A compact and low-profile wearable antenna is presented for on-body wireless body area network (WBAN) applications. The proposed triangular patch antenna is designed using low-cost widely available vinyl polymer-based flexible substrate. The final antenna topology is obtained by the combination of Koch fractal geometry, meandering slits and defected ground structure, to achieve a novel hybrid structure with compact footprint, good structural conformability and enhanced impedance bandwidth to operate in the Industrial, Scientific, and Medical (ISM) band with center frequency at 2.45GHz. The fabricated prototype of the antenna has shown good agreement between numerical and experimental results. In comparison to state of the art prototypes, our design has more compact-form-factor of $\rm 0.318\lambda_o \times 0.318\lambda_o \times 0.004\lambda_o$ , along with 7.75% impedance bandwidth, a peak gain of 2.06dBi and overall radiated efficiency of 75%. For the assessment of Specific Absorption Rate (SAR) performance of our design, it is tested on realistic heterogeneous HUGO voxel model. Both numerical and experimental investigations revealed extremely good robustness to both human body loading and structural deformation, making it an ideal candidate for flexible and body-worn devices.

We propose a low-cost, easy-to-fabricate, contactless microwave sensor for dielectric characterization of liquids. The design of the proposed sensor is based on a multiple complementary split-ring resonator (MCSRR) fabricated on a low-cost FR-4 substrate. A glass capillary tube having an inner diameter of 0.008λ0 is inserted in the high electric field region of the MCSRR to carry the liquid under test. The sensor is designed to operate at a resonant frequency of 2.45GHz for an empty tube and shifted resonant peaks are utilized for the dielectric characterization of different liquids. The maximum observed shifts in resonant frequency and Q factor are up to 400MHz and 31, respectively. The numerically established relations are experimentally verified through fabricated sensor for various binary mixtures of water and ethanol. The percentage errors between the calculated and reference permittivity of different samples are noticed to be less than 5%. The proposed device promises to be a cost-effective and convenient solution for accurate dielectric characterization of liquids and their binary aqueous solutions.

Smart energy has evolved over the years to include multiple domains integrated across multiple technology themes, such as electricity, smart grid, and logistics, linked through communication technology and processed in the cloud in a holistic way to deliver on global challenges. Advances in sensing, communication, and computation technologies have been made that enable better smart system implementations. In smart energy systems, sensing technologies have spanned multiple domains with newer techniques that are more accurate, have greater dynamic ranges, and are more reliable. Similarly, communication techniques have now evolved into very high-speed, flexible, and dynamic systems. Computation techniques have seen a quantum leap with greater integration, powerful computing engines, and versatile software stacks that are easily available and modifiable. Finally, the system integration has also seen advances in the form of management, automation, and analytics paradigms. Consequently, smart energy systems have witnessed a revolutionary transformation. The complexity has correspondingly grown exponentially. With regard to smart meters, the measurement component has to scale up to meet the demands of the evolved energy eco-system by relying on the advancements offered. The internet of things (IoT) is a key technology enabler in this scenario, and the smart meter is a key component. In recent years, metering technology has evolved in both complexity and functionality. Therefore, it must use the advances offered by IoT to deliver a new role. The internet of things (IoT) is a key technology enabler in this scenario and the smart meter a key component. In recent years, metering technology has evolved in both complexity and functionality. To deliver on its new role, it must use the advances offered by IoT. In this review, we analyze the smart meter as a combination of sensing, computing, and communication nodes for flexible and complex design paradigms. The components are, in turn, reviewed vis-à-vis the advances offered by IoT. The resultant gaps are reported for future design challenges in the conclusion. The identified gaps are the lack of usage of the full spectrum of the available technology and the lack of an inter-disciplinary approach to smart meter design.

This work presents multifunctional metasurfaces for generating focused optical vortices of visible light.

Helicity-multiplexed metasurfaces based on symmetric spin–orbit interactions (SOIs) have practical limits because they cannot provide central-symmetric holographic imaging. Asymmetric SOIs can effectively address such limitations, with several exciting applications in various fields ranging from asymmetric data inscription in communications to dual side displays in smart mobile devices. Low-loss dielectric materials provide an excellent platform for realizing such exotic phenomena efficiently. In this paper, we demonstrate an asymmetric SOI-dependent transmission-type metasurface in the visible domain using hydrogenated amorphous silicon (a-Si:H) nanoresonators. The proposed design approach is equipped with an additional degree of freedom in designing bi-directional helicity-multiplexed metasurfaces by breaking the conventional limit imposed by the symmetric SOI in half employment of metasurfaces for one circular handedness. Two on-axis, distinct wavefronts are produced with high transmission efficiencies, demonstrating the concept of asymmetric wavefront generation in two antiparallel directions. Additionally, the CMOS compatibility of a-Si:H makes it a cost-effective alternative to gallium nitride (GaN) and titanium dioxide (TiO₂) for visible light. The cost-effective fabrication and simplicity of the proposed design technique provide an excellent candidate for high-efficiency, multifunctional, and chip-integrated demonstration of various phenomena.