What defines a linearly polarized wave?

The tip of the E vector moves along a straight line at a fixed point

The E vector rotates with the frequency of the carrier only

When do two orthogonal components Ex and Ey give linear polarization?

When they are in phase or 180° out of phase (Δφ = nπ), with any amplitudes

Only when they have equal amplitudes and are 90° apart

Only when their amplitudes are equal and Δφ = 0

2072 Magh · 3 marks

Short note: Linear polarization

Short answer

Linear polarization occurs when the tip of the electric field vector at a fixed point moves along a straight line. This happens when only one component exists or two orthogonal components are in phase or 180° out of phase. Types are vertical, horizontal and slant; PLF = cos²ψ, giving zero for cross-polarization.

Write a short note on linear polarization.

An antenna or wave is linearly polarized when the tip of its electric field vector, at a fixed point, always moves along a straight line as time passes.

Conditions (with components Ex, Ey):

Only one component exists, or
Two orthogonal components are in phase or 180° out of phase (Δφ = nπ), with any amplitudes.

  Vertical   Horizontal   Slant (45°)
     |                       /
     |        -------       /
     |                     /

Types:

Vertical polarization: E perpendicular to the earth, e.g. vertical monopole, AM/mobile.
Horizontal polarization: E parallel to the earth, e.g. horizontal dipole, TV broadcast.
Slant (±45°): used for polarization diversity in cellular base stations.

Axial ratio = ∞. A linearly polarized receiving antenna gets PLF = cos²ψ, where ψ is the angle between wave and antenna polarizations; cross-polarized (ψ = 90°) reception gives zero signal. A linear antenna receives half of the power (3 dB loss) of a circularly polarized wave.

✓ Answer checked by Claude Opus 5.5 (high effort)

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