Figures of Merit for a Hybrid TEM-Reverberation Chamber

A hybrid TEM-reverberation chamber would allow efficient radiated field immunity tests to be performed from DC to microwave frequencies in a single facility. TEM cells are limited to testing comparatively small equipment at relatively low frequencies. Reverberation chambers must be very large to be effective at low frequencies, because the statistical properties of the randomly polarised field break down when insufficient mode stirring occurs [1]. Since there is no frequency overlap between TEM and reverberation operation for a chamber of any given size, a combined TEM/reverberation facility must also operate in a transition mode in order to cover the entire frequency band. This paper proposes performance parameters for overmoded TEM and undermoded reverberation frequency ranges, and gives an example of how the figures of merit can be used to evaluate potential hybrid cell designs.