Characterization of TEM cell discontinuities due to filtered DUT test harnesses

Transverse electromagnetic (TEM) cell immunity testing of a multi-pin electronic module requires the use of low pass filtering to contain RF energy inside the cell while still allowing communication with the device under test (DUT) for diagnostic and control purposes. These filters, because of how they couple the DUT wire harness to the wall (side or floor) of the TEM cell, can greatly affect the uniformity of the test field at certain frequencies. To quantify this phenomena, the equivalent circuit model for a DUT and filtered wire harness in a TEM cell is empirically derived. Two different filter topologies are evaluated.