1,721,112 research outputs found
Measurement of Time-Based Arrays for Massive Tags Localization
No full textThe paper describes a time-based driving strategy of a compact antenna array suitable for future 5G IoT applications. Array elements are selectively activated in real-time for agile localization of and energy transfer to tagged objects, randomly distributed in harsh electromagnetic environments. The exploitation of time-modulation technique allows to simultaneously radiate at both the carrier frequency and the sideband harmonics due to the superposition of the nonlinear switches driving (or modulation) frequency. These arrays result in a very simple architecture if compared to standard arrays. Despite this, their characterization is not straightforward: in this paper some preliminary measurements of a two-element array for localization purposes are presented
Dual-Purpose Metasurface for Background Insensitive UWB Tag : (Invited Paper)
No full textA circularly polarised metasurface is proposed in this paper. The design of the surface aims at improving the performance of a hybrid radiating structure made of one dipole and an Archimedean spiral antenna designed on the same surface. The antennas operate in UHF and lower European UWB bands, respectively, and realize a compact single-port antenna for future generation autonomous RFID tags. A High Impedance Surface (HIS) is employed as the ground plane to serve as a Perfect Magnetic Conductor (PMC), with the double purpose to maintain both the circular polarization in the UWB band and the low-profile stack-up, while assuring an insensitive behaviour to the background material
Ad-hoc WPT Exploiting Multi-sine Excitation of Linear Frequency Diverse Arrays
No full textIn this work an effective solution for real-time focusing of frequency diverse arrays (FDAs) is proposed, to be exploited for intentional far-field wireless power transfer (WPT) applications. With respect to the literature where improved focusing capabilities of the traditional linear (1-D) FDAs are achieved at the expense of frequency distributions following non-linear rules (e.g., logarithmic) or complex 2-D arrangements of the transmitting architecture (e.g., concentric circular distribution), the proposed solution provides the best performance with a simpler transmitting layout. In fact, this technique proposes a multi-sine excitation for each radiating element: in this way the performance in terms of dimension of the radiated beam are improved, avoiding the well-known and critical 'S-shape' of the beampattern (BP) that is useful for radar and localization application, but not for precise and ad-hoc smart WPT. The mathematical model able to fully describe the radiation properties of the multi-sine frequency diverse array (MSFDA) is presented and the unprecedented capabilities, in terms of power focusing and ease of design, are demonstrated. MSFDA is thus proposed as an excellent solution for far-field precise WPT able to avoid sensible targets when powering: this is obtained by moving the complexity from the antenna design to the signal generation block, where advanced and sophisticated systems as software defined radio (SDR) are envisaged
RF/microwave energy-autonomous systems
No full textThis work overviews the design methodologies and
system architectures for the successful activation of batteryless RF/microwave systems and their reliable operation in the
context of the Internet-of-things paradigm, which is usually
characterized by harsh electromagnetic environments. A
multi-domain design approach is outlined, combining EM
theory and numerical simulation with nonlinear circuit
design, enabling consistent performance predictions of the RF
systems. System examples are considered for both the TX and
the RX sides suitable for application in Industrial and civil
scenario
Engineered and miniaturized 13.56 MHz omni-directional WPT system for medical applications
No full textThis paper proposes the design of an engineered Wireless Power Transfer circuit for a 13.56 MHz miniaturized Inductive Resonant Wireless Power Transfer (IR-WPT) link for medical applications. The IR-WPT system is composed of a miniaturized receiver realized through three orthogonal coils winded up around a 3D-printed spherical structure. In order to create a compact system and maximize the EM coupling all the rectification circuitry needs to be placed inside the geometrical sphere. Thus, the PCB dimensions and arrangement are limited by the small volume available inside the plastic structure, less then 1 cm3, and by the 3D shape of the system, which forces the PCB layout to exploit an orthogonal arrangement with separated blocks. The circuitry component packages are chosen in order to minimize the encumbrance and ease the connection with each orthogonal coil. The equivalent circuit model is optimized with respect to the Power Transfer Efficiency (PTE) at a 5 cm Tx-Rx distance. To investigate the effect of the human body on the system performance, simulations are carried out exploiting an equivalent model of the human body tissues inside which the receiver is placed, at the same reference distance. The system performance is comparable for both cases: a 15 % average PTE and dc-output voltage exceeding 1.5 V are calculated for a 10 V input source
Range selective power focusing with time-controlled bi-dimensional frequency diverse arrays
No full textIn this contribution an effective solution for the exploitation of frequency diverse arrays (FDAs) for a precise transfer of power is proposed. The time-dependent radiation mechanism is controlled by a periodic pulse sequence at the radiating elements port. In this way, one can easily select the distance where the power has to be sent, thanks to the direct relationship established between the distance and the time window position within one period. The effectiveness of the time-based architecture is numerically demonstrated through a multi-finger planar array operating at millimeter-wave. Preliminary measured results in the microwave range confirm the FDA unique capability of controlling the range-dependent behavior if pulsed excitations are adopted
Wireless Power Transfer Procedure via Hybrid Frequency Diversity
No full textThis paper investigates the versatility of Frequency Diverse Arrays (FDAs) for smart transmission of power. A linear frequency distribution is compared to a logarithmic one in case of a series-fed multi-finger planar array operating at 24 GHz. Both the localization and the powering of potential targets placed in the scanning plane can be effectively performed with an FDA: however, the retrieval of the target position calls for a linear arrangement of the frequencies, whereas a logarithmic one is suitable for a precise transmission of the power. The envisaged scenario needs for an agile software control of the radiating system but pave the way to future capillary transfer of power
Smart beamforming techniques for “on demand” WPT
No full textThis chapter focuses on smart radiating solutions for wireless power transfer (WPT) purposes, being the energy-aware transmission of power the weakest and less efficient step in the entire link budget estimation. The exploitation of time as additional degree of freedom in the transmitting array synthesis makes time-modulated arrays (TMAs) potential candidate for future telecommunication applications, as WPT: their almost real-time ease of reconfiguration allows an agile and dynamic transmission of the signal/energy. Moreover, TMAs rely on a peculiar radiation phenomenon: the possibility to deploy additional radiating frequencies, besides the fundamental radio-frequency (RF) carrier, generated by the superposition of the carrier itself and the low frequency used to drive the nonlinear switches placed at each antenna port. This sideband radiation can be favorably exploited thus making TMAs multiharmonic radiators at the same time: a smart WPT procedure relying on this capability is demonstrated. The importance of a complete software tool, combining full-wave and nonlinear circuit techniques for the accurate estimation of TMAs complex regime, is also highlighted in the chapter
Ranging On-Demand Microwave Power Transfer in Real-Time
Full text linkThis letter presents a novel system for real-time ranging wireless power transfer (WPT) 'on-demand.' This is obtained by duty-cycling a frequency diverse array (FDA) and by suitably choosing the time delay of the pulse. First, the theoretical design of the time-and frequency-dependent array is developed, and then it is applied to predict the ranging performances of a 16-element linear array. The simulations demonstrate the system's ability not only to dynamically select the area for energy focusing but also to reduce the energy intensity in undesired areas. The sharpness of this operation depends on the number of elements of the array. For validation purposes, a demonstrator has been implemented making use of the software-defined radio (SDR) Xilinx RFSoC ZCU111 to dynamically generate various radio signal excitations of the antenna array. To comply with the adopted SDR the operating frequency is 1.8 GHz and a four-element array is used. First measurements confirm the ranging capabilities of the proposed solution
A New Wheel-Spoke Transmitter for Efficient WPT Based on Frequency Diversity
No full textIn this work an effective and feasible solution at
millimeter-wave for real-time focusing of Frequency Diverse
Arrays (FDAs) is proposed, to be exploited for intentional farfield Wireless Power Transfer (WPT) applications. A confined
and precise spot to concentrate the power is obtained by a novel
3-D multi-layer wheel-spoke like array of patch antennas,
exploiting circular symmetry, directly connected with microstrips
through metallized via holes. The system is theoretically
developed and numerically demonstrated by the full-wave
analysis of the realistic layout of 32-element, wheel-spokearranged FDA with a center frequency of 24 GHz. The simulated
results of the realistic layout demonstrate that this solution offers
unprecedent capabilities in terms of power focusing and ease of
design, with respect to the state-of-the-art. Preliminary
measurements of the wheel-spoke transmitter are provided for
validation of the adopted feeding technique based on direct
connection between microstrips and patches through metallized
via hole arranged in circular symmetr
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