System for measuring the transfer function on a path from a feed antenna via a reflector to a radar sensor testing zone

1. A system for measuring the transfer function on a path from a feed antenna via a reflector to a radar sensor testing zone, the system comprising:

an anechoic chamber;

the feed antenna, wherein the feed antenna is configured to transmit and receive a radar signal, and wherein the feed antenna is disposed, together with the reflector, within the anechoic chamber;

the radar sensor testing zone, wherein the radar sensor testing zone is a predetermined area within the anechoic chamber, in which area a radar sensor under test is to be tested with the aid of a radar target simulator via a radar signal transmitted by the feed antenna; and

a retroreflector disposed in the radar sensor testing zone, wherein the retroreflector is configured to cause at least a portion of a measurement signal in the radar frequency range to be reflected back to the feed antenna via the reflector, wherein the measurement signal is received from the feed antenna via the reflector.

2. The system as recited in claim 1 , further comprising:

a network analyzer which is connected to the feed antenna and configured to cause the measurement signal to be applied to the feed antenna so that it is transmitted by the feed antenna and, in addition, to receive a portion of the measurement signal that is reflected back to and received by the feed antenna.

3. The system as recited in claim 2 , further comprising:

an evaluation unit configured to determine the transfer function from the feed antenna to the retroreflector.

4. The system as recited in claim 3 , further comprising:

a time-gating device configured to allow signals received by the network analyzer to be distinguished in terms of their propagation time.

5. The system as recited in claim 2 , wherein the network analyzer is provided with an input for receiving the portion of the measurement signal that is reflected back to and received by the feed antenna, and wherein an amplifier is connected in series to the input.

6. The system as recited in claim 1 , further comprising:

a transmit frequency converter for applying to the feed antenna the measurement signal to be transmitted; and

a receive frequency converter for receiving the reflected portion of the measurement signal.

7. The system as recited in claim 6 , wherein the transmit frequency converter is configured for conversion to a higher frequency, and the receive frequency converter is configured for conversion to a lower frequency.

8. The system as recited in claim 6 , wherein the transmit frequency converter and the receive frequency converter, are part of the radar target simulator that is to be used for the testing of the radar sensor under test.

9. The system as recited in claim 6 , wherein a coupler is connected between the feed antenna, on one side, and the transmit frequency converter and the receive frequency converter on the other side, wherein the coupler is configured to separate the received measurement signal from the transmitted measurement signal.

10. The system as recited in claim 9 , wherein a bandpass filter is connected between the transmit frequency converter and the coupler, the bandpass filter being configured such that the feed antenna can only transmit measurement signals within a predetermined frequency range.

11. The system as recited in claim 10 , wherein an isolator is connected between the transmit frequency converter and the bandpass filter to attenuate reflected signals coming from the direction of the bandpass filter and the coupler and to not feed them back to the transmit frequency converter.

12. The system as recited in claim 1 , wherein the retroreflector is mounted on a movable robot arm.

13. A method for measuring the transfer function on a path from a feed antenna via a reflector to a radar sensor testing zone in an anechoic chamber, the method comprising:

transmitting a measurement signal in a radar frequency range from the feed antenna via the reflector into the radar sensor testing zone; and

reflecting, by a retroreflector disposed in the radar sensor testing zone, at least a portion of the measurement signal transmitted into the radar sensor testing zone back to the feed antenna via the reflector.

14. The method as recited in claim 13 , wherein the portion of the measurement signal that is reflected back and received by the feed antenna and a reflection signal produced based on the measurement signal being coupled into the feed antenna are separated by windowing in the time domain.

15. The method as recited in claim 14 , further comprising:

transforming frequency range data of the received portion of the measurement signal and frequency range data of the reflection signal by an inverse Fourier transform from the frequency domain into the time domain in a time-gating device;

selecting a predetermined time interval which, on the one hand, includes the time that is composed of the expected propagation time of the measurement signal on the path from the feed antenna via the reflector to the retroreflector and back and the propagation time of the measurement signal from the feed antenna to the time-gating device, but which, on the other hand, does not include the expected propagation time of the reflection signal from the feed antenna to the time-gating device, so that a windowed time signal is obtained; and

transforming the windowed time signal from the time domain back into the frequency domain.