In this paper, a new metamaterial absorber (MMA) has been presented that shows dual-band absorption at 1.8 GHz and 3.5 GHz. The MMA cell has been designed on an FR4 substrate with the electrical dimension of 0.14λ₀ × 0.14λ₀ × 0.01λ₀, calculating wavelength, λ₀ at 1.8 GHz. Maximum absorption of 98.7% and 99.7% are attained by a unique design of a resonating patch consisting of two modified circular rings that are finalized through numerical Simulation in CST microwave studio. The MMA exhibits high angular stability up to 60° for incident angle as well as polarization angle variations. The analogous equivalent circuit is modeled in advanced design system (ADS) software, providing the same reflection, transmission, and absorption characteristics of 3D Simulation in CST. The absorption mechanism is investigated through current and electromagnetic field analysis. The MMA exhibits negative permittivity within 1 GHz—1.8 GHz and 2.08 GHz – 3.49 GHz and negative permeability with other frequency ranges. The prototype of a 3 × 6 array of the MMA cell is developed, and measurement is accomplished. The measured result exhibits well match with the simulated result. Moreover, The MMA displays good shielding effectiveness of 40.12 dB and 36.81 dB at 1.8 GHz and 3.5 GHz, respectively. The quality factors of the MMA are 30 and 22.3, with half power bandwidth of 60 MHz and 157 MHz. This new and unique MMA can be incorporated with various electronic devices for microwave shielding from GSM 1.8 GHz and sub-6, 5G 3.5 GHz signals.

Recent research reveals that multi-phase motors in electric propulsion systems are highly recommended due to their improved reliability and efficiency over traditional three phase motors. This research presented a comparison of optimal model design of a six phase squirrel cage induction motor (IM) for electric propulsion by using Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). A six phase squirrel cage induction motor is designed and simulated by ANSYS Motor-CAD. In order to find the best fit method, simulation results are compared and applied to the motors for electric propulsion, considering the influence of design upon the motor performance. The six-phase squirrel cage induction motor is more energy efficient, reliable and cost effective for the electric propulsion compared to the conventional three phase motor. In this study, first the initial parameters of the six phase squirrel cage induction motor have been determined and then these parameters have been compared with optimized values by Genetic Algorithm (GA) and PSO optimization. The motor designed is optimized using efficiency and power losses as the fitness function. The six phase squirrel cage induction motor is designed using ANSYS Motor-CAD and the simulation results were also presented along with two-dimensional and three-dimensional geometry. The result shows that the weight and power loss are reduced to 161 kg and 0.9359 Kw respectively, while the efficiency and power factor are increased to 0.95 and 0.87 respectively when PSO is used. This shows that the result is promising.

This paper presents a novel tri-band Multiple Input Multiple Output (MIMO) antenna module designed for millimeter and microwave frequency bands, employing metamaterial (MTM) technology to enhance performance. The compact antenna module measures 36 × 36 × 1.6 mm² and uses a Rogers RT-5880 substrate. Its structure includes a multi-stubbed radiating patch, a partial ground plane, and a 2 × 1 epsilon-negative MTM array positioned between antenna elements in an orthogonal layout. Operating at 3.5 GHz, 5.2 GHz, and 28 GHz, the integration of MTM significantly improves the antenna’s overall performance by influencing phase, amplitude, and electromagnetic field distribution. Bandwidth enhancements of 10.01% and 6.4% are achieved for the 3.5 GHz and 5.2 GHz microwave bands, respectively, and 4.43% for the 28 GHz millimeter-wave band. Isolation levels improved from 20 dB to 24 dB in microwave bands and from 26 dB to 32 dB in the millimeter-wave band, ensuring reduced interference. The realized gain also increased from 3.6 dBi, 4.2 dBi, and 7.4 dBi to 4.8 dBi, 5.3 dBi, and 9.3 dBi across the respective frequency bands. The proposed MIMO antenna showcases excellent diversity performance with an envelope correlation coefficient (ECC) of below 0.002/0.001/0.0003 across all bands and a diversity gain (DG) exceeding 9.98 dB. Machine learning-based performance verification analysis assessed bandwidth and efficiency, where the K-Nearest Neighbors (KNN) model achieved 97.8% accuracy. This MIMO antenna holds great potential for various Internet of Things (IoT) applications, including Vehicle-to-Network, Vehicle-to-Cloud communications, 5G cellular networks, Wi-Fi, WiMAX, and both sub-6 GHz and millimeter-wave 5G bands, reinforcing its suitability for 5G IoT sectors.

Chipless RFID has the potential to bring in a paradigm change in industrial applications, notably in the world of the Internet of Things (IoT). This wireless technology permits distant identification, sensing, and tracking, giving tremendous development prospects. Despite substantial advances over the previous century, designing high-performance chipless RFID for IoT applications remains a problem. This research presents a new chipless planar RFID tag for item tracking and identification in IoT systems. The suggested tag uses numerous T-shaped slow-wave structures as micro-reflecting resonators with different dimensions on a lossy substrate to encode information in the tag’s backscattered signal after illumination. The mutual coupling between the resonators has been minimized to improve tag performance and printing variety. A tag with a coding capacity of 24 bits and a compact size of 60 x 40 mm ² was simulated in CST Microwave Studio to validate the suggested approach. To create tags, several patterned configurations were applied on a Rogers RO4350B substrate, and their radar cross-section responses were studied. When compared to typical multi-resonator tags, the suggested tag design demonstrated excellent downsizing and efficient frequency spectrum usage. Furthermore, the Q-factor and coding strength were both high, showing that the suggested technology is capable of manufacturing high-performance chipless tags.

In this paper a numerical investigation on the double diffusive natural convection in a finned solar still is performed using the finite volume method. The 3D vector potential-vorticity formalism is used to eliminate the gradient pressure terms and due to the complex shape of the cavity the blocked-off-region method is adopted. After getting the dimensionless governing equations, they are written in a generalised form then discretised. The effects of the buoyancy ratio, conductivity ratio and Rayleigh number of the flow structure, temperature field and heat and mass transfer are studied. The results show that the increase of conductivity ratio and Rayleigh number leads to an enhancement of the heat and mass transfer.