This study investigated the thermal dynamics of conductive metal meshes under electromagnetic exposure to determine the correlation between the temperature rise observed in conductive metal meshes exposed to incident plane waves and the geometric configuration of the unit structure of the mesh. Multiphysics analysis conducted in this study demonstrated that a metal mesh characterized by narrow wire widths and short edges effectively mitigated the maximum temperature rise observed across the metal mesh despite maintaining equivalent sheet resistance. Furthermore, the results revealed that a metal mesh configured with regular hexagons could reduce the temperature rise by 3.7% and 2.2% compared with metal meshes composed of regular triangles and squares, respectively, and simultaneously maintained the sheet resistance and shielding effectiveness. The results of this study highlighted the significance of the unit structure shape in enhancing the thermal performance of conductive metal meshes and proposed a novel methodology for optimizing electromagnetic shielding structures.

In this paper, we report the results of reflection imaging of silicon wafers using terahertz waves, aiming to achieve both high resolution and transparency in sensing technology. We compare the theoretical calculations of the transmittance of silicon wafers with the experimental results obtained through imaging. Through this study, we were able to confirm the frequency characteristics of silicon wafers using terahertz reflection imaging.

In recent years, crime clearance rates have remained low. To improve them, current methods have used deep learning and crowdsourcing to automatically detect crimes. However, these methods suffer from false positives and false negatives and also fail to achieve high accuracy (AUC, correct answer rate). This paper proposes a method that supports the judgments of crowdworkers by providing them with anomaly-score output from deep learning models. The proposed method enhance the number of correct judgments made by crowdworkers. As a result, false positive and false negative rates are reduced and accuracy is improved.

This paper presents a metasurface-loaded X-band dual-polarized deployable mesh reflector antenna with a high gain of 48dBi and a low side-lobe level (SLL) of -32dB. The proposed unit used to comprise the metasurface features structurally symmetric, angle-insensitive, and a smooth phase gradient. The architecture of the metasurface-loaded mesh reflector antenna is investigated in detail. A prototype experiment to demonstrate the focusing capability of such proposed metasurfaces is conducted. The simulation and measurement results are in good agreement and indicate this type of the proposed planar metasurface can effectively enhance the gain and suppress the SLL of the mesh reflector antenna. It is believed that the designed metasurface unit, as well as the metasurfaces formed by such units, has potential in the applications of large antennas for Low-Earth-Orbit (LEO) satellites.

This study answers the basic question of whether a simple lumped-constant (LC) resonator works for harmonic reactions in diode rectifiers. To explore how the LC resonator generally reacts to harmonic waves, we present three typical diode rectifier topologies: double-voltage, double-current, and full-bridge. Through an algebraic circuit analysis of the diode’s time-domain switching operation, we find that the second- and higher-order harmonic waves generated by the diodes are fully reflected by the LC resonator, return to the diodes, and are recycled for effective dc power generation. This outcome offers a simpler alternative solution for high-efficiency RF rectification than usual class-E and -F implementation.

This letter proposes a visible light indoor position tracker employing a newly developed Angle of Arrival (AOA) with Multiple Input Multiple Output (MIMO) channel model algorithm. The position tracker utilizes indoor illumination lights and a photodiode (PD) array. An adaptive digital spatial filter attached to the output of the PD array performs MIMO signal processing and decomposes the light signals received from different illumination light sources that are simultaneously input to the PD array. The position tracker then estimates the angle of arrival of each light signal and finally its position. This letter demonstrates a position tracker with an adaptive digital filter tunning the Least Mean Square (LMS) algorithm and evaluates its positioning error performance. Experiments show excellent performance as the positioning errors were as low as 0.05m in an indoor environment with dimensions of 1.75×2×2m.

Recently, Intelligent Reflecting Surface (IRS), which controls the direction of reflected waves in a desired direction, has been investigated to improve the wireless environment. This paper presents outdoor measurements using a prototype IRS that controls the direction of ±45° reflection by switching the incident polarization. The received power in each reflection direction was improved by more than 20dB by placing the IRS, and the results using the IRS agreed well with the radar equation, indicating the effect of the IRS.

With the arrival of the IoT era, the problem of interference has become even more serious, and the challenge is to establish techniques for separating and demodulating collide signals. To achieve this, we are conducting research on stored data batch signal processing technology using short-time Fourier transform (STFT). In this paper, we used a feature quantity demodulation method proposed as a method for stored data batch signal processing to evaluate the effect of IQ imbalance, which is a factor in signal degradation in the transmitter, on signal separation and demodulation performance. Furthermore, we proposed a receiver configuration that estimates the amount of degradation due to IQ imbalance from the extracted feature quantities and compensates for the signal degradation. Computer simulation results confirmed that the proposed compensation method can improve signal separation and demodulation performance when degraded by IQ imbalance.

This paper proposes a compact microwave rectifier achieving a fractional bandwidth of 162.7% using a double-voltage rectification circuit. The impedance matching section was designed with lumped elements for miniaturization of the circuit. Moreover, the circuit configuration of the impedance matching section was multi-stage matching to realize the wideband characteristic. Theoretically, this wideband performance was achieved by reducing the impedance conversion ratio of the L-shaped circuit and shortening the impedance locus. The measured frequency bandwidth where the RF-DC conversion efficiency exceeds 50% was from 1.1 GHz to 10.7GHz while the DC load resistance of 200Ω, achieving a fractional bandwidth of 162.7%.