Abstract Recently, there is a renewed interest in Earth Observation (EO) of the cryosphere as a proxy of global warming, soil moisture for agriculture and desertification studies, and biomass for carbon storage. Global Navigation Satellite System-Reflectometry (GNSS-R) and L-band microwave Radiometry have been used to perform these measurements. However, it is expected that the combination of both can largely improve current observations. 3 Cat-4 mission aims at addressing this technology challenge by integrating a combined GNSS-R and Microwave Radiometer payload into a 1-Unit CubeSat. One of the greatest challenges is the design of an antenna that respects the envelope and stowage requirements of 1-Unit CubeSat, being able to work in the different frequency bands: Global Positioning System (GPS) L1-band (1575 MHz), GPS L2-band (1227 MHz), and microwave radiometry at 1400–1427 MHz. After a trade-off analysis, a helix antenna was found to be the most suitable option. This antenna has 11 turns equally distributed with 68.1 mm of diameter. This design generates an antenna with 506 mm of axial length, providing the maximum radiation gain in the endfire direction. Additionally, a counterweight is added at the tip of the antenna to enhance the directivity, and it is used as gravity gradient technique. The deployment of this antenna in vacuum and extreme temperature conditions is the greatest mechanical challenge that needs to be addressed for the success of the mission. This work presents a mechanical solution that enables to deploy the helix antenna from 25.5 mm (stowed configuration) to the final 506 mm (deployed configuration). By sequentially deploying different parts of the antenna, the final configuration is reached without impacting the attitude pointing of the CubeSat. This is accomplished using dyneema lines that are melted sequentially by commands. In addition, the deployment velocity, acceleration, and waving are presented as part of its characterization. The current test results in a Thermal Vacuum Chamber indicate also that the deployment can be achieved in −35 °C. The 3 Cat-4 CubeSat, with the L-band helix antenna, will be launched in Q4 2020 as part of the “Fly Your Satellite!” program of the European Space Agency (ESA).

中文翻译：

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1-Unit Cubesat中L波段螺旋天线的部署机制

摘要 最近，人们对冰冻圈地球观测 (EO) 作为全球变暖、用于农业和荒漠化研究的土壤水分以及用于碳储存的生物量的代理重新产生了兴趣。全球导航卫星系统反射计 (GNSS-R) 和 L 波段微波辐射计已用于执行这些测量。然而，预计两者的结合可以在很大程度上改善当前的观察结果。3 Cat-4 任务旨在通过将组合的 GNSS-R 和微波辐射计有效载荷集成到 1 单元 CubeSat 中来解决这一技术挑战。最大的挑战之一是设计符合 1-Unit CubeSat 包络和装载要求的天线，能够在不同频段工作：全球定位系统 (GPS) L1 频段 (1575 MHz)、GPS L2 -频段（1227 MHz），和 1400–1427 MHz 的微波辐射测量。经过权衡分析，发现螺旋天线是最合适的选择。该天线有 11 匝，直径为 68.1 毫米，平均分布。这种设计产生了一个轴向长度为 506 毫米的天线，在端射方向上提供了最大的辐射增益。此外，在天线尖端增加了一个配重以增强方向性，并用作重力梯度技术。在真空和极端温度条件下部署这种天线是任务成功需要解决的最大机械挑战。这项工作提出了一种机械解决方案，能够将螺旋天线从 25.5 毫米（收起配置）部署到最终 506 毫米（部署配置）。通过依次部署天线的不同部分，在不影响 CubeSat 的姿态指向的情况下达到最终配置。这是使用由命令顺序熔化的迪尼玛线完成的。此外，部署速度、加速度和波动是其特征的一部分。当前在热真空室中的测试结果也表明部署可以在 -35 °C 下实现。带有 L 波段螺旋天线的 3 Cat-4 CubeSat 将于 2020 年第四季度作为“飞你的卫星！”的一部分发射。欧洲航天局 (ESA) 计划。当前在热真空室中的测试结果也表明部署可以在 -35 °C 下实现。带有 L 波段螺旋天线的 3 Cat-4 CubeSat 将于 2020 年第四季度作为“飞你的卫星！”的一部分发射。欧洲航天局 (ESA) 计划。当前在热真空室中的测试结果也表明部署可以在 -35 °C 下实现。带有 L 波段螺旋天线的 3 Cat-4 CubeSat 将于 2020 年第四季度作为“飞你的卫星！”的一部分发射。欧洲航天局 (ESA) 计划。