Solved Exercise/Numericals - Transmission Lines - 1.
Q.1) A transmission line operating at 500 MHz has Z o = 80Ω, α = 0.04Np/m, β = 1.5 rad/m. Find the line parameters R, L, G and C. Answer: Since Z o is real & α ǂ 0, this is a distortionless line. R o = α Z o = 0.04 x 80 = 3.2 Ω / m G = α / Z o = 0.04 / 80 = 5 x 10-4 Ω / m L = β Z o / ω = 1.5 x 80 / (2 π x 5 x 108 ) = 38.2 nH / m C = L G / R = 38.2 x 10-9 x 5 x 10-4 / 3.2 = 5.97 pF / m Q.2) A telephone line R = 30 Ω /km, L = 100 mH/km, G = 0 , and C = 20 µF/km. At f = 1 kHz, obtain: a) The characteristics impedance of the line. b) The propagation constant. c) The phase velocity. Answer: Q.3) A 40 m long transmission line has V g = 15 ∠0 o V rms , Z o = 30 + j60 Ω, and V L = 5 ∠-48 o V rms . If the line is matched to the load, calculate: a) The input impedance Z in b) The sending end current I in and voltage V in c) The propagation constant γ Answer: a) Z g = Z 1 --> Z in ...