TEM-mode E-field uniformity in a GTEM cell

TEM-mode electric field uniformity on the transverse plane that was perpend icular to a floor conductor of a GTEM (gigahertz transverse electromagnetic ) cell, and the usable test volume in the cell, were evaluated both theoret ically and experimentally at frequencies of up to 1 GHz. Electric fields in the GTEM cell were calculated by using the FD-TD (finite-difference time-d omain) method. The fields were measured by using an optical E-field (electr ic field) sensor in order to confirm the calculation result. CISPR/A (CISPR : Comite International Special des Perturbations Radioelectriques) and IEC (International Electrotechnical Commission) SC77B proposed in their committ ee draft that the usable test volume was 0.6W x 0.33h, where W and h were a width of the septum (inner conductor of the cell) and a distance between t he septum and the floor conductor of the cell, respectively. We found that the usable test volume, i.e. the maximum width and height of an EUT, by the committee draft are reasonable and applicable for a GTEM cell.