Electromagnetic Radiation
CHAPTER 11.5 Electromagnetic Radiation
The PCB traces and ICs carrying the high speed signal can be source of radiation. A high edge rate causes more chances of signal radiation. Traces that are not adequately terminated lead to more reflection and higher emission. The clock oscillators are major sources of radiation. The radiation pattern observed in a spectrum analyzer shows frequencies that are usually a multiple or harmonics of clock oscillators used in design. It is impossible to completely suppress the radiation. PCB designers need to follow few design rules to minimize the signal radiation. A product is not market worthy if it radiates too much and fails FCC tests.
If all the five areas of the high speed PCB design along with the circuit design are addressed, we have a product that is less likely to fail in the lab tests and in field because of the errors, distortion, crosstalk and radiation in the high speed signaling.
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