This strange device makes underwater objects invisible to sonar

<pre>This strange device makes underwater objects invisible to sonar

A team of researchers at the University of Pennsylvania, led by Amanda D. Hanford, developed an underwater masking device based on a protective metamaterial capable of intercepting and “deforming” sound waves radiated by the sonar. As a result, waves are scattered, and an “effect of absence” of the real object is created.

Metamaterials have properties that are not found in nature. They are usually made of composite materials – metals, plastics or ceramics, combined in repetitive microscopic structures.

The goal of the Hanford team is to create a metamaterial that will hide underwater objects and, above all, submarines from detection facilities. Previously, the camouflage effect could only be simulated in the laboratory, and only in the air.

According to A.Hendford and her colleagues, the protective “cloak” should consist of a metamaterial, the cells of which are smaller than the length of the sound wave. As a result, a prototype prototype was created in the form of a pyramid of perforated steel plates 91 cm in height. It was placed in a large laboratory tank filled with water, where a hydrophone was also built, generating sound waves with a frequency of 7000 to 12000 Hz and several receiving hydrophones for fixing echo- signals.

The researchers found that sound waves are reflected from the protective material in such a way that the object inside becomes invisible.

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