Computational Modeling of TLH Coaxial Sensor for Investigation of Shielding Effectiveness

Annotation Bachelor's thesis deals with computer simulation of ASTM D4935-99 standard coaxial measuring tools. Such devices are used in order to determine the electric characteristics of materials. Recently an idea emerged that these tools can also help determine the shielding effectiveness of different materials. In the current thesis a computational model of coaxial transmission line holder TLH is developed. Model describes the structure of this device, gives possibility to observe the propagation of electromagnetic fields and to calculate the shielding effectiveness of desired material shield. The computational model is based on the Finite-Difference Time-Domain method. The results obtained with simulations are compared to the laboratory measurements. Conclusion is that the TLH measurement device should not be used for determination of shielding effectiveness of conductive materials. As an alternative, analytical methods of calculating the shielding effectiveness, knowing the material’s conductivity, dielectric permittivity and magnetic permeability, are proposed. The thesis consists of an introduction and three chapters: • The first chapter describes shielding theory and several standards of measuring the shielding effectiveness. • The second chapter describes modeling of the coaxial sensor and comparison of the results with measurements. • The third chapter describes analytical methods of calculating shielding effectiveness and comparison of these methods.