Aperture Efficiency of Active and Passive Radar Targets in Cluttered Environments

Calibration and verification of radar systems usually requires well defined targets to calibrate and to evaluate the system capabilities. This paper compares active and passive radar reflectors and their field of application. Theoretical considerations regarding the aperture efficiency are made and compared over frequency. Wavelength and radial resolution are found to be a key factor for surrounding clutter levels. It is shown that for single-digit GHz, active reflectors have advantages compared to passive structures. In contrast, passive targets can be better suited for higher frequencies that are used in automotive bands due to technical simplicity and sufficient radar-cross-section.