Metasurface-Primarily based Antenna Turns Ambient Radio Waves Into Electrical Energy

Electricity Energy Harvesting Concept

Know-how might make it potential to make use of radio emissions from mobile phone networks to wirelessly energy sensors and LEDs.

Researchers have developed a brand new metasurface-based antenna that represents an necessary step towards making it sensible to reap power from radio waves, equivalent to those utilized in mobile phone networks or Bluetooth connections. This know-how might doubtlessly present wi-fi energy to sensors, LEDs and different easy gadgets with low power necessities.

“By eliminating wired connections and batteries, these antennas might assist scale back prices, enhance reliability and make some electrical techniques extra environment friendly,” mentioned analysis crew chief Jiangfeng Zhou from the College of South Florida. “This may be helpful for powering sensible residence sensors equivalent to these used for temperature, lighting and movement or sensors used to observe the construction of buildings or bridges, the place changing a battery may be troublesome or unattainable.”

Within the journal Optical Supplies Specific, the researchers report that lab assessments of their new antenna confirmed that it could actually harvest 100 microwatts of energy, sufficient to energy easy gadgets, from low energy radio waves. This was potential as a result of the metamaterial used to make the antenna displays excellent absorption of radio waves and was designed to work with low intensities.

Metamaterial Based Antenna in Anechoic Chamber

The researchers examined their metamaterial-based antenna in an anechoic chamber. The radio wave is shipped out from the horn antenna on the left and acquired by the metasurface antenna mounted on the wooden body on the proper. The anechoic chamber eliminates background indicators from different sources and prevents stray indicators from the radio wave supply from bouncing across the room and perturbing measurements. The picture of metamaterial-based antenna is enlarged on the proper. Credit score: Jiangfeng Zhou and Clayton Fowler

“Though extra work is required to miniaturize the antenna, our system crosses a key threshold of 100 microwatts of harvested energy with excessive effectivity utilizing ambient energy ranges present in the true world,” mentioned Clayton Fowler, the crew member who fabricated the pattern and carried out the measurements. “The know-how may be tailored so {that a} radio wave supply might be supplied to energy or cost gadgets round a room.”

Harvesting power from the air

Scientists have been attempting to seize power from radio waves for fairly a while, but it surely has been troublesome to acquire sufficient power to be helpful. That is altering because of the event of metamaterials and the ever-growing variety of ambient sources of radio frequency power out there, equivalent to mobile phone networks, Wi-Fi, GPS, and Bluetooth indicators.

“With the massive explosion in radio wave-based applied sciences, there can be loads of waste electromagnetic emissions that might be collected,” mentioned Zhou. “This, mixed with developments in metamaterials, has created a ripe setting for brand spanking new gadgets and functions that would profit from amassing this waste power and placing it to make use of.”

Metamaterials use small, carefully designed structures to interact with light and radio waves in ways that naturally occurring materials do not. To make the energy-harvesting antenna, the researchers used a metamaterial designed for high absorption of radio waves and that allows a higher voltage to flow across the device’s diode. This improved its efficiency at turning radio waves into power, particularly at low intensity.

Testing with ambient power levels

For lab tests of the device, which measured 16 cm by 16 cm, the researchers measured the amount of power harvested while changing the power and frequency of a radio source between 0.7 and 2.0 GHz. They demonstrated the ability to harvest 100 microwatts of power from radio waves with an intensity of just 0.4 microwatts per centimeter squared, approximately the level of intensity of the radio waves 100 meters from a cell phone tower.

“We also placed a cell phone very close to the antenna during a phone call, and it captured enough energy to power an LED during the call,” said Zhou. “Although it would be more practical to harvest energy from cell phone towers, this demonstrated the power capturing abilities of the antenna.” 

Because the current version of the antenna is much larger than most of the devices it would potentially power, the researchers are working to make it smaller. They would also like to make a version that could collect energy from multiple types of radio waves simultaneously so that more energy could be gathered.

Reference: “High efficiency ambient RF energy harvesting by a metamaterial perfect absorber” by Clayton Fowler, Sinhara Silva, Grija Thapa and Jiangfeng Zhou, 28 February 2022, Optical Materials Express.
DOI: 10.1364/OME.449494

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