Mid-infrared metamaterial absorbers have many applications in the field of infrared detection, infrared thermal energy utilization, radiation refrigeration, invisible camouflage, etc. In this study, we designed an ultra-broadband mid-infrared metamaterial absorber based on multi-sized resonators. The structure of the absorber consisted of a gold substrate and nine resonators. The simulated results showed that the absorptivity of the absorber was higher than 90% in the 8.33–15.09 μm waveband with an average absorptivity of 95.17%. The energy distributions of the electric and magnetic fields were introduced to investigate the physics of broadband absorption. Moreover, we combined the multi-layer structure with the plane random arrangement structure to achieve a balance between thickness and width. Our study further illustrates the potential application of multi-sized resonators in metamaterial absorbers to realize high absorptivity and ultra-broadband to improve the performance of devices applied in infrared detection, radiation refrigeration, and other fields.

This paper presents a novel Spiral Slot Planar Inverted-F Antenna (SSPIFA) specifically designed for telemedicine and healthcare applications, featuring compact size, biocompatible safety, and high integration suitability. By replacing the conventional top metal patch of a Planar Inverted-F Antenna (PIFA) with a slot spiral radiator whose geometry is precisely matched to the ground plane, the proposed antenna achieves a significant size reduction, making it ideal for encapsulation in miniaturized medical devices—a critical requirement for implantation scenarios. Tailored for the ISM 915 MHz band, the antenna is fabricated with a four-turn slot spiral etched on a 30 mm-diameter dielectric substrate, achieving an overall height of 22 mm and an electrically small profile of approximately 0.09λ × 0.06λ (λ: free-space wavelength at the center frequency). Simulation and measurement results demonstrate a −16 dB impedance matching (S11 parameter) at the target frequency, accompanied by a narrow fractional bandwidth of 1% and stable right-hand circular polarization (RHCP). When implanted in a layered biological tissue model (skin, fat, muscle), the antenna exhibits a near-omni directional radiation pattern in the azimuthal plane, with a peak gain of 2.94 dBi and consistent performance across the target band. These characteristics highlight the SSPIFA’s potential for reliable wireless communication in implantable medical systems, balancing miniaturization, radiation efficiency, and biocompatible design.

The manipulation of electromagnetic waves using metasurfaces is important in areas such as stealth and communication. In this paper, we reported on the use of an element-based polarizer for the first step, which enables the incident electromagnetic waves to integrate into the cross-polarized waves with a relative bandwidth of 88% within 15–37.1 GHz. Then, an eight-element coding metasurface based on the Pancharatnam–Berry phase is presented for circular polarization anomalous reflection. The simulated values show that our work can achieve a high-efficiency (94%) and wide-angle (70°) anomalous reflection under normal incidence. The simulated values present good agreement with the experimental values. Our work reveals the ability to manipulate the waves and electromagnetic stealth.

This study presents a planar helical electromagnetic bandgap (EBG) structure designed for integration with an equiangular spiral antenna operating at 2.5 GHz. An equivalent-circuit model is introduced, and the effects of the unit-cell width, substrate thickness, metallic-strip width, and interstrip gap on the electromagnetic response are investigated through full-wave parametric simulations. The optimized periodic structure is subsequently employed as a backing reflector for the spiral antenna and is compared with both an unbacked configuration and a perfect electric conductor (PEC) reflector. At 2.5 GHz, the EBG-backed antenna achieves a simulated gain of approximately 6.15 dBi, compared with 2.58 dBi for the unbacked antenna, while producing an axial-ratio response that is less strongly disturbed over the investigated frequency range than that of the PEC-backed configuration. The mean axial-ratio value over the investigated band is reduced from 2.22 for the PEC-backed case to 1.67 for the EBG-backed case. The results demonstrate that the proposed helical EBG structure provides a compact approach for controlling the radiation characteristics of spiral antennas in S-band electromagnetic and wireless systems.

Accurate pavement-distress detection in unmanned aerial vehicle (UAV) imagery remains challenging because defects exhibit weak texture, irregular geometry, scale variation, and visual similarity to markings, shadows, water, and repaired pavement. This study presents YOLO-MCG, an engineering adaptation of YOLOv10 that integrates an adapted Context-Guided (CG) feature-fusion block and Multi-Scale Dilated Attention (MSDA) at the stride-8 P3 node, with fixed summation fusion. A direct audit of UAV-PDD2023 identified 11,158 boxes in 2440 images, including 44.8% small targets. Under the primary parent–frame–disjoint split, YOLO-MCG achieved precision 0.781, recall 0.503, mAP@0.5 0.562, and mAP@0.5:0.95 0.308. Across three independent parent–frame–disjoint splits, the corresponding mean metrics were $0.783\pm 0.010$, $0.505\pm 0.011$, $0.564\pm 0.004$, and $0.309\pm 0.006$, respectively. The mAP@0.5 improvement over YOLOv10n was statistically significant ($p<0.01$). Small-object AP@0.5 was $0.433\pm 0.015$, compared with $0.643\pm 0.008$ for large objects, while the mean AP of the rare repair and pothole classes was $0.535\pm 0.016$. Direct-transfer mAP@0.5 on the India, Japan, and Czech subsets of RDD2022 was $0.418\pm 0.015$, $0.392\pm 0.018$, and $0.374\pm 0.020$, respectively. A same-site, multi-condition pilot covering three altitudes and two pavement types obtained recall ranging from 0.43 to 0.52. Given the current limits of split-level resampling, multi-site validation, and survey-grade geolocation, the evidence supports human-in-the-loop screening rather than autonomous or survey-grade inspection.

Microwave resonance sensors are promising for dielectric characterization and biochemical detection. However, their sensing performance is constrained by the relatively long wavelength at microwave frequencies and the limited electromagnetic interaction with small-volume samples. In this paper, an exceptional-point (EP)-enhanced chiral spoof localized surface plasmon (SLSP) resonator is proposed for high sensitivity microwave biosensing with sub-microliter sample volumes. By rotating the chiral resonator relative to the microstrip feeding line, two EPs are obtained at α = 49° and α = 210°. The simulated results show that the EP states generate larger frequency splitting than the reference state under both dielectric-constant variation and detection-limit evaluation, confirming the squareroot response to weak perturbations. Experiments further validate the sensing performance using low-loss dielectric materials and high-loss glucose solutions. For dielectric samples with relative permittivities from 2 to 6.15, the frequency splitting increases from 0.287 GHz to 0.359 GHz. For glucose solutions, the frequency splitting decreases from 1.506 GHz to 1.372 GHz as the glucose amount increases from 2.78 nmol to 27.8 nmol. The proposed sensor requires only about 0.5 μL of sample volume and shows higher sensitivity than reported microwave glucose sensors. These results demonstrate that the EP-enhanced chiral SLSP resonator provides a compact and sensitive platform for trace-volume biochemical detection and integrated microwave biosensing.