whatsapp

whatsApp

Have any Questions? Enquiry here!
☎ +91-9972364704 LOGIN BLOG
× Home Careers Contact
Back
RF-based Wireless Charging and Energy Harvesting Enables New Applications and Improves Product Design
RF-based Wireless Charging and Energy Harvesting Enables New Applications and Improves Product Design

RF energy is currently broadcasted from billions of radio transmitters around the world, including mobile telephones, handheld radios, mobile base stations, and television/ radio broadcast stations. The ability to harvest RF energy, from ambient or dedicated sources, enables wireless charging of low-power devices and has resulting benefits to product design, usability, and reliability. Battery-based systems can be trickled charged to eliminate battery replacement or extend the operating life of systems using disposable batteries. Battery-free devices can be designed to operate upon demand or when sufficient charge is accumulated. In both cases, these devices can be free of connectors, cables, and battery access panels, and have freedom of placement and mobility during charging and usage.

Energy Sources     

RF Harvesting Receivers

RF energy harvesting devices, such as Powercast’sPowerharvester® receivers, convert RF energy into DC power. These components are easily added to circuit board designs and work with standard or custom 50-ohm antennas. With current RF sensitivity of the P2110 Powerharvester receiver at -11dBm, powering devices or charging batteries at distances of 40-45 feet from a 3W transmitter is easily achieved and can be verified with Powercast’s development kits. Improving the RF sensitivity allows for RF-to-DC power conversion at greater distances from an RF energy source. However, as the range increases the available power and rate of charge decreases.

An important performance aspect of an RF energy harvester is the ability to maintain RF-to-DC conversion efficiency over a wide range of operating conditions, including variations of input power and output load resistance. For example, Powercast’s RF energy-harvesting components do not require additional energy-consuming circuitry for maximum power point tracking (MPPT) as is required with other energy-harvesting technologies. Powercast’s components maintain high RF-to-DC conversion efficiency over a wide operating range that enables scalability across applications and devices. RF energy-harvesting circuits that can accommodate multi-band or wideband frequency ranges, and automatic frequency tuning, will further increase the power output, potentially expand mobility options, and simplify installation.

Typical Applications

RF energy can be used to charge or operate a wide range of low-power devices. At close range to a low-power transmitter, this energy can be used to trickle charge a number of devices including GPS or RLTS tracking tags, wearable medical sensors, and consumer electronics such as e-book readers and headsets. At longer range the power can be used for battery-based or battery-free remote sensors for HVAC control and building automation, structural monitoring, and industrial control. Depending on the power requirements and system operation, power can be sent continuously, on a scheduled basis, or on-demand. In large-scale sensors deployments significant labor cost avoidance is possible by eliminating the future maintenance efforts to replace batteries.

Harvesting Ambient RF Enegry from an iPhone


Unable to view this video? 
Click to send a link to another source. 

For more RF Energy harvesting news visit Powercast's blog - 
RF-Powered Wireless Sensors

Available power from a 3W transmitter will be low milliwatts within a few feet and tens of microwatts at around 40 feet. This amount of power is best used for devices with low-power consumption and long or frequent charge cycles. Typically, devices that operate for weeks, months, or years on a single set of batteries are good candidates for being wirelessly recharged by RF energy. In some applications simply augmenting the battery life or offsetting the sleep current of a microcontroller is enough to justify adding RF-based wireless power and energy harvesting technology.

A network of transmitters can be positioned in a facility to provide wireless power on a room-by-room basis, or for a many-to-many charging topology. Mobile phones can be used as portable power sources for a number ofbattery-free wireless devices. Imagine a mobile phone powering a battery-less, body-worn sensor that sends data to the phone via a commonly used protocol such as Wi-Fi, Bluetooth, or ZigBee. This data can be displayed locally on the handset or transmitted by the phone to a monitoring service. Powercast has already demonstrated this application using ambient RF energy from an iPhone (see video to right).

Improved Product Design

Products with embedded wireless power technology can be sealed from environmental conditions such as moisture and from user access. In addition, connectors and cables can be eliminated. Product reliability and lifecycle can be significantly improved as a result. When in range of a suitable RF source, charging is automatic and transparent to the end-user which provides increased convenience of use. With Powercast’s components, multiple battery chemistries and charge voltages can be supported which allows for maximum power storage flexibility.

Conclusion

Ambient radio waves are universally present over an ever-increasing range of frequencies and power levels, especially in highly populated urban areas. These radio waves represent a unique and widely available source of energy if it can be effectively and efficiently harvested. The growing number of wireless transmitters is naturally resulting in increased RF powerdensity and availability. Dedicated power transmitters further enable engineered and predictable wireless power solutions. With continued decreases in the power consumption of electronic components, increased sensitivity of passive receiversforRF harvesting, and improved performance of low-leakage energy storage devices, the applications for wire-free charging by means of RF-based wireless power and energy harvesting will continue to grow.

Popular Coures