1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

Applications of Antenna Technology in Sensors

During the past few decades, information technologies have been evolving at a tremendous rate, causing profound changes to our world and to our ways of living. Emerging applications have opened u[ new routes and set new trends for antenna sensors. With the advent of the Internet of Things (IoT), the adaptation of antenna technologies for sensor and sensing applications has become more important. Now, the antennas must be reconfigurable, flexible, low profile, and low-cost, for applications from airborne and vehicles, to machine-to-machine, IoT, 5G, etc. This reprint aims to introduce and treat a series of advanced and emerging topics in the field of antenna sensors

Compact Reconfigurable Antennas for Wireless Systems and Wearable Applications

The fast growth of wireless communications has driven the necessity of exploiting technological solutions for the needs of faster connectivity. While bandwidth allocation and effective radiated power (ERP) are subjected to regulatory constrain, alternative solutions have been developed to overcome the challenges that arise in terms of wireless coverage and number of users. Reconfigurable antennas (RAs) technology is one of the hardware solutions developed to enhance the connectivity between wireless devices. These new class of radiating elements are able to adapt their physical characteristics in response to the environmental changes or users density and location. Reconfigurable antennas can be divided into two main categories: frequency reconfigurable antennas and pattern reconfigurable antennas. The former class of RAs are able to switch the operational frequency in order to move the communication within unoccupied channels. The latter category defines those antennas that are able to change their radiation characteristics (radiation pattern or polarization) in response to the dynamics of the surrounding environment. Unlike conventional static antennas where the energy is wasted around the surrounding space, the use of RAs allows for a smarter management of the radiated energy as the beam can be focused toward specific directions. As a result, not only data throughput between two devices can be improved but also the interference between adjacent networks can be reduced significantly. n this PhD thesis we focus on the design, prototyping and system application of compact RAs for wireless base stations and mobile devices. Specifically, the first task focuses on the design of a compact reconfigurable antenna capable of generating omnidirectional and directional beams in a single planar design. Next, we propose to apply a miniaturization technique in order to drastically reduce the size of Composite Right-Left Handed Reconfigurable Leaky Wave Antennas (CRLH RLWAs). The large beam steering capabilities along with the miniaturized dimension open new venues for the integration of this antenna technology into mobile devices such as laptop or tablets. Similarly for electrically reconfigurable antennas, characteristics such as input impedance and radiation properties of a radiating element can vary by mechanically change its physical dimension. In other words, instead of changing the metallic geometry through electrical components, the characteristics of an antenna can be changed through physical deformation of its geometry. This principle addresses the second main application of reconfigurable antennas this PhD thesis. Wearable technologies are gaining a lot of attentions due to their strong potential for sensing, communication and tactile interaction applications. Thanks to the progress in knitting facilities and techniques, smart fabrics are generally implemented through sewn-in sensors especially in the fields of medical and athletic applications. Such wearable sensors provide a means to monitor the wearers health through physiological measurements in a natural setting or can be used to detect or alert care providers to potential hazards around the wearer. The feasibility of building electrical devices using conductive fabrics has been analyzed through electrical characterization of textile transmission lines and antennas where conductive fabrics have been applied onto woven fabrics have been demonstrated in recent literature. Previous works show conductive copper foils or fabrics bonded to a flexible substrate. However, these techniques show limitations in terms of electrical losses caused by adhesives or glue chemicals. It is desirable to address these drawbacks by knitting conductive and non-conductive yarns in a single process resulting in smart textiles that are unobtrusively integrated into the host garment so as to eliminate the need for chemical adhesives that degrade electrical performance. The characteristics variations of a fabric-based antenna under physical deformations can be exploited to provide a fully wireless sensing of certain body movements. The second task of this PhD thesis, focuses on the design and testing of these purely textile wireless sensors for biomedical applications. The Radio-Frequency Identification (RFID) technology will be applied fordesigning fabric-based strain sensors through the use of novel inductively-coupled RFID microchips (MAGICSTRAP). As opposed to conventional surface-mount microchips, the MAGICSTRAP does not require any physical soldering connection as the RF energy is inductively coupled from the microchip pads to the antenna arms. A separate interrogator unit can communicate with this knit passive RFID architecture by sending a probing signal; the backscattered component received from the knit tag will indicate the level of stretch, and this information will be translated in the physical phenomenon being monitored. The change in the electrical characteristics of the textile antenna, along with the decoupling of the MAGICTRAP chip allow for more reliable detection of contraction/elongation movements. This study will include comprehensive design and characterization of the textile tag sensor along with performance analysis using a mechanical human mannequin.Ph.D., Electrical Engineering -- Drexel University, 201

Antenna Designs for 5G/IoT and Space Applications

This book is intended to shed some light on recent advances in antenna design for these new emerging applications and identify further research areas in this exciting field of communications technologies. Considering the specificity of the operational environment, e.g., huge distance, moving support (satellite), huge temperature drift, small dimension with respect to the distance, etc, antennas, are the fundamental device allowing to maintain a constant interoperability between ground station and satellite, or different satellites. High gain, stable (in temperature, and time) performances, long lifecycle are some of the requirements that necessitates special attention with respect to standard designs. The chapters of this book discuss various aspects of the above-mentioned list presenting the view of the authors. Some of the contributors are working strictly in the field (space), so they have a very targeted view on the subjects, while others with a more academic background, proposes futuristic solutions. We hope that interested reader, will find a fertile source of information, that combined with their interest/background will allow efficiently exploiting the combination of these two perspectives

Analysis and solutions for RFID tag and RFID reader deployment in wireless communications applications. Simulation and measurement of linear and circular polarised RFID tag and reader antennas and analysing the tags radiation efficiency when operated close to the human body.

The aim of this study is to analysis, investigate and find out the solutions for the problems associated with the implementations of antennas RFID Reader and Tag for various applications. In particular, the efficiency of the RFID reader antenna and the detection range of the RFID tag antenna, subject to a small and compact antenna¿s design configuration have been studied. The present work has been addressed directly to reduce the cost, size and increase the detection range and communication reliability of the RFID framework antennas. Furthermore, the modelling concept of RFID passive tags mounted on various materials including the novel design of RFID reader antenna using Genetic Algorithm (GA) are considered and discussed to maintain reliable and efficient antenna radiation performances. The main benefit of applying GA is to provide fast, accurate and reliable solutions of antenna¿s structure. Therefore, the GA has been successfully employed to design examples: meander-line, two linear cross elements and compact Helical- Spiral antennas. In addition, a hybrid method to model the human body interaction with RFID tag antenna operating at 900MHz has been studied. The near field distribution and the radiation pattern together with the statistical distribution of the radiation efficiency and the absorbed power in terms of cumulative distribution functions for different orientation and location of RFID¿s tag antenna on the human body have been demonstrated. Several tag antennas wi th symmetrical and unsymmetrical structure configurations operating in the European UHF band 850-950 MHz have been fabricated and tested. . The measured and simulated results have been found to be in a good agreement with reasonable impedance matching to the typical input impedance of an RFID integrated circuit chip and nominal power gain and radiation patterns

Biomedical Engineering

Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development