An Innovative Deployable VHF/UHF Helical Antenna for Nanosatellites

This paper presents an innovative design of a deployable VHF/UHF band helical antenna for nanosatellites. The antenna is designed to stow into a space smaller than 1U (100x100x100 mm) of a 3U nanosatellite in transportation and launch stage, then deployed into full operational space of 180 mm in diameter and 300 mm in length when the satellite reaches to designated orbit. The helices are supported and deployed by a central boom which is controlled and driven by a step motor. This ensures a reliable deployment and a minimum disturbance to the space craft during deployment. The deployable helical antenna presented in this paper produces a circular-polarized axial mode radiation pattern, and this is achieved by the combination of winding sense of helices and the feeding-phase and amplitude of the feed Balun. There is no ground plane in this design, which is required normally in a conventional helical antenna.