Recent Articles
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Design and Analysis of a Carbonyl Iron Powder/Epoxy Composite-Based Ultra-Wideband Multi-Pyramidal Magnetic Absorber Using an Equivalent Circuit Model
25 September 2024 Aparna Parameswaran, Nohgyeom Ha, Soo Hyun Kim, Sukjin Kwon, Byeongjin Park and Sangkil Kim present a CIP/epoxy composite based ultra-wide band electromagnetic multipyramidal absorber. The constituent parameters of the CIP/epoxy composite is experimentally extracted using a waveguide measurement setup. This raw data is then quantified using a least-square fit polynomial based curve fitting technique to facilitate its use in the design and the analysis of the pyramidal absorber. Four asymmetrical truncated pyramids supported by a grounded base constitute the absorber unit cell. The absorption bandwidth of the design ranges from 3.21 GHz to 40 GHz (FBW of 170.3%, S - band to V - band) and stable absorption characteristics under oblique incidences is observed up to 35°.
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Efficient Synthesis of Large Finite Patch Arrays for Scanning Wide-Angle Anomalous Reflectors
24 September 2024 Sravan Kumar Reddy Vuyyuru, Risto Valkonen, Sergei A. Tretyakov and Do-Hoon Kwon propose a design methodology for planar loaded antenna arrays to synthesize a perfect anomalous reflection into an arbitrary direction by optimizing the scattering characteristics of passively loaded array antennas. It is based on efficient and accurate prediction of the induced current distribution and the associated scattering for any given set of load impedances. For a fixed array of finite dimensions, the deflection angles can be continuously adjusted with proper tuning of each load.
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Path Loss Modeling of Wireless Signals in Underground Tunnels
24 September 2024Yaning Li, Baoguo Yu and Lu Huang propose a hybrid model describing the propagation attenuation of wireless signals in underground tunnels which divides the propagation channel into three subdomains according to the length of the tunnel, namely, the region of the free space propagation model, the region of the multimode propagation described by the ray tracing method, and the region of the improved waveguide model by adding the influences of tunnel roughness, tunnel inclination, and metal pipes. The determination of the breakpoints separating each region depends on the variation of the angle between the arrival direction of the signal ray and the axial direction of the tunnel.
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Frequency Diverse Array for Signal Geofencing in Wireless Communications: Does it Work?
23 September 2024 Simone Del Prete, Marina Barbiroli and Franco Fuschini carry out a detailed analysis of the sensitivity of the geofencing effectiveness to the main array parameters. The analysis covers many aspects of the design, including the selection of the geometrical layout and the number of elements of the array, the frequency increase policy and the frequency offset across the elements and their spacing. The study also discusses the trade-offs between different design choices and provides insights into the performance in terms of focus efficiency and size of the focus area. Results show that bidimensional layouts, e.g., circular or planar, often represent effective solutions, whereas the linear arrangement can be a viable option only in case the frequencies are spread across the elements in a random-like fashion.
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Advanced Metasurface-Based Antennas: A Review
23 September 2024 Wanchen Yang, Jinghao Li, Dongxu Chen, Yue Cao, Quan Xue and Wenquan Che present an analytical model for an antenna-embedded wall, also called signal-transmissive wall. In the signal-transmissive wall, multiple antenna elements are distributed periodically on both wall sides, and connected back-to-back through coaxial cables. Numerical full-wave simulations of the signal-transmissive wall are computationally demanding due to the fine meshes required in the cables while having an electrically large wall size. Therefore the simulations above 8 GHz are not feasible even with a powerful cluster computer of the authors’ research site. The analytical model is an attractive alternative to the full-wave simulation of the wall, which combines the individual transmission characteristics of the bare wall, realized gains of antenna elements and cable losses.
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Dual-Polarized Wideband Filtering Antenna Array Based on Stacked-PCB Structure
23 September 2024 Matti Kuosmanen, Sten E. Gunnarsson, Johan Malmström, Juha Ala-Laurinaho, Jari Holopainen and Ville Viikari investigate a thin low-pass filtering antenna array based on dual-polarized Vivaldi elements. The low-pass filtering in the antenna elements reduces the requirement for the front-end filtering between the antenna and the microwave electronics, resulting in improved overall out-of-band suppression, size reduction, and lower cost. The array employs a novel stacked-PCB structure, where simple two-sided PCBs are stacked on top of each other. The via-connected metal layers of all PCBs form a tapered slotline along the surface normal of the PCBs. The filtering effect is realized by corrugating the tapered slotlines, which provides effective, space-saving integration of the filters that fit into a half-wavelength lattice.
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A Metallo-Dielectric Groove Gap Waveguide Slotted Array Antenna With Hybrid Glide-Symmetric Holes & “Mushroom”-Type Metasurfaces
23 September 2024 Panagiotis Petroutsos and Stavros Koulouridis present a hybrid multilayer slot array antenna, targeting next-generation wireless communication systems, particularly in mmWave bands like the Ka-band. The hybrid structure utilizes a high-performance metal Groove Gap Waveguide (GGW) feeding network and facilitates the practical manufacturing of slotted antennas and dielectric substrate metasurfaces using printed circuit boards. The proposed antenna incorporates a hybrid glide symmetric holey metasurface into the GGW feeding. This integration addresses assembly challenges between metal and dielectric layers, avoiding delicate welding techniques. It prevents energy leakage between the two different materials, even when a small air gap is maintained between them.
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Compact Dual-Band Dual-Sense Circularly Polarized Fragmental Patch Antenna Optimized by Improved Simulated-Annealing-Based Algorithm
19 September 2024 Tianyu Shu, Bowen Feng, Long Zhang, Chuyue Chen, Hui Chen, Yaling Chen and Qinyu Zhang present a compact dual-band dual-sense circularly polarized (CP) fragmental patch antenna that advanced by an improved simulated-annealing-based optimization algorithm. This design replaces truncated corners of traditional truncated patch antennas with fragmental structures, generating dual-band dual-CP radiation with a small frequency ratio and a high front-to-back ratio. The proposed optimized framework tackles the multi-objective optimization problem through hierarchical optimization to achieve an optimal balance among various performance metrics.
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Through-the-Wall Human Activity Recognition Using Radar Technologies: A Review
12 September 2024 Jawad Yousaf, Satanai Yakoub, Sara Karkanawi, Taimur Hassan, Eqab Almajali, Huma Zia and Mohammed Ghazal presents an in-depth review of Ultra-wideband (UWB) radar systems for recognizing human activities in a room and through-the-wall (TTW) with other diverse applications. After briefly discussing different UWB radar working principles and architectures, the study explores their role in various TTW applications in real-world scenarios. An extensive performance comparison of the legacy studies is presented, focusing on detection tools, signal processing, and imaging algorithms. The discussion includes an analysis of the integration of machine learning models.
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Wideband Solar-Cell Integrated Yagi-Uda Antenna
12 September 2024 Ahmed Ali, Heesu Wang, Yong Bae Park and Ikmo Park present a wideband ultra-low-profile Yagi-Uda type of solar-cell integrated antenna. The proposed antenna consists of a driver, reflector, and director, and is also designed to function as a solar cell. An ultra-low-profile copper indium gallium selenide (CIGS) based solar cell is used as a driver, and a slit is cut from it to make a built-in solar-cell antenna. A CIGS solar cell-based reflector and director are added to increase the impedance bandwidth and gain of the proposed antenna. A narrow slit is used, and the spacings between the reflector, driver, and director are minimized to increase the solar-cell form factor. A coaxial-to-microstrip line transition type feeding structure is used to excite the antenna, which is printed under the second substrate.
