Engineering, Electrical and Electronic Engineering, Industrial and Manufacturing Engineering, Multidisciplinary
21
Scopus Publications
Scopus Publications
ML-SDR Framework for Selective and Rapid Detection of Volatile Organic Compounds Hemant Kumari, Amartya Paul, Kai-Da Xu, Shubhankar Majumdar IEEE Sensors Journal, 2026 Volatile organic compounds (VOCs) pose significant environmental and health risks, yet their rapid and selective detection remains a persistent challenge due to the limited sensitivity and real-time adaptability of conventional sensors. This work presents a machine learning-integrated software-defined radio (ML–SDR) framework for the selective and rapid detection of VOCs using a 2.4 GHz coupled block resonator-based microwave sensor with a milled channel. The sensing element is interfaced with a custom-designed power amplifier (PA) and a Raspberry Pi–controlled SDR to achieve a compact and real-time measurement setup. Each VOC sample of 100 μL was introduced into the sensing channel, and its attenuation, group delay, and coupling factor responses were recorded. Distinct variations in these parameters were observed across eight VOCs, namely distilled water, acetone, chlorobenzene, chloroform, ethanol, isopropanol, methanol, and toluene, demonstrating the dielectric sensitivity of the proposed structure. A supervised learning model based on the Random Forest algorithm achieved a classification accuracy of 98.25%, with multi-class ROC curves exhibiting an average AUC exceeding 0.9. The calculated limit of detection (LOD) of the sensor was approximately 7.3 μL, confirming its high resolution and selectivity toward dielectric perturbations. This integrated ML–SDR system thus establishes a versatile and scalable platform for on-field VOC monitoring with high reliability, real-time response, and minimal hardware complexity.
Design and Optimization of an SSPP-Matched GaN HEMT Power Amplifier Using Bayesian Optimization Hemant Kumari, Amartya Paul, Wanchi Sangma, Shubhankar Majumdar International Journal of Numerical Modelling Electronic Networks Devices and Fields, 2025 This paper presents a data‐driven methodology for designing a highly efficient power amplifier (PA) incorporating spoof surface plasmon polariton (SSPP) based matching networks. The PA employs a CG2H40010F GaN HEMT transistor and is optimized to operate across 3.0–4.8 GHz. Log‐periodic line (LPL)‐based SSPP unit cells are utilized in both the input and output matching networks to achieve enhanced field confinement and circuit miniaturization. A two‐stage design approach is adopted: initial optimization is performed through harmonic balance simulations using simplified real frequency technique (SRFT), followed by electromagnetic (EM) co‐simulation to capture full‐wave effects. A Bayesian Optimization framework is applied to systematically tune the SSPP geometrical parameters and LPL configurations, using output power ( P out ), power‐added efficiency (PAE), and gain as optimization objectives. The final design demonstrates a peak P out of 43 dBm, a drain efficiency exceeding 80%, and a gain of 13.6 dB. The proposed approach enables an efficient and compact SSPP‐based PA design without requiring hardware measurements, offering a promising direction for future wideband front‐end amplifier solutions.
APD–SSPP: Enhancing Linearization of Power Amplifier Using Spoof Surface Plasmon Polariton Propagation Hemant Kumari, Amartya Paul, Gaurav Bhargava, Shubhankar Majumdar Microwave and Optical Technology Letters, 2025 This paper presents a compact analog predistortion (APD) employing spoof surface plasmon polaritons (SSPPs) to enhance the linearization of high‐frequency radio frequency (RF) power amplifiers (PAs). The APD–SSPP architecture integrates a Schottky diode (DBES105a) with a high‐Q tank circuit to improve harmonic suppression and mitigate third‐order intermodulation distortions (IMD3). The SSPP‐enabled impedance transformation enhances electromagnetic wave confinement, suppresses parasitic resonance effects, and optimizes power transfer efficiency by minimizing impedance mismatches along the signal path. Furthermore, broadband harmonic rejection is achieved by integrating radial stub elements, effectively mitigating spectral regrowth while maintaining high‐power‐added efficiency. Applied to the PA (ZX60‐V63), the proposed APD–SSPP achieves a gain tuning range of 3 dB, a phase variation of 0.9°, and an insertion loss of 4 dB. Experimental validation confirms that by using APD–SSPP, 65.9% IMD3 suppression, 14.5% carrier‐to‐intermodulation improvement, and a 36% adjacent channel power ratio reduction are achieved, significantly reducing out‐of‐band spectral emissions and improving the linearization performance of ZX60‐V63. These results establish the APD–SSPP as a highly efficient, miniaturized predistortion solution for next‐generation RF front‐end architectures in high‐data‐rate wireless communication systems.
Reconfigurable Triple-Path Matching Network for Wide-Band and High-Efficiency Power Amplifier Hemant Kumari, Amartya Paul, Shubhankar Majumdar 2025 IEEE Microwaves Antennas and Propagation Conference Mapcon 2025, 2025 This study presents a high-efficiency GaN HEMT power amplifier (PA) operating across the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.6-2.4 \text{GHz}$</tex> band, developed using a novel impedance-matching strategy optimized for multiband and compact radar systems. The proposed architecture integrates a triple-path (TP) structure with a series of inverse continuous modes (SICMs), forming a buffered matching network that enables both bandwidth expansion and enhanced efficiency. Implemented with a 10 W GaN HEMT device, the amplifier achieves a saturated output power of 39 dBm, a peak drain efficiency (DE) of 76%, and a power-added efficiency (PAE) of 70%. The measured gain remains steady at 11 dB, while thermal power dissipation is limited to 2.5 W, indicating effective thermal management. These performance metrics confirm the viability of the proposed TPs-SICM design as a compact and scalable solution for broadband, high-efficiency RF front ends targeting radar and aerospace use cases.
EconoScan: Affordable Microwave Imaging for Nondestructive Strength Testing of Bituminous Materials Amartya Paul, Rinaldo Snaitang, Pradeep Kumar Gautam, Shubhankar Majumdar IEEE Sensors Letters, 2025 This paper presents a novel, low-cost, and portable microwave sensing system for non-destructive classification of bituminous pavement materials using a log-periodic feedline-based ring resonator integrated with a software-defined radio (SDR) platform. Traditional mechanical tests, such as Marshall stability and fatigue testing, are often time-consuming, destructive, and lack sensitivity to microstructural variations. In contrast, the proposed system measures attenuation and group delay with high spatial resolution at 400 MHz and 600 MHz. These parameters are extracted from the frequency-domain response using the Fast Fourier Transform (FFT). The system successfully distinguishes between bituminous concrete (BC) and open graded friction course (OGFC) samples, achieving a classification accuracy of 97.42%. Its low cost and high portability make it a promising tool for real-time, field-level pavement diagnostics.
