Radiated immunity tests of automotive EMC challenge vehicle active antenna designs

Designing vehicle active antennas for weak signal performance while meeting the requirements of vehicle radiated immunity tests according to ISO 11451-2 and ISO 11452-2 remains one of the big challenges for the automobile and vehicle antenna manufacturers. Past vehicle testing has shown that some vehicle active antenna systems had during those tests performance issues (e.g. antenna burning or intermodulation distortion) which are caused by the vehicle body size. Component radiated immunity tests of ISO 11452-2 challenge active antenna system designs. In order to effectively reach a good reception performance, a deep knowledge about the design of the vehicle active antennas is required for the automotive EMC. There are three major topics this paper addresses: 1) clarifying the technical parameters of the vehicle antenna designs (e.g. transfer functions for vehicles and component set ups); 2) characterizing parameters useful for the ldquoelectromagnetic compatibilityrdquo (EMC) in order to pass the radiated immunity tests (e.g. injection RF-power); and finally 3) Identifying the causes of the antenna amplifier failures (amplifier distortion and destruction).