Which of the following modes does the condition πD << λ is satisfied in helical antenna?

Question

Which of the following modes does the condition πD << λ is satisfied in helical antenna?

(a) Axial mode

(b) Normal mode

(c) Conical mode

(d) Axial, Normal and Conical

Answer 1

The correct choice is (b) Normal mode

To explain: The circumference of the helical antenna C= πD varies with the wavelength in different modes as follows

In Normal mode: πD << λ

     Axial mode:  C ≈ λ

     Conical mode: C ≈n λ