UK firm harvest ambient RF for IoT

Ambient RF signals are a viable source of energy, claims UK-based Drayson Technologies, which has patented a technique to harvest them.

Branded Freevolt, it uses an antenna, ‘non-linear device’, RF filter and a power manager (PMM in diagram).

“To integrate Freevolt into different devices, Drayson Technologies has developed standard harvesters but can also provide different antenna and rectifier designs, depending on the application requirements,” said the firm, adding: it is important to note that a harvesting antenna can have different and unique characteristics depending on the application.

It gives the example of a device placed on a wall, where the antenna can be optimised to cover a broad angle and have the appropriate polarisation and frequency bands to take advantage of the maximum number of existing RF sources.

In a white paper, the firm predicts efficacy, and describes ambient field measurement results that yielded 600-700nW/cm² peak in a office block from Wi-Fi, GSM and 4G LTE, and a peak of 6.7uW/cm² from 3G signals in busy outdoor London locations.

Drayson is marketing a UK-made RF-powered air quality sensor tag called CleanSpace. “This technology creates a crowd-sourced network of personal air sensors, initially across the UK and then expanding to major cities across the world, which will all be powered by Freevolt,” said the firm.

steve bush

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via Yuichun