Electromagnetic Shielding - Part 2 — Lesson 4

This lesson covers the concept of electromagnetic shielding, focusing on the factors that contribute to total shielding effectiveness. It delves into the details of attenuation due to absorption, reflections, and multiple reflections. The lesson also discusses the impact of low-frequency magnetic shielding and the role of the thickness of the shield in absorption. It further explains how the shielding effectiveness due to absorption phenomena is proportional to the thickness, frequency, magnetic permeability, and conductivity. The lesson concludes by discussing the methods to design effective shields and the impact of multiple reflections on shielding effectiveness.

Video Highlights

00:13 - Attenuation due to absorption and its relation to shield design
03:52 - Analysis of absorption loss against frequency for common materials
06:21 - Attenuation due to reflection and its impact on electric and magnetic fields
11:31 - Shield in near field region and reflection loss example
14:30 - Attenuation due to multiple reflection and its effect
17:45 - Low frequency magnetic field shielding

Key Takeaways

- Total shielding effectiveness is composed of three factors: reflection loss at the boundaries, absorption in the metal, and multiple reflection within the metal.
- Shielding absorption is proportional to the thickness of the shield, frequency, magnetic permeability, and conductivity.
- High-frequency, high permeability, and high conductivity materials result in higher absorption loss.
- Reflection and absorption always come together, making the final product hard to predict.
- Attenuation due to multiple reflection can be neglected if the thickness is much greater than the skin depth.
- High permeability materials and super-conducting materials can be used for effective low-frequency magnetic field shielding.