EMI problems? Part three: strength of EMI-radiated signals

摘要

How far away from radiating sources do you need to be so that the radiated signal does not interfere with your system? As you answer this question, consider both the amount of radiated energy from a source and your system's electromagnetic-interference-protection circuitry. Radiating EMI signals propagate from a source to a receiving element (references 1 and 2). The power, or voltage level, of these signals as they hit your sensitive circuits depends on the transmitter's power and antenna gain and the distance between the source and the receiver (Figure 1).