## 3 Antennas with General Aspects Utilized for CubeSat
### Planar Phased Patch Antennas and Their Arrays
The authors utilize the Fabry-Perot cavity approach and a parallel sequential rotation feeding network technique to achieve CP and enhance antenna performance. The feeding network is an unequal power divider with four output ports with a 50 \(\Omega\) impedance, providing a 90\({}^{\circ}\) phase delay between ports in an anticlockwise direction. The antenna is constructed using a combination of indium tin oxide (ITO) and copper (Cu)-coating layers on a transparent polyethylene terephthalate (PET-G) substrate, ensuring high transparency and good conductivity. This design allows for the solar panel to be placed between the TMM10i and PET-G substrates, maximizing the space for solar cells on the CubeSat and facilitating better energy harvesting. The authors report simulated and measured reflection coefficients of \(-25\) dB and \(-18\) dB at \(10\) GHz, respectively, with a wide \(-10\) dB bandwidth of \(40\%\) (covering 8-12 GHz). Additionally, when the solar cell was integrated with the antenna design, it achieved a high measured gain of \(15\) dB at \(10\) GHz. This innovative approach enhances the communication capabilities and optimizes the power efficiency for CubeSat missions. Reference [33] presents a high-gain X-band patch array antenna design for small satellites, including CubeSats, to achieve enhanced aperture efficiency and low sidelobe levels for circular polarization (CP). The proposed antenna measures \(100\) mm \(\times\)\(100\) mm and operates within the \(7.52\) to \(8.82\) GHz frequency range. It features a \(4\times 4\) patch array comprising \(16\) stacked CP patch elements, contributing to its high aperture efficiency. The authors employed unequal 1-16 series parallel power dividers for the antenna feed to minimize sidelobe levels. Additionally, each of the \(16\) driven patch elements includes a slot and two truncated corners to facilitate CP radiation. The antenna demonstrated measured reflection coefficients of \(-15\) dB and \(-12\) dB at frequencies of \(7.7\) GHz and \(8.6\) GHz, respectively. It also provided a measured \(-10\) dB bandwidth of \(15.85\%\), an impressive gain of approximately \(20.03\) dBi, a low sidelobe level of \(-20\) dB, and an aperture efficiency of \(86.5\%\). Reference [34] outlines the creation of a deployable high-gain antenna for the Mars CubeSat. The antenna is an innovative crumpled reflectarray engineered to be tailored within a \(6\)U CubeSat (\(8.425\) GHz). With RHCP, it achieved a \(29.2\) dBic gain. A significant benefit of the design is its compact stowage, occupying only about \(4\%\) of the available spacecraft payload volume and weighing less than \(1\) kg. In Ref. [35], an antenna was implemented on a \(40\times 40\) mm\({}^{2}\) PCB and operated in the X-band. HFSS 2013 software was used for the evaluations. The antenna incorporates circular and rectangular slot structures to enhance the BW and achieve dual resonance. Measured values for an S\({}_{11}\) of \(-17.14\) dB and \(-14.29\) dB, consistent radiation efficiency of \(78.85\%\), and \(4.31\) gain dBi were obtained. The impedance BW of the proposed design was recorded at \(1.59\) GHz. A miniature pentagonal patch antenna was designed for dual-band operation at \(7.6\) GHz and \(12\) GHz, catering to satellite communication, \(5\)G, and high-speed applications. Built on an FR4 substrate with dimensions of \(16\times 16\) mm\({}^{2}\) and a thickness of \(0.8\) mm, the antenna also cut the patch with four corner circles and a cross-shaped slot to enhance performance. A partial ground plane improved the BW and gain, achieving \(7.13\) dBi and \(8.07\) dBi peak gains at \(7.6\) GHz and \(12\) GHz, respectively. Its small size and wide BW make it suitable for C-, X-, and Ku-band applications, including satellite ground stations and remote sensing [36]. Various MPAs aimed at medical, wireless technology, and satellite communication applications. Antennas operating in the S-, C-, and X-bands were developed using FR4 and polyimide substrates.