Laurent Cirio

A Dual Circularly Polarized 2.45-GHz Rectenna for Wireless Power Transmission

A 2.45-GHz rectifying antenna (rectenna) using a compact dual circularly polarized (DCP) patch antenna with an RF-dc power conversion part is presented. The DCP antenna is coupled to a microstrip line by an aperture in the ground plane and includes a bandpass filter for harmonic rejections. It exhibits a measured bandwidth of 2100 MHz (10 dB return loss) and a 705-MHz CP bandwidth (3 dB axial ratio). The maximum efficiency and dc voltage are respectively equal to 63% and 2.82 V over a resistive load of 1600 Ω for a power density of 0.525 mW/cm2.

Diversity Measurements of a Reconfigurable Antenna With Switched Polarizations and Patterns

A reconfigurable parasitic patch array is designed to provide polarization and pattern diversities. The performance of the device is predicted using a commercial simulator including a pin diode modelling and an optimization procedure of the switched loads based on an equivalent flow graph. Measurements of the correlation factor and the diversity gain in an indoor environment are performed with a dedicated platform for two orientations of the antenna.

Low-cost converter for harvesting of microwave electromagnetic energy

Energy harvesting receives a lot of attention whatever the physical domain of energy. Microwave electromagnetic energy represents a large reserve to harvest. Present papers details conversion schemes depending on the value of the electromagnetic field. Practical measurements show that fields from 1.5V/m to 30V/m may be encountered. There is a need for high-efficiency converters and various architectures are considered depending on the field range. Simulation results give the analysis of the architectures and the attainable efficiency. Experiments confirm the results. Associated to multiantenna system, it is possible to design a harvesting converter for various consumers.

A 2.45-GHz localized elements rectenna

This paper presents new methodology of rectenna circuit conception. Succeeding sources theory, generally used for power electronics conversion, is presented here and integrated to rectenna circuit design. Circuit simulation based on good filter dimensioning which is sufficient for rectenna design is presented. Localized elements technology is employed here to make the circuits instead of micro strip lines technology usually used to make rectenna circuits. Simulation results are presented and validated by measurement results.

An Efficient Dual - Circularly Polarized Rectenna for RF Energy Harvesting in the 2 . 45 GHz ISM Band

This paper reports a 2.45 GHz, low power dual circularly polarized (DCP) and dual access rectenna. It contains two dc-recombined rectifiers and a cross-slot coupled square patch antenna fed by a microstrip line. A judicious dc recombination scheme allows to minimize the RF power imbalance between accesses caused by multipath effects and consequently arbitrary polarized incident waves. The proposed rectenna is then able to harvest linearly polarized, right-hand circularly polarized (RHCP) and left-hand circularly polarized (LHCP) electromagnetic waves, with nearly stable performances. The rectenna has been optimized at -15 dBm per access and dedicated to remote and contactless supply low consumption sensors. It has been experimentally tested with very low power densities from 0.057 μW/cm2 (Erms=0.46 V/m) to 2.3 μW/cm2 (Erms=2.95 V/m). At 1.49 μW/cm2 (-15 dBm on each rectifier), the structure exhibits an output dc voltage and a global efficiency of 189 mV and 37.7%, respectively when the azimuthal angle (Φ) of the incident field is equal to 0°. Due to the nearly constant total gain of the DCP antenna and an appropriate dc recombination of the two rectifiers, the global efficiency slightly varies between 37.7% and 41.4% when the azimuthal angle (Φ) varies between -90 and 90°.

A 2.45-GHz dual-diode rectenna and rectenna arrays for wireless remote supply applications

This paper describes a compact and efficient rectenna based on a dual-diode microstrip rectifier at 2.45 GHz. This circuit has been designed and optimized using a global analysis technique which associates electromagnetic and circuit approaches. Due to the differential topology of the rectifier, neither input low-pass filter nor via-hole connections are needed. This makes the structure more compact reducing losses. Measurements of a single rectenna element show 83% efficiency over an optimal load of 1050 V at a power density of 0.31 mW/cm2. To increase the received RF power and then increase dc power over the load, identical rectennas have been interconnected to form arrays. Two and four elements rectenna arrays, connected either in parallel or in series, have been developed. It was shown that by properly choosing the interconnection topology and the optimal output load, higher dc voltage or dc power have been obtained. The four-element series-connected array can provide experimentally up to 3.85 times output dc voltage compared to the single rectenna. The parallel-connected rectenna arrays generate approximately 2.15 and 3.75 times output dc power for two and four elements, respectively.

Design and Characterization of an Efficient Dual Patch Rectenna for Microwave Energy Recycling in the ISM Band

This paper describes the design, modeling and optimization of an efficient ISM band dual patch rectenna capable of achieving more than 80% RF-to-DC conversion efficiency at low/medium power densities. The circuit is based on a full-wave rectifier, designed and optimized at 2.45 GHz with ADS software and the FDTD algorithm. The performances of the rectenna have been accurately predicted using the full-wave 3D-FDTD method extended to lumped linear and non-linear elements. It exhibits 73% (VDC = 1.1 V for RL= 1.2 kΩ) measured efficiency at a low power density of 14 μW/cm2 and 84% (VDC = 1.94 V) at 43 μW/cm2. The differences between the experimental and FDTD simulated efficiencies are less than 3%. The proposed circuit is particularly suitable for low/medium power recycling and power remote supply of wireless sensors, sensor nodes and actuators.

Ultra-Low Power, Low Voltage, Self-Powered Resonant DC-DC Converter for Energy Harvesting

This article presents a resonant DC-DC converter suitable for ultra-low power and low voltage sources. This original topology allows a self-starting and a self-operation under harsh conditions of input voltage and power without any additional start-up assistance. A global theoretical modeling of the converter which includes start-up and steady-state phases is presented and a methodology for optimal design is detailed. It is based on the combination of both theoretical calculations and circuit simulations. Experimental tests based on discrete prototypes are carried out in order to demonstrate the good operation of the converter. Experimental tests have been achieved using an RF energy harvesting source. Ultra-low power and low voltage conditions as low as 3 μW and 100 mV respectively can be achieved as demonstrated by the experimental measurements. The input low voltage is stepped-up to a conventional level of some volts, what allows to power autonomously and solely low power circuits from energy harvesting sources.

A differential printed antenna design for multiband impulse radio transmitter at 60 GHz

We propose in this paper two microtrip planar antennas dedicated to a 60 GHz high data rate Impulse Radio Multi-band On Off Keying (IR-MBOOK) low power consumption transmitter architecture. The planar antennas were designed and simulated on a conventional and low-cost RT/Duroid 5880 substrate, and then are connected after two differential Power Amplifiers. The antennas serve for radiation as well as an out-of-phase power combiner. In this solution, the 57.05-63.7GHz dedicated band is separated into four balanced sub-bands. We propose the use of two differential planar antennas to cover the dedicated bandwidth on the transmitter architecture. An antenna covers the first 57.05-60.257GHz sub-band (band 1 and 2) and a second antenna covers the 60.257-63.7GHz sub-band (band 3 and 4). The planar antennas 1 and 2 were designed and simulated using the electromagnetic HFSS software and they give a maximum gain of 9.81 dBi and 10.03 dBi, respectively.

CPW-fed patch antenna with switchable polarization sense

This paper presents the design and development of a CPW-fed microstrip patch antenna with polarization reconfigurability (RHCP/LHCP). The basic antenna is a circular microstrip antenna excited by a CPW-fed diagonal slot and a CPW open end. First, experimental and simulated results are presented for the passive antenna. Then, an active antenna using beam-lead PIN diodes to switch the polarization sense is proposed. Simulations are presented including electrical parameters for the diode modeling. The deviation between simulated and experimental results is finally discussed.