Question

For a feeder length of 0.5λ, which among the following would be the director length?

(a) 0.525λ

(b) 0.455λ

(c) 0.493λ

(d) 0.55λ

This question was addressed to me in final exam.

My query is from Construction of Yagi topic in portion Folded Dipole & Yagi – Uda Antenna of Antennas

Answer 1

Right choice is (b) 0.455λ

The explanation: The director length is approximately 5% less than the driven element length.

⇨ 0.5-(0.5(5/100)) = 0.475

So, l = 0.455λ is correct as it is the only option which is less than 0.475λ.