Question

The sinusoidally time varying vector field

F̅ = 2cos (ωt + 30°) a̅_x + 2 cos (ωt – 30°) a̅_y is 

1. elliptically polarized 
2. circularly polarized 
3. linearly polarized 
4. unpolarized 

Answer 1

Correct Answer - Option 1 : elliptically polarized 

The time-varying form of the field is given as:

E̅wi = E0cosωt âx – E0sinωt ây 

At ωt = 0

E̅wi =  E0 âx  + E0 ây

At ωt = π/2

E̅wi = - E₁ âx  + E₁ â_y

As the tip of the electric field intensity is tracing an ellipse in the anti-clockwise direction with the direction of propagation as time varies, the wave is said to be elliptically polarized in the clockwise direction (or) RHCP.