Diego Masotti

Remotely Identify and Detect by a Compact Reader With Mono-Pulse Scanning Capabilities

In this paper, we develop a new microwave reading system able to select and detect hidden tagged objects, static and mobile, in harsh electromagnetic (EM) environments. This is obtained by augmenting standard RF identification reader operations with electronic beam scanning of a mono-pulse array. We present detailed description of the system blocks design, carried out making use of nonlinear EM co-simulation. Custom designed components, such as the printed-dipole array and the wide-range phase shifter, are integrated with low-power commercial transceivers and MCUs. The system architecture is optimized in such a way that a low-cost light weight handheld prototype is obtained, able to perform tagged-ambient scanning with practically no need for time consuming signal processing. The system, i.e., remotely identify and detect (RID), is developed to operate in the 2.45-GHz band, but the design approach is frequency scalable: the higher the operating frequency, the closer can the tags be to be successfully selected or detected. RID functions are successfully tested in public indoor spaces and demonstrate RID aptness of being used as interaction device capable to map physical spaces into smart spaces.

A reconfigurable impedance matching network entirely manufactured in RF-MEMS technology

In this work we present a reconfigurable impedance matching network for RF (Radio Frequency) applications, entirely manufactured in MEMS technology (RF-MEMS). The network features four impedance sections. The way they load the RF line (i.e. in series or shunt configuration) as well as the type of impedance they realize (purely capacitive, inductive, or both in parallel) are reconfigured by means of RF-MEMS cantilever-type ohmic switches. A few specimen of the network have been fabricated using the RF-MEMS technology platform available at FBK and experimentally characterized. In particular, the electromechanical characteristic of the RF-MEMS switches is observed, and the upward bending of the switches contact tips made the characterization of the RF behavior impossible. The non-planarity is due to the accumulation of residual stress within the suspended Gold layer during the release of suspended structures, and is currently being mitigated by performing a low-temperature release step. Electromagnetic simulations (S-parameters) of the RF-MEMS network are also reported in this paper, showing the wide range of impedance transformations enabled by such a complex device based on MEMS technology.

A flag-shaped printed dipole array for ambient scanning

The design and performances of a low-cost light-weight two-element array in printed circuit technology is presented. The array far-field is designed in such a way to be suitably adopted by “smart” RFID readers, which do not limit themselves to collect IDs only. On the contrary they are capable to interact with tagged objects, even hidden, widely distributed in physical ambient, and to exchange data with them. For this purpose the array implements the RADAR-Monopulse technology coupled with beam steering capabilities which allow the reader to track the signal direction of a specific tag, located in close proximity to others, and selectively interact with it. The design is developed to operate in the 2.45-GHz band but it is frequency-scalable: the higher the operating frequency the closer can be the tags to be successfully selected or detected.

Detection of closely-spaced objects by a low-cost reader at 2.45 GHz

A new long-distance microwave reading system is introduced, that we shall call RID (Remotely Identify and Detect), able to locate and identify objects in harsh indoor environments. This is obtained by augmenting standard RFID reader operations with the mono-pulse RADAR principle and electronic beam scanning capabilities. In this way reading failures due to operation in severe fading environments are effectively overcome. The technique is experimented at 2.45 GHz and may be frequency-scalable: the higher the operating frequency the closer can be the tags to be detected. The system is realized by a suitable combination of custom designed components, such as a double printed-monopole array with electronic scanning capability, and of low-power commercial transceivers and MCUs. This results in an handheld low cost device with total dimensions comparable with typical PDAs. The system capabilities are demonstrated in indoor scenarios locating and selecting closely-spaced tagged items, fixed or moving. From this view point RID could be an answer to the intense research and industrial interest solicited by the needs of interacting with systems of devices, such as sensors and actuators, capable of improving the living conditions both at home and in a work space.

Circuit-level nonlinear/EM co-simulation and co-design of UWB receivers

The paper describes an efficient and accurate circuit-level approach to the co-design of UWB receivers integrated with broadband antennas. A full nonlinear simulation of the front end is integrated with the electromagnetically (EM)-based description of the antenna impedance and far-field performance. For each direction of incidence of the transmitted UWB pulse, a circuit description of the receiver excitation under the form of a set of Norton equivalent current sources is generated by EM theory. The source internal impedance is the antenna impedance determined by full-wave EM analysis. The receiver nonlinear analysis is carried out by a model-order reduction Harmonic Balance (HB) technique based on Krylov subspaces. The procedure allows the actual receiver sensitivity to be accurately evaluated by taking into account the amplitude and phase distortion introduced by the antenna, which may significantly change with the UWB pulse direction of incidence. It also allows an effective prediction of the link power budget, which is particularly critical in ultra-low power Impulse Radio (IR) -UWB applications.

Micro-Power Scavenging from Multiple Heterogeneous Piezoelectric and RF Sources

Since power harvesting applications are often constrained by the low levels of power available from individual energy transducers, it is essential for energy converters to efficiently deal with multiple independent and heterogeneous sources. This paper will present two actively controlled power conversion schemes able to deal with multiple piezoelectric and radio-frequency (RF) energy sources. Both converters are based on active control and make use of an ultra-low power standard microcontroller unit. The intrinsic power consumption of the harvesters are respectively 5.5 and 6.8μW per source. The power harvesters were characterized with commercial piezoelectric transducers and with a custom designed rectenna. The achieved values of harvested power of tens of μW show that active control boosts performance of at least +41% as a worst case at the expense of a negligible intrinsic power consumption.