## 3 Antennas with General Aspects Utilized for CubeSat
### Dielectric Lenses, Reflectors, and Beam Control
The design includes a parabolic reflector with a deployable rib structure, offering efficient X-band communication with improved directivity. The findings demonstrated successful deployment, stable radiation patterns, and enhanced gain, making it viable for deep-space and Earth observation missions. However, the reliance on mechanical deployment introduces potential failure points, increasing the risk of malfunction due to mechanical wear, space debris impact, or deployment errors. Additionally, the mechanically steered reflectors lack real-time electronic beam control, making them less suitable for dynamic CubeSat communication, which requires agile and adaptive beam-steering capabilities [47]. Reference [48] outlines a 1.5 \(\times\) 1.5 m\({}^{2}\) reflect array antenna that is designed to be stored within a cylinder with a 20 and 9 cm diameter and height, respectively. After deployment, the antenna offers a gain of 39.6 dB, and the reflect array's mass is 1.75 kg. The reflect array, composed of multiple crossed dipoles positioned 5 mm above a ground layer, is supported by thin composite face sheets, with collapsible \"S\"-shaped springs maintaining the spacing between the dipole layer and the ground plane. The structure, divided into concentric quartz-epoxy composite strips, is interconnected with sliding folds, allowing the strips to be compressed, star-folded, and wrapped, which enables the entire assembly to fit within a compact cylindrical volume. After the construction and testing of a full-scale prototype, it successfully demonstrated stowage within the specified volume while meeting all RF performance criteria, as verified by both pre- and post-deployment RF tests. The authors of Ref. [49] introduced two innovative high-gain deployable reflect-array antennas for CubeSats. The first ISARA design was developed for 26 GHz and planned for employment in a 3U CubeSat. This antenna consists of three reflect-array panels measuring 33.9 cm \(\times\) 8.26 cm. The second design features an antenna with a reflect array, crafted explicitly for station communication on the ground, and a 6U CubeSat (8.425 GHz). This antenna features three reflect arrays of 33.3 cm \(\times\) 19.9 cm. The ISARA and MarCO antennas offer high gain (33 dBi) with very low stowed volumes, making them suitable for LEO and deep space use (0.38% BW at 8.425 GHz). The antennas are deployed once the CubeSat reaches orbit. The antenna that operates in the X-band provides a 28 dBi gain and a 1.19% BW. These designs deliver high-gain communication capabilities while maintaining compact form factors for space missions. Reference [50], which was presented at the 2018 International Symposium on Space Terahertz Technology, discusses the design of a dielectrically embedded mesh lens intended for deployment on a 6U CubeSat. The primary objective is to observe the 556 GHz water emission line, a spectral feature inaccessible from ground-based observations due to atmospheric absorption. The proposed lens design aims to provide a significant effective collecting area at this frequency, enabling the CubeSat to detect and study water emissions in space. This approach offers a cost-effective solution for space-based water detection, leveraging the CubeSat platforms' compact and versatile nature. In Ref. [51], a dielectrically embedded mesh lens composed of stacked printed circuit board (PCB) material layers with embedded copper elements was designed. The mesh lens consists of layers of dielectric material containing sub-wavelength-dimension metal elements arranged in a grid pattern, resulting in a flat and lightweight structure. This configuration is particularly advantageous for CubeSats with stringent size, weight, and power (SWaP) constraints. The design aims to provide a cost-effective solution for high-frequency applications, such as water detection in space missions, by leveraging the compact and efficient nature of the mesh lens. The study demonstrates the feasibility of this approach, offering a promising avenue for future CubeSat antenna designs.