  Automotive radar sensors play a key role in the current development of
advanced driver assistance systems (ADAS). Their ability to detect objects even
under adverse weather conditions makes them indispensable for
environment-sensing tasks in autonomous vehicles. Since an operational failure
presents a potential risk to human life, thorough and practical validation
testing must be performed, requiring an integrative test solution. Radar target
simulators (RTS) are capable of performing over-the-air validation tests by
generating virtual radar echoes that are perceived as targets by the radar
under test (RuT). Since the authenticity and credibility of these targets is
based on the accuracy with which they are created, their simulated position
must be arbitrarily adjustable. In this work, an existing approach to
synthesize virtual radar targets at an arbitrary angle of arrival (AoA) is
extended to cover both, the azimuth and elevation domain. The concept is based
on the superposition of the returning signals from four neighboring RTS
channels. A theoretical model describing the basic principle and its
constraints is developed. In addition, a measurement campaign is conducted to
verify the practical functionality of the proposed approach.
