The Design Of Omni-directional Antenna For Small Satellite

Small satellite is a hotspot in the field of the space industry today. With the advantages of small size, short development cycle and low research and development costs, small satellite gradually gains national attention, it’s used more and more widely in communications, earth remote sensing, interplanetary exploration, scientific research, technological experiment and so on. Antenna system is an integral part of the satellite communications module, and it has crucial impact on the performance of the satellite system. With the miniaturization of small satellite, antenna applied to small satellite also should meet the needs of miniaturization.Quadrifilar helix antenna has good hemisphere heart-shaped pattern, and its excellent wide beam and circular polarization characteristics are widely used in satellite communications. This paper reviews general requirements for small satellite antenna, analyzes the structure and operating principle of quadrifilar helix antenna, and we solved the poblems of quadrifilar helix antenna miniaturization for small satellite applications, which has laid the foundation for the applications of quadrifilar helix antenna on the small satellite especially pico satellite.The main work of this paper and achievement are listed as follows:1. We analyze the requirements of small satellite antenna and get the general design objective for the antenna:omnidirectional pattern with upper half-space, right-handed circular polarization, and the operating frequency is2.065GHz with gain2dBi. For the lack of traditional quadrifilar helix antenna, we studied solutions to its miniaturization and feed.2. We designed a cylindrical dielectric-loaded quadrifilar helix antenna whose operating frequency was2.065GHz,14mm high, and the radius was5mm. The antenna loaded a microwave ceramics and its relative dielectric constant was36. The coaxial line through the axis of the antenna and feed the antenna axis at the top, and at the bottom of antenna integrated sleeve balun to achieve balanced feed. And at the same time, we used laser to etch the spiral arms on the top of the antenna to achieve quadrifilar orthogonal feed. We simulated the antenna by3D electromagnetic simulation software CST, and the results showed that the antenna has a wide beam of heart-shaped pattern,3dB beam width is greater than120degrees, circular polarization is good in the range of beam width. Finally, the simulation showed the feasibility of laser etching spiral arms for orthogonal feed.3. For the production of dielectric antenna, a novel manufacture method for dielectric-loaded quadrifilar helix antenna combing magnetron sputtering metallization and laser etching is introduced. Though computer numerical control and laser etching technology, we completed the process of spiral arm on ceramic matrix. This method simplified the traditional process, and improved the machining accuracy. The obtained antenna has good mechanical properties, which provide a reference for related surface conformal antennas process. Finally, we led measurement of related project on the made antenna, and the test results meet our expectations.