## 3 Results and Discussion
### Simulation and Measured Evaluations Integrated with CubeSat  
Figure 12 illustrates the full-wave simulation setup of a 1U CubeSat integrated with four arrays of the proposed MTS-based leaky-wave MIMO antenna. The CubeSat structure is modeled with copper walls to accurately represent the conductive boundaries typically used in real satellite platforms, accounting for possible reflections and mutual coupling effects during electromagnetic simulation. The antenna arrays are strategically mounted on four lateral faces of the CubeSat to provide nearly omnidirectional spatial coverage in the azimuthal plane. This configuration enables robust link availability with ground stations or other satellites, regardless of the CubeSat's orientation in low Earth orbit. The integration setup was designed to study the radiation performance, mutual coupling between elements, and the effects of CubeSat's metallic enclosure on the antenna's behavior. The cavity-backed design and spacing from the CubeSat body also help minimize surface currents and enhance directional gains. By simulating this realistic deployment scenario, we ensure the proposed antenna maintains its high gain, wideband performance, and beamsteering capabilities even when installed on the satellite, which is critical for validating its suitability for practical CubeSat communication missions. Figure 13 presents the simulated S-parameters--specifically, the reflection (S11) and transmission (S21, S31, etc.) coefficients--of the proposed antenna when integrated into a 1U CubeSat platform. The reasonable effects of the metallic and copper walls of the CubeSat on impedance matching and working BWs are observed in Figure 13. These effects can be seen by the created stopbands in the simulated band, which might have been produced by the mutual coupling created after locating the antennas that interacted with the CubeSat. Nevertheless, the antenna maintains effective operation across the target frequency bands (3.75-5.25 GHz, 6.4-15.4 GHz, and 22.5-30 GHz), confirming its robustness in a realistic satellite environment. Figure 13 also illustrates the transmission coefficients between ports located on different antenna arrays. The results demonstrate excellent port-to-port isolation, particularly between port 1 on array 1 and all other ports. The transmission coefficients  
Figure 11: The simulated and measured radiation patterns of the antenna’s electric and magnetic fields in free space at (**a**) 3.8 GHz, (**b**) 5.2 GHz, (**c**) 8 GHz, (**d**) 10 GHz, (**e**) 24 GHz, and (**f**) 28 GHz. consistently remain below -15 dB across the operating bands, indicating minimal mutual coupling. Having a high degree of isolation among the antenna arrays' ports is vital, because this assures signal loss reduction and independence between the ports, which enhances the channel capacity and allows for a high data rate. This also proves that it is suitable for MIMO communications, showing minimum interference. The simulated radiation patterns of the proposed antenna for arrays A1 and A2, when they are integrated with the CubeSat, are presented in Figure 14. This figure also depicts how these arrays behave at the working bands and that the radiation pattern is all directed outward from the CubeSat. Therefore, the proposed antenna arrays can have a wide-ranging spatial coverage, improving communication links even with different orientations. It should be mentioned that this assessment was carried out considering far-field principles during the simulations (the red lines are the radiation, the light blue is the 3 dB beamwidth, and dark blue line is the main direction). After evaluating the radiation pattern and far-field characteristics, like directivity, gain, and efficiency, this antenna array in CubeSat offered a 3 dB beamwidth of up to 28.8\({}^{\circ}\). In addition, the sidelobe levels (SLLs) were also calculated, offering \(-\)14.1 dB and \(-\)10.5 dB for full array integration and individual arrays, respectively.