] EP 3258288A1 is prior art under Art. 54(3) EPC and discloses a test setup is used for measuring the impact of automotive radome bodies.SUMMARY OF THE INVENTION

[0007] According to the invention, a test setup is used for measuring the impact of radar antenna covers, which antenna covers are not automotive radome bodies as disclosed in EP3258288A1.

[0008] The test set up comprises: a test antenna configured to generate radar radiation and to receive radar radiation a radar sensor antenna configured to receive radar radiation emitted by the test antenna (2) and to generate radar radiation to be received by the test antenna a radar sensor antenna cover an analyzer unit, wherein the test antenna (2) comprises several antenna elements in elevation and / or azimuth direction.

[0009] The analyzer unit is configured to compare measurement data taken with the radar sensor antenna cover, which covers the radar sensor antenna, and measurement data taken without the radar sensor antenna cover , wherein for measuring the angular accuracy effects caused by the radar sensor antenna cover, the radar sensor antenna is designed to measure the elevation and azimuth angle of the received signal gone through the radar sensor antenna cover, and the analyzer unit is designed to compare this data with the measurement data of the elevation and azimuth angle of the radar sensor signal not gone through the radar sensor antenna cover.

[0010] For measuring the antenna beam pattern distortion caused by the radar sensor antenna cover, the test antenna is designed to measure the radar signals, emitted by the radar sensor antenna, gone through the radar sensor antenna cover and the analyzing unit is designed to compare this data with the measurement data obtained when the test antenna receives the radar radiation emitted by the radar sensor antenna without going through the radar sensor antenna cover.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Exemplary embodiments of the invention are now further explained with respect to the drawings by way of example only, and not for limitation. In the drawings: Fig. 1shows a block diagram of an exemplary test setup of the first aspect of the invention; Fig. 2shows a block diagram of an exemplary test setup including a robotic arm of the first aspect of the invention; Fig. 3shows a flow chart of exemplary testing method steps 1-4 of the second aspect of the invention; and Fig. 4shows a flow chart of exemplary testing method steps 5-8 of the second aspect of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Fig. 1 illustrates an exemplary test setup for measuring the impact of radar antenna covers, comprising a radar sensor antenna 1, a test antenna 2, a radar sensor cover 3 and an analyzer unit 4.

[0013] The radar sensor antenna 1 may exemplarily be a multi-antenna array consisting of several antenna elements 5, each antenna element 5 being connected to a phase shifter 6. The phase shifters 6 in this exemplary case, are connected via a connection line 7 to a control / processing unit 8 that may be part of the analyzing unit 4, for configuring the phase of the applied signals. Furthermore, the phase shifters 6 are connected via a connection line 9 to a transmission / receiving unit 10 that may be part of the analyzing unit 4, configured to transmit / receive radar signals. The transmission / receiving unit 10 is connected to the control / processing unit 8. It is also conceivable that the transmission / receiving unit 10 and / or the control / processing unit 8 are provided as separate units and are not necessarily included into the analyzer unit 4.

[0014] The test antenna 2 comprises several antenna elements 11 in elevation and / or azimuth direction. Furthermore the antenna elements 11 may be exemplarily connected to a phase shifter 12, wherein the phase shifters 12 are connected via a connection line 13 to the control / processing unit 8 that may be part of an analyzing unit 4, for configuring the phase of the applied signals. Furthermore, the phase shifters 12 are connected via a connection line 14 to a transmission / receiving unit 15 that may be part of the analyzing unit 4, configured to transmit / receive radar signals. Thus, the feed current for each antenna element 11 passes through a phase shifter 12. The transmission / receiving unit 15 is connected to the control / processing unit 8. It is also conceivable that the transmission / receiving unit 15 and / or the control / processing unit 8 are provided as separate units and are not necessarily included into the analyzer unit 4.

[0015] Based on several antenna elements 11, wherein each element 11 is provided with a phase shifter 12, it is possible to create a beam of radar waves that can be electronically steered to point in different directions, without moving the antennas. Thus, radar radiation is generated, identical to radar echos that are normally generated, when radar radiation is reflected by a real object. Thus, the test antenna 2 is able to simulate targets since the control / processing unit 8 in combination with the transmitter / receiver unit 15 are configured to produce radar echos to simulate targets.

[0016] Furthermore, Fig. 1 shows a material 3 that covers the radar sensor antenna 1. The material 3 is located between the radar sensor antenna 1 and the test antenna 2 and influences the radar radiation going through the material 3. However, during the measurements according to step 2, described in Fig. 3 and the measurements according to step 6, described in Fig. 4 no material is present between the two antennas 1, 2 to obtain reference data without a material influencing the radar radiation. For this reason, the cover material 3 is drawn with a dashed line, to point out, that measurements are conducted with the material between the two antennas and without the material between the two antennas.

[0017] The analyzing unit 4 compares measurement data taken without material influencing the radar radiation 3, such as a radome, bumper, weather shield or similar that covers the radar sensor antenna 1, and measurement data taken with material influencing the radar radiation 3. For measuring the angular accuracy effects caused by the cover material 3, the radar sensor antenna 1 measures the elevation and azimuth angle of the received signal gone through the material, and the analyzing unit 4 compares this data with the measurement data of the elevation and azimuth angle of the radar sensor signal not gone through the cover material 3. For measuring the antenna beam pattern distortion caused by the cover material 3, the test antenna 2 measures the radar signals, emitted by the radar sensor antenna 1, gone through the material 3 and the analyzing unit 4 compares this data with the measurement data obtained when the test antenna 2 receives the radar radiation emitted by the radar sensor antenna 1 without going through the material 3.

[0018] Beside the given example for generating and receiving radar radiation, other implementations known to the person skilled in the art can be provided. In contrast to the presented array in Fig. 1, which shows a so called passive electronically scanned array (PESA) including several phase shifters and antenna elements, but only one transmitter / receiver per antenna, an active electronically scanned array (AESA) antenna, which comprises a separate transmitter and / or receiver unit for each antenna element, can be implemented.

[0019] Advantageously, the test setup according to the present invention does not require corner reflectors to measure the angular accuracy impact of the cover material as known from state of the art solutions. The known state of the art method requires the measurement of corner reflector positions (R, azimuth, elevation) with the radome cover for several corner reflectors, which means increased effort and which is very time consuming. The test setup of the present invention allows the measurement of the angular accuracy impact of the cover material within seconds and additionally the measurement of the antenna beam pattern distortion caused by the antenna cover is possible within seconds.

[0020] For an easier understanding of similar elements in different Figures, the number 100 has been added to the reference numbers given in Fig. 1 to number the elements in Fig. 2. Fig. 2 illustrates an exemplary test setup for measuring the impact of radar antenna covers, comprising a radar sensor antenna 101, a test antenna 102, a radar sensor cover 103, an analyzer unit 104 and a robotic arm 116 including a connection adapter 117 to connect the test antenna 102 to the robotic arm 116. To ensure mechanical stability and to fix the robotic arm, the robotic arm is mounted on a mounting plate 118.

[0021] The radar sensor antenna 101 may exemplarily be a multi-antenna array consisting of several antenna elements 105 each antenna element 105 being connected to a transmission / receiver unit 110 via a connection line 109 and with a process / control unit 108 via a connection line 107. In this exemplary case, not only a first antenna array is provided, but a duplicated second antenna array symmetrically mirrored to the first antenna array is shown. Additionally or alternatively, a radar sensor antenna with antenna arrays that are orientated in different directions in respect to the first antenna array are conceivable. Furthermore, the transmission / receiving unit 110 is connected to the control / processing unit 108.

[0022] In addition it is also conceivable that the transmission / receiving unit 110 and / or the transmission / receiving unit 115 and / or the control / processing unit 108 are provided as separate units and are not necessarily included into the analyzer unit 104.

[0023] The test antenna 102 comprises several antenna elements 111 in elevation and / or azimuth direction. Furthermore the antenna elements 111 are connected via a connection line 113 to the control / processing unit 108 that may be part of the analyzing unit 104, for configuring the phase of the applied signals. Furthermore, the antenna elements 111 are connected via a connection line 114 to a transmission / receiving unit 115 that may be part of the analyzing unit 104, configured to transmit / receive radar signals.

[0024] Based on several antenna elements 111, wherein each element 111 is configured to be switchable individually and controllable via the control / processing unit 108, it is possible to create a beam of radar waves that can be electronically steered to point in different directions, without moving the test antenna 102, and generate radar radiation that is identical to radar echos that are normally generated, when radar radiation is reflected by a real object. Thus, the test antenna is able to simulate targets.

[0025] Additionally to the radar beam movement generated electronically by controlling each single antenna element 111 independently, a robotic arm 116 is provided to allow a movement of the test antenna 102 to a desired location around the radar sensor antenna 101. In this exemplary case, the movement of the robotic arm 116 is realized by motors 119 that move the robotic arm 116 in x, y and z direction. The robotic arm is controlled by the control processing unit 108 and connected to the control / processing unit 108 via connection line 120. Since robotic arms are well known and available in different configurations, no more details are given regarding the robotic arm. Furthermore, a connection adapter 117 to connect the test antenna 102 to the robotic arm 116, and a mounting plate 118 to mount the robotic arm and ensure mechanical stability is shown.

[0026] Furthermore, Fig. 2 shows a material 103 that covers the radar sensor antenna 101. The material 103 is located between the radar sensor antenna 101 and the test antenna 102 and influences the radar radiation going through the material 103. However, during the measurements according to step 2, described in Fig. 3, and the measurements according to step 6, described in Fig. 4, no material is present between the two antennas 101, 102 to obtain reference data without a material influencing the radar radiation. For this reason, the cover material 103 is drawn with a dashed line, to point out that measurements are conducted with the material 103 between the two antennas 101, 102 and without the material 103 between the two antennas 101, 102.

[0027] The analyzing unit 104 compares measurement data, taken without material 103 influencing the radar radiation, such as a radome, bumper, weather shield or similar that covers the radar sensor antenna 101, and measurement data taken with material 103 influencing the radar radiation 103. For measuring the angular accuracy effects caused by the cover material 103, the radar sensor antenna 101 measures the elevation and azimuth angle of the received signal gone through the material 103 and the analyzing unit 104 compares this data with the measurement data of the elevation and azimuth angle of the radar sensor signal not gone through the cover material 103. For measuring the antenna beam pattern distortion caused by the cover material 103, the test antenna 102 measures the radar signals, emitted by the radar sensor antenna 101, gone through the material 103 and the analyzing unit 104 compares this data with the measurement data obtained when the test antenna 102 receives the radar radiation emitted by the radar sensor antenna 101 without going through the material 103.

[0028] Advantageously, the test setup according to the present invention does not require corner reflectors to measure the angular accuracy impact of the cover material as known from state of the art solutions. The known state of the art method requires the measurement of corner reflector positions (R, azimuth, elevation) with and without radome cover for several corner reflectors, which means a higher effort and is very time consuming. The test setup of the present invention, allows the measurement of the angular accuracy impact of the cover material 103 within seconds. The additional robotic arm 116 further reduces the testing time, since in addition to the beam movement performed without antenna movement the robot arm 116 movement can position the test antenna 102 and can define a rough scan position. The fine positioning, so called fine tuning of the beam is conducted by the electronic beam movement.

[0029] In addition, the robot arm 116 can be adapted to fulfill a further function, which is to place the radome / bumper 103 around the radar sensor antenna 101 or to remove the radome / bumper 103 being positioned around the radar sensor antenna 101 depending on the measurement step. This configuration is especially time saving when doing automated production line testing.

[0030] Fig. 3 shows a flow chart of the inventive test method with the test antenna 2, 102 switched to transmission mode generating radar radiation and the radar sensor antenna 1, 101 switched to receive mode receiving radar radiation. In a first step 1, radar radiation comprising elevation and azimuth data, is generated by the test antenna 2, 102. Due to the elevation and azimuth data included in the radar radiation, radar waves that are comparable to radar waves reflected by a real object are generated, which allows a target simulation. In the next step 2, the radar sensor antenna 1, 101 receives the radiation from the test antenna 2, 102 without going through a material 3, 103 that covers the radar sensor antenna 1, 101. The measurement without any material 3, 103 between the radar sensor antenna 1, 101 and the test antenna 2, 102 is required as a reference measurement. In step 3, the radar sensor antenna 1, 101 receives the radar radiation generated from the test antenna 2, 102, wherein the radar radiation has gone through a material 3, 103 that covers the radar sensor antenna 1, 101.

[0031] Even though the material 3, 103 provides a high transparency to radar radiation and is as homogenous as possible to minimize the impact on the radiation passing through the material, there is an influence on the radar radiation going through the material that causes a beam pattern distortion and angular measurement errors. Step 4 analyzes the radar radiation received directly, without going through any material 3, 103 and the radar radiation received after having gone through a material 3, 103 that influences radar radiation. Based on a measurement without a sensor antenna cover 3, 103 and another measurement with a sensor antenna cover 3, 103, the impact of the cover 3, 103 on the radar radiation emitted from the test antenna is evaluated. The information related to the impact of the sensor antenna cover on the radar radiation is required to maintain angular accuracy of the radar sensor antenna, when a cover 3, 103 that influences the radar radiation by absorption, reflection or scattering, covers the radar sensor antenna 1, 101.

[0032] Finally, Fig. 4 shows a flow chart of the inventive test method with the radar sensor antenna 1, 101 switched to transmission mode, generating a continuous radar wave (cw), and the test antenna 2, 102 switched to receive mode, receiving the radar waves emitted by the radar sensor antenna 1, 101. The generation of the continuous radar wave is shown in step 5 of the inventive test method. In step 6, the emitted continuous radar wave is received and measured by the test antenna 2, 102 without going through the material 3, 103 that covers the radar sensor antenna 1, 101. In step 7 the emitted continuous radar wave is received and measured by the test antenna 2, 102 having gone through the material 3, 103 that covers the radar sensor antenna 1, 101. In step 8, based on the two measurements, one measurement without the influence of the sensor antenna cover material 3, 103 and one measurement with the influence of the sensor antenna cover material 3, 103, the calculation of the antenna beam pattern distortion caused by the cover material 3, 103 is performed.

Claims

1. Use of a test setup for measuring the impact of radar antenna covers, which antenna covers are not automotive radome bodies, the test set up comprising: - a test antenna (2) configured to generate radar radiation and to receive radar radiation - a radar sensor antenna (1) configured to receive radar radiation emitted by the test antenna (2) and to generate radar radiation to be received by the test antenna (2) - a radar sensor antenna cover (3) - an analyzer unit (4), wherein the test antenna (2) comprises several antenna elements (11) in elevation and / or azimuth direction, characterized in that the analyzer unit (4) is configured to compare measurement data taken with the radar sensor antenna cover (3), which covers the radar sensor antenna (1), and measurement data taken without the radar sensor antenna cover (3), wherein for measuring the angular accuracy effects caused by the radar sensor antenna cover (3), the radar sensor antenna (1) is designed to measure the elevation and azimuth angle of the received signal gone through the radar sensor antenna cover (3), and the analyzer unit (4) is designed to compare this data with the measurement data of the elevation and azimuth angle of the radar sensor signal not gone through the radar sensor antenna cover (3), and that for measuring the antenna beam pattern distortion caused by the radar sensor antenna cover (3), the test antenna (2) is designed to measure the radar signals, emitted by the radar sensor antenna (1), gone through the radar sensor antenna cover (3) and the analyzing unit (4) is designed to compare this data with the measurement data obtained when the test antenna (2) receives the radar radiation emitted by the radar sensor antenna (1) without going through the radar sensor antenna cover (3).

2. The use according to claim 1, wherein the radar radiation generated by the test antenna (2) is such, that radar echoes are emitted to simulate a target.

3. The use according to any of claims 1 to 2, wherein each of the test antenna elements (11) is configured to be switchable individually.

4. The use according to claim 3, wherein the switchable test antenna elements (11) are configured to form a beam.

5. The use according to any of claims 1 to 4, wherein the radar sensor antenna (1) is a multi-antenna array.