Antenna Systems for Emerging Applications

Abstract

Antenna systems are fundamental to many modern technologies, enabling reliable communication and sensing in challenging environments. This thesis focuses on two emerging applications that require specialized antenna designs: deep-sea communications and terahertz (THz) science for sensing, communication, and spectroscopy. With increasing interest in climate research, understanding ocean dynamics has become critically important. To support this, we propose various antenna designs suitable for deep-sea and through-sea ice communication scenarios. Furthermore, the demand for ultra-fast communication beyond 5G drives exploration into the THz frequency band. However, antenna systems operating at these high frequencies are still under development and less mature compared to millimeter-wave (mm-wave) and microwave technologies. As part of this work, we also develop a comprehensive database of dielectric material properties essential for designing dielectric antennas—promising candidates for low-cost THz antennas. Deep-Sea Communication and AUV Docking Challenges: One significant challenge in ocean exploration is establishing reliable data transfer between autonomous underwater vehicles (AUVs) and docking stations. Although AUVs offer autonomous and flexible underwater operation, low docking success rates—stemming from alignment sensitivity and limited communication range—pose persistent barriers. To address this, we introduce two dedicated antenna systems: An Out-of-Line Series Feed Slot (OLSFS) antenna operating at 2.4 GHz, designed for omnidirectional, centimeter-range wireless data transfer. Its design reduces angular alignment constraints during docking procedures. A loaded waveguide antenna functioning in the lower UHF band, enabling decimeter-range communication. This antenna offers broad operational bandwidth, a wide radiation pattern, and circular polarization, resulting in a robust link that is less sensitive to misalignment. Both antenna systems have been extensively validated through simulations and experimental testing, demonstrating strong agreement and reliable performance in underwater conditions. Through-Sea-Ice Communication for Polar Exploration: In addition to AUV docking, this thesis presents a novel antenna solution for through-sea-ice communications, addressing vital needs in polar regions. Floating sea ice obstructs direct communication paths, hindering ocean exploration. To overcome this, we develop an integrated RF system comprising a loaded waveguide antenna, a matching layer, and a guiding tube. This configuration facilitates stable communication links between AUVs and satellites through sea ice—an essential capability for polar research and long-range underwater operations. Advancing Terahertz (THz) Technology: Finally, this thesis explores the promising field of THz systems, motivated by their potential applications in next-generation 6G wireless communications, spectroscopy, and sensing. Due to their sub-millimeter wavelengths, THz signals exhibit unique electromagnetic behaviors distinct from mm-wave and infrared (IR) frequencies. Precise knowledge of materials’ dielectric properties at these frequencies—above 100 GHz—is critical for effective antenna design. However, material characteristics at THz are often different from those at lower frequencies, necessitating a dedicated database. To this end, we perform comprehensive material characterization using a standard transmission-based method, employing a vector network analyzer. Additionally, we propose a novel, cost-effective approach using a compact frequency-modulated continuous-wave (FMCW) radar-on-chip platform, making high-frequency material testing more accessible. The resulting database provides a vital resource for developing and optimizing THz antennas. Collectively, these studies demonstrate how tailored antenna system designs can overcome physical challenges, enhance operational performance, and unlock new capabilities in underwater communication and high-frequency applications. They pave the way for advancements across multiple frontier applications in ocean exploration and beyond.