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.

This paper presents a novel biotelemetry system based on a fully-passive architecture; High Electron Mobility Transistors are used as sensing elements. The main advantages and drawbacks related to the approach here proposed are deeply analyzed and some possible solutions identified. Furthermore, some preliminary experimental results are given and discussed.

This paper presents a novel electrical model of multi-walled carbon-nanotube based gas sensors completely patterned using low-cost inkjet printing. The obtained results (validated through measurements from 50 MHz to 3 GHz) demonstrate that the nanostructure-based sensing mechanisms yields a quite evident shift of circuit resistive elements. A narrowband investigation of the resistive variation depending on gas concentration has been performed as well. The input impedance has been found to be significantly lower than that reported for metal oxide sensors, thus facilitating the integration in electronic circuitry. The suggested equivalent model can be exploited in the implementation of large-scale nanotechnology-enabled inkjet-printed modules.

This paper presents a wireless energy link for wearable applications. The proposed link exploits a magnetic coupling between two resonators fabricated by using a conductive non-woven fabric for the conductive parts and leather as substrate, thus resulting in a prototype that can be easily embedded in wearable accessories such as fashion bags. Experimental data referring to a prototype working in the ISM band (433.05 - 434.79 MHz) demonstrate a power transfer efficiency of about 69 %.

A wireless charger for low capacity thin-film batteries is presented.Theproposed 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 434MHz 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 434MHz, 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 dBmis 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.

This paper presents a new wireless power link fabricated by using a conductive non-woven fabric on a leather substrate, thus resulting in a prototype that can be easily embedded in wearable accessories such as fashion bags. More in detail, in the fabricated prototype (which was designed to work in the ISM band 433.05 - 434.79 MHz), the power transfer was implemented by exploiting a magnetic coupling between two planar resonators. The results related to the characterization of the fabricated wireless power link are presented and discussed. In particular, from experimental data, a power transfer efficiency of about 69 % is demonstrated.

The paper presents a novel planar dipole for Ultra-High-Frequency (UHF) Radio Frequency Identification (RFID) systems is here presented. Referring to a realization based on the use of a chip produced by Texas Instruments, the proposed design approach has been numerically and experimentally investigated. Reported results demonstrate that the proposed antenna exhibits good radiation properties and matching (|S11|<-10 dB) over the entire UHF RFID bandwidth (860-960 MHz).

This paper presents a broadband planar antenna; experimental results demonstrate a relative bandwidth of 122%. As an example of application, the antenna is used in the design of a rectenna for RF energy scavenging, with promising performance.

In this paper, a wearable resonator suitable to be used for both power and data transmission is presented. The basic element is a complementary split ring resonator that has been optimized to operate both as a dipole-like antenna at 2.45 GHz and as the receiver of a resonant energy link operating at 915 MHz when coupled with an identical external resonator connected to a power source. Experimental data referring to a prototype fabricated by using a conductive adhesive fabric on a leather substrate are reported and discussed. With regard to the wireless resonant energy link (WREL), it is demonstrated that at 915 MHz, the RF-to-RF power transfer efficiency of the link is approximately 78.1%. As for the performance obtained when the resonator is used as an antenna, a gain of approximately −0.43 dB was obtained. Additionally, the performance of the proposed link when connected to a Power Management Unit (PMU) that converts the radio frequency (RF) energy received by the wearable resonator into DC energy that can be directly used for recharging a thin-film battery was also investigated. Experimental tests were performed in order to evaluate both the total efficiency of the wireless charger (i.e., the WREL link connected to the PMU) and the time necessary to recharge a THINERGY MEC201 battery. The obtained results demonstrate the feasibility of using the proposed WREL for implementing a battery charger; in particular, by providing an input power higher than 8 dBm, the time necessary to recharge the considered thin-film battery is shorter than 38 min.

This paper provides a rigorous theoretical formulation to obtain an inductive resonant wireless power transfer (WPT) link with load-independent output voltage or current. This is a crucial working condition for wireless battery recharging, where there is no deterministic knowledge of load variation with respect to the battery charging level. The ideal lossless and the realistic lossy configurations are considered for both voltage- and current-excited WPT links. The link transfer matrix (ABCD matrix) is used to determine the operating frequencies where a load-independent output voltage or current can be obtained. It is shown that in the lossy cases that an almost load-independent behavior can be achieved, provided that the load resistance lies in a suitable range and analytical conditions on the load resistance value have been derived. The analytical relationships obtained by this theory are validated by means of both circuit simulation and experimental data at 13.56 MHz.

The paper presents some experimental results obtained for RF-MEMS phase shifters in X-band. Two different phase shifters are considered: a loaded-line and a reflect-line phase shifter. Both devices have been monolithically manufactured on a 525 μm -thick high resistivity silicon substrate. The realized samples exhibit a good agreement between simulated and measured results. Moreover, excellent performance in terms of phase shift have been obtained for the two phase shifters: measurements show a phase error of 0.5% in the case of the loaded-line type and of 4.7% in the case of the reflect-line type.

The paper deals with the design of a wireless power transfer link realized by coupled inductors. It is shown that, for given values of the coupling coefficient and quality factors, by specifying the desired input and output resistances we can find the values of the inductances that realize the maximally efficient wireless power transfer link. Numerical and experimental verifications of the proposed approach are also presented.

In this paper, a rigorous procedure for the circuit-level analysis and design of entire systems, developed to provide power wirelessly, is presented. A unified theoretical approach is first introduced, based on a two-port-equivalent circuit representation, to describe the wireless power transfer link when the transmitter and the receiver are either in the near-field or in the far-field region reciprocally. This approach allows one to compute in a straightforward manner the system figure of merit, namely the power transfer efficiency. Specific guidelines for the two configurations are then intensively discussed together with the adopted software tools based on the combination of full-wave analysis and nonlinear harmonic balance techniques. Several practical examples based on this design procedure are presented, demonstrating predicted and experimental behavior of unconventional devices for both near-field and far-field power transfer usage.

The paper presents a novel multilayer micro-ring structure suitable to be used as THz emitter or detector. The realization process exploits the self-rolling properties of a suspended InGaAs/GaAs bi-layer obtained by controlled strain release of a thin film from a substrate. Numerical and preliminary experimental results will be presented and discussed. It is demonstrated that the proposed approach is an optimum candidate for the design of very high-frequency resonators.

This paper proposes a novel harvester for sensors powering by spurious electromagnetic emissions from compact fluorescent lamps. The proposed device is based on a magnetic coupling and consists of a resonant loop and an RF-to-DC rectifier. Experimental results are reported and discussed. It is shown that up to 0.61 mW can be generated from a 30 W compact fluorescent lamp, thus demonstrating that the proposed harvester is an optimum candidate for powering low-power sensors.

This paper presents an experimental study of the performance of a wireless resonant energy link for implantable biomedical devices. More specifically, the proposed system consists of two planar resonators: a primary resonator that is connected to a power source and operates outside the body, and a secondary resonator that is connected to the implanted device and operates inside the body. Each resonator is a planar spiral resonator; the wireless power transmission is obtained by exploiting the magnetic coupling between the two resonators when they are operating at small distances. A prototype working in the ISM band centered at 434MHz has been developed and analyzed. Reported results confirm that the proposed system is a viable solution for wirelessly providing implantable devices with the power necessary for operation.

This paper investigates the use of different techniques and conductive materials for the fabrication of textile patch antennas. Experimental results referring to the use of a conductive thread, an adhesive copper tape and an adhesive conductive non-woven fabric are reported and discussed. Reported results demonstrate the suitability of the proposed prototypes to be used for wearable applications. © 2013 European Microwave Association.

The solution of large and complex electromagnetic (EM) problems often leads to a substantial demand for high-performance computing resources and strategies. This is true for a wide variety of numerical methods and applications, ranging from EM compatibility to radio-coverage, circuit modeling, and optimization of components. In the last decades, graphics processing units (GPUs) have gained popularity in scientific computing as a low-cost and powerful parallel architecture. This paper gives an overview of the main efforts of researchers to port computational electromagnetics (CEM) codes to GPU. Moreover, GPU implementation aspects of two well-known techniques, namely the finite-difference time domain (FDTD) and the method of moments (MoM), are investigated. The impressive speed-ups achieved (up to 60× and 25× for FDTD and MoM, respectively) demonstrate the effectiveness of GPUs in accelerating CEM codes. © 2012 John Wiley & Sons, Ltd.

This paper proposes a rectifying antenna (rectenna) for operation in the ISM (Industrial, Scientific and Medical) band centered at 2.45 GHz. It consists of a modified circular monopole loaded with a rectangular ring and a half-wave rectifier. Numerical and experimental data are reported and discussed. From measurements, it is demonstrated that, when the power density incident on the monopole is 155 μW/cm², the device here presented exhibits values of the RF-to-DC conversion efficiency higher than 30 % in the frequency range 2.35-2.5 GHz with a maximum of about 50 % at 2.45 GHz.

This paper presents a novel logo-shaped antenna. The proposed antenna has been fabricated by using a conductive non-woven textile on a layer of jeans. Experimental data referring to a prototype working at 1.8 GHz are presented and compared with numerical results. A relative bandwidth of about 70% and a dipole-like radiation pattern is demonstrated.

In this paper a wireless power transfer resonant link using inductive coupling is considered and analyzed on the basis of an artificial transmission line approach. More specifically, a periodic network consisting of inductively coupled LC resonators is studied. It is demonstrated that the analyzed system exhibits a pass-band characterized by negative effective parameters (i.e., a double negative pass-band). In order to validate the proposed approach, comparisons with experimental data and circuital simulations are reported and discussed.

By using a network approach, a wireless inductive link for power transmission from multiple transmitters to multiple receivers is considered. The problem of maximizing the power delivered to the receivers is solved and analytical formulas are presented and validated by circuital simulations.

This work focuses on the use of metal foams, a relatively new class of materials, for high added-value electromagnetic (EM) shields. First, the Shielding Effectiveness (SE) of aluminum foam slabs is experimentally evaluated, showing very good shielding properties. Successively, accurate numerical models of metal foams are proposed and used in a proprietary Variable-Mesh Parallel Finite Difference Time Domain code, in order to characterize the EM properties of slabs of such materials. Afterwards, a third approach is adopted. It consists in the application of the effective medium theories in order to obtain an analytical EM model of the metal foams; this way, their SE can be evaluated with a negligible computational time by using common mathematical tools. Finally, a methodology to design/analyze customized metal foams for EM shield applications is suggested. It takes advantage from the joint use of the numerical and analytical presented approaches, thus allowing a computationally effcient evaluation of SE and other electromagnetic properties of metal foams. Results demonstrate the suitability of metal foam structures for effective EM shielding in many industrial applications, as well as the accuracy of the proposed analytical and numerical approaches.

By using network theory, a wireless power transfer network based on coupled capacitance, that is, on electric field coupling, is numerically investigated. Three possible solutions of interest are considered: one that maximizes efficiency, one that maximizes the power delivered to the load and one that realizes power matching (conjugate matching). In each case, at a selected frequency, the optimal source/load impedances are derived in closed form. It is shown that maximum efficiency solution has the possibility of achieving almost unitary efficiency. It is also shown that, as the efficiency is increased, the power delivered to the load is decreased.

This paper presents a novel antenna for Ground Penetrating Radar (GPR) applications. It consists of two crossed bowtie antennas loaded with an annular ring. Numerical and experimental results are reported demonstrating that the proposed antenna exhibits both a broadband impedance bandwidth and very good radiation properties

This paper presents a rectifying antenna (rectenna) for the harvesting of the microwave energy associated to UHF (Ultra- High Frequency) Radio Frequency IDentification (RFID) systems. The proposed device uses a capacitively loaded T-shaped monopole with a coplanar waveguide feeding line as receiving antenna and a five-stage voltage multiplier as rectifier. Experimental results demonstrating an RF-to-DC conversion efficiency of about 54% with an input power density of 80W/cm2 will be presented and discussed.

In this paper, we describe an accelerated implementa- tion of the Method of Moments (MoM). A framework is proposed, exploiting the graphics processing unit (GPU) computing power by means of the software platform compute unified device archi- tecture (CUDA). The mixed-potential integral-equation formula- tion, applied to microstrip circuit modeling, is adopted, and both the impedance matrix computation and the linear system solution of the MoM are accelerated. The latter point has been handled by considering both a direct dense (LU-based) and an iterative sparse (bi-conjugate gradient stabilized) solver. The best suited method is selected automatically during a thresholding phase, which renders the impedance matrix as sparse as possible. The effectiveness of the GPU-enabled MoM has been extensively tested in the analysis of planar circuits and components. The results achieved confirm the validity, accuracy, and high performance of the proposed ap- proach.

In this article, the use of metal foams for shielding problems is investigated on the bases of an effective medium approach. Specifically, a shielding effectiveness analysis has been performed by modeling metal foams as a homogeneous medium described by a plasma dispersion profile.The suggested approach is experimentally validated demonstrating that metal foams behave like a plasma medium, with a plasma frequency in the microwave range. The proposed effective medium approach has also been implemented both with a proprietary and with a commercial full-wave simulator. Results demonstrate that, by using the plasma model, general electromagnetic analysis of metal foams can be performed with common simulators and with affordable computational efforts.

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.

This paper presents a novel low-profile antenna with a broadside radiation. The proposed design strategy consists in modifying the layout of a classical Vivaldi antenna, thus resulting in compact dimensions and a broadside radiation pattern. Two different ways of implementing the proposed design approach are presented and discussed. More specifically, experimental data referring to two prototypes on a FR4 substrate with an operating frequency of 2.45 GHz are reported. The first layout has approximately the same dimensions of a Vivaldi antenna and a directivity of about 7 dBi, the second one has more compact dimensions (the dimensions are smaller than the ones of a standard patch antenna) and a directivity of about 5 dBi.

The optimal design problem for a wireless power transfer link based on a resonant inductive coupling is addressed in this paper. It is assumed that the magnetic coupling coefficient and the inductor quality factors are known. By employing the conjugate image impedances, the values of the inductances realizing the optimal design with respect to given values of the network input and load impedances are derived. It is demonstrated that there is just one optimal design maximizing both the power delivered to the load and the power transfer efficiency of the link. The four possible schemes corresponding to the use of a parallel or a series arrangement for the two coupled resonators (Parallel-Parallel, Series-Series, Parallel-Series, and Series-Parallel) are considered and discussed. Closed form analytical formulas are derived and validated by circuital simulations.

The problem of determining the optimal loads for realizing maximum power transfer in a wireless energy link between one transmitter and multiple receivers has been considered and solved by applying the maximum power transfer theorem for an N-port. Simple analytical expressions for the load impedances have been derived and validated through experiments and circuital simulations. These expressions are also valid in the case of mutual coupling between receivers

In this article we adopt the graphical processing units as a low-cost and efficient solution of challenging electromagnetic numerical problems. Based on the compute unified device architecture, an optimized method of moments algorithm has been implemented which adopts direct solvers based on LU decomposition. Numerical results obtained on the practical case of a patch antenna analysis demonstrate the high performance of the approach

Based on a magnetic coupling, this paper presents a novel device for power generation by spurious electromagnetic emissions from compact fluorescent lamps. The proposed scavenger consists of a resonant loop and an RF-to-DC voltage converter. Results of experimental tests performed with a 30 W compact fluorescent lamp are reported and discussed. It is shown that 0.61 mW can be generated, thus demonstrating the suitability of the proposed device for powering low-consumption sensors.

This chapter provides a general overview of magnetic resonant wireless power transfer systems based on network models. The power transferred to a receiver load at resonance is derived and explained. It is also shown the importance of using appropriate matching networks and how to design the oscillator and the load rectifier.

This paper focuses 1 on power generation by spurious electromagnetic emissions from compact fluorescent lamps. Based on magnetic induction, a novel device consisting of a resonant loop and an RF-to-dc voltage converter is presented. Experimental tests referring to different configurations and fluorescent lamps are reported and discussed. It is demonstrated that the proposed harvester is an optimum candidate for enabling energy autonomy of a wireless sensor node.

This paper presents a wireless power link for powering implantable medical devices. The proposed link operates at 403 MHz and exploits magnetic coupling between an external resonator and an implanted resonator to wirelessly provide power to implantable devices. Experimental results for remote powering of pacemakers are reported and the compliance with safety guidelines is discussed. It is demonstrated that the proposed wireless link is able to deliver up to 1 mW with an induced 10-g average specific absorption rate lower than 1.08 W/kg. This value is significantly below the 2-W/kg recommended limit, thus proving the suitability of the proposed system to be used to energize modern pacemakers.

In this paper the possibility of achieving a coupling-independent operating regime for a Wireless Power Transfer Link based on resonant inductive coupling is theoretically and experimentally investigated. The two different cases of a link using either asynchronous or synchronous resonators are analyzed and discussed. It is shown that a coupling-independent regime can be realized by an appropriate selection of the operating frequency of a synchronous WPT link having a coupling coefficient above a critical value which depends on the resistive load of the link.

In this paper the feasibility of achieving a coupling-independent performance for a Wireless Power Transfer Link based on resonant inductive coupling is investigated. Theoretical and experimental results demonstrating that a coupling-independent regime can be realized by an appropriate selection of the operating frequency of a strongly-coupled synchronous WPT link are reported and discussed.

The paper focuses on a near-field wireless power transmission link consisting of two magnetically coupled inductances. The case of a resonant coupling realized by adding appropriate compensating capacitances is solved. By using a network formalism, the link is modeled as a two-port network and rigorously analyzed in the case where both the input impedance and the load are specified. In particular, it is demonstrated that there is just one optimum design of the network that allows maximizing both the efficiency and the active power on the load. Closed-form design formulas for the optimum design are presented and validated by circuital simulations.

In this work, the validation and the practical implementation of a methodology exploiting a time domain reflectometry (TDR)-system for monitoring rising damp in building structures are described in detail. The proposed system employs wire-like, passive, diffused sensing elements (SEs) that are embedded, at the time of construction or renovation, inside the walls of the building to be monitored. The SEs remain permanently inside the wall, ready to be interrogated when necessary. Experimental and simulation results are reported, which demonstrate the possibility of practical implementation and the associated performance in terms of sensitivity.

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.

In this work we concentrate on the two possible regimes at which wireless power transfer can be attained. One regime allows to maximize either the power on the load or the efficiency, at a given fixed frequency, by changing the load value. Another regime keeps a fixed value for the load and, for a relatively wide variations of the coupling coefficient, attains fixed efficiency and power transfer by selecting an appropriate working frequency. These two operating regimes are rigorously introduced, relative solutions are analytically expressed and illustrated via numerical simulations.

We investigate the thickness dependence of the amplified spontaneous emission (ASE) threshold and operational lifetime in air-poly(9,9-dioctylfluorene)(PF8)-glass asymmetric active waveguides. We show that the ASE threshold decreases with the film thickness up to about 200 nm, and increases for higher thicknesses. The ASE operational lifetime increases with the thickness up to about 300 nm, and it is almost thickness independent for higher thickness. We show that the observed results are related to the guided mode confinement in the waveguide and to the spatial overlap between the guided modes and the excited region in the film.

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.

This study presents a wearable antenna for a global positioning system-global system for mobile communication (GPS-GSM)-based anti-theft tracking system to be embedded in high-cost clothing and luggage accessories (such as leather bags). To assess the feasibility of this solution, a prototype antenna was designed mimicking the shape of one of the Levi Strauss & Co.'s logos, and it was fabricated using a conductive non-woven fabric on a layer of leather. Furthermore, to cover both the GPS L1 and the GSM-1800 bands with a single radiating element, positive-intrinsic-negative (PIN) diodes were employed to reconfigure the operating frequency of the antenna. Experimental data demonstrating the feasibility of the proposed design strategy are presented and discussed.

This paper presents a wireless energy link for rechargeable implantable pulse generators for deep brain stimulation. The proposed link exploits a magnetic coupling between two compact planar resonators. From experimental results referring to a prototype working in the MedRadio band a transfer efficiency of about 10.62% is demonstrated.

This paper focuses on non-radiative wireless power transfer implemented by means of a resonant magnetic coupling. The case of one transmitter and two receivers is considered and a rigorous analytical procedure is developed demonstrating that maximum power transfer or maximum efficiency can be achieved by appropriately selecting the load values. Both cases of coupled and uncoupled receivers are solved; closed formulas are derived for the optimal loads, which maximize either power or efficiency. It is shown that the resistances that realize maximum power transfer are always greater than the resistances that realize maximum efficiency. According to this observation, an optimal range of operation for the load resistances is also determined. Furthermore, it is demonstrated that in the case where the receivers are coupled the introduction of appropriate compensating reactances allows retrieving the same results corresponding to the uncoupled case both for powers and efficiency. Theoretical data are validated by comparisons with numerical results.

This paper proposes a novel wireless link for energizing pulse generators for deep brain stimulation. The proposed link consists of two magnetically coupled planar resonators. Experimental results referring to a prototype working in the MedRadio band and using minced pork in order to take into account the presence of human tissues are reported and discussed. Results obtained this way demonstrate a transfer efficiency of about 10.62 %. The compliance with safety regulations is also verified by means of full-wave simulations.

A wireless transfer link between three magnetically coupled resonators has been considered. Two different configurations have been investigated. In one case a single transmitter and two receivers are present. In the other case two transmitters and a single receiver are employed. For each case optimal analytical solutions for the load values that maximize the power delivered to the load(s) and the efficiency have been found and validated by comparisons with circuit simulations.

A wireless power transmission link with two transmitters and single receiver is analyzed and the problem of how to maximize the power delivered to the load is solved. The case of three magnetically coupled resonators is considered and analytical formulas are derived and validated by circuit simulations.

We propose the realization of a compact fully-passive biotelemetry tag composed of a high-electron mobility transistor (HEMT) connected to a wireless link. The Gallium Arsenide based gateless HEMT serves both as the environmental sensing element and as the amplitude modulator of the carrier signal received by the antenna. A prototype demonstrator operating in the MHz range has been developed: it consists of an array of transistors with different gate geometries and two spiral loop resonators implementing the wireless link. More specifically, one resonator (Tag-resonator) is connected to the array of transistors, while the other one (Reader-resonator) is connected to a power generator/reader device; the wireless link uses the magnetic coupling between the two resonators. Experimental results demonstrate that the reader-resonator exhibits an intensity modulation of the resonance dip depending on the voltage applied to the HEMT gate. These results will be used as a guideline for the realization of biocompatible sub-millimeter tags operating in the Gigahertz frequency range.

This letter presents a novel X-band planar rectenna (i.e., a rectifying antenna). The proposed device consists of a slot antenna and a microstrip rectifying circuit. A realization on a low- cost FR4 substrate, using a surface-mount Schottky barrier diode (the HSMS-8202 diode by Avago Technologies) as the rectifying element, is proposed

L’invenzione proposta è un ‘harvester’ ottimizzato per la generazione di energia a partire dalle emissioni elettromagnetiche spurie delle lampade a fluorescenza. Nello specifico, il prototipo sviluppato è costituito da una spirale in rame (il trasduttore) e da un rettificatore ad onda intera (un ponte di diodi) e da un filtro passa-basso. La generazione di energia è ottenuta grazie ad un accoppiamento magnetico tra la spirale in rame e le emissioni spurie di lampade a fluorescenza comunemente utilizzate per l’illuminazione in ambiente domestico.