Question

The expression of the characteristic impedance of a symmetrical T-section is?

(a) ZOT=√(Z1^2/4-Z1Z2)

(b) ZOT=√(Z1^2/4+Z1)

(c) ZOT=√(Z1^2/4+Z2)

(d) ZOT=√(Z1^2/4+Z1Z2)

The question was posed to me at a job interview.

My query is from Filter Networks topic in chapter Filters and Attenuators of Network Theory

Answer 1

The correct option is (d) ZOT=√(Z1^2/4+Z1Z2)

Explanation: For a T-section, the value of input impedance when it is terminated in Zo is

Zin=(Z1/2)+(Z2((Z1/2)+Zo))/((Z1/2)+Z2+Zo) and Zin=Zo. On solving, the expression of the characteristic impedance of a symmetrical T-section is ZOT=√(Z1^2/4+Z1Z2).