Question

All transmission line section in Figure, have a characteristic impedance R0 + j0. The input impedance Zin equals

(a) 2/30

(b) 0

(c) 3/20

(d) 20

Answer 1

Correct option (b) R0

Explanation:

For λ/4 line, zin1 = z20/zL = R20/R0/2 = 2R0

For λ/2 line, zL2 = 2R0

For λ/8 line, zL = (2R0)|| 2R0

= R0

For transmission line of length l, zin = z0[(zL + jz0tanβl)/(z0 + jzLtanβl)]

l = λ/8, zin = z0[(zL + jz0)/(z0 + jzL)]

zin = R0[(R0 + jR0)/(R0 + jR0)] = R0