Analysis of electromagnetic radiation from a video output amplifier inside a monitor by using FDTD method

The finite-difference time-domain (FDTD) method is used to analyze the electromagnetic compatibility and interference (EMC and EMI) problems due to the electromagnetic radiation from a video output amplifier located inside a computer monitor. The multiple grid technique is implemented in the FDTD method to improve the computational efficiency. The video output amplifier is modeled by a rectangular iron container with an equivalent dipole antenna located at the center of one opened wall facing the cathode-ray-tube (CRT). The coupled electric fields inside and outside the monitor are calculated. It is found that higher values of coupled electric fields occur near the monitor screen. It is also found that the coupled electric fields outside the CRT region drop sharply in amplitude. Simulation results of coupled electric fields at a distance of 3 m from the monitor screen also comply with the FCC regulations. Calculation results also agree with the experimental data for coupled electric fields outside the monitor screen at a measured distance of 3 m.