An all-dielectric metasurface with high sensing performance is designed to achieve dual-polarization and dual-band Q-BIC resonance. The physical mechanism is analyzed by calculating eigenmodes and multipole decomposition.

Anisotropic gold nanoparticles (AuNPs) are well-known for their remarkable optical properties, particularly their dual-band surface plasmon resonance (SPR) behaviour. In this study, we harnessed these unique features to develop a rapid fungicide detection system. The sensing approach relies on monitoring changes in the intensity and position of the SPR peaks, with the absorbance spectrum serving as the primary detection signal. Upon light exposure, the sensor could detect chlorothalonil in at least three seconds. Notably, chlorothalonil alone does not produce significant SPR peaks; however, when combined with AuNPs, two distinct SPR bands emerge, corresponding to the transverse (t-SPR) and longitudinal (l-SPR) resonance modes. As chlorothalonil concentration increases, the absorbance intensity of the AuNPs also rises, likely due to an increase in refractive index around the nanoparticles. Stability assessments revealed minimal variation in SPR peak values, which were consistently recorded at 1.30 ± 0.00001 and 1.18 ± 0.00001 a.u. over a 600-second period. In repeatability tests, the sensor demonstrated dependable performance across six measurement cycles, with the signal reliably returning to baseline after each medium change. The AuNPs exhibited a fast optical response, reaching maximum spectral shifts within 30 seconds. These findings underscore the potential of anisotropic AuNPs as an effective platform for rapid, consistent, and sensitive detection of fungicides.

This study introduces a dual-band circular split-ring resonator (CSRR)-based metamaterial absorber (MTMA) designed for high-sensitivity sensing of both solid and liquid materials. The proposed structure, fabricated on a Rogers RT 5880 substrate with copper layers, achieves near-perfect absorption rates of 99.99% at 10.48 GHz (X-band) and 99.97% at 14.57 GHz (Ku-band), optimized through CST Microwave Studio simulations. The MTMA’s triple-stage design refinement enhances resonance characteristics, enabling precise detection of dielectric variations in substrates and liquids via measurable frequency shifts. Experimental validation confirms robust performance, with sensitivity of up to 2.51 GHz/εᵣ and quality factors reaching 189, thus outperforming existing single-band metamaterial sensors. The absorber’s compact size and consistent response under varying permittivity’s make it suitable for applications in biomedical diagnostics, fuel adulteration detection, and industrial quality control. By bridging gaps between simulation and real-world implementation, this work advances metamaterial-based sensing technology, offering a scalable and efficient solution for electromagnetic wave manipulation in next-generation sensor systems.

Non-invasive glucose monitoring remains a significant challenge in diabetes management, with existing approaches often limited by poor accuracy, high cost, or patient discomfort. Microwave-based biosensors offer a promising label-free alternative by exploiting the dielectric contrast between glucose and water. This paper presents a compact, dual-band concentric square-shaped split-ring resonator (SRR-type) biosensor fabricated on a low-cost FR-4 substrate for aqueous glucose detection. The sensor leverages electric field confinement in inter-ring gaps to transduce glucose-induced permittivity changes into measurable shifts in resonance frequency and reflection coefficient. Experimental results demonstrate a linear, monotonic response across the clinical range up to 250 mg/dL, with a frequency-domain sensitivity of 1.964 MHz/(mg/dL) and amplitude-domain sensitivity of 0.0332 dB/(mg/dL), achieving high coefficients of determination (R2 = 0.9956 and 0.9927, respectively). The design achieves a normalized size of 0.137 λg2, combining high sensitivity and compact size within a scalable platform. Operating in the UWB-adjacent band (2.76–3.25 GHz), the proposed biosensor provides a practical, reproducible, and PCB-compatible solution for next-generation label-free glucose monitoring.

Abstract Presented in this study is a compact, dual-band, and highly flexible inverted slotted triangular-shaped monopole antenna. It is backed with a dual-band artificial magnetic conductor for off-body wireless and low specific absorption rate (SAR) medical applications. The antenna is designed to radiate at 2.45 GHz of the Industrial, Scientific, and Medical-band and achieves dual-band resonance by etching two inverted L-shaped slots off the monopole antenna. By doing so, the antenna operates at 5.2 GHz of the wireless local area network frequency band. In off-body operation, the integrated design achieves gain improvements at both operating frequencies by 6 and 4.9 dBi, respectively, compared to the standalone antenna. In the case of the on-human-body operation scenario, low SAR levels of 0.39 and 0.07 W/kg were realized at both resonant frequencies, respectively. The proposed integrated design was fabricated and tested, where the tested results highly align with the simulated ones in free space and on-body cases. The antenna size is only 39 × 25 mm 2 which is claimed to be an ultra-size. Thus, the presented antenna is claimed to be very competitive in terms of the small size and the achieved antenna parameter results.

Abstract This work presents an innovative compact dual-band microstrip sensor based on a complementary split-ring resonator (CSRR) for the precise characterization of water–ethanol mixtures. The sensor, optimized via HFSS, offers high sensitivity and an impressive quality factor through dual-band operation at 3.5 GHz and 4 GHz. The validity of the sensor’s performance is supported by both simulated and measured results, which demonstrate its capacity to extract the complex dielectric permittivity of liquids. The proposed sensor utilizes CSRR and offers dual-band resonance, making it a promising alternative to traditional CSRR. This innovative sensor’s dual-band capability, achieved through its unique use of CSRR, renders it particularly suitable for applications in chemical and biomedical fields.

Co-excitations of diverse non-radiative scattering states in a single metasurface are promising for multifunctional nanophotonic devices. Anapole and bound state in the continuum (BIC) are two typical manifestations of nonradiation; however, it is challenging to simultaneously support them in a single metasurface. We propose and experimentally demonstrate all-dielectric Si-based dimer metasurfaces supporting magnetic anapole and quasi-BICs in the optical communication band. By exploiting inherent meta-atom resonator interactions and transforming dimer structures, we achieve dual-band high-Q resonances (one magnetic anapole and one quasi-BIC) and tri-band high-Q resonances (one magnetic anapole and two quasi-BICs) within a single metasurface. For the tri-band resonances, the measured Q-factors are 321.0 at 1508.5 nm, 313.4 at 1535.5 nm, and 287.1 at 1693.7 nm, respectively. Additionally, the magnetic anapole state always persists throughout the entire structural transformation processes, and the effect of structural parameter variation on its formation is investigated. Our work provides insights into the design of multifunctional metasurfaces supporting multiple non-radiative scattering states; it also could advance magnetic anapole applications associated with magnetic molecules or magneto-optic effects.

This study investigates a novel dual-band plasmonic refractive index (RI) sensor, to our knowledge, based on an air-silver metal-insulator-metal waveguide configuration, incorporating a circular cavity featuring a centrally embedded elliptical notch. The sensor design was modeled using COMSOL Multiphysics (version 6.2) and optimized through a two-dimensional finite element method analysis. The proposed sensor exhibits dual-band resonance behavior in the ranges of 800-1200nm and 1300-1900nm. It demonstrated remarkable sensitivities ranging from 1137 to 1970nm/RIU-1 for lead nitrate [Pb(NO3)2] detection and from 682 to 1136.4nm/RIU for thyroxine (T4) sensing, alongside a high figure of merit (FoM) reaching 76 and a quality factor (Q.factor) of approximately 83. The structure also achieved a maximum transmission of ∼88% and a narrow full-width at half-maximum of 24.8nm, underscoring its suitability for high-resolution detection.

This study investigates the electromagnetic performance of two carbon fiber monopole antennas integrated into a UAV copter frame, with emphasis on design adaptation, impedance matching, and propagation behavior. A comprehensive experimental campaign was conducted to characterize key parameters such as center frequency, bandwidth, gain, VSWR, and S11. Both antennas exhibited dual-band resonance at approximately 381 MHz and 1.19 GHz, each achieving a 500 MHz bandwidth where VSWR ≤ 2. The modified antenna achieved a minimum reflection coefficient of –14.6 dB and a VSWR of 1.95 at 381.45 MHz, closely aligning with theoretical predictions. Gain deviations between measured (0.15–0.19 dBi) and calculated (0.19 dBi) values remained within 0.04 dB, while received power fluctuations did not exceed 1.3 dB under standard test conditions despite the composite material’s finite conductivity. Free-space link-budget tests at 0.5 m and 2 m of separation revealed received-power deviations of 0.9 dB and 1.3 dB, respectively, corroborating the Friis model. Radiation pattern measurements in both azimuth and elevation planes confirmed good directional behavior, with minor side lobe variations, where Antenna A displayed variations between 270° and 330° in azimuth, while Antenna B remained more uniform. A 90° polarization mismatch led to a 15 dBm signal drop, and environmental obstructions caused losses of 9.4 dB, 12.6 dB, and 18.3 dB, respectively, demonstrating the system’s sensitivity to alignment and surroundings. Additionally, signal strength changes observed in a Two-Ray propagation setup validated the importance of ground reflection effects. Small-scale fading analysis at 5 m LOS indicated a Rician-distributed envelope with mean attenuation of 53.96 dB, σdB = 5.57 dB, and a two-sigma interval spanning 42.82 dB to 65.11 dB; the fitted K-factor confirmed the dominance of the LOS component. The findings confirm that carbon fiber UAV frames can serve as effective directional antenna supports, providing proper alignment and tuning. These results support the future integration of lightweight, structure-embedded antennas in UAV systems, with potential benefits in communication efficiency, stealth, and design simplification.

A triangle shaped microstrip patch antenna (TMPA) design is suggested for dual band resonance through multiple C designed slots on DGS structure. Further the frequency tunable TMPA is investigated through the reshaping of the C-shaped slot length by using two RF switches. Here the proposed TMPA with dimension of 0.47λ x 0.47λ x 0.01λ show the frequency tunability for two resonant frequencies at 3.84 and 1.91 GHz for S and L band. A prototype of TMPA design is fabricated and the measured results show good agreement with HFSS based simulations. The measured results of the TMPA show a gain of 2.3 dB at 3.84 GHz and 1.5 dB at 1.91 GHz resonant frequencies, respectively. The designed DGS based TMPA further shows the antenna high speed communication for 5G-NR (n77 band) (3.3–4.2 GHz) and GPS (L-Band) based applications as per FCC.

Organic core-shell heterostructures (CSHs) offer a unique platform for integrating complementary properties of the core and shell materials, leading to an optimized multifunctional performance. However, the growth mechanism within CSHs remains unclear due to the poor crystallographic compatibility between different components and fast crystallization. This study elucidates the detailed process for fabricating organic crystalline CSHs with tunable morphologies through an in situ epitaxial growth approach, by employing IDF-TCNB (CryDFNB) and IDT-TCNB (CryDTNB) charge-transfer cocrystals. After the lattice matching in three dimensions is satisfied, the shell CryDTNB epitaxially grows on the core CryDFNB surface along specific crystallographic orientations, with the growth sequence determined by differences in attachment energy. The unique bilayer structure of the CSHs results in distinct dual-emission optical properties, including differentiated polarization, dual-band quasi-whispering gallery mode resonance, and dual-band optical waveguides. This work provides a new framework for the design and synthesis of organic CSHs with controlled structures and advanced photonic functionalities.

Abstract This paper presents the design and performance evaluation of a novel implantable antenna for biomedical applications. Implantable antennas are used in biomedical devices for wireless communication, enabling applications like health monitoring, drug delivery, and bio-sensing within the human body. The proposed antenna structure features a compact configuration consisting of three rhombus-shaped resonators of varying sizes attached to a rectangular resonator. The antenna is ideal for implantation because of its small size (5 × 5 × 1.27 mm3), which adds up to a total volume of 31.75 mm3. Compatibility with essential wireless communication standards for medical applications is ensured by the antenna’s dual-band resonance at 2.42 GHz in the Industrial, Scientific, and Medical (ISM) band and 1.4 GHz in the Wireless Medical Telemetry Service (WMTS) band. A notable feature of the design is its high fractional bandwidth of 18.29%, which is superior compared to similar implantable antennas. Additionally, the Specific Absorption Rate (SAR) is substantially within the IEEE safety standards’ permissible bounds, guaranteeing safe operation close to human flesh. A promising option for next-generation biomedical devices, this small, dual-frequency, wideband antenna allows for dependable and effective wireless communication for implanted applications.

This paper introduces the design and exploration of a compact, high-performance multiple-input multiple-output (MIMO) antenna for 6G applications operating in the terahertz (THz) frequency range. Leveraging a meta learner-based stacked generalization ensemble strategy, this study integrates classical machine learning techniques with an optimized multi-feature stacked ensemble to predict antenna properties with greater accuracy. Specifically, a neural network is applied as a base learner for predicting antenna parameters, resulting in increased predictive performance, achieving R², EVS, MSE, RMSE, and MAE values of 0.96, 0.998, 0.00842, 0.00453, and 0.00999, respectively. Utilizing regression-based machine learning, antenna parameters are optimized to attain dual-band resonance with bandwidths of 3.34 THz and 1 THz across two bands, ensuring robust data throughput and communication stability. The antenna, designed with dimensions of 70 × 280 μm², demonstrates a maximum gain of 15.82 dB, excellent isolation exceeding − 32.9 dB, and remarkable efficiency of 99.8%, underscoring its suitability for high-density, high-speed 6G environments. The design methodology integrates CST simulations and an RLC equivalent circuit model, substantiated by ADS simulations, with comparable reflection coefficients validating the accuracy of the models. With its compact footprint, broad bandwidth, and optimized isolation and efficiency, the proposed MIMO antenna is positioned as an ideal candidate for future 6G communication applications.

Due to the critical importance of carbon neutrality for the survival of humanity, passive thermal management, which manages thermal energy without additional energy consumption, has become increasingly attractive. Camouflage materials offer a promising solution for passive thermal management, as they can dissipate heat through thermal radiation, reducing the need for energy-intensive cooling systems. However, developing effective infrared (IR) camouflage solutions for low-temperature environments and small-sized applications remains a challenge because the low temperatures limit the ability to dissipate radiative energy from the surface. Moreover, conventional IR camouflage materials, typically optimized for single band (5-8 μm), face significant limitations in energy dissipation at lower temperatures, which requires a novel way to increase the energy dissipation without the additional energy consumption. Herein, we present a novel low-temperature IR camouflage material (LICM) designed to address these challenges by employing dual-band resonances in the nondetection bands, 5-8 and 14-20 μm based on the atmospheric transmittance. LICM demonstrated an increase in energy dissipation of 273 and 167% at 250 and 350 K, respectively than the conventional IR camouflage materials. Despite the enhanced dissipation, the LICM maintained an IR signature reduction of around 10% of blackbody radiation, ensuring effective IR camouflage. Thermographic measurements using an LWIR camera (7.5-14 μm) further demonstrated the LICM's superior IR camouflage performance. This dual-band resonance design not only extends IR camouflage to low-temperature environments but also facilitates significant energy savings, making it a key ingredient for broad-scale deployment in areas such as energy conversion, aerospace, and sustainable thermal management technologies.

The design and characterisation of a novel dual-band implantable antenna with compact size is presented in this research. The antenna, which is in size and operates at two critical frequencies—0.954 GHz in the UHF band and 2.4 GHz in the ISM band—was fabricated on an RT6010 substrate. The U-shaped slot and shorting pin on the radiating element have been exploited to achieved dual-band and circular polarization. The antenna is noteworthy for achieving circular polarization with a broad axial ratio bandwidth of 24.6%, which enables strong performance throughout its operating frequencies. The proposed antennas SAR values satisfy IEEE safety standards for implantable medical devices with a gain of − 28.1 dB at 2.4 GHz and − 31.2 dB at 0.954 GHz, despite its small size. The design represents a significant advancement in the field of medical implant technology since it prioritizes effective wireless communication capabilities while upholding strict safety regulations.

Dual-Band Dual-Polarized Glass Dielectric Resonator Antenna with Wide Bandwidths and Low Sidelobes

Abstract Motivated by the imperative demand for chirality manipulation within mid-infrared (mid-IR) range, this study presents an innovative solution to obtain selective perfect absorption and chiroptical responses with conventional Otto configuration. Optical responses of the structure have been calculated numerically by the 4 × 4 anisotropic transfer matrix method. The results show that the proposal supports the chiral response with dual-band resonance in absorption spectra by displaying different properties for left-hand circular polarization (LCP) and right-hand circular polarization (RCP) light, its circular dichroism (CD) and working wavelength could be tuned by adjusting the layer thickness and incidence angle. It is demonstrated that the proposed device exhibits an extraordinary absorption efficiency of unity for RCP light and zero for LCP light at a wavelength of 9.32 μm, accompanied by a maximum CD in absorption of −1. The strategy in manipulating dual-band selective chiroptical responses holds great potential in realizing mid-IR devices capable of chirality manipulation.

ABSTRACT A novel method is proposed to achieve a low-profile miniaturized dual-band dielectric resonator antenna (DRA) for wireless communication applications. The cylindrical dielectric resonator (DR) is fed by a microstrip loop on the top surface of the substrate and a mountain shaped ground on the bottom surface of the substrate. This structure not only effectively transfers energy to the DR but also plays a pivotal role in establishing a lower resonance frequency of 1.73 GHz, achieving this with a compact structure (0.21λ 0 × 0.18λ 0 × 0.02λ 0, and λ 0 is the free-space wavelength at 1.73 GHz). HEM11δ mode of the cylindrical DR is employed to cover the upper frequency band of 2.8 GHz. Ultimately, the effectiveness of our suggested approach and the antenna’s performance are confirmed through the measurement.

This paper presents a novel filter-based analysis for the conventional rectangular patch antenna (RPA) using the Composite Right/Left-Handed Transmission Line (CRLH-TL) theory. We introduce two circuit models for RPA, described by lumped components and transmission line (TL) elements. An RPA is considered a Symmetric CRLH-TL (SCRLH-TL). We validated the analysis by comparing the circuit model and full-wave analysis simulation results. The TL circuit model error in the full-wave analysis was less than 5%. A dual-band Zeroth-Order Resonant (ZOR) antenna is designed and manufactured based on the introduced Lumped element circuit model, which exhibits filtering characteristics in both bands. We obtain the antenna circuit model by incorporating the RPA lump circuit model with LC resonators. We implemented the antenna structure by combining the RPA and complementary split-ring resonators (CSRR) modeled by the LC resonators. We initialized the antenna center frequency bands for WiMAX 2.45 GHz and 3.60 GHz. The CSRRs control the configuration of the center frequencies. The simulation and measured results are in good agreement. The proposed antenna dimensions are 0.66×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}0.66×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}0.012 λg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda _g$$\\end{document} at 2.45 GHz (43.22×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}43.22×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}0.81 mm3). The measured gains are 3.47 dB and 4.64 dB for 2.45 GHz and 3.60 GHz, respectively. Two radiation nulls were observed at 2.09 GHz and 2.98 GHz for the 2.45 GHz band and one radiation null at 3.45 GHz for the 3.60 GHz band. Also, the fractional bandwidth is 4.03% and 1.39%, respectively. The radiation pattern is nearly omnidirectional. The simulated efficiency is 90% for 2.45 GHz and 87% for 3.60 GHz frequency bands.

A dual-band frequency reconfigurable cylindrical dielectric resonator antenna (DRA) for 5G New Radio (NR) application within a Sub-6 GHz is presented in the proposed work. In this work, nine n7, n30, n38, n40, n41, n46, n47, n53 and n79 5G NR bands are presented. A novel approach for 5G NR bands has been presented to provide dual-band capabilities and frequency reconfigurability with machine learning (ML). We achieve this reconfigurability by using two PIN diode switches that operate in various configurations, allowing for a maximum wide tuning range of 80.19%. In cylindrical DRA HEM 11δ and HEM 12δ modes are responsible for dual-band operation. The K-nearest neighbor (KNN) ML technique achieves an accuracy of more than 98%, as compared to artificial neural network (ANN), random forest (RF), extreme gradient boosting (XGB), and decision tree (DT) across all configurations for the S 11 prediction. Frequency reconfigurable antenna (FRA) is a concept that has grown to allow dynamic changes in operating frequencies without structural alterations to the antenna. These antennas can change their working frequencies to support multiple frequency bands at once or adapt to changing system needs. An FRA is essential for the next generation of wireless communication devices because many technologies such as Wi-Fi, Internet of Things (IoT), Bluetooth, and cellular communication are combined in the 5G Sub-6 GHz frequency spectrum. The FRA creates an efficient spectrum, which enables many frequency bands to be covered by a single antenna. Inside the 5G frequency range, they are helpful for wireless communication because they provide B Pinku Ranjan