Empirical Characterization and Modeling of a Propagation Channel inside the VIRC

Abstract

<p>Electromagnetic compatibility (EMC) measurements and over-the-air (OTA) testing are widely performed in classical reverberation chambers. A less-known reverberation chamber, yet a rather efficient environment for generating multipath conditions, is the Vibrating Intrinsic Reverberation Chamber (VIRC), which is yet to be fully characterized. Therefore, this article thoroughly investigates a propagation channel inside a VIRC in terms of its first- and second-order temporal and spectral characteristics for EMC measurements and OTA testing of wireless baseband algorithms in narrowband single-input single-output systems. The investigated characteristics are coherence time, Doppler spectrum, Doppler spread, frequency autocovariance function, coherence bandwidth, rejection rate of Chi-squared goodness-of-fit test for Rician distribution, Rician 𝐾-factor, and channel gain. The investigation considers the effect of different rotational speeds of the VIRC motors, two loading conditions, and the frequency range 670 – 2740 MHz. An analysis of the measurement results shows that the stirring effectiveness degrades at frequencies below 820 MHz in general. For the loaded VIRC in particular, rotational speeds below 28.3 rpm are another degradation contributor. Moreover, the analysis reveals many interesting behavioral trends. This in turn is used to introduce a number of mathematical models closely fitting the behavior of various of the investigated characteristics. Such models are useful, for instance, at shortening similar measurement campaigns of comparable VIRCs.</p>