There are a number of design concepts and techniques in existence which are aimed at improving EMC. Many of them are supported by the analytical approach. But some are not. A concept that can be traced back for many decades is that of the `equipotential ground plane'. There is no such thing. Since the 'method of images' of electromagnetic theory is often quoted as the basis for this concept, it is useful to identify the fallacies underlying the correlation. Section 8.1 does just that. Designers should resist the temptation to treat the structure as a convenient return path for signals and power. The most effective use of the conducting structure is as a shield. One deduction which is continually reinforced during the process of creating circuit models is the fact that the signal and return conductors should be as close together as possible.

Chapter Contents:

• 8.1 Grounding
• 8.2 Conductor pairing
• 8.3 Ground loops
• 8.4 Common-mode rejection
• 8.4.1 Differential amplifier
• 8.4.2 Differential logic driver
• 8.4.3 Differential analogue driver
• 8.4.4 Common-mode choke
• 8.4.5 Transformer coupling
• 8.4.6 Center-tapped transformer
• 8.4.7 Opto-isolator
• 8.5 Differential-mode damping
• 8.5.1 Transient damping
• 8.5.2 Mains filtering
• 8.5.3 Solenoid switching
• 8.5.4 Commercial filters
• 8.5.5 Use of carbon
• 8.6 Common-mode damping
• 8.6.1 Common-mode resistor
• 8.6.2 Minimizing pickup
• 8.6.3 Triaxial cable
• 8.6.4 Transformer inter-winding
• 8.6.5 Common-mode filter
• 8.6.6 Transformer-coupled resistors
• 8.7 Shielding
• 8.7.1 Equipment shielding
• 8.7.2 Shielding of buildings
• 8.7.3 Use of carbon

Inspec keywords: electromagnetic shielding; electromagnetic compatibility; electromagnetic field theory; conductors (electric)

Other keywords: return path; electromagnetic theory; equipotential ground plane; method of images; circuit models; EMC design; conducting structure; return conductors

Subjects: Conductors; Electric and magnetic fields; Electromagnetic compatibility and interference