TMA: EMI/EMC FUNDAMENTALS FOR RF/MW ENGINEERS

Date & Time: Monday, June 13; 1:00 PM to 5:00 PM

Location: Long Beach Convention Center, Room 204

Topics & Speakers:  

• Introduction to EMC, W.H. Cantrell

• EMC Fundamentals, Part I. , A. Mediano

• EMC Fundamentals, Part II, W.H. Cantrell

• Basic Design & Diagnosis / Problem Solving Techniques, A. Mediano

• RF/MW EMI Problem Solving Strategies, W.H. Cantrell  

Organizers:

W. H. Cantrell, Motorola & The University of Texas at Arlington

A. Mediano, The University of Zaragoza  

Sponsors:

MTT-17: HF, VHF, UHF Techniques  

Many companies are beginning to view Electromagnetic Compatibility (EMC) as an important part of an engineer's basic training, as well as a desirable skill-set for obtaining a competitive edge in the marketplace. This tutorial provides a basic introduction to EMC, and covers the four EMC coupling mechanisms:  

1. Common impedance coupling (sharing a common impedance for the return currents)

2. Capacitive coupling (electric field coupling in the near-field)

3. Inductive coupling (magnetic field coupling in the near-field, Faraday's Law)

4. Radiated coupling (electromagnetic propagation in the far-field)  

Some of the EMC regulatory requirements are discussed, including how to make radiated emissions measurements at an Open Area Test Site (OATS), and how to make conducted emissions measurements using a Line Impedance Stabilization Network (LISN). Other topics include return current flow and the concept of minimum loop area, filtering techniques with ferrites, decoupling and bypassing, grounding strategies, and PCB design techniques to minimize emissions. The performance of shields and their shielding effectiveness is discussed including methods to obtain extremely high levels of isolation between system components, in excess of 150 dB. This includes an analysis of the role of apertures and airholes, seams and gaps in an enclosure, as well as wires (I/O lines) that penetrate the enclosure. Basic design techniques are presented to avoid EMC problems in a design. Practical tools, hints and examples are presented on how to find and solve EMC problems. Finally, a unique problem solving strategy is presented using two examples common to the RF & microwave industry: (1) Identifying the amount of isolation, the shielding requirements, and the I/O filtering needed between stages in a typical transmitter line-up to avoid gain flatness problems, and (2) Elimination of undesired radiated coupling between a co-located transmitter & receiver, both operating on the same carrier frequency.