Design

EMI shielding is a critical component of many electronics-based medical devices, which are in turn integral for life-saving procedures and ongoing patient health care. Medical devices are frequently used in the vicinity of other electronic instruments, resulting in an increased risk of electromagnetic interference (EMI). This risk can be mitigated through the use and care of EMI shielding gaskets. For more than a decade the FDA has also expressed concerns for public health and safety in regards to device EMI and the solutions for these concerns.

There has been much to do about the sudden unexpected acceleration EMI connection. There is no shortage of opinions on this subject. We’ve heard from manufacturers and their EMI consultants as well as from many recognized industrial and academic EMI experts. Most manufacturers have been very supportive of each other but have been very careful not to utter direct EMI related statements as they would rather not be seen in the spotlight of any investigations aimed in their direction. I guess they think that the EMI gods have decided to target just one automobile manufacturer.

The Method of Moments has become one of the most powerful tools in the RF engineer’s arsenal. In this chapter, we make the transition from theory to practice, first by attempting to compute the characteristics of a “short dipole” by hand, and then by demonstrating that a computer can do that in just a few seconds.

In the past EMC Engineers have relied on metallic enclosures to contain electromagnetic fields and meet radiated emissions limits in military and consumer products. Modern commercial electronics products typically use molded plastic enclosures since they are considered to be aesthetically more pleasing than a metal enclosure, but also to save weight and cost.

It is time to put these equations to work by computing the radiation from a simple structure, a short wire element.

In the preceding chapters we have derived Maxwell’s Equations and expressed them in their “integral” and “differential” form. In different ways, both forms lend themselves to a certain intuitive understanding of the nature of electromagnetic fields and waves. In this installment, we will express Maxwell’s Equations in their “computational form,” a form that allows our computers to do the work.