The electrical design of a membrane antenna for a lunar-based low-frequency radio telescope

Detecting primordial fluctuations from the cosmic dark ages requires extremely large low-frequency radio telescope arrays deployed on the far side of the Moon.The antenna of such an array must be lightweight,easily storable and transportable,deployable on a large scale,durable,and capable of good electrical performance.A membrane antenna is an excellent candidate to meet these criteria.We study the design of a low-frequency membrane antenna for a lunar-based low-frequency(<30 MHz)radio telescope constructed from polyimide film widely used in aerospace applications,owing to its excellent dielectric properties and high stability as a substrate material.We first design and optimize an antenna in free space through dipole deformation and coupling principles,then simulate an antenna on the lunar surface with a simple lunar soil model,yielding an efficiency greater than 90%in the range of 12-19 MHz and greater than 10%in the range of 5-35 MHz.The antenna inherits the omni-directional radiation pattern of a simple dipole antenna in the 5-30 MHz frequency band,giving a large field of view and allowing detection of the 21 cm global signal when used alone.A demonstration prototype is constructed,and its measured electrical property is found to be consistent with simulated results using|S11|measurements.This membrane antenna can potentially fulfill the requirements of a lunar low-frequency array,establishing a solid technical foundation for future large-scale arrays for exploring the cosmic dark ages.

Review of Large Spacecraft Deployable Membrane Antenna Structures

The demand for large antennas in future space missions has increasingly stimulated the development of deployable membrane antenna structures owing to their light weight and small stowage volume. However, there is little literature providing a comprehensive review and comparison of different membrane antenna structures. Space-borne membrane antenna structures are mainly classified as either parabolic or planar membrane antenna structures. For parabolic membrane antenna structures, there are five deploying and forming methods, including inflation, inflation-rigidization, elastic ribs driven, Shape Memory Polymer （SMP）-inflation, and electrostatic form- ing. The development and detailed comparison of these five methods are presented. Then, properties of membrane materials （including polyester film and polyimide film） for parabolic membrane antennas are compared. Additionally, for planar membrane antenna structures, frame shapes have changed from circular to rectangular, and different ten- sioning systems have emerged successively, including single Miura-Natori, double, and multi-layer tensioning systems. Recent advances in structural configurations, tensioning system design, and dynamic analysis for planar membrane antenna structures are investigated. Finally, future trends for large space membrane antenna structures are pointed out and technical problems are proposed, including design and analysis of membrane structures,materials and processes, membrane packing, surface accuracy stability, and test and verification technology. Through a review of large deployable membrane antenna structures, guidance for space membrane-antenna research and applications is provided.