Abstract
A gain-enhancement scheme that combines an active integrated antenna (AIA) and an optically transparent reflectarray on solar cells is proposed for CubeSat applications. As CubeSat antennas require a compact footprint, improving the gain over limited design space is challenging. The proposed gain-enhancement scheme exploits the distinct environmental feature of the space, namely, unlimited and sustainable solar energy. This energy is fed into a microwave power amplifier, which is cascaded with a quasi-Yagi antenna. This AIA approach can increase the gain by 22.7 dB. Furthermore, the AIA is arranged as the feed of the transparent reflectarray, which provides twofold advantages. First, the gain can be further improved by 11.0 dB; second, this transparent reflectarray is placed on already existing solar panels, so no additional clearance area is required. We organize the proposed scheme by three modules, including an AIA module, a reflectarray module, and a power management module. The proposed scheme is demonstrated by a prototype designed at 25.0 GHz. By fabricating the transparent reflectarray using Indium Tin Oxide printed on soda-lime glass, the proposed antenna provides realized gain of 41.3 dB with dimensions of $110\times80$ mm2; meanwhile, onboard electronics can still be activated due to the power management.
Highlights
The gain enhancement of antennas has gathered great importance in radiofrequency (RF) satellite communications
In this paper, a new antenna sub-system with enhanced gain and compact size is proposed for CubeSat applications
By integrating the active integrated antenna (AIA) module, transparent reflectarray module, and power management module, the measured realized peak gain is as high as 41.3 dB at 25.0 GHz, whereas the reflectarray dimensions are only 110 × 80 mm2
Summary
The gain enhancement of antennas has gathered great importance in radiofrequency (RF) satellite communications. At the design frequency (25.0 GHz), the simulated and measured reflection coefficients are −12.1 dB and −10.9 dB, respectively, which indicate that 93.8% and 91.9% of the input power can be accepted by the antenna. We arrange the quasi-Yagi antenna as the feed, optimizing reflectarray designs for different numbers of unit cells. A frequency shift is observed, the simulated and measured reflection coefficients at 25.0 GHz are −12.4 dB and −13.4 dB, respectively, demonstrating that 94.2% and 95.4% of the input power are collected by the antenna. As the prototype of the overall antenna system requires a 3D-printing fixture (εr = 3.5), which is modelled as free space (εr = 1) in the full-wave simulation, this causes disagreement between simulation and measurement These observations indicate that the dielectric constant of the substrate used is higher than the nominal value, and the assembly process introduces experimental errors. These results indicate that the desired directional property with enhanced gain can be achieved using the proposed antenna sub-system
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