| ??? 12/27/09 20:42 Read: times |
#171962 - Principle of function... Responding to: ???'s previous message |
Richard said:
The steel (I might use copper screen soldered to the PCB's GND-plane, but even aluminum screen with pressed contact, would work) screen is a capital idea for managing EMI, yet, at distance, it won't be visible at all, and a fine screen won't even be very visible at normal reading distance. Some time ago I made some measurements on this kind of shielding an found out, that the shielding effectiveness can be incredibly high, even if you can easily look through the meshes! The explanation for this is, that the light rays penetrate through the meshes entirely undisturbed, but the electrical field lines end on the grounded steel grid. Only a very small fraction of field lines penetrate through the meshes and end on the circuit inside. To provide a good shielding even at highest frequencies, though, you must keep in mind this wavelength stuff, will say, the apertures of the grid shouldn't be wider than Lambda/100. Kai Klaas |
