Reverberant cavity loaded with a liquid to reproduce in-vehicle radio propagation environments

In this paper, we report, on the one hand, on some significant car bodies multipath radio channel characteristics obtained by numerical simulation and, on the other hand, on a dedicated test facility able to reproduce continuously and smoothly multipath characteristics corresponding to different car body shapes. The goal is to test different radio communication protocols at a very early stage of the design of a new vehicle. Considering the current development of infotainment systems, we select a center frequency of 2.5 GHz. Moreover, since in a car body very short communication paths exist, we select a bandwidth of 1 GHz to analyze these short ranges paths radio channel. The test facility prototype is a reverberant cavity whose volume is less than that of a vehicle body, pierced with openings and loaded with a conductive liquid volume adjusted to reproduce the desired propagation environment. We show that it is possible to reproduce the same RMS delay spreads in the test environment as those obtained by numerical simulations.