Question

Which of the following is the condition for the Log periodic antenna to be in active region?

(a) \(L = \frac{λ}{2} \)

(b) \(L > \frac{λ}{2} \)

(c) \(L < \frac{λ}{2} \)

(d) \(L = \frac{λ}{4} \)

I got this question in a national level competition.

Question is from Frequency Independent Antenna topic in section Frequency Independent Antenna of Antennas

Answer 1

Correct answer is (a) \(L = \frac{λ}{2} \)

To explain I would say: Based on the lengths of the dipoles in LPDA, operation region is classified into three types:

Inactive transmission line region \(L < \frac{λ}{2} \)

Active region \(L=\frac{λ}{2} \)

Inactive stop region \(L > \frac{λ}{2}. \)