Transmitting data and power through a Faraday Cage boundary

September 10, 2013 // By Graham Prophet
Engineers at The Technology Partnership (TTP) have discovered a way to “break through” the Faraday Cage that prevents the entry or escape of an electromagnetic field through a metallic enclosure.

While the Faraday Cage effect is essential in many contexts – preventing leakage from microwave ovens, lightning strike protection, screening data cables – TTP’s Fluxor technology will have major benefits for power and data transfer through metal shielding. TTP is already using the technology for monitoring fluid levels in steel pipes, taking readings from medical implants and measuring data from inside high-performance F1 engines.

The Fluxor method creates a ‘window’ for electromagnetic transmission of power and data by applying a strong DC magnetic field, which lines up the magnetic dipoles in the material to ‘saturate’ a small area of the metal screen. This reduces the permeability and increases penetration to make it possible to transfer electromagnetic power and signals. Experiments conducted by TTP using steels from 5-15mm thick show that the optimum operating frequency range is in the region of 400-500Hz.

In a typical operating scenario, a portable interrogator unit with a permanent magnet or electromagnet could be placed adjacent to a fixed sensor, through a metal wall. A Fluxor window is opened to transmit power to energise the sensor and transmit a signal back – all without the need for physical openings in the enclosure.

“The ability to overcome the shielding characteristics of a Faraday Cage opens up many exciting opportunities, combined with new battery-free, ultra-low power wireless sensor technology also being pioneered at TTP,” said Dr Allan Carmichael from TTP. “We see these developments as major enablers for delivering the Internet of Things that will allow billions of devices to communicate and interact with each other. We are currently working with a number of customers on use cases that exploit the Fluxor technology and expect to see practical applications deployed in the next few years.”

TTP Group is an independent technology and product development company; www.ttp.com