# Antenna Designs for 5G/IoT and Space Applications, 2 nd Edition
## 2 Short Presentation of the Papers  
[PERSON] et al. [1] presented a comprehensive review of tailored Internet of Things (IoT) antenna designs, categorizing them based on their application areas, such as biomedical applications, smart homes, and smart cities. The authors highlight the evolution and specialization of antennas for each sector, noting the specific demands of antennas such as low-profile, efficient antennas for biomedical devices (e.g., implantable antennas) and tunable antennas for smart home connectivity. The review also emphasizes the importance of multifunctional antennas capable of adapting to different IoT environments, with a particular focus on challenges like beam-switching techniques for smart cities. The authors emphasize the need for interdisciplinary collaboration to drive innovation in antenna design, ensuring that both technical performance and practical user needs are met as IoT technology continues to evolve. [PERSON] et al. [2] presented a review that explores the advancements in beam-steering antennas for CubeSats, addressing key challenges such as power efficiency, miniaturization, and integration with CubeSat platforms. Their review provides a detailed analysis of state-of-the-art techniques such as phased arrays, metasurface-based designs, and reconfigurable antennas. The paper highlights the limitations of traditional omnidirectional CubeSat antennas and the need for adaptive communication solutions to improve gain and coverage in Low Earth Orbit (LEO). Moreover, their review paper compares various beam-steering approaches, such as phased arrays (offering fast electronic beam steering, but high complexity and power demands), dielectric lenses (efficient, but reliant on mechanical steering), and leaky-wave antennas (simpler, but constrained by bandwidth limitations). The study suggests hybrid techniques, including passive beamforming networks and metamaterial-based designs, as potential solutions for overcoming current constraints. [PERSON] et al. [3] proposed a single-layer, dual-band, shared-aperture phased array that operates at S-/C-band direct-to-cellular satellite communications, using high-dielectric ceramic substrates for miniaturization and optimal element spacing. The 8 \(\times\) 8 Right Hand Circular Polarization (RHCP) S-band receive array and the 16 \(\times\) 16 Right Hand Circular Polarization (LHCP) C-band transmit array achieve \(\pm\)50\({}^{\circ}\) beam scanning without grating lobes. To further enhance this performance, the authors used a sequential rotation technique, ensuring improved circular polarization with an axial ratio (AR) of less than 3 dB. Covering 1.93-2.03 GHz (S-band) and 3.32-3.71 GHz (C-band), this design offers a compact, scalable solution for future LEO satellite networks. [PERSON] et al. [4] designed a novel sum channel radiating element for a patch-monopole monopulse feed for the prime-focus illumination of deep symmetric reflectors in S-band satellite ground stations. The circularly polarized slotted patch enhances monopulse tracking, radiation symmetry, and channel isolation, improving aperture illumination efficiency to 75%. The proposed design demonstrated a LHCP gain of 8 dBi and a 30 MHz narrowband sum channel, making it suitable for LEO-satellite ground stations and small satellite antennas. The design optimizations minimize spillover losses, contributing to efficient and precise satellite tracking systems. [PERSON] [5] introduced a low-cost, semitransparent, 3D-printed mesh patch antenna design for urban communication that can be integrated into buildings' windows to enhance 5G/6G connectivity while preserving natural lighting. The proposed sub-strateless metal mesh structure, fabricated using 3D printing and silver conductive paint, achieves 60% transparency, a 2.7% bandwidth, and a peak gain of 5.4 dBi at 2.6 GHz. By eliminating the substrate, the antenna minimizes losses, cost, and environmental impact, offering a lightweight, scalable solution for smart building applications and urban network infrastructure enhancement.