A Corrugated SIW Based Slot Antenna for Terahertz Application

This paper proposes a Corrugated Substrate Integrated Waveguide (CSIW) based slot antenna for THz application. A CPW to CSIW transition is realized and the antenna operates around 0.9 THz. The antenna uses Cyclo Olefin Copolymer (COC) as a dielectric material which exhibit a loss tangent of 0.0007 at THz frequencies. The proposed slot antenna has realized gain of 5.9 dB when using Gold. The radiation, as well as total efficiency of the antenna, is around 50% using Gold which increases to 85% with a gain of 7.6 dB by replacing it with Graphene

On the Reduction of Uplink Electromagnetic Field Exposure Using Reflecting Intelligent Surfaces: An Experimental Validation

The dataset represents the measured values of power captured during uplink transmission by an E-field probe near a head phantom model to evaluate Specific Absorption Rate (SAR) in the presence of a Reconfigurable Intelligent Surface (RIS). A combination of different configurations (effective unit cells which are switched on) of RIS. The head phantom was marked with 120 different positions. For each RIS configuration, 120 measurements were recorded to measure sensed power at a head phantom model using an E-field probe

A miniaturized series fed tri-slot coplanar Vivaldi antenna for RADAR application with reduced ground plane effect

In this article, a printed series fed tri-slot coplanar Vivaldi antenna is studied and investigated for RADAR application. The antenna consists of three exponentially tapered slots excited by a single microstrip line. The three slots are series fed simultaneously with a radial stub on the microstrip feed line for impedance matching. The proposed antenna covers a frequency of 7.8-11.8 GHz at -10 dB impedance bandwidth. The antenna gain varies from 7.5 dB at the lowest operating frequency and increases to around 9.5 dB at the center frequency of 10 GHz. A key versatility of the proposed design is the ability to modify the ground plane size without affecting the antenna impedance and gain. This makes the antenna suitable to incorporate RADAR transceiver components without modifying the existing antenna design. The proposed antenna is fabricated and measured results show good agreement with simulated results

A survey on reconfigurable intelligent surfaces: wireless communication perspective

Using reconfigurable intelligent surfaces (RISs) to improve the coverage and the data rate of future wireless networks is a viable option. These surfaces are constituted of a significant number of passive and nearly passive components that interact with incident signals in a smart way, such as by reflecting them, to increase the wireless system's performance as a result of which the notion of a smart radio environment comes to fruition. In this survey, a study review of RIS-assisted wireless communication is supplied starting with the principles of RIS which include the hardware architecture, the control mechanisms, and the discussions of previously held views about the channel model and pathloss; then the performance analysis considering different performance parameters, analytical approaches and metrics are presented to describe the RIS-assisted wireless network performance improvements. Despite its enormous promise, RIS confronts new hurdles in integrating into wireless networks efficiently due to its passive nature. Consequently, the channel estimation for, both full and nearly passive RIS and the RIS deployments are compared under various wireless communication models and for single and multi-users. Lastly, the challenges and potential future study areas for the RIS aided wireless communication systems are proposed

High-resolution programmable scattering for wireless coverage enhancement: an indoor field trial campaign

This paper presents a multi-bit reconfigurable intelligent surface (RIS) with a high phase resolution, capable of beam-steering in the azimuthal plane at sub-6 Gigahertz (GHz). Field trials in realistic indoor deployments have been carried out, with coverage enhancement performance ascertained for three common wireless communication scenarios. Namely, serving users in an open lobby with mixed line of sight and non-line of sight conditions, communication via a junction between long corridors, and a multi-floor scenario with propagation via windows. This work explores the potential for reconfigurable intelligent surface (RIS) deployment to mitigate non-line of sight effects in indoor wireless communications. In a single transmitter, single receiver non-line of sight link, received power improvement of as much as 40 dB is shown to be achievable by suitable placement of a RIS, with an instantaneous bandwidth of at least 100 MHz possible over a 3 to 4.5 GHz range. In addition, the effects of phase resolution on the optimal power reception for the multi-bit RIS have been experimentally verified, with a 2.65 dB improvement compared to a 1-bit case

Wireless on walls: revolutionizing the future of health care

No abstract available

Wireless microwave signal transmission for cryogenic applications

Microwave wireless signal propagation in cryogenic environments has applications in radio astronomy and quantum computing. This paper demonstrates for the first time a cryogenic wireless setup and investigates the antenna-to-antenna signal transmission in Liquid Nitrogen (LN) and inside the dilution refrigerator at room temperature (296 K). The antenna under investigation consists of a wideband antenna operating in from 8-12 GHz. The antenna was modelled and designed in CST MWS and fabricated on the Rogers RT/duroid 5880 substrate. The measured transmission coefficient (S21) results demonstrate that there was reasonable signal transmission between the antenna pairs when tested in LN (77 K) and inside the dilution refrigerator (tested at 296 K). The results indicate that the proposed Over- The-Air (OTA) system is suitable for cryogenic applications down to 77K

Characterization of a compact wideband microwave metasurface lens for cryogenic applications

In this paper, we present characterization of a compact flat microwave lens operating between 6 GHz and 14 GHz using a near field scanning system. An X-band horn antenna and open-end rectangular waveguide were used as an illumination source and probe, respectively. |S21| is measured as the probe antenna moves on a plane orthogonal to the optical axis vertically and horizontally. The lens is made of a metasurface layer that is sandwiched by two layers of cross-oriented gratings. The overall dimension of the lens is 10 cm in diameter and 0.57 cm in thickness. The measurement results show that the lens's focal length is 8 cm, and the beamwidth (full width at half maximum (FWHM)) is 3.5 cm, A transmission efficiency of over 90% and a cross-polarization gain of 25 dB were achieved over the entire bandwidth. The measurement results at room temperature are in good agreement with numerical simulations. The proposed lens will be used in a cryogenic environment e.g. dilution refrigerators for quantum computing systems. More results at cryogenic temperature e.g, below 30 K will be shown at the conference

Reconfigurable intelligent surface for future wireless communication

In the current era of wireless communication, there is a constant demand for higher data rates to support the increasing use of data-intensive applications such as streaming video, online gaming, and high-definition video conferencing. These applications require a fast and reliable wireless connection to function properly. The demand for wireless services is constantly increasing, but the amount of available spectrum is finite. This means that network operators must find ways to use the available spectrum efficiently in order to support a large number of users and data-intensive applications. A more straightforward choice is to utilise higher frequencies which provide more bandwidth, but this, on the other hand, reduces the coverage area. Consequently, this would require a smaller cell size with more base stations raising deployment costs. Overall, meeting the demands of users in the current era of wireless communication requires a comprehensive and strategic approach to addressing the various challenges faced by network operators. Lately, the concept of Reconfigurable Intelligent Surface (RIS) has been introduced, which is a technology that consists of nearly passive elements, i.e., active only when voltage is applied, with no Radio Frequency (RF) chain. Instead of tuning the network endpoints, the RIS is utilized to manipulate the propagation channel environment. It is envisioned that RIS will provide numerous benefits by 1) expanding the coverage area, 2) reducing the network deployment cost, 3) improving the energy efficiency of the network and 4) increasing the network capacity. The thesis presents the world’s first in-house developed RIS prototype consisting of ‘4096 elements’ at Sub-6 GHz. The operation frequency of the RIS is kept around 3.75 GHz, which is compatible with the existing 5G operating bands. The elements are controlled via PositiveIntrinsic-Negative (PIN) diodes which switch between two-phase states. Furthermore, every unit element is individually controlled, which makes it usable to operate in the near field and perform channel estimation. The operational power consumption of the proposed RIS is observed to be 12-15 watts with beam switching speed reaching 15 ms. Two distinct application areas have been explored, i.e., RIS-assisted wireless communication and RIS-assisted health care for vitals detection. In the communication scenario, the RIS is able to focus the beam at different angles and perform conventional beam steering in real time. Additionally, a demonstration of the Orthogonal Frequency Division Multiplexing (OFDM) communication setup shows the channel manipulation by the RIS with transmitter and receiver in the non-line-of-sight (NLoS). Experiments reveal improved signal conditions attained in the presence of RIS. In the context of health care, the benefit of RIS is investigated for vitals detection, including heartbeat and breathing rate. It is shown that RIS can assist in detecting the heartbeat and breathing rate in the NLoS. Alongside, the E-field exposure around the human head (Phantom model) is investigated in the presence of RIS. Measurement results show that the RIS can reduce the E-field exposure around the head by dynamically changing its electrical aperture, thereby resulting in a reduction of the uplink energy at the user’s terminal. Hence, the overall motivation of the thesis is to explore and investigate the efficacy of RIS both in communication and healthcare scenarios