Influence of Electrically Large Structures on the EMC-Compliance of a Semi-Anechoic Chamber

As the number of radio systems in modern vehicles increases, electromagnetic interference between them becomes an issue. The investigation and testing of new wireless devices regarding the immunity against radio disturbances and the emission of unwanted signals is essential to reach high reliability in later applications. Usually, these tests are performed in fully or semi anechoic chambers to achieve defined, undisturbed wave propagation mimicking free-space conditions. The degree of achieving these nearly ideal conditions can strongly influence the measurement results. As a consequence, international standards provide procedures to validate test facilities. This paper discusses the influence of an electrically large antenna measurement arch on the norm compliance of the Virtual Road Simulation and Test Area (VISTA) of the Thuringian Center of Innovation in Mobility at the Technische Universität Ilmenau, with focus on the frequencies of modern wireless communication systems. Time domain information of received test signals is used to identify reflections and their sources in the chamber. This approach provides access to the site voltage standing wave ratio (sVSWR) demanded by standards and presents a novel generalized technique for reliable site qualification in consideration of installed structures.