A large hexagonal loop antenna with a metallic core for the YES2 space-tethered satellite
- Paper number
IAC-05-B3.6.07
- Author
Mr. Luis Rolo, European Space Agency (ESA)/ESTEC, The Netherlands
- Year
2005
- Abstract
This paper presents the design, simulation and prototype testing results of an hexagonal large loop antenna implemented on the Young Engineers Satellite 2 (YES2) communications system. YES2 is a space-tethered project, promoted by Delta-Utec Space Research and Consultancy and supported by the European Space Agency (ESA). This project has as aims at low cost satellite construction and stands on a keep it simple philosophy, giving the students an outstanding opportunity to participate in this ambicious initiative.
The antenna enables one-way radio communication between one re-entry capsule and FLOYD, the YES2 module responsible for the tether deployment. The major design challenges were the avoidance of tether-wrapping, exploiting the potential beneficial effect of the metallic hexagonal prism enclosed by the antenna and attaining at least 140 degrees of 0 dB gain beamwidth.
Studies on polygonal loop antennas, loop antennas with a cylindrical core and also loops with non-uniform current distribution were already developed by many authors. However, this design does not match any of these, instead, it merges them all. This study is focused on an electrically large hexagonal loop antenna, with a hexagonal metallic core exhibiting a non-uniform current distribution. Due to the pigtailed position of the spacecraft, the 1.8 m diameter battery pack of the carrier, FOTON, was used as a reflector and simulations show that in the optimal position the reflector is a key element to shape the radiation pattern as needed. The distance of the loop to the bottom of FLOYD and the gap between the loop and the spacecraft surface are the two degrees of freedom that were adjusted to achieve an optimal solution in terms of radiation pattern. Very good results were obtained so far: the radiation pattern was shaped in the simulator to ensure a 300 km radio communication link, although measurements for the far field radiation pattern, to be performed at ESTEC/ESA, the Netherlands, will only be completed in March 2005. The simulation results were obtained using the Numerical Electromagnetic Code 2 (NEC2) engine, a widely avaliable software for antenna characterization. The antenna was designed to have circular polarization and the impedance matching network is to be developed using lumped elements right after the anechoic chamber tests. A full-scale mockup of the complete satellite structure was constructed at home with cardboard and projected polyurethane, ensuring light weight and very low cost, adding also a lot of enthusiasm to the construction of the structure prototype.
This paper shows how the design requirements were met by the use of an atypical loop antenna with unusual dimensions. The spacecraft structure was used to shape the radiating characteristics of the antenna, ensuring, in this particular, case the safety of the tether and it proved to be a good design approach.
- Abstract document
- Manuscript document
IAC-05-B3.6.07.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.