Radiated emission from CRT of computer VDU

Abstract

The author presents a radiation model for the electron beam in a CRT (cathode ray tube) and give an analytical solution to the radiation, which could be utilized to compute the radiated field at both near and far zones. It is demonstrated that the electron beam is equivalent to conductive current in a wire which carries current of the same intensity as the electron beam. Because the electrons are focused to a beam before moving to, and bombarding on, the CRT screen, the equivalence is valid and feasible. It is concluded that, in calculating the radiated field from the CRT, the shielding effect of the aluminized screen and graphic film in the CRT should be taken into account. However, for the evaluation of maximum radiated field, the shielding effect may be neglected because the thickness of these sheaths is much thinner than their skin depth. >