The research investigates the sensing characteristics of the ultrathin metamaterial absorber for refractive index detection of biomedical samples. The absorber is made up of a novel spanner resonator and has an abortion peak of 99.7% at 105.7 GHz with FWHM (Full Width Half Maxima) and Q factor of 5.4 GHz and 19.57 respectively. The designed absorber is evaluated for biomedical sensing applications to enhance the output variation, linearity and sensitivity. The majority of the biological samples had refractive indices in the extremely close range and detecting such samples with close refractive indices is a substantial challenge. The proposed resonator is capable of sensing such kind of near refractive index samples with an average sensitivity and FoM (Figure of Merit) of 14.81 GHz/RIU (Refractive Index Unit) and 3.48 respectively. Moreover, the absorber sensor is capable of handling thick and thin biological materials. The suggested design paves the path for the development of a millimeter-wave metamaterial absorber to be used in biosensor applications. The results findings are validated using full-wave electromagnetic simulations, curve fitting and measurements. Furthermore, the design is constructed in a flat and ultrathin manner and because of its compact size, has a high potential for integration with any sensor equipment.

Free space optical (FSO) communication technology has established a reputation for itself as a next-generation network capable of delivering high-speed data access to end-users. In light of the upcoming launch of 5G services, this paper aims to evaluate the performance of the FSO system for the implementation of 5G technology in diverse geographical locations of India. The proposed 16x10 Gbps wavelength division multiplexing (WDM) based FSO link uses orthogonal frequency division multiplexing (OFDM) and digital signal processing (DSP) module to mitigate channel-induced limitations. Additionally the proposed FSO design also employs Erbium-doped fiber amplifier (EDFA) with optimized gain characteristics to ensure consistent transmission power levels. Using the data sourced from the Meteorological Department of India, the link analysis reveals that due to weak fog events in coastal areas effective link range of upto 10.75 km can be achieved while maintaining bit error rate (BER) of 10-9. Despite dominant foggy conditions in hilly, plains and desert areas, the proposed FSO link significantly limits the degrading effects of channel. Hence, in pursuit of futuristic smart city models, heterogeneous combination of FSO and 5G infrastructure can conveniently cover diverse geographical locations of India to support high-speed data connectivity.

A wideband antenna design with double negative metamaterial (DNG) has been designed and evaluated for 4G and 5G applications. The antenna design is investigated for wideband operations for 5G NR (New Radio) n78 band and TDD LTE (Long Term Evolution) bands from LTE band no. 33 to 43. The design is ruled out for size miniaturization and wide bandwidth using a radiating folded dipole. The radiating elements can be tuned to adapt to different configurations using controlling parameters. Moreover, the antenna designed is also investigated for SAR, gain, polarization and efficiency using metamaterial integration. CST microwave studio is used for designing and analysis of the design and the results are validated for the fabricated prototype. The measured and simulated results are in good agreement with each other and proofs to be a good design for 4G and 5G communications.

The fast growth of wireless technology for mobile communication devices requires broad bandwidth, high data rate facilities and compact device size. The solution to the next generation user equipment is high data rate 4G/5G technologies. In this research, wideband antenna design was analyzed and evaluated for 4G, 5G and NB-IoT applications. CST microwave studio was used for simulations and investigations of the performance parameters. The antenna was designed as a folded dipole with a tunable bandwidth and resonates for 5G NR n78, NR-IoT bands B1, B2, and B25, and eleven TDD LTE frequency bands with a bandwidth percentage and minimum scattering loss of 69.02% and −42 dB respectively. Additionally, the designed antenna is small (35 × 48 × 1.62 mm³) and planar in structure and can be easily integrated with radio equipment. The antenna design was also investigated for SAR minimization and gain enhancement using metamaterial integration. For all operating frequency bands, the antenna design results in a considerable gain improvement. The metamaterial was shown to be an excellent absorber of radiation, particularly in high frequency regions. This research also included a SAR examination with and without metamaterial integration. SAR values were found to be significantly reduced throughout all operating bands. The results were validated by fabricating the design prototype on FR-4 substrate for 4G, 5G and IoT bands. The antenna will be possibly used for communication in high data rate applications.

Plant-derived carbon dots (P-CDs) are gaining attention in environmental remediation due to their cost-effectiveness, availability, and lower toxicity compared with chemically synthesized carbon dots. This review comprehensively examines the recent advancements in the synthesis and application of P-CDs, with a particular emphasis on their efficacy in the sensing of heavy metals, which are among the most pervasive environmental contaminants. A detailed comparative analysis is presented by evaluating the performance of P-CDs against their chemically synthesized counterparts based on key parameters, such as optimal operating conditions and detection limits. Furthermore, sensing the potential of P-CDs towards every heavy metal ion has been discussed with in-depth mechanistic insights. Additionally, this review explores the industrial applications and future directions of P-CDs. This review provides a comprehensive analysis of -P-CDs for heavy metal sensing, aiming to enhance their sensitivity and selectivity toward heavy metal ions.