Question

The dipoles in the inactive stop region offer ________ impedance.

(a) Capacitive

(b) Resistive

(c) Inductive

(d) Characteristic

This question was posed to me in unit test.

The query is from Frequency Independent Antenna topic in section Frequency Independent Antenna of Antennas

Answer 1

Right option is (c) Inductive

The best explanation: The varying length of the dipoles in LPDA forms different regions and they offer different resistances. The Inactive transmission line region at \(L < \frac{λ}{2}\)  offers Capacitive Impedance, Active region at \(L=\frac{λ}{2} \)  offers Resistive Impedance and Inactive stop region \(L > \frac{λ}{2} \)  offers Inductive impedance.