Question

Which of the following modes of radiation, the radiation of helical antenna is along the end-fire direction?

(a) Axial mode

(b) Normal mode

(c) Perpendicular mode

(d) Beam mode and Normal mode

I had been asked this question by my school teacher while I was bunking the class.

My question comes from Frequency Independent Antenna in chapter Frequency Independent Antenna of Antennas

Answer 1

Correct option is (a) Axial mode

Explanation: In Axial mode of radiation, the radiation is in end-fire direction along the helical axis. In Axial mode of radiation, the dimensions of antenna are approximately equal to the wavelength and spacing space of λ/4.  Axial mode is also known as beam mode or end-fire mode. In normal mode, the radiation is perpendicular to axis.