A Dual-Band Circularly-Polarized Quadrifilar Helix Antenna

In this paper, a new design of an dual-band printed quadrifilar helical antenna (QHA) for S-band has been presented. This quadrifilar antenna has four helical arms wrapped around a dielectric cylinder which has low permittivity and low loss. Each arms consists of two parallel elements long and short which opened at the top of the helix. The lower end of helix is simultaneously fed, the long element resonates at 1.995 GHz (1.98 GHz-2.01 GHz with the center frequency 1.995 GHz), and the short element resonates at 2.185 GHz(2.17 GHz-2.2 GHz with the center frequency 2.185 GHz). The four arms are fed with equal amplitudes with 0°, 90°, 180°, 270° phase by integrated feeding network. Simulated results of the proposed antenna show that the antenna can provide good wide-beam circular polarization characteristics in both frequency bands. The proposed antenna has a smaller size, light weight and low cost to be suitable for mobile handset applications.