Search Results (393)

Conventional antenna designs generally have fixed configurations and are difficult to assemble rapidly and flexibly. To address this limitation, this paper proposes a magnetic antenna building block that enables the rapid assembly of functional antennas. Based on this building block design, a kind of reconfigurable frequency scanning leaky wave antenna is implemented. The antenna module consists of the RF structure, dielectric housing, and embedded magnets. Magnets align and attach adjacent modules, while RF signals are transmitted through non-contact capacitive coupling interfaces and radiated by the RF structures on individual modules. The Port module, low-radiation module L, and high-radiation module H are designed. A variable number of cascaded modules can be rapidly cascaded through magnetic attachment to form different antenna arrays. The H module incorporates a pair of symmetric circular patches connected in parallel and exhibits stronger radiation characteristics than the L module, which does not include this parallel structure. Simulation and measurement results showed that the antenna arrays achieved effective port impedance matching in the C-band for cascades of the same type of modules and several mixed cascades of different types of modules. Far-field measurements also showed that arrays with different module combinations produced distinct far-field radiation patterns and allowed adjustment of the main beam gain and direction over 6.30–6.90 GHz. The main beam direction varied over a range of approximately 30°, and continuously covered the region around normal direction. The beamwidth varied with module types and the number of cascaded modules. The 3 dB beamwidth decreased from 48° to 21°, and the highest peak gain reached 6.98 dBi. The proposed magnetic antenna building block supports module cascading, combinations of different module types, and frequency scanning, providing a low-cost and flexible implementation of reconfigurable antenna arrays for communication and sensing applications. Full article

This paper presents a feature-level defective pixel cluster (DPC) correction method specifically designed for dual-band infrared detectors. Due to inherent manufacturing limitations, antimonide-based type-II superlattice (T2SL) focal plane arrays (FPAs) commonly suffer from DPC issues. Existing DPC correction methods often fail to preserve dual-band imaging characteristics, leading to texture distortion and incomplete structure recovery. Inspired by infrared imaging mechanisms and image inpainting theory, we propose PRISM, a patch-based reconstruction framework that leverages inter-band structure migration with hierarchical feature decomposition, decoupling dual-band images into micro-textures, edge gradients, and spatial relationships. Leveraging this multi-level feature representation, we extract prior information to guide DPC correction. The correction process is formulated as a “structure-to-pixel” optimization problem, where an improved feature-guided patch search strategy effectively combines structure completion with texture reconstruction. Experimental results demonstrate that the proposed method not only recovers image content effectively but also faithfully preserves band-specific imaging characteristics. Furthermore, to facilitate quantitative evaluation, we construct a benchmark dataset containing simulated DPCs with corresponding ground truth. Comparative experiments on both our self-constructed dataset and public multimodal benchmarks confirm that PRISM achieves higher PSNR, SSIM, VIF, and CC metrics than state-of-the-art multimodal inpainting methods. Full article

The accurate evaluation of gastrointestinal (GI) diseases such as celiac disease (CeD) relies on the assessment of villous architecture, yet progress in imaging-based diagnostics, particularly video capsule endoscopy (VCE), is constrained by the absence of anatomically realistic and reproducible physical models of the intestinal mucosa. Existing benchtop phantoms typically reproduce gross luminal curvature but fail to capture the sub-millimeter villous microstructure, the optical scattering behavior, and the luminal folding of native mucosa that together shape its endoscopic appearance. We developed a modular fabrication framework for an anatomically realistic small intestinal phantom with controlled villous microstructure. High-resolution drop-on-demand photopolymer material jetting was used to print discrete patches of villous-like micropillar arrays with tunable height, diameter, and spacing parameterized from histological data spanning Marsh 0 to 3c classifications. The printed patches were then dyed for mucosal-color realism, bonded onto a polyester–spandex substrate, rolled into a continuous tube, and shaped with adjustable retainer rings to introduce luminal folds. Optical microscopy confirmed dimensional fidelity within ±10% of design values with patch-to-patch variation below 7%, and VCE imaging of healthy and atrophic configurations achieved structural similarity (SSIM) values of 0.625 and 0.761 against clinical mucosal imagery. This reproducible platform supports VCE device validation, imaging dataset generation, and clinician training in gastrointestinal imaging. Full article

Conventional oral and injectable drug administration still struggles with unstable plasma levels, weak targeting, and considerable systemic toxicity, problems that become especially acute in chronic disease management. Implantable and wearable biomedical devices offer one path around these limits, yet device-only platforms continue to fall short on drug loading, release control, and protection of fragile therapeutics. Integrating nanoparticle-based biomaterials into such devices has therefore moved from a research curiosity to a serious clinical strategy. As a result, understanding the design principles, translational challenges, and clinical potential of these hybrid platforms has become increasingly important. This review provides a comprehensive assessment of four major nanoparticle families—polymeric carriers (PLGA, chitosan, and micelles), lipid-based vehicles (liposomes, SLNs, and NLCs), inorganic systems (gold, mesoporous silica, iron oxide, and calcium phosphate), and hybrid composites—focusing on how their physicochemical properties govern drug encapsulation, release behavior, and tissue compatibility. These classes are then linked to specific implantable formats such as drug-eluting stents, nano-enabled scaffolds, and reservoir depots, and to wearable formats including transdermal patches, microneedle arrays, biosensor-coupled patches, and patient-actuated devices. A dedicated section addresses stimuli-responsive release driven by pH, enzymes, temperature, and electrical or magnetic fields, alongside closed-loop platforms that pair real-time biosensing with on-demand dosing. Surface engineering strategies, ligand targeting, antifouling coatings, antimicrobial layers, and immune-modulating chemistries are also discussed, together with the central translational hurdles: long-term stability, foreign body response, scale-up, sterilization, and regulatory classification of combination products. Finally, the review outlines near-term directions, including AI-driven dosing, 4D bioprinting, biomimetic nanocarriers, gene therapy delivery, and bioresorbable electronics, that together suggest where these hybrid platforms are likely to mature next. Full article

Background: Dermal interstitial fluid (ISF) contains both plasma-derived biomarkers and biomarkers unique to ISF, making it a promising biofluid for painless, scalable, and decentralized liquid biopsy and continuous health monitoring. However, efficient ISF collection remains challenging due to the small accessible fluid volume in the dermis, slow physiological turnover, and stratum corneum. Methods: This review reframes dermal ISF sampling as a pressure gradient engineering problem using Darcy’s law. We examine how vacuum-assisted microneedle platforms can effectively drive ISF through the dermal extracellular matrix in a minimally invasive manner. We compare the two architectures: micropore-based and hollow microneedle approaches. Results: In the micropore approach, a vacuum chamber is placed over the transient micropores left by withdrawn microneedles, supporting off-device, multi-omic downstream analyses of the collected ISF. The hollow microneedle approach retains the microneedles in the skin and applies vacuum through internal lumens, allowing integration of the vacuum source, microneedles, and biosensors into a single wearable platform for in situ biomarker detection. Comparative studies across these architectures identify the vacuum seal between the device and the skin as the major engineering bottleneck shared by both architectures. Conclusions: Vacuum-assisted microneedle platforms provide a practical route for generating pressure gradient-driven ISF transport while preserving minimally invasive skin access. Future development should prioritize device–skin vacuum seal robustness, reproducible ISF recovery across users and skin sites, integrated vacuum sources, scalable fabrication, and usability in clinical or at-home settings. Full article

This paper presents a compact dual-band reconfigurable MIMO antenna array for frequency-agile, high-isolation operation in densely integrated wireless systems. Each element employs an air-gap-suspended patch fed by an L-shaped probe, with two sets of varactor diodes placed at different current-concentration regions to enable approximately independent continuous tuning of the low band (1.27–1.7 GHz) and the high band (2.21–2.55 GHz). Surface-current analysis shows that the low band is dominated by the fundamental patch mode, whereas the high band is excited by the U-shaped slot edge resonance; the spatial separation of the two modes supports their quasi-independent control. At the array level, U-shaped defected ground structures (DGS) are etched between adjacent elements to modify the coupling current paths and enhance inter-element isolation in both operating bands, without degrading impedance matching. Parametric studies confirm that the DGS consistently improves isolation across all tuning states. Simulation results show low envelope correlation coefficient (ECC), high diversity gain (DG), and stable radiation characteristics throughout the entire tuning range. The proposed design combines a compact structure, approximately independent dual-band continuous tuning, and stable isolation performance, offering a promising solution for space-constrained next-generation wireless communication systems. Full article

In the context of pavement management, conventional data collection methods for the evaluation of pavement functional condition are limited by relatively slow acquisition speeds, that prevent fast-lane motorway surveying at 120–130 km/h, and by survey frequency, which on vast networks typically occurs twice a year. Given these limitations, continuous pavement condition monitoring from moving vehicles offers an attractive solution to move towards real-time digital road assessment. In particular, such a result is achieved by making use of “intelligent” or “smart” tires, which by means of appropriate arrays of sensors can capture contact patch information, thereby providing quantitative information related to pavement roughness and macrotexture. In this study, smart tire data functional condition indicators, Dynamic Index (DI) and Pr index, were collected over several segments of a motorway network, with a total length of 405 km. Correlations were investigated between such parameters and the results of measurements coming from a traditional pavement monitoring technique, expressed in terms of international roughness index (IRI) and mean profile depth (MPD). Furthermore, the ability of smart tire indicators to identify time-dependent trends and to rank different motorway segments was assessed. Obtained results, which were generated by adopting different data processing and homogenization techniques, showed that DI displays a moderate correlation with IRI, while Pr exhibits a strong correlation with MPD. Pavement-age analysis highlighted the existence of meaningful trends for both dense-graded and open-graded asphalt-wearing courses. Motorway rankings based on average DI and Pr values were found to be in agreement with those obtained from average IRI and MPD values, thereby confirming the potential of smart tire technology as a complementary network-level monitoring tool for pavement asset management systems. Full article

In this manuscript, a graphene-based four-port linear MIMO antenna is proposed for terahertz (THz) applications. The antenna is designed on a polyimide substrate with a compact footprint of 60 µm × 240 µm × 4 µm. A modified triangular patch with a tip-fed configuration is employed to enhance asymmetric current distribution, enabling dual-band operation at 2.88 THz and 4.36 THz. A parametric analysis is carried out by varying the chemical potential and relaxation time of graphene to optimize the antenna performance in terms of S-parameters. The proposed design achieves an inter-element isolation > 20 dB, with a realized gain exceeding 3.28 dBi and radiation efficiency above 65% across both operating bands. Furthermore, key MIMO diversity parameters are evaluated, demonstrating an envelope correlation coefficient (ECC) ≤ 0.008 and channel capacity loss (CCL) ≤ 0.27 bits/s/Hz over the entire operating range. The total active reflection coefficient (TARC) remains stable under varying excitation phase conditions, indicating minimal mutual coupling between adjacent ports. An equivalent circuit model is also developed to validate the simulated results. The antenna is analyzed using CST Microwave Studio, and the obtained results confirm its suitability for emerging THz wireless applications. Full article

A low-profile, low radar cross-section (RCS) omnidirectional metasurface antenna is investigated and proposed in this letter. The antenna consists of a top circular patch, a three-layer dielectric substrate, a full metal ground, a multi-layer polarization conversion metasurface, and four short vias for connecting the top patch to the ground. Wideband impedance matching is achieved by modifying an F-shaped feeding structure. The broadband RCS reduction is realized by loading the antenna with the polarization conversion metasurface (PCM) in an appropriate array configuration. The antenna prototype has been fabricated and measured in an anechoic chamber. Experimental results illuminated that the antenna features a low profile of 0.051λ₀ (λ₀ is the wavelength at 2.35 GHz) and a 10 dB impedance bandwidth of 2.11–2.62 GHz (a fractional bandwidth of 21.56%). Significantly broadband RCS reduction is achieved from 7.05 to 16.96 GHz, with a maximum reduction of –28 dB and an average reduction of –12.51 dB. Full article

In this paper, a high-gain wideband filtering antenna with metasurface structures is presented for Sub-6 GHz 5G applications. The proposed antenna consists of a 3 × 3 metasurface array, a driven patch, a short-circuited stepped impedance resonator (SIR) feedline, and two parasitic patches. The metasurface is used to manipulate the modal behavior of the radiator and to introduce an additional resonant mode for bandwidth enhancement. Meanwhile, two radiation nulls are generated by different mechanisms to realize filtering performance. The low-frequency radiation null at 2.81 GHz is introduced by the short-circuited SIR feedline, whereas the high-frequency radiation null at 5.76 GHz is produced by radiation cancelation among the driven patch, parasitic patches, and metasurface. The measured results show a 10 dB impedance bandwidth of 35.5% from 3.62 to 5.18 GHz and an average realized gain of 8.61 dBi. In addition, the proposed antenna achieves lower- and upper-band selectivity of 42.57 dB/GHz and 33.43 dB/GHz, respectively. The proposed antenna also achieves a compact radiation aperture of 0.60 × 0.60 λ₀² and effective out-of-band radiation suppression, making it a promising candidate for integrated 5G RF front-ends. Full article

This paper presents a flexible conformal beam-scanning leaky-wave antenna (LWA) array based on a PI-ABS composite substrate and spoof surface plasmon polariton (SSPP) structure for Ku-band (12–18 GHz) applications. The proposed design features periodically symmetric gradient linear metallic stubs and interleaved tapered radiating patches to realize efficient SSPP slow-wave transmission, −1st spatial harmonic radiation, and open-stopband (OSB) suppression simultaneously. Benefiting from the flexible PI-ABS composite structure, the antenna maintains stable radiation performance under different curvatures, overcoming the mechanical instability and beam-scanning sensitivity of conventional flexible LWAs. The four-element conformal array achieves continuous beam scanning from −67° to 32° with a peak gain of 16.5 dBi and radiation efficiency above 58% across the entire band. Both simulation and measurement results validate that the proposed design integrates flexible conformality, wideband beam scanning, and high radiation efficiency, providing a novel solution for conformal wireless communication systems. Full article

A single-band-notched ultra-wideband (UWB) low-sidelobe planar array antenna for millimeter-wave (mmWave) applications is presented. The antenna element employs a planar dipole excited through an H-shaped coupling slot to achieve broadband impedance matching, while a centrally loaded parasitic patch acts as a half-wavelength resonator to generate a controllable notch band. Additional parasitic patches are introduced to recover the high-frequency matching without degrading the notch response. An $8\times 8$ array is then developed using a Taylor-weighted feed network implemented with three classes of 1-to-4 microstrip power dividers. Measured results show that the array operates from 19.0 to 45.0 GHz with $\mathrm{VSWR}<2$, while providing a rejection band from 35.0 to 38.5 GHz. The notch suppresses the realized gain by about 5 dB around 37.0 GHz, the peak gain reaches 20.5 dBi in the passband, and average sidelobe levels better than $-17$ dB are obtained. The proposed design provides a practical approach for combining ultra-wide bandwidth, in-band interference rejection, and low-sidelobe radiation in a compact mmWave planar array. Full article

This paper presents a systematic qualification process for an electronic beam-steering antenna assembly for a low-Earth orbit (LEO) communication satellite. The transmitting/receiving antenna for the LEO communication satellite is based on a cavity-backed slot radiator, which has improved radiation efficiency and low mutual coupling compared to conventional PCB patch structures. In order to verify the electrical performance and reliability of the manual soldering process in a tightly spaced array structure with narrow element spacing and densely connected multi-channel RF modules, a reduced model was designed and fabricated and qualification tests were conducted under launch and on-orbit environments. The integration equipment was developed to ensure precise mechanical alignment and integration/disassembly between the radiating element arrays of the transmitting and receiving antenna modules and the RF modules, thereby establishing a manufacturability strategy for the antenna module and RF integrated module, which comprise a large array structure. Finally, the qualification tests of the transmitting and receiving antenna were performed to evaluate the structural and thermal stability considering the launch and orbital environments. The systematic qualification process proposed in this paper can be used in the development of the antenna system of the communication satellite. Full article

Reliable and fast radiation pattern prediction is critical for large-scale tightly coupled linear antenna arrays. Strong mutual coupling and finite-array edge effects limit the accuracy of conventional array factor methods, while full-wave simulations become computationally prohibitive for large arrays. To address this issue, a fast and efficient radiation pattern prediction method (FERPP) is proposed. For central elements, the far-field response is obtained from a calibrated reference array and extended through position-dependent phase compensation. For edge elements, responses are extracted from independent local full-wave simulations. All element responses are assembled into a global far-field response matrix, enabling direct radiation pattern synthesis using the extended method of maximum power transmission efficiency. Simulation results obtained with a 1024-element linear microstrip patch antenna array operating at 3.5 GHz, with small inter-element spacing, demonstrate close agreement with full-wave simulations. For a broadside single-beam case, the predicted peak gain is 29.10 dBi, compared with 29.02 dBi from full-wave simulation. For a scanned beam at 30°, the predicted peak gain is 28.22 dBi, while the full-wave result is 28.99 dBi. For an equal-weight three-beam configuration at −30°, 0°, and 30°, the proposed method yields a peak gain of 23.87 dBi, compared with 24.21 dBi from full-wave simulation. In terms of computational efficiency, the proposed method requires only about 1.8% of the computational time required for a full-wave simulation. These results demonstrate that the proposed FERPP method provides a practical and efficient solution for radiation pattern prediction and beamforming analysis of large-scale tightly coupled linear antenna arrays. Full article

This paper proposes a non-overlapping planar cross-arranged ultra-wideband shared-aperture base station antenna array targeting the 2 to 6 GHz application bandwidth. The low-frequency module (double-layer parasitic coupling) and the high-frequency module (chamfered slotted patch) are independently designed, and metal baffles are introduced around the antenna elements to reshape the boundary conditions and physically block the electromagnetic coupling paths. Both simulation and experimental results demonstrate that the fabricated prototype successfully exceeds the targeted 2–6 GHz spectrum, achieving an actual continuous coverage from 1.84 to 6.3 GHz. Specifically, the antenna achieves a gain higher than 5.9 dBi in the measured low-frequency band (1.84–3.72 GHz) and higher than 6.1 dBi in the high-frequency band (3.63–6.3 GHz), with a voltage standing wave ratio (VSWR) below 2 across the entire band. The metal baffles successfully correct the high-frequency radiation pattern distortion and ensure stable directional radiation over the full operating bandwidth. This design provides an efficient, robust, and manufacturable solution for 5G offshore wind power multi-band base station antennas. Full article