Design and implementation of quadrifilar helix antenna for satellite communication

Abstract

In this paper two bifilar helices are employed in the design of a quadrifilar helix structure that is used as an antenna for satellite communication. The antenna is purely made to resonate at GPS L2 frequency band that is 1227.75 +/- 10MHz having 90° out of phase feeds to obtain a circularly polarized electric field. Simulation results show that the bandwidth of the antenna for VSWR≤ 2 is about 50MHz from 1205MHz to 1260MHz. The antenna is giving a fairly directional pattern in its elevation plane at its resonant frequency of 1228 MHz and the simulated front to back ratio is more than 20dB with a front gain of nearly 6dB. Measured results show that the antenna is resonating at the desired resonant frequency with a span of 1192.5-1246.5 MHz with feed 1 and a span of 1174.5-1211.7 MHz with feed 2 when referenced to a VSWR≤2 same as those were obtained in simulation.