## 3 Antennas with General Aspects Utilized for CubeSat
### Dielectric Lenses, Reflectors, and Beam Control  
A one-meter mesh reflector was devised to be compatible with 12U CubeSat telecommunications. This reflector is designed to work with NASA's DSN in the X-band and Ka-band frequencies. The following three categories of RHCP antennas are presented: only-X-band, only-Ka-band, and both X- and Ka-band operations [43]. Reference [44] proposed a compact, high-gain antenna designed for CubeSat applications. The use of a cavity-backed reflector enhances the gain. It ensures a directional radiation pattern, which is crucial for establishing efficient communication links, while the CPW-fed design simplifies integration with CubeSat circuitry and minimizes the system weight. Additionally, its low-profile and compact form factor aligns well with the space constraints of CubeSats. However, the design has several limitations for modern CubeSat communications. It lacks dynamic beam-steering capabilities, which are essential for handling frequent repositioning and enabling multi-ground-station or intersatellite links. The antenna is likely optimized for a single frequency band, limiting its support for the multi-band or wideband communications required in diverse CubeSat missions. Furthermore, the inclusion of a cavity-backed reflector, while effective for enhancing gain, poses scalability challenges for advanced systems like phased arrays or MIMO systems, which are becoming increasingly relevant. Finally, the antenna's fixed radiation parameters reduce its adaptability to dynamic and rapidly changing communication demands in low Earth orbit (LEO). Parabolic antennas, recognized for their substantial dimensions, can deliver high gains surpassing 30 dBi across frequency ranges of 0.3-300 GHz [45]. They have recently attracted considerable interest for CubeSat missions in elevated orbits and deep space due to their ability to support long-range communications with enhanced gains. However, the primary obstacle is their bulky size, making their accommodation within a CubeSat's restricted space more challenging. Several reflector-based antenna configurations are recommended for CubeSat applications, offering high gains spanning 28-48.7 dBi, functioning across X-band and W-band frequencies. Despite these benefits, the considerable physical size of these antennas remains a significant drawback, consuming a large portion of a CubeSat's available surface area. In Ref. [46], the challenges of limited storage volume and deployment complexity associated with reflector antennas are addressed by suggesting a CP, elevated gain feed horn antenna for CubeSat applications and operating in the W-band. The key innovation proposed is the use of a horn antenna to illuminate a reflector with an offset parabolic shape, integrating a polarizer with circular cavities that generate LHCP while shortening  
Figure 5: Design and fabrication of a crescent-shaped microstrip patch antenna with an annular ring structure for X-band applications and compact integration [41]. the overall length compared to conventional polarizers. The resulting reflector antenna, with a diameter of 100 mm, was designed to fit within a 1U CubeSat. Together, both the horn and reflector antennas occupied the entire 1U CubeSat volume. The feed horn and parabolic reflector antennas were integrated within a 6U CubeSat model. The system achieved a 9.88% BW, demonstrating an LHCP gain of approximately 8.8 and 9.2 dBic. At the same time, the antenna with a reflector in an offset parabolic shape delivered exceptional right-hand circular polarization gains of around 33.77 and 34.36 dBic at 86 GHz and 83 GHz, respectively. An ultra-compact, X-band deployable wrap-rib antenna was designed for space applications, particularly small satellites. The antenna employs a wrap-rib deployment mechanism, which allows it to remain compact during launch and expand in orbit, ensuring a balance between high gain, compact stowage, and structural stability.