Method for calibrating a radar system

A radar system, comprising:

• a main channel;
• and
• a reference channel formed symmetrically in relation to the main channel;
• a first oscillator to generate a first input signal, which is feedable into an antenna in the main channel, a reflected portion of the first input signal being feedable to a first mixer;
• a second directional coupler to feed the first input signal in the reference channel to a second mixer;
• a second oscillator to generate a second input signal having a frequency which differs from the first input signal in a defined manner, which is feedable to the first mixer and the second mixer;
• a comparing arrangement to compare the signal coming from the mixer of the main channel and the signal coming from the mixer of the reference channel;
• and
• a dimensioning arrangement to dimension a terminating impedance of the reference channel as a function of the comparison so that the output signals of the main channel and of the reference channel have identical properties.

A radar sensor, comprising:

• a radar system, including:
• a main channel;
• and
• a reference channel formed symmetrically in relation to the main channel;
• a first oscillator to generate a first input signal, which is feedable into an antenna in the main channel, a reflected portion of the first input signal being feedable to a first mixer;
• a second directional coupler to feed the first input signal in the reference channel to a second mixer;
• a second oscillator to generate a second input signal having a frequency which differs from the first input signal in a defined manner, which is feedable to the first mixer and the second mixer;
• a comparing arrangement to compare the signal coming from the mixer of the main channel and the signal coming from the mixer of the reference channel;
• and
• a dimensioning arrangement to dimension a terminating impedance of the reference channel as a function of the comparison so that the output signals of the main channel and of the reference channel have identical properties.

A method for calibrating a radar system, the method comprising:

• providing a radar system, the radar system including:
• a main channel;
• and
• a reference channel formed symmetrically in relation to the main channel;
• a first oscillator to generate a first input signal, which is feedable into an antenna in the main channel, a reflected portion of the first input signal being feedable to a first mixer;
• a second directional coupler to feed the first input signal in the reference channel to a second mixer;
• a second oscillator to generate a second input signal having a frequency which differs from the first input signal in a defined manner, which is feedable to the first mixer and the second mixer;
• aligning the radar system to an area without a detectable target;
• ascertaining a ratio between the output signal of the main channel and the output signal of the reference channel at least three times at different terminating impedances of the reference channel in each case;
• ascertaining resulting reflection coefficients) from the ascertained ratios;
• ascertaining a calibration coefficient of the antenna from the reflection coefficients;
• and
• setting the terminating impedance of the reference channel with the impedance tuner to an impedance which corresponds to the calibration coefficient.