Characterization of electric field distribution in a GTEM cell

Ubin, Aizan (2004) Characterization of electric field distribution in a GTEM cell. Masters thesis, Kolej Universiti Teknologi Tun Hussein Onn.



Two of the most important measurements related to electromagnetic compatibility (EMC) are radiated emission and radiated immunity. These measurements must be performed in a facility which provides reliability and reproducibility. The Gigahertz Transverse Electromagnetic Mode (GTEM) cell is one of the facilities for EMC measurement due to its well defined electric and magnetic field distribution in addition to being cost effective. The research undertaken in this project is to determine the field distribution in the GTEM by using Finite Difference Time Domain (FDTD). The results from the modeling are then compared with actual measurements and any differences will be noted and explained. The field strength inside a GTEM cell is a fl.lI1ction of the input power as well as location along the longitudinal axis or septum height. Radiated immunity measurements require field uniformity (+6 dB according to IEC 61000-4-3 standard) which depends on the design aspects of the GTEM such as size, material and absorbing condition. The capability of the GTEM cell to provide the unifo1111 field can be tested theoretically and experimentally. FDTD is a numerical method that can be used to predict the electric field distribution in a GTEM cell. The electric field distribution for frequencies at 100 MHz, 200 MHz, and 400 MHz were calculated using the EZ-FDTD software. In this report, theoretical study on the field strength and distribution in a GTEM cell is described. It is followed by making measurements of the field based on the radiated immunity test setup. It is found that at septum height 63 cm for frequency 100 MHz, the measured and simulated results are very close. This is the location recommended by the manufacturer for the placement of equipment under test (EUT) in radiated emission and radiated immunity test. The difference varies from 0.01 dB to 4.91 dB. The difference between modeling and actual measurement can be attributed to the input field distribution, inhomogeneous characteristics of the septum and existence of standing wave. In the future, it is recommended that other numerical methods such as Finite Element Method (FEM) and Transmission Lines Method (TLM) be used and more accurate model and absorbing boundary condition parameters be implemented.

Item Type:Thesis (Masters)
Subjects:T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK7800-8360 Electronics
ID Code:1489
Deposited By:Norfauzan Md Sarwin
Deposited On:20 Apr 2011 15:29
Last Modified:29 Apr 2011 14:44

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