Question

Which of the following is the condition for the Log periodic antenna to be inactive stop region?

(a) \(L=\frac{λ}{2} \)

(b) \(L > \frac{λ}{2} \)

(c) \(L < \frac{λ}{2} \)

(d) \(L = \frac{λ}{4} \)

The question was asked in an interview.

The doubt is from Frequency Independent Antenna in division Frequency Independent Antenna of Antennas

Answer 1

The correct choice is (b) \(L > \frac{λ}{2} \)

The best explanation: Based on the lengths of the dipoles in LPDA, operation region is classified into three types:

 Inactive transmission line region, Active region and Inactive stop region. The region below \(L < \frac{λ}{2} \) belongs to Inactive transmission region. The region above \(L > \frac{λ}{2} \) is Inactive stop region.