An international team of physicists has created what might seem like a contradiction in terms: a non-radiating source of electromagnetism. By placing

Introducing the non-radiating antenna – Physics World

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2021-08-04 21:30:03

An international team of physicists has created what might seem like a contradiction in terms: a non-radiating source of electromagnetism. By placing antennas inside a hollow dielectric disc, the researchers exploited interference phenomena to create a non-radiative “meta-atom” that could have applications in several areas, including sensing and wireless power transfer.

Maxwell’s equations tell us that accelerating charges radiate energy in the form of electromagnetic waves. This idea has led to the development of much modern technology, most notably radio communications in all its various guises. But it also posed a challenge to early 20th century physicists seeking to explain the stability of atoms, given that electrons were thought to follow (curved) orbits around atomic nuclei and therefore continuously lose electromagnetic energy.

The response to that problem was Niels Bohr’s atom and the development of quantum mechanics – in particular, the idea that electrons can only occupy certain discrete energy levels. Beyond the quantum world, however, some physicists wondered whether it might be possible to create classical “meta-atoms”: macroscopic objects containing alternating currents that confine the electromagnetic energy they generate and so prevent emission to the far-field.

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