Definition of circular polarization: Under what condition are two orthogonal field components said to produce circularly polarized electromagnetic waves?

Introduction / Context:
Circular polarization (CP) is vital in satellite and radar links because it reduces sensitivity to orientation and can mitigate multipath. Knowing the exact amplitude and phase conditions that generate CP is a foundational skill in antenna engineering.

Given Data / Assumptions:

• Two orthogonal components (e.g., Ex and Ey) at the same point in space.
• Sinusoidal steady state with constant phase relationship.
• Right- or left-hand sense determined by the sign of the phase offset.

Concept / Approach:

Perfect CP requires equal magnitudes and a phase quadrature of ±90 degrees. The electric-field tip traces a circle with constant magnitude. Any amplitude inequality or phase offset other than ±90 degrees yields elliptical polarization; equal magnitudes with 0 degrees phase difference give linear polarization.

Step-by-Step Solution:

Verification / Alternative check:

Phasor diagrams show the resultant vector has constant magnitude and rotates uniformly. Laboratory polarizers and OMTs are designed to enforce these amplitude and phase constraints.

Why Other Options Are Wrong:

• Equal magnitudes alone (no phase shift) produce linear polarization.
• Unequal magnitudes with ±90° phase produce elliptical polarization.
• Unequal and in phase also gives linear polarization, oriented at an angle.
• Co-linear equal fields are not orthogonal and cannot make CP.

Common Pitfalls:

Confusing CP with simply “two components present”; both amplitude equality and quadrature phase are mandatory. Also, forgetting that axial ratio equals 1 for perfect CP.

Final Answer:

Their magnitudes are equal and they differ in phase by ±90°