RF-based Energy HarvestingCatching a Wave

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No matter how smart and fast your devices would be, the biggest issue is always with the battery technology.

Whenever you go to buy any electronic gadget smartphone, laptop, or any wearable the most important specification isnt its processor speed or its camera quality but its Battery Backup, which is not getting better any time soon.

What if you could eliminate the very thing entirely? Statement(C) Jitendra Adhikari, 20162

Radio frequency (RF) is any of the electromagnetic wave frequencies that lie in the range extending from around 3 kHz to 300 GHz, which include those frequencies used for communications or radar signals. RF usually refers to electrical rather than mechanical oscillations. However, mechanical RF systems do exist.Radio Frequency (RF) communications is based on laws of physics that describe the behavior of electromagnetic energy waves. RF communication works by creating electromagnetic waves at a source and being able to pick up those electromagnetic waves at a particular destination. These electromagnetic waves travel through the air at near the speed of light. The wavelength of an electromagnetic signal is inversely proportional to the frequency; the higher the frequency, the shorter the wavelength.Imagine an RF transmitter wiggling an electron in one location. This wiggling electron causes a ripple effect, somewhat akin to dropping a pebble in a pond. The effect is an electromagnetic (EM) wave that travels out from the initial location resulting in electrons wiggling in remote locations. An RF receiver can detect this remote electron wiggling.Frequency is measured in Hertz (cycles per second) and radio frequencies are measured in kilohertz (KHz or thousands of cycles per second), megahertz (MHz or millions of cycles per second) and gigahertz (GHz or billions of cycles per second). Higher frequencies result in shorter wavelengths. The wavelength for a 900 MHz device is longer than that of a 2.4 GHz device.In general, signals with longer wavelengths travel a greater distance and penetrate through, and around objects better than signals with shorter wavelengths.

Intro to Radio Frequency (RF)3(C) Jitendra Adhikari, 2016

4The Idea(C) Jitendra Adhikari, 2016

Nikola Tesla

Wardenclyffe Tower, also known as the Tesla Tower, was an early wireless transmission station designed and built by Nikola Tesla.

Tesla intended to transmit messages, telephony and even facsimile images across the Atlantic to England and to ships at sea based on his theories of using the Earth to conduct the signals. InventorElectrical engineerMechanical engineerPhysicistFuturist

Best known for his contributions to the design of the modern alternating current (AC) electricity supply system.

5Free Energy - Nikola Tesla

(C) Jitendra Adhikari, 2016https://youtu.be/qdIAwcgtqac

The basics of RF Harvesting6(C) Jitendra Adhikari, 2016

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 and/or usage of low-power devices and has resulting benefits. 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. RF Source7(C) Jitendra Adhikari, 2016

RF energy harvesting devices, such as Powercasts Powerharvester receivers, convert RF energy into DC power. These components are easily added to circuit board designs and work with standard or custom antennas. 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. 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.RF Harvesting Receivers8(C) Jitendra Adhikari, 2016

Powercasts Powerharvester9(C) Jitendra Adhikari, 2016

10A tiny computer

A team of researchers from the University of Washingtons Sensor Lab and the Delft University of Technology has developed a new gadget that doesnt need a battery or any external power source to keep it powered; rather it works on radio waves.

The device sucks radio waves out of the air and then converts them into electricity.Dubbed Wireless Identification and Sensing Platform (WISP), the device is a combination sensor and computing chip that uses a standard off-the-shelf RFID (Radio Frequency Identification) reader to suck in radio waves and convert them into electricity.

The discovery could highly transform the Internet of Things (IoT) world as the WISP is even more low maintenance compared to Bluetooth Low Energy sensor chips being used today.

The next step in making the WISP usability even more convenient and easy is to create module (Wisent) that would allow for wireless programming of the WISP. With the help of Wisent, the WISP can be programmed wirelessly and uses the very same radio waves to communicate.(C) Jitendra Adhikari, 2016

11RF 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 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 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.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 or Bluetooth. This data can be displayed locally on the handset or transmitted by the phone to a monitoring service.Typical Applications(C) Jitendra Adhikari, 2016

12Powercast P2110 Harvests Ambient RF Energy from iPhone(C) Jitendra Adhikari, 2016

https://youtu.be/uox8Rmm9_c4

13(C) Jitendra Adhikari, 2016