A 75 Ω air-filled coaxial cable has an inner conductor diameter of 1.5 mm. What is the approximate inner diameter of the outer conductor? (Take ln(5.87) ≈ 1.77)

A 300 km long, three-phase transmission line operates at 400 kV and 50 Hz. The inductance of the line is 0.97 mH/km/phase, and the capacitance is 0.0115 μF/km/phase. Assuming the line is lossless, calculate its characteristic impedance (Zc).

Two transmission lines are connected in series: Line 1 (length 40 m, attenuation 0.08 dB/m) and Line 2 (length 25 m, attenuation 0.2 dB/m), with an additional joint loss of 2 dB. What percentage of the input power reaches the output?