Error Analysis of the Maximum Coupling for HEMP Illumination Tests With EUT Rotations

The maximum electromagnetic (EM) coupling is directly related to the polarization angle of the incident field in the high-altitude EM pulse (HEMP) illumination test. Aimed at the linear system, this letter analyzed the test error of the maximum coupling corresponding to the change of the angle between the polarization direction and the direction of the equipment under test (EUT) in EMP illumination tests. Characterized by the EM norm, the quantization estimation formula of the maximum coupling test error under illuminations with EUT rotations is deduced. The results show that the maximum measurement accuracy is the cosine of 1/2 of the maximum rotation angle of the EUTs. Finally, a test scheme of five illuminations (with rotations of the EUT and the rotation angle of each rotation is 36°) with 95% test accuracy of the maximum coupling of the method itself is recommended in this letter. The results can provide support for the design and evaluation of the EM illumination test.