**Subject :**Microwave Engineering

## Faraday Rotatation in Ferrites

A plane circularly polarised wave propagating in H_{o} direction will have two different propagation constants given by

**Figure : Faraday Rotation in Ferrites
**

Therefore, for a linearly polarised wave propagating along H_{0}, the plane of polarisation rotates. This phenomenon is a non-reciprocal one. The rotation of the elec- tric field of a linearly polarised wave passing through a magnetised ferrite is known as Faraday rotation as explained above with Figure.

Let a linearly polarised TEM wave propagates in Ferrite along the Z-axis with

The linearly polarised wave may be decomposed into the sum of clockwise and anti-clockwise circularly polarised waves. The component waves propagate with different phase constants β^{ } and β^{-} respectively, and the two corresponding electric field vectors rotate at different rates. Over a distance A, the resultant linearly polarised wave will undergo a phase delay of

Therefore ,

and corresponding rotation angle.

The rotation per unit distance is

This property is utilised in designing ferrite isolator and circulators.