## 3 Antennas with General Aspects Utilized for CubeSat
### Planar Phased Patch Antennas and Their Arrays
However, the transparency of the antenna is poor at lower frequencies (below 2.4 GHz). Reference [17] introduced a design for a CP, meshed antenna suitable for 1U CubeSats. The antenna has compact dimensions of 24.1 \(\times\) 24.8 mm\({}^{2}\) and operates at 2.45 GHz. Both the bandwidth and overall gain were enhanced when it was seamlessly integrated with a solar cell. CP was achieved by orthogonally exciting the antenna through two terminals, with the feed network positioned below the solar cell. This configuration improves the performance while maintaining a high transparency, as the meshed lines are placed on glass, allowing sunlight to pass through to the solar cells. This integration is significant for maximizing the space for solar cells, thereby increasing the satellite's power budget for its subsystems. Both simulated and measured reflection coefficients were reported, with values of \(-18\) dB (1.35% bandwidth) and \(-19\) dB (2.45% bandwidth) at 2.385 GHz, respectively. In Ref. [18], a patch antenna array designed for intersatellite communication on a 1U CubeSat was introduced. The configuration consisted of a 3 \(\times\) 3 array comprising nine identical subarrays, with each subarray made up of 2 \(\times\) 2 rectangular patch elements connected sequentially. CP was achieved by orienting every two elements within the 2 \(\times\) 2 subarrays orthogonally. Operating at 5.8 GHz, the antenna array demonstrated a measured reflection coefficient of \(-21\) dB and a simulated total gain of 6.98 dBi, though it featured a narrow bandwidth of 1.20%. A key advantage of this design was beam steered by modifying the feeding angles. This enhances communication between CubeSats and ground stations, particularly during maneuvers, adjusting the consistency and adaptability of the communication system. A high-gain F-shaped patch antenna was developed for a 3U CubeSat, designed to operate at 2.45 GHz (S-band). The antenna had dimensions of 100 \(\times\) 100 mm\({}^{2}\). This innovative approach minimized the physical size by effectively extending the electrical length of the radiating patch. To increase the bandwidth around the two bands, two arms were utilized. The F-shaped patch antenna also obtained a wide BW and boosted the gain when assessed against other types of patches. However, a significant limitation was its lack of durability, as the reliance on shorting pins between the upper patch and ground plane posed potential challenges to its robustness in practical applications (Figure 3) [19]. In Ref. [20], researchers developed a 16 \(\times\) 16 array for CubeSat communications, considering the 6U. It incorporates two layers folded into a compact 2U volume, supported by four deployable formations, and is designed to operate at 3.6 GHz. A key benefit of this design is its ability to minimize the usage of space while folded, leaving extra space for solar panels and other components on the 6U CubeSat. Once in orbit, the patch antenna array expands to improve communication. The results indicate an impressive gain of 30.5 dBi, highlighting the antenna's efficiency in transmitting data. However, the design faces a critical limitation due to its reliance on a complex deployment mechanism. Any failure in deployment could lead to mission failure, emphasizing the need for highly reliable disposition systems. Reference [21] introduced a CP two-band transmitter for CubeSat communications on three units. Designed for communication with ground stations, the antenna operates in the following two distinct bands: L-band and S-band. The design positions the antenna on one side of the CubeSat, with dimensions of 100 \(\times\) 100 mm\({}^{2}\). The \(-27\) dB and \(-40\) dB S\({}_{11}\) with BWs of 9.55% and 9.66% were obtained for the lower and upper bands, demonstrating strong performances at both operating frequencies. However, the design has certain drawbacks. The ground plane measures 110 \(\times\) 110 mm\({}^{2}\), exceeding the CubeSat face's  
Figure 3: A metal-only wideband patch antenna designed for a CubeSat [19].