For low frequency signals (up to 100MHz) radiated and conducted emission can be ignored but as wavelength becomes comparable to the trace length circuit approximation is no longer valid. The trace geometry and its separation become important in case of PCB. The signal's rise time, fall time, period and pulse width play the role in determining the EMC of PCB’s. A lack of knowledge of fundamental EMI sources also makes anticipating potential EMI problems at the design stage troublesome.
Read the full article on page 18 of our January digital edition.