Antenna Performance Research Articles

Comprehensive accuracy analysis for large closed-loop deployable structures based on matrix structure analysis and linear-complementarity-based contact analysis of spatial joint clearances

The surface accuracy of the deployable structure is crucial in determining the electromagnetic performance of the large satellite antenna. This paper proposes a comprehensive accuracy analysis framework for deployable structures considering clearances of spatial joints, geometric deviations, elastic deformations, external loads, and preloads, all of which can affect surface accuracy during the assembly process. Surface accuracy is calculated by combining the global equilibrium analysis of the deployable structure with the local equilibrium analysis of clearance-affected joints. First, a global elastostatic equilibrium analysis of the deployable structure is performed based on a unified mathematical formulation that describes the elasticity of beams and joints. Then, the local equilibrium analysis for the clearance-affected joints is transformed into a quadratic optimization problem through a linear-complementarity-based method. This method avoids the necessity for a combinatorial search for several traditional discontinuous contact configurations. Considering both global and local equilibrium in iterative analysis, the surface accuracy of the antenna is calculated. This integration avoids prior artificial assumptions about contact configurations of the joints. Finally, the proposed method is validated by comparing it with simulations and experimental results.

A Miniaturized Dual-Band Circularly Polarized Implantable Antenna for Use in Hemodialysis.

Hemodialysis is achieved by implanting a smart arteriovenous graft (AVG) to build a vascular pathway, but reliability and stability in data transmission cannot be guaranteed. To address this issue, a miniaturized dual-band circularly polarized implantable antenna operating at 1.4 GHz (for energy transmission) and 2.45 GHz (for wireless telemetry), implanted in a wireless arteriovenous graft monitoring device (WAGMD), has been designed. The antenna design incorporates a rectangular serpentine structure on the radiation surface to reduce its volume to 9.144 mm3. Furthermore, matching rectangular slots on the radiation surface and the ground plane enhance the antenna's circular polarization performance. The simulated effective 3 dB axial ratio (AR) bandwidths are 11.43% (1.4 GHz) and 12.65% (2.45 GHz). The simulated peak gains of the antenna are -19.55 dBi and -22.85 dBi at 1.4 GHz and 2.45 GHz, respectively. The designed antenna is implanted in a WAGMD both in the simulation and the experiment. The performance of the system is simulated in homogeneous human tissue models of skin, fat, and muscle layers, as well as a realistic adult male forearm model. The measurement results in a minced pork environment align closely with the simulation results.

Design and Performance of Dual Band Microstrip Nano-Fractal Patch Antenna

Design and Performance of Dual Band Microstrip Nano-Fractal Patch Antenna

Metasurface loaded dual band antenna for high gain on- and off- body communication

Metasurfaces are specially made materials designed to have unique properties not found in nature. They are categorized into different types, such as artificial magnetic conductor (AMC), partial reflecting surfaces (PRS), and frequency selective surfaces (FSS). Among these, FSS is commonly used in today’s technology to improve antenna performance, especially in boosting signal strength by blocking unwanted radiation. Recent research is focused on creating FSS-based antennas for Ultra-wideband (UWB) or single band applications, with a significant emphasis on enhancing signal strength. Unlike traditional methods, this study concentrates on designing antennas that are both simple in shape and offers broader frequency coverage, specifically for 2.45 GHz and 5.8 GHz applications. To enhance antenna performance, a dual-band FSS is employed, optimizing the system for improved operation at both resonating frequencies. This results in a high-gain antenna system, which is further investigated for body area network (BAN) systems, considering the crucial performance metric of specific absorption rate (SAR). The findings are compared with recently reported FSS-based antennas to underscore their scientific contribution and potential for high gain, low SAR applications within the 2.45 GHz and 5.8 GHz frequency bands.

Water penetrating radar: A fluvial scour study of antenna performance and data processing

AbstractGround‐penetrating radar (syn. water‐penetrating radar, or WPR hereon) has been used previously in the detection and characterisation of riverine scour. This paper presents field data, equipment calibration and processing output results from a new generation of high dynamic range (HDR) radar systems. These provide a new and more sophisticated model of fluvial scour for the study site. The adaptability for deployment on water, wide bandwidth and good quality in raw and processed data, demonstrates the advantages of the system. Data processing and depth calibration are issues in the interpretation of WPR data, which are both discussed. WPR demonstrates the potential for surveying sedimentation where palaeoscour occurred and thus anticipated. This maybe in conjunction with other techniques or where aquatic vegetation, rocky substrates or methane gas bubble release preclude use of sonar.

An Ultra-Thin Multi-Band Logo Antenna for Internet of Vehicles Applications

In this paper, an ultra-thin logo antenna (LGA) operating in multiple frequency bands for Internet of Vehicles (IoVs) applications was proposed. The designed antenna can cover five frequency bands, 0.86–1.01 GHz (16.0%) for LoRa communication, 1.3–1.36 GHz (4.6%) for GPS, 2.32–2.71 GHz (16.3%) for Bluetooth communication, 3.63–3.89 GHz (6.9%) for 5G communication, and 5.27–5.66 GHz (7.1%) for WLAN, as the simulation indicated. The initial antenna started with a modified coplanar waveguide (CPW)-fed circular disk monopole radiator. To create extra current paths and further excite other modes, the disk was hollowed out into the shape of the car logo of the Chinese smart EV brand XPENG composing four rhombic parasitic patches. Next, four triangular parasitic patches were inserted to improve the impedance matching of the band at 5.6 GHz. Finally, four metallic vias were loaded for adjusting resonant points and the return loss reduction. Designed on a flexible substrate, the antenna can easily bend to a certain degree in complex vehicular communication for IoV. The measured results under horizontal and vertical bending showed the LGA can operate in a bending state while maintaining good performance. The proposed LGA addresses the issue of applying one single multi-band antenna to allow vehicles to communicate over several channels, which relieves the need for a sophisticated antenna network.

Design of a miniaturized dual circularly polarized implantable antenna by using characteristic mode method

The characteristic mode method is used to design a miniaturized dual-band dual circularly polarized (CP) implantable antenna operating in ISM bands. The miniaturization and dual-band characteristics are gained by using the slotting method and by inserting a short-circuit probe between the radiation patch and the ground plane. We use the characteristic mode method to study the current distribution of circular radiation patches with T-shaped slots in different modes. After opening a cross-shaped slot at the center of the radiation patch and the ground plane, we obtained two orthogonal modes with equal amplitude and phase difference of 90° in two operating frequency bands, ultimately achieving CP characteristics of the antenna. Its overall size is only π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi$$\\end{document}×(0.014 λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\uplambda$$\\end{document}0)2 × 0.0027 λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\uplambda$$\\end{document}0, smaller than other CP implantable antennas with similar performances, and it has satisfactory radiation efficiency and gain characteristics. Measurements show that it can operate in the ISM bands of 0.9 and 2.4 GHz with an effective 3 dB axial ratio bandwidth greater than 220 MHz (0.87 to 1.09 GHz, 22.45%) and 230 MHz (2.31 to 2.54 GHz, 9.48%), and its peak gain is − 29.5 dBi and − 19.2 dBi, respectively. And, this design complies with IEEE safety guidelines.

A mechanics and electromagnetic scaling law for highly stretchable radio frequency electronics

Many classes of flexible and stretchable bio-integrated electronic systems rely on mechanically sensitive electromagnetic components, such as various forms of antennas for wireless communication and for harvesting energy through coupling with external power sources. This efficient wireless functionality can be important for body area network technologies and can enable operation without the weight and bulky size of batteries for power supply. Recently, antenna designs have received increased attention because their mechanical and electromagnetic properties significantly influence the wireless performance of bio-integrated electronics, particularly under excessive mechanical loads. These mechanical factors are critical for skin-integrated electronics during human motion, as complex skin deformations can damage the conductive traces of antennas, such as those used for near-field communication (NFC), leading to yield or fracture and affecting their electromagnetic stability. Serpentine interconnects have been proposed as a geometric alternative to in-plane circular or rectangular spiral antenna designs to improve the elastic stretchability of the metallic traces in NFC antennas and prevent mechanical fractures. Despite the use of serpentine interconnects within the physiologically relevant strain range for skin (<20 %), the electromagnetic stability of the antennas decreases. This instability, reflected by shifts in resonance frequency and scattering parameters due to inductance changes, reduces the antennas' wireless power transfer efficiency and readout range. Therefore, maintaining the electromagnetic stability of antennas, specifically NFC antennas, under various mechanical deformations has become a critical challenge in practical wireless skin-integrated applications, such as sensing and physiological monitoring. Here, we establish a new mechanics and electromagnetic scaling law that quantifies the inductance changes under strain in a rectangular-loop serpentine structure typically used for NFC wireless communication in stretchable electronics. We present a systematic analysis of the antenna's geometric parameters, material properties of the antenna and substrate, and the applied strain on the inductance change. Our findings demonstrate that the relative change of inductance is solely influenced by the serpentine structure's width-radius ratio, arc angle, aspect ratio of the NFC antennas, and the applied strain. Additionally, under physiological strain conditions for the skin, the relative change of inductance can be minimized to preserve the NFC antenna's performance and prevent mechanical fracture and electromagnetic stability loss.

Enhanced Antenna Performance at 3.5 GHz With a Compact and Intelligent Reflecting Surface

Enhanced Antenna Performance at 3.5 GHz With a Compact and Intelligent Reflecting Surface

An ultra-wideband antenna design optimization for biomedical applications using artificial neural networks

This paper presents an innovative method based on Artificial Neural Networks (ANN) for optimizing the design of microstrip antennas using HFSS software. The method leverages a dataset generated from comprehensive full-wave electromagnetic simulations to accurately predict antenna performance. In the ANN model, coefficients of reflection as input parameter, and five output parameters representing key geometrical variables of the antenna are utilized. The study demonstrates how ANNs effectively predict these variables, thereby enhancing design efficiency and significantly reducing the computational time required for antenna optimization. By providing a robust and efficient framework, the results highlight the promising potential of ANNs in optimizing antenna designs for diverse applications, including medical and wireless communication systems. Specifically, the proposed Ultra-Wideband (UWB) antenna operates over a frequency range from 5.17 GHz to 7.02 GHz and maintains an S11 value of -20.49 dB at 5.8 GHz within the Industrial, Scientific, and Medical (ISM) bands. This research contributes valuable insights into advancing electromagnetic performance through efficient antenna design methodologies.

Design of Electrically Small Intraocular Antenna for Retinal Prosthesis System and Its Validation.

This paper presents an ultra-miniaturized circular-shaped triple band microstrip antenna as an intraocular unit applicable for retinal prosthesis. The reported antenna is developed by modifying a conventional circular-shaped patch with a pair of open-ended circular annular rings and a semicircular ring-loaded rectangular stub. Additionally, a shorting pin is used at the periphery of the patch to achieve the frequency bands of interest. Further, to make the structure electrically small and accommodate highly dense electrodes, the circular ground plane is modified by making symmetrical slots over the four quadrants and edges. Specific absorption rate distribution for 1g and 10g of different tissue layers over three operating frequencies has been studied by placing electromagnetic sources at different locations. With these arrangements, the proposed strip antenna offers multiband operation within the frequency band of 1.25 GHz (1.13-1.46 GHz), 2.45 GHz (2.24-2.66 GHz), and 3.32 GHz (3.09-3.50 GHz). Besides, circularly polarized radiation has also been achieved at 1.25 GHz with a 3-dB axial ratio bandwidth of 10 MHz. Finally, the proposed antenna structure is fabricated, and its measured performance metrics are in close aggreement with the simulated parameters. The proposed antenna's performance inside a customized canonical eye model (DMCM) and anthropomorphic Zubal head model is studied and compared with the prior studies.

Flexible low-profile shield for reducing back radiation of wrist-worn antenna

A flexible conducting lossy shield is developed and demonstrated for a reduction in the back radiation of a linearly polarized X-band patch antenna for Wireless Body Area Network (WBAN) applications. The proposed structure comprises a flexible patch antenna backed by a laminated sheet of Expanded Graphite (EG). This flexible sheet is prepared from EG powder pressed uniformly over a thin adhesive tape. The conducting nature of EG is exploited, and the EG sheet is used as a protective shield to prevent back radiation emanating out of the WBAN antenna from propagating toward the human body. The antenna performance is tested over human wrist phantoms experimentally and through full wave simulation studies. The results indicate the marginal variation in the −10 dB impedance bandwidth with a slight increase in the gain and directivity values for a resonant frequency in the range 9.7–10.3 GHz (bending radius variation of 40, 30, and 20 mm and along two bending planes). A measured on-body gain of 6.7 dBi is exhibited by the antenna backed by the EG shield and bent over a 20 mm radius human wrist phantom with an S11 of −19 dB, a −10 dB % bandwidth of 8%, and a directivity of 9.4 dBi. All the other bending configurations exhibit values higher than these. Electric field and Specific Absorption Rate (SAR) studies reveal a reduction in wave penetration by the EG shield antenna inside the wrist phantom with a decrease in the SAR by a maximum of 5%. The measured front-to-back ratio values indicate the lowering of back radiation with a maximum average increase of 76% exhibited by an EG backed antenna. The developed EG shield has an additional advantage of being a standalone structure, which can be integrated with any wearable antenna for a possible reduction in the back radiation.

Meander-Lined Implantable Antenna Design at 2.45 GHz Using Transmission Line Model

Scientists mostly follow a trial-and-error approach using simulators for designing implantable antennas which may increase time complexity and memory usage. In this article, the Transmission Line Model (TLM) is utilized to design a miniaturized meander-line implantable antenna at 2.45 GHz for reducing time and memory requirements. The meander-line antenna is first decomposed into different segments – x-directed, y-directed, and bends. Each segment is considered a transmission line and each line is replaced by its equivalent lumped LC network. The lumped parameters are calculated using the dimensions of the segment and guided wavelength inside the body. Here, a three-layered body model is represented by a T-type resistor, inductor and capacitor (RLC) network. The antenna within the human body is then simulated using Finite Element Method (FEM)-based CST Microwave Studio software. FEM technique is taking 4.94-MB memory space and 13-minutes time to analyze this implanted system whereas TLM is analyzing the same system by considering 726-KB memory within 52 s. TLM is predicting implanted antenna performance considering ∼0.8% error concerning simulated response. The designed antenna is fabricated and measured within a homogeneous body phantom and minced pork to verify the simulated response. The effect of chamfering of the corners of the meander-line antenna is also analyzed here. From this study, it is observed that TLM can predict implantable antenna response efficiently with low memory and less time requirement with respect to FEM which is helpful for antenna engineers. Analysis of implantable antenna with low memory and time requirements using TLM is a novel approach to this work.

Curvature-Adaptive Compact Triple-Band Metamaterial Uniplanar Compact Electromagnetic Bandgap-Based Printed Antenna for Wearable Wireless and Medical Body Area Network Applications

A novel, compact, monopole apple-shaped, triple-band metamaterial-printed wearable antenna backed by a uniplanar compact electromagnetic bandgap (UC-EBG) structure is introduced in this paper for wearable wireless and medical body area network (WBAN/MBAN) applications. A tri-band UC-EBG structure has been utilized as a ground plane to minimize the impact of antenna radiation on the human body and improve antenna performance for the proposed wearable antenna. Metamaterial triangular complementary split ring resonators (TCSRRs) are incorporated into the antenna and UC-EBG structure, resulting in a compact UC-EBG-backed antenna with an overall size of 39 × 39 × 2.84 mm3 (0.41 λg × 0.41 λg × 0.029 λg). The printed textile antenna operates at 2.45 GHz for the wireless local area network (WLAN), 3.5 GHz for 5G new radio (NR), and 5.8 GHz for the industrial, scientific, and medical (ISM) bands with improved gain and high-efficiency values. Furthermore, the performance of the antenna is analyzed on the human body, where three models of curved body parts are considered: a child’s arm (worst case) with a 40 mm radius, an adult’s arm with a 60 mm radius, and an adult’s leg with a 70 mm radius. The results demonstrate that the proposed antenna is an attractive candidate for wearable healthcare and fitness monitoring devices and other WBAN/MBAN applications due to its compact size, high performance, and low SAR values.

Frequency reconfigurable microstrip patch antenna for multiband applications

Wireless communication technology is well-established, and several antennas have been developed and produced specifically for this purpose. However, antenna performance and communication system development need to be enhanced in order to adapt to the present era. The performance of the antenna is significantly influenced by its design. Thus, this work produced a novel wideband antenna design via the use of a frequency reconfigurable approach. In the recommended study, microstrip patch antennas (MPAs) were used in wideband applications to switch frequencies using shunt-series microelectromechanical systems (MEMS). The suggested antenna, which has two switches built into it, is tested in ON-ON, OFF-ON, and OFF-OFF switching scenarios. Radiation pattern, voltage standing wave ratio (VSWR), gain, bandwidth, and return loss are among the antenna performance metrics used to assess the suggested antenna's performance in each switching situation. The simulation findings suggest that the optimal antenna design for usage in wireless communication systems is one that works well with a shunt-series MEMS switch.

Novel nanocomposite based microstrip patch antenna for C and X band applications

Microstrip patch antennas (MPAs) are essential components in modern wireless communication systems, and their design is significantly influenced by the properties of the materials used. In this study, we investigate the impact of incorporating composites of fumed silica within RT-Duroid dielectric material on the performance of microstrip patch antennas. The effective permittivity of the composite is calculated using the Maxwell-Garnett model. Through systematic theoretical studies, we analyze the performance of composite antennas with varying composite volumes and dielectric substrate thicknesses. Utilizing HFSS 13.0 software, we optimize the substrate thickness and antenna dimensions to design MPAs resonating at 10 GHz. The proposed antenna, with dimensions of 11.85 mm by 9.044 mm for the patch and 50 mm by 50 mm for the substrate, exhibits superior performance compared to conventional antennas, achieving a higher gain of 10 dB, good efficiency of 96 % along with favorable return loss characteristics. The frequency ranges of the C and X bands are better suited for military applications, weather radar, satellite communication, air traffic control, maritime radar, and remote sensing. This research underscores the significance of incorporating composite materials into MPA design to enhance performance and broaden application potential in modern communication technologies.

Coupling Modeling for Ripple of Array Power Supply and Electromagnetic Performance of Active Phased Array Antennas

Coupling Modeling for Ripple of Array Power Supply and Electromagnetic Performance of Active Phased Array Antennas

Multifunctional Design for Arbitrary Multiband Radome Wall Accelerated by Artificial Intelligence

A hypersonic airborne radome must possess multiband electromagnetic transparency, high specific strength, and thermomechanical resistance to ensure proper antenna operation. However, achieving these multifunctional properties in radome wall design is challenging due to conflicting material requirements. Moreover, existing design methods for arbitrary multiband and broadband hypersonic radomes are insufficient. This paper presents an efficient method that integrates artificial intelligence and an evolutionary algorithm to enable the multidisciplinary synchronous design of the radome wall. The designed radome walls using multilayered porous silicon-nitride ceramics achieve power transmission efficiency exceeding 90% in a broadband of 30 GHz or arbitrary multiple bands with bandwidths of 5 GHz, covering the centimeter-to-millimeter wave range. Moreover, the designed laminate also meets requirements of flexural strength surpassing 60 MPa and a maximum thermal stress–strength ratio below 1. Notably, the utilization of artificial intelligence accelerates the design process by at least 1093 times compared to conventional methods.

Design of a Simulated Tri-Bandwidth circular patch with slot for X and C bands applications

Scientists continue to improve the performance and efficiency of microstrip antenna designs as technology evolves, aiming to improve their adaptability to different environments and constraints. These antennas play an important role in modern communication technologies and in signal path systems demonstrate development, computer modeling and testing of microstrip line and coaxial cable with G-shaped slots in the strip. The antenna was designed and simulated using CST simulation software. Antenna performance was analyzed, considering several factors such as return loss, gain, directness, bandwidth, 3D radiation patterns and more. Simulated results showed that the proposed antennas exhibit a wide frequency range, with the microstrip line feed antenna and coaxial cable obtaining a value of 61% and 65%, respectively. These two antennas exhibited remarkable gain which are 7.784 dBm and 7.787 dBm, respectively. The microstrip line achieved a maximum feed efficiency of 93.12%, while the coaxial cable achieved a maximum feed efficiency of 97.65%. The findings suggest that providing the antenna with coaxial cable as opposed to fine tape line improves its performance. Antennas with coaxial cable have wider bandwidth, higher gain, and better efficiency compared to microstrip line antennas.

Study of the dielectric properties of Y3TaO7 electroceramic

In this work, the Y3TaO7 weberite-type structure was synthesized by solid state reaction at 1773 K for 6 h, and its crystalline phase was characterized using X-ray diffraction (XRD). Morphological analysis was performed using scanning electron microscopy (SEM). Electrical characterization of the electroceramics was investigated with temperature variation employing complex impedance spectroscopy (CIS). The Nyquist diagram was fitted employing one resistor (R) – constant phase element (CPE) associations correlating to grain boundary. Activation energy (Ea) values for the relaxation processes were determined as 1.07, 1.06 and 1.15 eV for imaginary impedance (Z″), imaginary electrical modulus (M”) and conductivity (σ′), respectively, indicating a consistent thermo-activated conduction process. The temperature coefficient of the resonant frequency (τf) was found to be 31.24 ppm.K−1, suggesting for the development of new dielectric materials with τf ∼ 0. The performance of the dielectric resonator antenna (DRA) was assessed through numerical simulation, demonstrating a strong correlation in impedance and operating frequency at 5.01 GHz. This study aims to facilitate the design of Y3TaO7-based materials, offering significant potential for applications in microelectronic devices in the radiofrequency (RF) and microwave (MW) range.