Sayan Sarkar

This paper presents an experimentally validated compact right‐hand circularly polarized (RHCP) metallic button antenna for garment‐integrated sub‐7GHz 5G New Radio applications. Departing from conventional monolithic button antenna designs with integrated feeding structures, the proposed design introduces a physically decoupled radiator–feed architecture enabling modular and detachable operation. The proposed radiator, realized as a metallic button element, enables seamless integration into garments without altering conventional clothing structures. To demonstrate practical feasibility, prototypes of both the radiator and feed modules are fabricated and characterized under realistic on‐body conditions. The measured S ₁₁ and axial ratio bandwidths exhibit consistent overlap over 6.3–6.9 GHz (9.1%) in a standing posture and 6.4–6.9 GHz (7.5%) in a sitting posture, thereby covering a significant portion of the 5G NR band. The antenna demonstrates stable CP characteristics with peak measured gains exceeding 7.1dBic across the operation band for both postures. Additionally, full‐wave simulations confirm low human exposure levels with a maximum point specific absorption rate (SAR) of 0.552 W/kg and a 1 g averaged SAR of 0.0598 W/kg for an input power of 0.5 W.

Vehicle-to-Everything (V2X) Communication is an important aspect of ADAS, significantly enhancing the safety of a vehicle and its passengers by providing free exchange of real-time data amongst them. This publication tries to give an overview of numerous research projects aiming to develop and deploy V2X communication systems. Finally, the chapter asserts how V2X communication impacts situational awareness and mentions contributions toward making travel safer and promoting efficient traffic flow. It outlines the various possibilities of V2X communication technology and guides future research directions based on deployment by summarizing the findings of different investigations and attempting to outline an Online Dashboard to support seamless Inter-Vehicle Communication and display important driving information to help other drivers and autonomous vehicles.

The high impedance surface (HIS) was introduced by Sievenpiper in 1999. It was a 2D periodic array of subwavelength unit cells and had two unique properties, namely, in-phase reflection and surface wave suppression. Sievenpiper proposed the utilization of the HIS as an in-phase reflector and for mutual-coupling/crosstalk reduction. With the passage of time, researchers found many additional applications of the HIS. They began to be used as electromagnetic absorbers as well as for radar cross section reduction. Utilizing the HIS structures along with metallic waveguides, researchers also developed the concept of impedance waveguides and gap waveguides. Recently, researchers have added PIN/varactor diodes with HIS unit cells to make their properties reconfigurable. With the increase in demand for dynamic communication systems, reconfigurable HIS designs are expected to be quite critical in many applications in the future. Flexible and lightweight graphene-based HIS structures are also expected to gain importance with the increasing focus on wearable communication systems for health monitoring and search-and-rescue operations.

This letter proposes a circularly polarized RFID reader which covers the European UHF (865MHz), North-American UHF (915MHz), and the microwave (2.45GHz) RFID bands. The reader consists of a coaxially-fed slotted-patch antenna and a metasurface-inspired superstrate placed 5mm above the radiator. The antenna-superstrate arrangement radiates broadside RCP waves within both the UHF bands and broadside LCP waves within the microwave band. The reader has measured gains of 3.95dBic, 3.98dBic, and 5.67dBic at 865MHz, 915MHz, and 2.45GHz, respectively. The main feature of the proposed reader is its wide 3dB axial ratio beamwidths of 134⁰, 158⁰, and 70⁰ within the three respective RFID bands. This ensures accurate CP identification for off-boresight tag detection. The antenna has a volume of 0.36 × 0.36 × 0.023$\lambda _{0}{^{3}}$; where $\lambda _{0}$ = free space wavelength at 865MHz. The compact size enables the reader to be used for both handheld and desktop applications.

This article presents a microstrip patch antenna-based permittivity sensor that can be used to characterize a wide range of liquids as well as solids. This is the first antenna-based sensor that can characterize both liquids and solids. The sensor can measure solid permittivity values from 1-13 and liquid permittivity values from 1-80. There are two separate sensing regions for liquids and solids with two different frequency bands used for characterization. There is also a dedicated uplink channel centered at 710MHz for transmitting the sensed information wirelessly via the FDD LTE Band 12 (698.2 – 716.2MHz) or TDD LTE Band 44 (703-803MHz). This uplink channel enables the sensor to be a part of wireless sensor networks. When not in use as a sensor, the antenna-based system can be utilized for dual-band and dual-linearly polarized communication within the 710MHz LTE band as well as the FDD LTE Band 1 (2110-2170MHz). This makes the system even more versatile. The solids and liquids can be removed with ease, thereby reducing the wait time between consecutive measurements. The sensor achieves a minimum sensitivity of 0.2% for both liquids and solids, which is at par with existing antenna-based sensors. Based on the different solid and liquid permittivity measurements performed, the maximum error in permittivity is found to be 3.18%, which is less than most antenna-based sensors in literature.