This study proposes a novel miniaturized circularly polarized (CP) ultrahigh frequency (UHF) quadrifilar helix antenna for spaceborne applications. The dual‐band operation is realized using four inverted‐U shaped helical strips (IUSHSs) that are rotated and alternately arranged on the four faces of a hollow polyimide cuboid in a sequential rotation manner, which effectively reduces the size of the antenna. Furthermore, the four IUSHSs are connected by a cross‐shape strip at the top of the antenna to control the dual resonant frequencies, resulting in a small dual‐band frequency ratio. The proposed antenna is both lightweight and robust when compared with the conventional miniaturized CP antennas operating at similar bands with similar performance. In particular, its compact radiator provides effective miniaturized spaceborne solution without the need of high‐dielectric coefficient materials. A device for spaceborne application that operates at 402/505 MHz is designed, fabricated, measured, and in‐orbit tested with a weight of 651 g and an effective size of 0.161 × 0.161 × 0.228 λ³_402MHz (λ_402MHz is the wavelength at 402 MHz). The measured gain and axial ratio of the proposed antenna are better than 5.32 dBi and 2.18 dB, respectively, within 2 and 12 MHz bandwidth for the two bands. The test results proved that the methods used to design the proposed antenna are effective.

中文翻译：

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频率比小的星载小型UHF双频螺旋天线

这项研究提出了一种新颖的小型化圆极化（CP）超高频（UHF）四线螺旋天线，用于航天应用。使用四个反向U形螺旋条（IUSHS）来实现双频操作，这些螺旋条依次旋转并交替排列在空心聚酰亚胺长方体的四个面上，从而有效地减小了天线的尺寸。此外，四个IUSHS通过天线顶部的十字形条连接，以控制双谐振频率，从而减小了双频带频率比。与在相似频带，相似性能下运行的常规小型CP天线相比，该天线既轻巧又坚固。特别是，其紧凑的散热器可提供有效的小型化空间解决方案，而无需使用高介电系数的材料。设计，制造，测量和在轨测试了工作在402/505 MHz的航天应用设备，其重量为651 g，有效尺寸为0.161× 0.161 × 0.228 λ ³ _402MHz（λ _402MHz是在402兆赫的波长）。在两个频段的2和12 MHz带宽内，建议天线的测量增益和轴向比率分别优于5.32 dBi和2.18 dB。测试结果证明，所设计天线的设计方法是有效的。