Section 11: Electromagnetics

What are Maxwell’s equations

fundamental equations that describe the behavior of electric and magnetic fields and how they interact with matter

What is electric flux?

Describes how an much electric field is passing through a surface

The more perpendicular the electric field is to the paper, the more flux you get

What is the divergence of an electric filed

measures how much electric field “spread out” from a point, and whether it is a source (positive) or a sink (negative)

Divergence is calculated using a dot product of the gradient and the electric field

∇⋅F = ∂Fx/∂x ​​+ ∂Fy/∂y ​+ ∂Fz/∂z​​

What is the permittivity of free space

The resistance a vacuum offers to the formation of an electric field

What is the curl of a vector field

A vector that describes how a field rotates around a point

Curl is a cross product of the vector gradient and electric field

∇×F = (∂Fz/∂y​​−∂Fy/∂z​ ​, ∂Fx/∂z​​−∂Fz/∂x ​​, ∂Fy/∂x​​−∂Fx/∂y​​)

What are incident and reflected waves?

In transmission lines, an incident wave is applied at one end and moves towards the load. When it hits the load, part of the incident wave is reflected back to the source

What is the reflection coefficient of a transmission line

How much of the incident wave is reflected back, determine by the difference between the transmission line’s impedance and the load impedance

tip: in application, you want to minimize the reflection by matching the transmission line’s impedance with your load’s impedance