The Simulation And Prediction Of The Shielding Efficiency Of A Communication Square Cabin

As it is expensive to construct a communication square cabin, the cost and shielding efficiency should be considered synthetically. The paper adopts the finite difference time domain (FDTD) method to predict and analyze the key parameter of the communication square cabin-the shielding efficiency (SE).The paper deduces FDTD algorithm of the slot of shielding door. By establishing the slot model when the electromagnetic wave irradiated over against it, the paper studies the FDTD algorithm when the shielding door lies on the obverse, left or right of the square cabin, and deduces the expression of each electromagnetic component of the slot respectively. As well, it compares Mur and PML absorbing boundary conditions which are usually used in FDTD.According to the above algorithm, the paper analyzes the effect of the slot width (a), length (b), and depth (h) on SE and presents its varying graph; as well, the paper analyzes the SE of common use sealing pads in shielding door- sponge rubber bar, complex rubber bar and spring plates. Aiming at different simulation structure of adding different sealing pads, it calculates the SE under different conditions. The results indicates that SE is low when a and b is big, and high when h is big, it can enhance SE effectively by dividing the long slot into a series of short slots. The SE of shielding door is different when adding different pads, it is lowest when adding sponge rubber bar (about 50dB), it is about 68～72dB when adding complex rubber bar, and 75～77dB when adding spring plates; it is highest when adding spring plates and complex rubber bar synchronously (above 84dB). So it can enhance the SE by use multi- sealing pads synthetically.The paper designs a communication square cabin and selects the best structure based on the simulation results, and do simulation and prediction to the cabin, the results indicates that the SE is bigger than 60dB, which is satisfy the requirements of GJB1126-91"CAF50PD cabin criterion". The SE prediction method discussed in the thesis is significative to the construction of cabin and the enhancement of its SE.Doing the EMC prediction and analysis before construction of the cabin, and selecting the logical design accordingly can help us complete the design of the cabin effectively.