This letter proposes a compact 435 MHz telemetry, tracking, and command (TT&C) CubeSat antenna, which does not require an in-orbit deployment mechanism for proper operation. It uses characteristic modes on spacecraft's body to increase the radiating aperture, resulting in a λ/4 sized antenna (as calculated along diagonal of the cube). The antenna aims to provide reliable communication, operating independently from spacecraft's orientation and does not rely on proper deployment of vulnerable mechanical components. The limited space in the launcher limits any protrusions to no more than 6 mm (1/115th of the wavelength) from the spacecraft's wall, which results in low input impedance of 0.4 – 3.2j. To overcome this issue, a differential feeding structure is proposed that incorporates a power divider with impedance matching circuit. It also incorporates a lumped capacitor that can adjust the antenna's operating frequency. The antenna offers a dipolelike radiation pattern with performances comparable to larger deployable UHF antennas. It is intended for reliable TT&C.

中文翻译：

---

无需部署用于CubeSat的UHF天线：基于特征模式的设计

这封信提出了一种紧凑的435 MHz遥测，跟踪和命令（TT＆C）CubeSat天线，该天线不需要在轨部署机制即可正常运行。它使用航天器主体上的特征模式来增加辐射孔径，从而产生λ/ 4尺寸的天线（沿立方体的对角线计算）。该天线旨在提供可靠的通信，独立于航天器的方向运行，并且不依赖于易受攻击的机械组件的正确部署。发射器中有限的空间将任何突出物限制在距航天器壁不超过6毫米（波长的1/115）处，这将导致0.4 – 3.2j的低输入阻抗。为了克服这个问题，提出了一种差分馈电结构，该结构结合了带有阻抗匹配电路的功率分配器。它还集成了可调节天线工作频率的集总电容器。该天线具有类似偶极子的辐射方向图，其性能可与更大的可部署UHF天线相媲美。它旨在用于可靠的TT＆C。