3D Mapping of Surface Profiles by Radar Measurements at E-Band Employing On-Site Near-Field Calibration

For many applications it is essential to know the exact information about a surface profile or a soil level. For this purpose, a very irregular surface is created with sand, and its surface profile is measured with the aid of a 4-D E-band radar sensor employing a total number of more than 1700 channels. Typically, high-precision in-situ calibrations are employed to ensure the best possible radar performance. Unfortunately, environmental influences, such as the temperature, vary strongly between the initial calibration scenario and the application scenario, making a re-calibration necessary. To ensure the proper operation of the sensor a re-calibration is performed at the exact time and location of application. To be independent of the scene under investigation, the calibration target is placed in the near-field of the sensor and out of the main lobe illuminating the area under test. Furthermore, the calibration in field-trials is performed by means of a calibration target without the need for a precise mechanical placement. Therefore, a highly precise in-situ calibration is used to estimate the position of the calibration target. A field-trial is deployed to show the radar performance with on-site near-field calibration and a comparison to an initial calibration in the far-field of the radar sensor is conducted to demonstrate the compensation of near-field effects on the calibration.