## 3 Results and Discussion
### Simulation and Measured Evaluations Integrated with CubeSat
This suppressed SLL also decreases the level of interference and enhances radiation efficiency. These characteristics confirm the antenna's effectiveness in space-constrained, high-performance CubeSat platforms. To demonstrate the stability of circular polarization under beamsteering, we evaluated the axial ratio (AR) at multiple steering angles across each operating band. Figure 12: Simulation setup of the proposed antenna arrays in CubeSat: (**a**) the CubeSat and the arrays and (**b**) antenna arrays. Figure 13: The reflection (**a**) and transmission (**b**) coefficient results of the proposed antenna arrays in CubeSat. The results, shown in Figure 15, confirm that the AR remains below 3 dB within the main beam direction for all relevant scan angles and frequency ranges. This verifies that the antenna maintains consistent CP performance across its operational bandwidth and beamsteering range, which is essential for preserving polarization alignment and reducing polarization mismatch losses in CubeSat communication links. The proposed antenna, as shown in Table 3, demonstrates significant improvements over previous studies in terms of compactness, frequency coverage, gain, and multifunctionality. This table also shows that the proposed antenna can outperform almost all the works presented in Table 3, even with its low profile of 40 \(\times\) 30 mm\({}^{2}\), especially designed for 1U CubeSat communications. It also offers multi-band operation across three distinct frequency ranges (6.4, 15.4, and 22.5-30 GHz), making it highly suitable for multifunctional CubeSat missions, including inter-satellite links, payload telemetry, and RF sensing. Unlike several references that lack the beamsteering capability or that operate in narrow bands, our design integrates MTS and leaky-wave antenna (LWA) principles, enabling beamsteering from 18\({}^{\circ}\) to 155\({}^{\circ}\) (Port 1) and 206\({}^{\circ}\) to 341\({}^{\circ}\) (Port 2)--a wide angular range rarely achieved in such compact formats. While works like [39; 40] offer high gains (20-29 dBi), they demand significantly larger footprints (e.g., 100 \(\times\) 200 mm\({}^{2}\)) and some support only  
Figure 14: The radiation pattern of the antenna in CubeSat with port 1 (P\({}_{1}\)) in array 1 (A\({}_{1}\)) at (**a**) 3.8 GHz, (**b**) 5.8 GHz, (**c**) 8 GHz, (**g**) 10 GHz, (**h**) 22 GHz, and (**i**) 28 GHz and port 7 (P\({}_{7}\)) in array 2 (A\({}_{2}\)) at (**d**) 3.8 GHz, (**e**) 5.8 GHz, (**f**) 8 GHz, (**j**) 10 GHz, (**k**) 22 GHz, and (**l**) 28 GHz. Figure 15: The simulated and measured axial ratio, gain, and radiation efficiency results of the proposed antenna. single-band or limited functionality. Additionally, our design achieves a commendable gain of 12.9 dBi and 85% radiation efficiency, positioning it ahead of most designs with incomplete efficiency data or values < 80% (e.g., [41]). Moreover, the use of circular polarization (CP) ensures robustness in orientation-sensitive CubeSat links, a feature shared with only a few high-performing systems [39; 42]. Overall, our work combines miniaturization, beam agility, high gains, and CP support, making it one of the most balanced and CubeSat-ready antenna solutions to date. In addition, compared to the other antennas listed in Table 3, the proposed antenna occupies only 1200 mm\({}^{2}\), which is 81-99% smaller in printed area than most existing designs. For example, it achieves a 95.6% reduction in area compared to [25] (27,480 mm\({}^{2}\)) and is 98.7% less than that of [41] (90,000 mm\({}^{2}\)). Additionally, some designs (e.g., [40]) require integration into larger CubeSats (6U), while our compact structure fits efficiently within a 1U CubeSat, offering up to 83% reduction in spatial volume requirements. The achieved radiation efficiency of 85% in the proposed MTS-based leaky-wave MIMO antenna is the result of a carefully engineered design that minimizes typical loss mechanisms while maximizing electromagnetic performance.