To Confirm The Shielding Performance Of Shielding Body By Using The Theory Of Input Impedance Of Transmission Line

Shielding is very important method to restrain and reduce EMI.Theory of shielding provides basic law to solve the problem of the engineer desighn in shielding.Thus the actual meaning in studying the theory of shielding is very strong.For ideal shielding body ,shch as boundless equal plane shielding body, infinitely long and equal column shielding body,and equal ball-shaped shielding body;their shielding performance can be analyzed by solving basic electromagnetic field equation(Maxwell equation) which is decided by eletromagnetic field boundary condition.In this paper I adopt the method of transmission line.The shielding performance of shielding body can be analyzed by using transmission line equation. This method can avoid using boundary condition and simultaneous equations.In the solution process the physical meaning is clear,and easy to understand.The meaning of shielding performance is expatiated by tracking the relation between voltage and current.It provides another method to probe into the theory of shielding performance of the shielding body.