## 3 Antennas with General Aspects Utilized for CubeSat
### Leaky-Wave Antenna (LWA) Technology
Reference [58] introduces a novel planar leaky-wave antenna (LWA) designed to enhance CubeSat communication capabilities. Using substrate-integrated waveguide (SIW) technology, the antenna features periodic fan-shaped slots etched on the SIW's surface, facilitating high-efficiency circular polarization (CP) radiation. This design is particularly advantageous for CubeSat applications, as it offers a compact and lightweight solution that meets the stringent size, weight, and power (SWaP) constraints typical of small satellite platforms. The antenna's high gain and broadside radiation pattern ensures reliable and efficient communication links, which are crucial for maintaining consistent data transmission during space missions. The study demonstrated that the proposed antenna design effectively addresses the communication challenges faced by CubeSats, providing a viable solution for future small satellite missions. Reference [59], which was presented at the 2024 17 th United Conference on Millimetre Waves and Terahertz Technologies (UCMMT), introduces an innovative antenna system designed to enhance communication capabilities for 3U CubeSats. This system integrated a planar leaky-wave antenna (LWA) with a reflectarray, aiming to achieve high gain and directivity within the compact constraints of CubeSat platforms. The LWA, based on substrate-integrated waveguide (SIW) technology, radiated in single-linear polarization and served as the feed for the reflectarray. A full-wave simulation was conducted to analyze the near-field radiation from the SIW LWA on a surface corresponding to the reflectarray, which was sized to fit within the 3U CubeSat's dimensions. This design approach optimizes the antenna's performance, ensuring efficient communication links for CubeSat missions. Reference [60] presents the development of a high-gain, broadband, and circularly polarized Fabry-Perot cavity (FPC) antenna designed to enhance data transmission capabilities for CubeSat and small satellite missions. The proposed antenna utilizes a spatially separated superstrate area excitation method to achieve broadband operations, which is crucial for accommodating the diverse communication requirements of CubeSats. The design aims to provide a compact and efficient solution that meets the stringent size, weight, and power (SWaP) constraints typical of small satellite platforms. The study includes detailed simulations and experimental validations to demonstrate the antenna's performance, highlighting its potential to support high-data-rate communication links in CubeSat applications. This advancement is significant for the small satellite community, as it addresses the growing demand for efficient and reliable communication systems in space missions. Reference [61] introduces a cost-effective dual-polarized leaky-wave antenna (LWA) fabricated using 3D printing technology, offering broad beam-scanning capabilities and dual-polarized operations. While the design benefits from low-cost manufacturing and relatively high radiation efficiency, its reliance on frequency-dependent beam steering limits its suitability for CubeSat communications, for which a stable and predictable link performance is essential. Additionally, LWAs suffer from gain degradation and beam distortion at large steering angles, which can negatively impact a signal's integrity in dynamic satellite environments. Using 3D printed materials raises concerns about mechanical stability and long-term reliability in space conditions. In contrast, electronically controlled phased arrays or metasurface-based antennas provide more adaptive beamforming capabilities, making them better suited for CubeSat applications requiring precise and reliable communication links.