Mohammad Shabi Hashmi

Non-contact detection of humans and metal objects remains a key challenge in security systems. To address this, a physics-guided machine learning approach is proposed for human and metal target classification using a custom-built, batterypowered S-band (2.3–2.6 GHz) frequency-modulated continuouswave radar. The radar system is implemented using discrete components, incorporating designed Vivaldi antennas and an active low-pass filter for target detection. From 117 measurement scenarios across three target classes: person, metal, and person-metal combine, a comprehensive framework of 51 base physics-guided features was developed and systematically aggregated across temporal windows to yield 199 calibration-independent features. Feature selection via Random Forest importance, Relief-F, mRMR, and Boruta analysis identifies 10-80 features maintaining baseline performance, with minimal subsets enabling resourceconstrained deployment. Nested cross-validation with hyperparameter tuning across five classifiers achieved 96.66% accuracy using Random Forest, with 100% recall for human-containing classes. Comparative evaluation demonstrated that physics-guided features outperform an optimized 17.3M-parameter CNN by 12.9% (96.66% vs. 83.8%). The calibrationindependent design, validated through ablation analysis, enables proposed radar deployment without specialized equipment and provides a standalone, battery-powered system suitable for practical security and surveillance applications.

This work presents a novel T-shaped transmission line structure designed for physical size reduction. It is analytically demonstrated that, for a specific operation frequency, the proposed structure behaves exactly like a λ/4 transmission line. Furthermore, the open-ended part of the structure can be tuned for controlled frequency rejection, thus exhibiting a built-in low-pass filtering behavior. The applicability of the network is illustrated through a practical design of the miniaturized 4 × 4 Butler Matrix (BM). As a result, the obtained BM is reduced in size by 65% compared to the classic implementation and is also capable of low-pass filtering. The theoretical and simulated return loss, insertion loss, and phase difference are in close agreement with the corresponding measured values, which proves the effectiveness of the proposed design. The designed BM has been further investigated for practical applicability as a beamforming network using patch array antennas in a simulation environment. The designed antenna array system achieves a maximum gain of 10 dBi in boresight with a possible output steering angle of ±40°.

Design of a conformal, low-profile, and compact metasurface (MS) backed monopole antenna operating at the medical body area network band (MBAN) is proposed in this paper. A novel blocking MS unit cell (B-UC) with dimensions of 13.8 × 13.4 × 0.5 mm³ is designed on the Roger 5880 board. A close symmetry of the proposed B-UC along the x- and y-axes results in excellent polarization stability for the normally incident transverse electric (TE) and magnetic (TM) modes. Moreover, a simple but elegant circuit model based on the surface current flow is presented for the proposed B-UC. Furthermore, an array of 3 × 3 B-UCs having dimensions of 45 × 43.6 mm² is also designed to act as a reflector and enhance the performance of a monopole antenna. Once again, the near symmetry of the proposed array results in excellent polarization stability along the x– and y–axes. Incorporating the developed MS array into the low-profile monopole antenna provides superior conformability, as demonstrated by bending it to three distinct radii of 40, 50, and 60 mm on a cylindrical platform. Finally, the proposed designs are fabricated, and the prototypes exhibit good agreement between the measured and simulated results, achieving a gain of 5.3 dBi and an efficiency of 80%.

This article presents the design of a perovskite photovoltaic (PV)-based power management system, which uses a power converter (a four-stage bootstrap charge pump) to boost the output of the solar cell and supply selectable rectified power rails to CMOS image sensor circuit blocks. A perovskite photovoltaic, also known as a perovskite solar cell (PSC) was fabricated in the laboratory. The PSC has an open-circuit voltage of 1.14 V, short-circuit current of 1.24 mA, maximum power of 0.88 mW, and a current density of 20.68 mA/cm² at 62% fill factor. These measured forward scan parameters were closely reproduced with a solar cell simulation model. In a Cadence simulation that used 180 nm CMOS process, the power converter efficiently boosts the maximum output voltage of the PSC from 0.85 V to a rectified 3.7 V. Stage modulation and level shifting enable selectable output rails in the 1.2–3.3 V range to supply the image sensor circuit blocks. Keeping the output capacitance of the power converter much larger than the flying capacitance reduces the ripple voltage to approximately 73 µV, much smaller than the typical 1 mV in several other literatures. Through simulation, this work demonstrates the concept of directly using PSC (to be implemented on an outer ‘packaging’, not on a die) to supply CMOS image sensor power rails, in the same sense as in wearable devices and other consumer devices. This work highlights a path toward self-powered image sensors with improved conversion efficiency, compactness, and adaptability in low-light and variable operating environments.

Unmanned aerial vehicle (UAV) roles and applications are rapidly growing, extending their variety and functionality. However, the battery dependency considerably limits the UAV's flight duration and coverage. To overcome associated challenges, a wireless power transfer (WPT) system has emerged as a viable solution, eliminating human assistance in battery depletion. Nevertheless, lateral misalignment in such systems can significantly degrade performance. In this regard, multiple‐input single‐output (MISO) systems have shown potential in addressing this challenge. This paper, therefore, proposes the development and modeling of a MISO WPT system with high robustness that also addresses the lateral displacement issues encountered in UAV powering. Initially, a defected ground structure‐based resonator is designed with a 50‐by‐50 mm ² area. Subsequently, two coupled resonators at 55 mm formed the WPT system. Performance validation under perfect alignment and lateral misalignment revealed the system's efficiency to reach 98% and decrease to 33% under ± 25 mm shift, accordingly. The obtained results leave room to realize a MISO WPT system with two resonators composing a transmitter and a single receiver. Furthermore, the 1.25 mm isolating substrate was embedded between adjacent resonators on the transmitter to mitigate interference. The developed MISO WPT system demonstrated stable efficiency exceeding 50% under lateral misalignment.

This work presents a compact metamaterial (MTM)-integrated near-field wireless power transfer (WPT) system with enhanced performance. The WPT is designed by magnetically coupling two slotted ground plane-based resonators oscillating at 433 MHz. The WPT performance elevation is achieved through a proposed systematic design approach encompassing two key stages. In the first stage, the plus-shaped fractal slot-based resonators are analyzed, revealing that successive iterations expand the magnetic field ($\mathbf {B}$) area and consequently extend the power transfer distance ($d$). In the second stage, MTM with dimensions of $30 \times 30$ mm$^{2}$ is integrated into the WPT system. The size of MTM does not exceed the area of the resonator, ensuring that the overall volume remains compact. The MTM is arranged in a configuration of $3 \times 3$ unit cells, with the latter being designed using octagonal spirals and exhibiting a permeability of $-1$ at 433 MHz. The MTM is carefully positioned between the coupled resonators in order to effectively mitigate the $\mathbf {B}$ leakage and increase coupling. As a result, the power transfer efficiency ($\eta$) and $d$ are both improved, achieving $\eta$ of 81% at $d=39$ mm. Experimental validation and benchmarking against state-of-the-art systems show a FoM reaching 1. The WPT performance was evaluated in practical application scenarios, considering the effects of misalignment and the presence of nearby objects. Overall, the obtained results confirm the effectiveness of the proposed systematic design approach, marking a significant advancement in WPT technology.