This article presents the design, fabrication, and measurement of a square Koch fractal slot antenna for UHF band using both the FR4-G10 and Cuclad 250 substrates. Conveniently, this 56.56 cm full-length antenna possesses a geometry that allows it to be incorporated into the standardized 10 cm × 10 cm faces of the CubeSats. Furthermore, it is shown that both selected substrates exhibit an acceptable performance at the frequency of interest despite the economic cost difference and relative permittivity. Hence, the commercial FR4-G10 antenna substrate can be preferred because of its low-cost and admissible performance at 458 MHz, which is a frequency in the UHF band that is commonly used for telemetry, tracking, and command downlinks of CubeSats. Measurements show that the proposed antenna exhibits a reflection coefficient of −16.53 dB, a bandwidth of 22.62 MHz at −10 dB, a VSWR of 1.3508, a normalized impedance of 0.794 − j0.173 at 50 Ω, and a directivity of 2.24 dBi. The contribution of this work consists in the use of a fractal geometry to construct a low-cost slot antenna working at UHF frequencies over the limited area of the CubeSat faces and in order to optimize the area for an eventual coexistence with solar cells.

中文翻译：

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在CubeSat小型卫星中用于UHF下行遥测应用的二次迭代方形Koch分形缝隙天线

本文介绍了使用FR4-G10和Cuclad 250衬底的UHF频段方形Koch分形缝隙天线的设计，制造和测量。方便地，这种56.56厘米长的全长天线具有一种几何形状，可以将其合并到CubeSats的10厘米×10厘米标准化面中。此外，表明尽管经济成本差异和相对介电常数，两种选择的基板在感兴趣的频率下都表现出可接受的性能。因此，商用FR4-G10天线基板因其低成本和在458 MHz时的可接受性能而成为首选，该频率是通常用于CubeSat的遥测，跟踪和命令下行链路的UHF频带中的频率。测量结果表明，所提出的天线的反射系数为−16.53 dB， j在50Ω时为0.173，方向性为2.24 dBi。这项工作的贡献在于使用分形几何结构构造了一种低成本的缝隙天线，该缝隙天线在CubeSat面的有限区域内以UHF频率工作，并为了最终与太阳能电池共存而优化了面积。