Assertion (A): A coaxial line is a non-radiating transmission line. Reason (R): In a coaxial line, the electric and magnetic fields are confined to the region between the concentric conductors. Which statement is correct?

Introduction / Context:
Coaxial transmission lines are widely used in RF applications because they confine electromagnetic fields and prevent radiation losses. The assertion-reason type question tests the understanding of why coaxial lines do not radiate.

Given Data / Assumptions:

• Structure: inner and outer concentric conductors.
• Fields confined to dielectric between conductors.

Concept / Approach:

The fields in coaxial geometry cancel outside the line. The outer conductor shields the fields, confining them to the dielectric region. This explains why coaxial lines are non-radiating.

Step-by-Step Solution:

Verification / Alternative check:

Coaxial cable is preferred for shielding-sensitive RF signals precisely for this reason.

Why Other Options Are Wrong:

• Option B: R is indeed the correct explanation.
• Option C: R is not wrong.
• Option D: A is not wrong.
• Option E: Both are correct.

Common Pitfalls:

Confusing coaxial with two-wire lines that radiate due to unconfined fields.

Final Answer:

Both A and R are correct, and R is the correct explanation of A