Inkjet-Printed Highly Transparent Solar Cell Antennas

Small satellites, especially Cube Satellites (CubeSats), have become important vehicles for space exploration. One of the challenges CubeSats face is limited surface area. This limitation poses a question for antenna design–where to mount the antenna? Transparent antenna is a solution to resolve the competition between solar cells and antennas for surface area. The transparent antennas can be directly integrated on top of solar cells without requiring additional space. It is for this reason that this thesis focuses on the integration of highly transparent meshed antenna with solar cells. Even though transparent antennas allow light to travel light through them, they do repel a small portion of total amount. It is important to consider that solar cells need a significant amount of solar light in order to work properly. It is for this reason that a transparency of 95% becomes one of the main aims of this study. This thesis explores different prototyping methods to achieve highly transparent and effective meshed patch antennas. Considering the trade-offs between three fabrication schemes (electroformation, screen printing, and inkjet printing), the inkjet printing method is chosen to be the prototyping method. The inkjet printing method is the economical of all methods given the reduced amount of materials needed. Conductive ink (Nanosilver aqueous dispersive ink Metalon JS-B25P), receptive PET film (Novele IJ-220), and a commercial inkjet printer (less than $100.00) are the only materials needed. The printing routine and curing techniques are discussed in detail as part of this thesis. After achieving highly transparent (≥ 95%) antennas, the next task is to integrate them on top of triple junction space-certified solar cells. There are two main objectives in initial integration: (1) to assess the effect of solar cells on the antenna’s performance, and (2) to assess the effect of the antennas on solar cell’s performance. In order to achieve the first objective, several different antennas (solid non-transparent patches and meshed transparent patches) were tested on substrates (solar cell cover glass) with and without solar cells embedded. In order to achieve the second objective, a meshed patch antenna with 95% transparency and without the feed-line is placed on an active solar panel. The efficiency of the solar panel was then measured using standard procedure at SDL (Space Dynamics Laboratory, Logan UT). It is found that the presence of solar cells cast a degree of gain reduction of the antenna, but such a loss may be improved with a more precise integration and by increasing the operational frequency. The effect of the antenna on solar cell performance is concluded to be less than 3%, promising a feasibility of implementing highly transparent antennas on CubeSats