scholarly journals Analytical Optimal Load Calculation of RF Energy Rectifiers Based on a Simplified Rectifying Model

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 8038
Author(s):  
Lichen Yao ◽  
Guido Dolmans ◽  
Jac Romme
Keyword(s):  
Numerical Method ◽  
Low Complexity ◽  
Input Power ◽  
Lambert W Function ◽  
Wireless Power ◽  
Closed Form Solutions ◽  
Optimal Load ◽  
Half Wave ◽  
Input Signals ◽  
Parasitic Parameters

Wireless power transfer (WPT) is an essential enabler for novel sensor networks such as the wireless powered communication network (WPCN). The efficiency of an energy rectifier is dependent on both input power and loading condition. In this work, to maximize the rectifier efficiency, we present a low-complexity numerical method based on an analytical rectifier model to calculate the optimal load for different rectifier topologies, including half-wave and voltage-multipliers, without needing time-consuming simulations. The method is based on a simplified analytical rectifier model based on the diode equivalent circuit including parasitic parameters. Furthermore, by using Lambert-W function and the perturbation method, closed-form solutions are given for low-input power cases. The method is validated by means of both simulations and measurements. Extensive transient simulation results using different diodes (Skyworks SMS7630 and Avago HSMS285x) and frequency bands (400 MHz, 900 MHz, and 2.4 GHz) are provided for validation of the method. A 400 MHz 1- and 2-stage voltage multiplier are designed and fabricated, and measurements are conducted. Different input signals are used when validating the proposed methods, including the single sinewave signal and the multisine signal. The proposed numerical method shows excellent accuracy with both signal types, as long as the output voltage ripple is sufficiently low.

scholarly journals Wireless power transfer system rigid to tissue characteristics using metamaterial inspired geometry for biomedical implant applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ramesh K. Pokharel ◽  
Adel Barakat ◽  
Shimaa Alshhawy ◽  
Kuniaki Yoshitomi ◽  
Costas Sarris
Keyword(s):  
Electromagnetic Waves ◽  
Wireless Power Transfer ◽  
Split Ring Resonator ◽  
Input Power ◽  
Power Transfer ◽  
Wireless Power ◽  
Biomedical Implant ◽  
Safety Regulations ◽  
Wireless Power Transfer System ◽  
Tissue Characteristics

AbstractConventional resonant inductive coupling wireless power transfer (WPT) systems encounter performance degradation while energizing biomedical implants. This degradation results from the dielectric and conductive characteristics of the tissue, which cause increased radiation and conduction losses, respectively. Moreover, the proximity of a resonator to the high permittivity tissue causes a change in its operating frequency if misalignment occurs. In this report, we propose a metamaterial inspired geometry with near-zero permeability property to overcome these mentioned problems. This metamaterial inspired geometry is stacked split ring resonator metamaterial fed by a driving inductive loop and acts as a WPT transmitter for an in-tissue implanted WPT receiver. The presented demonstrations have confirmed that the proposed metamaterial inspired WPT system outperforms the conventional one. Also, the resonance frequency of the proposed metamaterial inspired TX is negligibly affected by the tissue characteristics, which is of great interest from the design and operation prospects. Furthermore, the proposed WPT system can be used with more than twice the input power of the conventional one while complying with the safety regulations of electromagnetic waves exposure.

scholarly journals A Wideband Rectenna Using High Gain Fractal Planar Monopole Antenna Array for RF Energy Scavenging

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Mohammad M. Fakharian
Keyword(s):  
Antenna Array ◽  
Conversion Efficiency ◽  
Power Level ◽  
Impedance Matching ◽  
High Gain ◽  
Input Power ◽  
Monopole Antenna ◽  
Energy Scavenging ◽  
Wireless Power ◽  
Circuit Performance

This paper introduces a wideband rectenna that can scavenge ambient wireless power to a range of frequency band from 0.91 GHz to 2.55 GHz efficiently. The proposed rectenna is based on a wideband 2 × 2 fractal monopole antenna array with omnidirectional radiation patterns and high gains of 5 to 8.3 dBi at the desired bands. An improved two-branch impedance matching technique is presented which is designed to enhance the rectifier circuit performance with a relatively low input power ranging from −25 dBm to 10 dBm. Also, a full-wave wideband rectifier that can suitably improve the RF-to-DC power conversion efficiency is designed for the rectenna. A peak efficiency of 76%, 71%, 61%, and 62% is obtained at 950, 1850, 2100, and 2450 MHz, respectively. Measurement results show that a conversion efficiency of 68% has been achieved over an optimal 4.7 kΩ resistor when the simultaneous four-band input power level is −10 dBm. Moreover, an output DC voltage of around 243 mV with voltage varying within 160–250 mV can be achieved by gathering the low ambient wireless power inside laboratory. This study proves that the proposed rectenna can be applied to a range of many low-power electronic applications.

scholarly journals Wireless Power Transfer to a Microaerial Vehicle with a Microwave Active Phased Array

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Shotaro Nako ◽  
Kenta Okuda ◽  
Kengo Miyashiro ◽  
Kimiya Komurasaki ◽  
Hiroyuki Koizumi
Keyword(s):  
Phased Array ◽  
Wireless Power Transfer ◽  
Axial Ratio ◽  
Input Power ◽  
Power Transfer ◽  
Wireless Power ◽  
Phased Array Antenna ◽  
Power Fluctuation ◽  
Microwave Beam ◽  
Yaw Angle

A wireless power transfer system using a microwave active phased array was developed. In the system, power is transferred to a circling microaerial vehicle (MAV) by a microwave beam of 5.8 GHz, which is formed and directed to the MAV using an active phased array antenna. The MAV is expected to support observation of areas that humans cannot reach. The power beam is formed by the phased array with eight antenna elements. Input power is about 5.6 W. The peak power density at 1,500 mm altitude was 2.63 mW/cm2. The power is sent to a circling MAV. Therefore, the transfer beam should be polarized circularly to achieve a constant power supply independent of its yaw angle. To minimize the polarization loss, a sequentially routed antenna (SRA) was applied to the transmitter antenna. Results show that the axial ratio of 0.440 dB was accomplished and that power fluctuation was kept below 1%.

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