he functional and spatial integration of a wireless power transfer system (WPTS) into electric vehicles is a challenging task, due to complex multiphysical interactions and strict constraints such as installation space limitations or shielding requirements. This paper presents an electromagnetic–thermal investigation of a novel design approach for an ultrathin onboard receiver unit for a WPTS, comprising the spatial and functional integration of the receiver coil, ferromagnetic sheet and metal mesh wire into a vehicular underbody cover. To supplement the complex design process, two-way coupled electromagnetic–thermal simulation models were developed. This included the systematic and consecutive modelling, as well as experimental validation of the temperature- and frequency-dependent material properties at the component, module and system level. The proposed integral design combined with external power electronics resulted in a module height of only 15mm. The module achieved a power of up to 7.2 kW at a transmission frequency of f0=85kHz with a maximum efficiency of 92% over a transmission distance of 110mm to 160mm. The proposed simulations showed very good consistency with the experimental validation on all levels. Thus, the performed studies provide a significant contribution to coupled electromagnetic and thermal design wireless power transfer systems.