Patent Description:
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.

<CIT> 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. <CIT> 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.

<CIT> discloses a test rig for testing a distance radar device for determining distance and speed of obstacles.

<CIT> discloses a test apparatus and a test method for testing a radome boresight error.

<CIT> is prior art under Art. <NUM>(<NUM>) EPC and discloses a test setup is used for measuring the impact of automotive radome bodies.

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 <CIT>.

wherein the test antenna (<NUM>) comprises several antenna elements in elevation and/or azimuth direction.

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.

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.

<FIG> illustrates an exemplary test setup for measuring the impact of radar antenna covers, comprising a radar sensor antenna <NUM>, a test antenna <NUM>, a radar sensor cover <NUM> and an analyzer unit <NUM>.

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

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

Based on several antenna elements <NUM>, wherein each element <NUM> is provided with a phase shifter <NUM>, 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 <NUM> is able to simulate targets since the control/processing unit <NUM> in combination with the transmitter/receiver unit <NUM> are configured to produce radar echos to simulate targets.

Furthermore, <FIG> shows a material <NUM> that covers the radar sensor antenna <NUM>. The material <NUM> is located between the radar sensor antenna <NUM> and the test antenna <NUM> and influences the radar radiation going through the material <NUM>. However, during the measurements according to step <NUM>, described in <FIG> and the measurements according to step <NUM>, described in <FIG> no material is present between the two antennas <NUM>, <NUM> to obtain reference data without a material influencing the radar radiation. For this reason, the cover material <NUM> 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.

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

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>, 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.

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.

For an easier understanding of similar elements in different Figures, the number <NUM> has been added to the reference numbers given in <FIG> to number the elements in <FIG> illustrates an exemplary test setup for measuring the impact of radar antenna covers, comprising a radar sensor antenna <NUM>, a test antenna <NUM>, a radar sensor cover <NUM>, an analyzer unit <NUM> and a robotic arm <NUM> including a connection adapter <NUM> to connect the test antenna <NUM> to the robotic arm <NUM>. To ensure mechanical stability and to fix the robotic arm, the robotic arm is mounted on a mounting plate <NUM>.

The radar sensor antenna <NUM> may exemplarily be a multi-antenna array consisting of several antenna elements <NUM> each antenna element <NUM> being connected to a transmission/receiver unit <NUM> via a connection line <NUM> and with a process/control unit <NUM> via a connection line <NUM>. 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 <NUM> is connected to the control/processing unit <NUM>.

In addition it is also conceivable that the transmission/receiving unit <NUM> and/or the transmission/receiving unit <NUM> and/or the control/processing unit <NUM> are provided as separate units and are not necessarily included into the analyzer unit <NUM>.

The test antenna <NUM> comprises several antenna elements <NUM> in elevation and/or azimuth direction. Furthermore the antenna elements <NUM> are connected via a connection line <NUM> to the control/processing unit <NUM> that may be part of the analyzing unit <NUM>, for configuring the phase of the applied signals. Furthermore, the antenna elements <NUM> are connected via a connection line <NUM> to a transmission/receiving unit <NUM> that may be part of the analyzing unit <NUM>, configured to transmit/receive radar signals.

Based on several antenna elements <NUM>, wherein each element <NUM> is configured to be switchable individually and controllable via the control/processing unit <NUM>, 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 <NUM>, 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.

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

Furthermore, <FIG> shows a material <NUM> that covers the radar sensor antenna <NUM>. The material <NUM> is located between the radar sensor antenna <NUM> and the test antenna <NUM> and influences the radar radiation going through the material <NUM>. However, during the measurements according to step <NUM>, described in <FIG>, and the measurements according to step <NUM>, described in <FIG>, no material is present between the two antennas <NUM>, <NUM> to obtain reference data without a material influencing the radar radiation. For this reason, the cover material <NUM> is drawn with a dashed line, to point out that measurements are conducted with the material <NUM> between the two antennas <NUM>, <NUM> and without the material <NUM> between the two antennas <NUM>, <NUM>.

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

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 <NUM> within seconds. The additional robotic arm <NUM> further reduces the testing time, since in addition to the beam movement performed without antenna movement the robot arm <NUM> movement can position the test antenna <NUM> and can define a rough scan position. The fine positioning, so called fine tuning of the beam is conducted by the electronic beam movement.

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

<FIG> shows a flow chart of the inventive test method with the test antenna <NUM>, <NUM> switched to transmission mode generating radar radiation and the radar sensor antenna <NUM>, <NUM> switched to receive mode receiving radar radiation. In a first step <NUM>, radar radiation comprising elevation and azimuth data, is generated by the test antenna <NUM>, <NUM>. 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 <NUM>, the radar sensor antenna <NUM>, <NUM> receives the radiation from the test antenna <NUM>, <NUM> without going through a material <NUM>, <NUM> that covers the radar sensor antenna <NUM>, <NUM>. The measurement without any material <NUM>, <NUM> between the radar sensor antenna <NUM>, <NUM> and the test antenna <NUM>, <NUM> is required as a reference measurement. In step <NUM>, the radar sensor antenna <NUM>, <NUM> receives the radar radiation generated from the test antenna <NUM>, <NUM>, wherein the radar radiation has gone through a material <NUM>, <NUM> that covers the radar sensor antenna <NUM>, <NUM>.

Even though the material <NUM>, <NUM> 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 <NUM> analyzes the radar radiation received directly, without going through any material <NUM>, <NUM> and the radar radiation received after having gone through a material <NUM>, <NUM> that influences radar radiation. Based on a measurement without a sensor antenna cover <NUM>, <NUM> and another measurement with a sensor antenna cover <NUM>, <NUM>, the impact of the cover <NUM>, <NUM> 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 <NUM>, <NUM> that influences the radar radiation by absorption, reflection or scattering, covers the radar sensor antenna <NUM>, <NUM>.

Claim 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 (<NUM>) configured to generate radar radiation and to receive radar radiation
- a radar sensor antenna (<NUM>) configured to receive radar radiation emitted by the test antenna (<NUM>) and to generate radar radiation to be received by the test antenna (<NUM>)
- a radar sensor antenna cover (<NUM>)
- an analyzer unit (<NUM>),
wherein the test antenna (<NUM>) comprises several antenna elements (<NUM>) in elevation and/or azimuth direction,
characterized in
that the analyzer unit (<NUM>) is configured to compare measurement data taken with the radar sensor antenna cover (<NUM>), which covers the radar sensor antenna (<NUM>), and measurement data taken without the radar sensor antenna cover (<NUM>), wherein for measuring the angular accuracy effects caused by the radar sensor antenna cover (<NUM>), the radar sensor antenna (<NUM>) is designed to measure the elevation and azimuth angle of the received signal gone through the radar sensor antenna cover (<NUM>), and the analyzer unit (<NUM>) 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 (<NUM>), and
that for measuring the antenna beam pattern distortion caused by the radar sensor antenna cover (<NUM>), the test antenna (<NUM>) is designed to measure the radar signals, emitted by the radar sensor antenna (<NUM>), gone through the radar sensor antenna cover (<NUM>) and the analyzing unit (<NUM>) is designed to compare this data with the measurement data obtained when the test antenna (<NUM>) receives the radar radiation emitted by the radar sensor antenna (<NUM>) without going through the radar sensor antenna cover (<NUM>).