A Complete Model for Simulating Magnitude and Phase of Emissions from a DUT Placed Inside a GTEM Cell

Abstract

Since the publication of IEC 61000-4-20, the gigahertz transverse electromagnetic (GTEM) cell has gained popularity in radiated emission and immunity electromagnetic compatibility tests. Various numerical methods such as finite-difference time-domain, finite element method, and method of moments have been used to model the GTEM cell in the pursuit of getting to know the characteristic of the GTEM cell with varying degrees of verification. In this paper, the time-domain transmission line model will be used to model the GTEM cell. The advantages of this method include high accuracy and the ability to model different materials. Thus, the GTEM is realistically modeled including radio absorbing material (RAM) and lumped terminations. In addition, the model of a realistic device under test (DUT) was also included in the GTEM model. The DUT consists of a standard sized box with an aperture, placed in different orientations inside the GTEM for power and phase measurements. The particular features of this paper are: 1) the inclusion of a realistic numerical model of RAM, 2) the inclusion of a realistic DUT model, 3) systematic verification of the model against measurements, and 4) the method of phase measurement in a GTEM cell. Good agreement between the experimental results and simulations is obtained.