A Novel Dual-Frequency Printed Quadrifilar Helical Antenna Based on Conformal Feed-Network

A novel printed dual-band octafilar helical antenna operational at two frequcecies is presented for satellite mobile communication systems in this paper. Two ways be used to improve radiation efficiency. Frist, four bifilar which is consists of two helices of different lengths, widths and picth angles raditors formed two resonant frequencies and reduced the mutual coupling. Second, integration design be used to feed network and radiation vibrator, and radiation efficience is improved. Experimental results show that 4. 3dBi circular polarisation gain is achieved at the low frequency with 6% bandwith (gain>4. 0dBi) and 4. 2dBi at the high frequency with 5% bandwith (gain>4. 0dBi),130° 3dB beamwidth is achieved at both low and high frequency. The proposed antenna displays several attractive characteristics for satellite mobile communication systems applications such as duel-frequency, hemispherical pattern, high radiation-efficiency.