Control and Measurement of Unintentional Electromagnetic Radiation

CHAPTER 3

SINUSOIDAL CIRCUIT-CURRENT RADIATIONS

3.1 INTRODUCTION

For those readers whose primary interest is the effective reduction of unnecessary electromagnetic radiation, this will be a key chapter. Circuit-current radiations are characterized here with simple mathematics, and the primary concepts on which to base the reduction and control of circuit-current radiations are identified. Also, several examples of the radiations of sinusoidal circuit currents are examined graphically.

To minimize the radiation of a rectangular circuit current, the path width W of the current's circuital path must be minimized. The path width of a circuit is illustrated in Fig. 3-1. It is the distance between the connecting-current paths from source to load. The maximum radiations of all of the rectangular circuit currents examined in this chapter are directly proportional to their path widths. The radiations of circuit currents depend on several other parameters as well, but no other parameter is as freely adjustable as the path of a circuit current. That is an additional reason path width is important in effectively controlling circuit-current radiations.

Nonrectangular circuits and other parameters that affect the radiations of periodic circuit currents, which are sums of sinusoidal components, are examined in Chapter 6. It is again emphasized there, however, that properly reducing the path width of any circuit current is the most significant step that can be taken to reduce and control its radiations. ...