Questions:

(a) Suppose a 100 kHz switching power supply.

(i) Evaluate the magnitude of the wave impedance of the radiated field of a very short wire in the switching power supply at a distance of 15 cm if it carries the fundamental frequency of the switcher of 100 kHz.

(ii) Evaluate the magnitude of the wave impedance of the radiated field of the transformer in switching power supply at a distance of 15 cm.

(b) Model the shield on a 2-m personal computer printer cable as a monopole antenna (with the metallic structure of the computer as the ground plane) and estimate the maximum radiated emissions at a measurement distance of 3 m if the voltage of the shield attachment point with respect to the metallic structure is a 1-mV, 37.5-MHz signal.

(c) Check a typical personal computer having a metallic enclosure and list the "penetrations" that allow signals from the inside to pass to the outside, avoiding the shielding of the metallic enclosure.