Analysis of radiation characteristics of multi-arm helix antenna using theory of circular array

A very popular method to analyze the quadrifilar helix antenna is by equalizing it into two mutually perpendicular dipoles and two mutually perpendicular magnetic dipoles. In most of the available literature analyzing the quadrifilar helix antenna by using circular array theory has not been reported. In this paper quadrifilar helix antenna is equivalent to a circular array antenna which is consisted of four helix antennas along the ring. By this method the radiation pattern and polarization of helix, bifilar helix, trifilar helix and five-arm helix antenna are proposed and researched. When the number of the arm of multi-arm helix antennas is more than two, the radiation patterns are similar, they have a wide beam, wide 3 dB axial ratio radiation pattern on the meridian plane and omnidirectional radiation pattern on the equatorial plane. And a trifialr helix antenna is modeled and simulated. Simulation results show that the proposed antenna exhibits the gain of 5.8 dB in the maximum radiation direction, half power beamwidth of 2θ05=120°, 3 dB axial ratio of θ = 155° on the meridian plane, and omnidirectional radiation pattern on the equatorial plane, and the reflection coefficient |Sn| <;-10dB over the frequency band from 1.505 to 1.627 GHz.