## 6 Discussion and Future Directions  
The evolution of CubeSat communication systems has necessitated significant advancements in antenna technologies, focusing on beamforming/beam-steering techniques that ensure efficient and reliable communication in resource-constrained environments. This review analyzes diverse approaches to passive antennas used for CubeSat communications, including planar phased patch antenna arrays, dielectric lenses, and leaky-wave antennas (LWAs), highlighting their respective merits and challenges in addressing the unique demands of CubeSat platforms. A significant takeaway from the reviewed studies is the growing shift toward innovative design methodologies to achieve high gain, compact form factors, wide-angle beam steering, and efficient polarization. For instance, planar phased patch arrays, though offering rapid and precise electronic beam steering, face power consumption-, cost-, and complexity-related challenges. These issues became particularly pronounced in CubeSat platforms, for which size, weight, and power (SWaP) constraints are critical. Similarly, dielectric lenses provide high efficiency and excellent polarization but rely on mechanical steering mechanisms that can hinder the response speed and complicate system integration. UWB antennas are ideal for wideband applications but encounter difficulties achieving consistent gain and effective beam steering across their operating range. To overcome these challenges, future research directions emphasize the need for hybrid systems that combine the strengths of multiple techniques. For example, integrating phased array principles with dielectric metasurfaces can mitigate power consumption issues while maintaining beam-steering capabilities. Similarly, using advanced materials, such as metamaterials or lightweight 3D printed dielectric structures, can facilitate the development of compact, efficient, and scalable antenna solutions. Emerging concepts, such as reconfigurable intelligent surfaces (RIS) and adaptive control algorithms, offer further opportunities to enhance beam-steering performance. RIS technology can dynamically manipulate electromagnetic waves to optimize beam steering in real-time, while adaptive algorithms can adjust beamforming parameters in response to changing link conditions and orbital dynamics. Together, these advancements hold the potential to unlock new levels of adaptability and efficiency in CubeSat communication systems. By leveraging the natural beam-steering capabilities of LWAs, this configuration can provide an optimal balance between simplicity, functionality, and performance. The two-port design reduces the complexity of feeding networks. At the same time, the four-element array enhances the gain and directivity, which are critical for maintaining robust communication links in low Earth orbit (LEO). To address the limitations of traditional LWAs, such as bandwidth constraints and gain degradation at extreme angles, the integration of passive beam-steering networks and advanced materials, such as metamaterials, can be proposed. Metamaterials and gradient-index structures offer broader bandwidth and improved beam scanning capabilities, while 3D printed dielectric materials facilitate the creation of lightweight, customizable designs that integrate seamlessly into CubeSat architectures. Additionally, flexible and deployable materials are being explored to develop antennas that can be stowed compactly during launch and deployed in orbit, maximizing the size and performance without exceeding launch constraints. In addition, HBF techniques, which combine passive networks with frequency-tuned operations, represent a viable path forward, enabling multi-directional coverage and high gain without excessive power requirements. Moreover, metasurface-based LWAs can expand bandwidth and improve beam control, aligning with CubeSat SWaP requirements while enhancing the overall communication performance.