Question

For an unbalanced to balanced signal conversion, if the turn’s ratio in a Balun is 1:2 then the balanced impedance is ______ times the unbalanced impedance.

(a) 4

(b) 2

(c) \(\frac{1}{2} \)

(d) \(\frac{1}{4} \)

I got this question in a national level competition.

Query is from Baluns topic in portion Radiation, Baluns & Polarization of Antennas

Answer 1

Right choice is (a) 4

To explain I would say: A Balun can be viewed as a transformer. \(\frac{Z_{unbal}}{Z_{bal}} = (turns \,ratio)^2=(\frac{1}{2})^2=\frac{1}{4} \)

⇨ Zbal = 4Zunbal

So the balanced impedance is four times the unbalanced impedance.