Rajesh Khanna

This paper presents the design, analysis, fabrication and testing of an ultra-thin narrow-band metamaterial (MM) absorber tailored for improving the sensitivity of pressure sensors. The proposed resonator achieves an impressive absorption characteristic of 99.85% at 5.355[Formula: see text]GHz. A prototype is fabricated using standard PCB technology and experimental validation is conducted in an anechoic chamber to verify the simulated results. The sensor design incorporates an analytical diaphragm layer between two substrates, demonstrating the ability to detect minor shifts in pressure with an average sensitivity of 2080[Formula: see text]MHz/mm. Key sensor characteristics include a high quality factor of 49.28 and a substantial Figure of Merit of 43.45. The linear behavior of the sensor is quantified through curve fitting, showing good agreement with the simulated sensitivity. The designed MM absorber exhibits merit such as perfect absorptivity, linear sensitivity, narrow bandwidth, high Q-factor, and a substantial Figure of Merit, making it a strong contender for pressure sensing applications.

This paper presents a compact, multiband, flexible metasurface (flexi-meta) antenna structure consisting of metasurface antenna elements designed exclusively for 5G sub-6 GHz applications. The proposed flexi-meta antenna is realized by first creating a double-negative (DNG) metamaterial unit cell on a flexible (0.4 mm thick) FR-4 substrate. Then, an array of these DNG unit cells is suitably placed inside the rectangular ring-slotted patch using the Theory of characteristic modes (TCM), to achieve optimal performance in the sub-6 GHz band. The resulting flexi-meta antenna is compact with an overall volume of 300 mm ³ ([ ]). It exhibits a wide bandwidth of 1100 MHz (3.15–4.25 GHz), a peak gain of 5.5 dBi, a return loss of [ ] dB, and a radiation efficiency of 85%. These characteristics distinguish the flexi-meta antenna as cost effective, compact, conformal, high-performance contender for 5G sub-6GHz and IoT applications.

This study introduces a novel method for microwave soil treatment using a Substrate Integrated Waveguide (SIW) H-plane horn antenna integrated with an Electromagnetic Band Gap (EBG) unit cell array. The design enhances penetration depth(thermal), coverage area, and soil temperature regulation. Comparisons highlight the EBG antenna’s better performance, maintaining reflection coefficients below −10 dB near soil, unlike the non-EBG configuration, which suffers higher energy losses. The EBG antenna achieves temperatures of 85 °C in simulation at distances of 10 mm, compared to 80 °C at 10 mm without EBG. It also covers a larger area (29 × 29 mm ² ) and ensures uniform heating, reaching 70 °C at a depth (thermal), of 25 mm, outperforming compared to the non-EBG antenna (27 × 27 mm ² ). Experimental results with 28 W (RMS) input confirm soil heating to 81 °C in 75 min over a 150 mm ² area with a penetration depth (thermal), of 50 mm. Additionally, the EBG structure minimally impacts soil nutrients, ensuring deeper penetration and uniform heating. These findings highlight the antenna’s potential to promote sustainable agriculture through optimized microwave soil sterilization

Artificial magnetic conductor (AMC) is widely employed in microwave applications to reduce electromagnetic interference (EMI) and enhance the gain of the antennas. In this work, an AMC was designed, examined, and fabricated alongside a chipless Radio Frequency Identification (RFID) tag operating in an ultrawideband (UWB) frequency range for wireless applications. The tag and AMC are constructed with low-cost FR4 substrate, with 0.15 mm and 1.6 mm thicknesses, respectively. An AMC of 0.3 m × 0.3 m is employed for a 0.22 m × 0.22 m tag. The size of the AMC rings is to be optimized to ensure that the resonating frequencies of both structures nearly coincide. The proposed tag, equipped with an AMC, has been fabricated and subjected to experimental testing to confirm its performance. The results of the tests have shown that the tag can achieve read ranges exceeding 1.2 m. The presented work can be effectively utilized in wireless RFID applications to enhance gain, reading distance, and protection against electromagnetic interference within the resonant frequency range.