The conductors of a coaxial transmission line are copper ( c = 5.8 10 7 S/m),

The conductors of a coaxial transmission line are copper (σ_c = 5.8 × 10⁷ S/m), and the dielectric is polyethylene (∈'_r = 2.26, σ/ω∈' = 0.0002). If the inner radius of the outer conductor is 4 mm, find the radius of the inner conductor so that

(a) Z₀ = 50 Ω;

(b) C = 100 pF/m;

(c) L = 0.2μH/m. A lossless line can be assumed.