A Compact Dual-Band Assembled Quadrifilar Helix Antenna for LEO Satellite Communications

This paper presents a compact dual-band quadrifilar helix antenna suitable for satellite communications. The antenna consists of two quadrifilar helix antennas stacked vertically as a single unit. The upper quadrifilar helix antenna operates in the S-band, while the lower one operates in the L-band. The upper quadrifilar helix antenna adopts a self-rotating spiral structure and is fed by a slotted coaxial balun. The lower antenna is excited by a feed network with equal amplitudes and phase differences of 90°. Simulation results show that the antenna has good circular polarization and wide beamwidth characteristics within the operating frequency band, with S
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<-12 dB at the S-band and S
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<-20 dB at the L-band. In addition, the gain is greater than 0 dBi in the ±60° beamwidth range for both bands.