A Compact Dual-Port Multi-Band Rectifier Circuit for RF Energy Harvesting

This paper presents a compact multi-band rectifier with an improved impedance matching bandwidth.It uses a combination of–matching network(MN)at Port-1,with a parallel connection of three cell branch MN at Port-2.The proposed impedance matching network(IMN)is adopted to reduce circuit complexity,to improve circuit performance,and power conversion efficiency(PCE)of the rectifier at low input power.The fabricated rectifier prototype operates at 0.92,1.82,2.1,2.46 and 2.65 GHz covering GSM/900,GSM/1800,UMTS2100,and Wi-Fi/2.45–LTE2600.The size of the compact rectifier on the PCB board is 0.13λ_(g)×0.1λ_(g).The fabricated rectifier achieved an RF-to DC(radio frequency direct current)PCE of 31.8%,24%,22.7%,and 15%,and 14.1%for−20 dBm at the five respective measured operating frequencies.The circuit attains a peak RF-to-DC PCE of 82.3%for an input power of 3 dBm at 0.92 GHz.The proposed rectifier realizes an ambient output dc voltage of 454 mV for multi-tone input signals from the two ports.The rectifier drives a bq25504-674 power management module(PMM)to achieve 1.21 V from the two-port connection.The rectifier has the ability to exploit both frequency domain through the multi-band operation with good impedance bandwidth and a spatial domain using dual-port configuration.Hence,it is a potential candidate for various applications in radio frequency energy harvesting(RFEH)system.

Design of a Five-Band Dual-Port Rectenna for RF Energy Harvesting

This paper proposed the design of a dual-port rectifier with multifrequency operations.The RF rectifier is achieved using a combination of L-section inductive impedance matching network(IMN)at Port-1 with a multiple stubs impedance transformer at Port-2.The fabricated prototype can harvest RF signal from GSM/900,GSM/1800,UMTS/2100,Wi-Fi/2.45 and LTE/2600 frequency bands at(0.94,1.80,2.10,2.46,and 2.63 GHz),respectively.The rectifier occupies a small portion of a PCB board at 0.20λg×0.15λg.The proposed circuit realized a measured peak RF-to-dc(radio frequency direct current)power conversion efficiency(PCE)of(21%,22.76%,25.33%,21.57%,and 22.14%)for an input power of−20 dBm.The RF harvester attains a measured peak RF-to-dc PCE of 72.70%and an output dc voltage of 154 mV for an input power of 3 dBm at 2.46 GHz.Measurement of the proposed rectifier in the ambiance gives a peak dc output voltage of 376.1 mV from the five signal tones.Similarly,a low-powered bq25504-674 evaluation module(EVM)is integrated with the rectifier.The module boost and drive the rectifier output dc voltage to 945 mV.The performance of the proposed rectifier in the ambiance environment makes it a suitable module for low-powered RF applications.

Cross Layered MAC Design for RF Energy Harvesting Sensor Network

The main research objective in wireless sensor networks (WSN) domain is to develop algorithms and protocols to ensure minimal energy consumption with maximum network lifetime. In this paper, we propose a novel design for energy harvesting sensor node and cross-layered MAC protocol using three adjacent layers (Physical, MAC and Network) to economize energy for WSN. The basic idea behind our protocol is to re-energize the neighboring nodes using the radio frequency (RF) energy transmitted by the active nodes. This can be achieved by designing new energy harvesting sensor node and redesigning the MAC protocol. The results show that the proposed cross layer CL_EHSN improves the life time of the WSN by 40%.

Strain-Insensitive Hierarchically Structured Stretchable Microstrip Antennas for Robust Wireless Communication

As the key component of wireless data transmission and powering,stretchable antennas play an indispensable role in flexible/stretchable electronics.However,they often suffer from frequency detuning upon mechanical deformations;thus,their applications are limited to wireless sensing with wireless transmission capabilities remaining elusive.Here,a hierarchically structured stretchable microstrip antenna with meshed patterns arranged in an arched shape showcases tunable resonance frequency upon deformations with improved overall stretchability.The almost unchanged resonance frequency during deformations enables robust on-body wireless communication and RF energy harvesting,whereas the rapid changing resonance frequency with deformations allows for wireless sensing.The proposed stretchable microstrip antenna was demonstrated to communicate wirelessly with a transmitter(input power of−3 dBm)efficiently(i.e.,the receiving power higher than−100 dBm over a distance of 100 m)on human bodies even upon 25%stretching.The flexibility in structural engineering combined with the coupled mechanical-electromagnetic simulations,provides a versatile engineering toolkit to design stretchable microstrip antennas and other potential wireless devices for stretchable electronics.