Laura Corchia

UHF Wearable Rectenna on Textile Materials

A wearable rectenna for operation in the ultra high frequency (UHF) band is presented. The proposed device consists of a compact patch antenna and a full-wave bridge rectifier, both fabricated with textile materials. The patch antenna has been realized by using an adhesive conductive fabric on a bi-layer substrate made of pile and jeans. As for the rectifier, it is on a layer of jeans on the back-face of the antenna. Experimental data referring both to the patch antenna and to the rectenna are reported and discussed. From measurements performed with an incident power density of 14 μ/cm2, it is demonstrated that the rectenna here presented exhibits a conversion efficiency higher than 20% over the frequency range 860-918 MHz with a maximum of about 50% at 876 MHz.

Patch Antenna with Reconfigurable Polarization

A reconfigurable patch antenna consisting of a square patch with two cross-shaped diagonal slots is presented. The proposed design approach is based on the use of two pairs of switches in order to obtain both frequency and polarization reconfigurability. Specifically, three different polarization states have been obtained: a Right-Hand Circular Polarization, a Left-Hand Circular Polarization and a Linear Polarization. Experimental results, referred to a realization on a FR4 substrate of the layouts corresponding to the useful switch configurations, are reported.

PLANAR BOWTIE ANTENNA WITH A RECONFIGURABLE RADIATION PATTERN

This paper presents a novel planar antenna with a reconflgurable radiation pattern. The proposed layout consists of N ‚ 2 monospaced planar bowtie antennas selected one by one by means of a pair of PIN diodes. Experimental results referring to the case of N = 2 and N = 4 are reported and discussed demonstrating the feasibility and efiectiveness of the proposed design approach.

Textile logo antennas

Two novel textile antennas are presented in this paper. The geometry of the two antennas has been shaped so to mimic the logo of two popular companies: the French clothing company LACOSTE and the American multinational corporation APPLE Inc. Two prototypes fabricated by using a conductive non-woven textile on a layer of jeans are presented. Both prototypes were optimized to work at 1.8 GHz. From experimental data excellent performance are demonstrated.

A Wearable Wireless Energy Link for Thin-Film Batteries Charging

A wireless charger for low capacity thin-film batteries is presented. The proposed device consists of a nonradiative wireless resonant energy link and a power management unit. Experimental data referring to a prototype operating in the ISM band centered at 434 MHz are presented and discussed. In more detail, in order to facilitate the integration into wearable accessories (such as handbags or suitcases), the prototype of the wireless energy link was implemented by exploiting a magnetic coupling between two planar resonators fabricated by using a conductive fabric on a layer of leather. From experimental data, it is demonstrated that, at 434 MHz, the RF-to-RF power transfer efficiency of the link is approximately 69.3%. As for the performance of the system as a whole, when an RF power of 7.5 dBm is provided at the input port, a total efficiency of about 29.7% is obtained. Finally, experiments performed for calculating the charging time for a low capacity thin-film battery demonstrated that, for RF input power higher than 6 dBm, the time necessary for recharging the battery is lower than 50 minutes.

A Network Approach for Wireless Resonant Energy Links Using Relay Resonators

In this paper, a network approach for the analysis of a wireless resonant energy link consisting of N inductively coupled LC resonators is proposed. By using an artificial transmission line approach, the wireless link is modeled as a transmission line described by effective parameters. It is shown that the analyzed system exhibits a passband filter behavior. More specifically, the reported results demonstrate that in the wireless link passband the effective parameters assume negative values resulting in a negative phase delay. Useful design formulas are derived and validated by comparisons with the experimental data.

Wearable Antennas for Remote Health Care Monitoring Systems

Remote monitoring of the elderly in telehealth applications requires that the monitoring must not affect the elderly’s regular habits. To ensure this requirement, the components (i.e., sensor and antenna) necessary to carry out such monitoring should blend in with the elderly’s daily routine. To this end, an effective strategy relies on employing wearable antennas that can be fully integrated with clothes and that can be used for remotely transmitting/receiving the sensor data. Starting from these considerations, in this work, two different methods for wearable antenna fabrication are described in detail: the first resorts to the combined use of nonwoven conductive fabrics and of a cutting plotter for shaping the fabric, whereas the second considered fabrication method resorts to the embroidery of conductive threads. To demonstrate the suitability of the considered fabrication techniques and to highlight their pros and cons, numerical and experimental results related to different wearable antennas are also reported and commented on. Results demonstrate that the presented fabrication techniques and strategies are very flexible and can be used to obtain low-cost wearable antennas with performance tailored for the specific application at hand.

Non-radiative Wireless Power Transmission: Theory and Applications

Non-radiative Wireless power transfer (NR-WPT) is currently receiving considerable attention in very different application scenarios. To design optimum solutions, a systematic approach based on circuit theory is needed and not yet available in the literature. In this chapter, by using a network formalism, the WPT link is modeled as a two-port network and a methodology to derive an equivalent circuit is proposed. This allows to compute in a rigorous and general way the maximum achievable performance for any given WPT link. The latter can be expressed in terms of either maximum power transfer efficiency (MPTE), or maximum power delivered to the load (MPDL), or by any suitable combination of the two. This chapter provides a comprehensive theoretical and general framework to predict such performance for both inductive and capacitive coupled links. In order to facilitate a practical implementation, both impedance and admittance matrix representations are discussed and computational examples are provided.

Durability of Wearable Antennas Based on Nonwoven Conductive Fabrics: Experimental Study on Resistance to Washing and Ironing

Adhesive nonwoven conductive fabrics are appealing materials for fabricating fully textile antennas for wearable wireless systems. Wearable antennas should be flexible, lightweight, and mechanically resistant. Additionally, the antenna performance should be robust to activities related to daily use of garments, such as washing and ironing. Accordingly, in this work, the results of several washing tests performed on fully textile antennas fabricated by exploiting three different adhesive nonwoven conductive fabrics are reported.

Wearable antennas for applications in remote assistance to elderly people

An effective remote monitoring of elderly people in telehealth applications requires their everyday activities not to be affected by the monitoring. In this regard, a possible strategy is to make sure that the components (i.e. sensor and antenna) necessary to carry out such monitoring are seamlessly integrated within the elderlys daily routine. Starting from these considerations, the present paper addresses the fabrication of wearable antennas that can be fully integrated with clothes and that can be used for remotely transmitting/receiving the sensor data. In particular, in this work, two different wearable antenna fabrication techniques (namely the use of non-woven conductive fabrics in combination with a cutting plotter and the embroidery of conductive threads) are investigated. The obtained numerical and experimental results demonstrate that the proposed fabrication techniques and strategies are very flexible, and can allow obtaining low-cost wearable antenna with tailored performance according to the specific application requirements.