## 7 Conclusions  
This review paper highlights advanced beamforming/beam-steering techniques for CubeSat communications, focusing on technologies like planar phased patch arrays, dielectric lenses, and leaky-wave antennas (LWAs). These approaches offer benefits such as high gain, compact design, wide-angle beam steering, and efficient circular polarization but face limitations like _phased arrays_ (which provide rapid electronic beam steering but are costly, complex, and power-intensive), _dielectric lenses_ (which deliver high efficiency but rely on slow mechanical steering and are challenging to integrate), and _leaky-wave antennas_ (which enable frequency-based beam steering without complex circuitry but suffer from limited bandwidth, gain degradation, and open stopbands at large angles).  
A two-port, four-element LWA is proposed as a viable solution for CubeSat communications, balancing simplicity, efficiency, and functionality. This design enhances gain and directivity while meeting size, weight, and power (SWaP) constraints, which are critical to CubeSats. However, limitations like bandwidth and beam control issues require advanced solutions. To address these challenges, integrating passive beamforming/beam-steering networks (e.g., Butler matrices and Rotman lenses) and advanced materials (e.g., metamaterials) can improve bandwidth, scanning range, and multi-beam operations. Hybrid beamforming/beam-steering techniques combining passive and frequency-tuned methods are recommended for efficient, multi-directional coverage.  
This review paper remains limited regarding experimental feasibility, future directions, real-world mission tests, and experimental validation. However, the techniques and the state of the art discussed here can pave the way for reaching an effective experimental performance. For instance, phased array systems have been tested in some satellite missions, demonstrating their capability for rapid electronic beam steering. However, their high power consumption and complexity restrict widespread CubeSat adoption. Dielectric-lens-based antennas have shown high efficiency in lab environments, but their reliance on mechanical steering poses integration challenges for small satellites. LWAs, another promising technique offering frequency-dependent beam steering, have been experimentally validated in terrestrial applications. However, their space-based implementation is still in its early stages, with concerns over bandwidth and gain degradation at extreme angles. While some CubeSat missions have explored reconfigurable antennas and passive beamforming networks, comprehensive on-orbit demonstrations of metasurface-based designs and hybrid beamforming solutions remain scarce. Future work should focus on integrating these technologies into CubeSat platforms for real-world testing, ensuring their feasibility for Earth observation, intersatellite networking, and deep-space communications.  
**Author Contributions:** [PERSON] investigated the CubeSat communications and the antennas utilized, as well as wrote the original draft of this review article. [PERSON] edited the article. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work has been jointly supported by the European Space Agency, under contract number: 4000145253, and by Silicon Austria Labs (SAL), owned by the Republic of Austria, the Styrian Business Promotion Agency (SFG), the federal state of Carinthia, Upper Austrian Research (UAR), and the Austrian Association for the Electric and Electronics Industry (FEEI).  
**Data Availability Statement:** The data are contained within the article.  
**Conflicts of Interest:** The authors declare no conflicts of interest.