Electromagnetic Shielding - Part 1 — Lesson 3

This lesson covers the concept of electromagnetic shielding, a solution to electromagnetic compatibility (EMC) problems. It delves into the definition of shielding effectiveness and how it is calculated. The lesson also explains the concept of transfer impedance and the role of absorption, reflection, and multiple reflections in the shielding effectiveness. It further discusses the properties of metals, such as skin depth, speed, wavelength, and characteristic impedance, and how they affect the shielding effectiveness. For instance, the lesson uses the example of a shielded cabinet to illustrate how the field strength inside the cabinet is reduced compared to the outside, demonstrating the effectiveness of the shield.

Video Highlights

00:13 - Electromagnetic shielding
04:40 - Review of wave propagation in metals
12:23 - Metallic plates
19:34 - Attenuation of fields by metal plates
23:33 - General expression for shielding effectiveness

Key Takeaways

- Shielding effectiveness is defined as the field strength on the source side divided by the field strength on the victim side.
- Shielding effectiveness is composed of three parts: absorption in the shield material, reflections from the shield, and multiple reflections inside the shield.
- The properties of metals, such as skin depth, speed, wavelength, and characteristic impedance, significantly affect the shielding effectiveness.
- The total shielding effectiveness is the multiplication of the absorption, reflection, and multiple reflection factors.