Mathias Fink and his team at the Langevin Institute have managed to rise nearly 10 times, or more precisely by 8.5 dB, the signal received by an antenna.
"We have, in some way, recycled the reverberating waves in a room," says Mathias Fink in an article in a Scientific Reports article published by the Nature review.
There is no amplification, so no increase in the background noise, but just a better use of the existing resource.
The signal received by an antenna is the sum of all the waves arriving on it, coming from, among others, multiple reflections from walls, furniture, etc. All these waves do not arrive in phase, some are offset. Instead of strengthening, they can even annihilate like sound waves. As these offsets are random, the resulting signal is, on average, lower.
It is nearly impossible to put all these waves in phase. But the team from the Langevin Institute realized that, by correcting only a portion, the reception improving was impressive.
For this purpose, 3 x 4.5 cm copper rectangles reflect the waves without modification, or delay them by half a period. An area of 0.4 m², with 102 of these pellets, is enough for a room.
How to choose which copper parts must be activated? Through the receiver which measures the received power: if it is too low, it controls the activation of some copper rectangles to achieve optimal focus on the antenna.
Consumption is minimal since a low signal is enough to switch a rectangle in a condition or the other.
According to Ping Sheng from the Hong Kong University of Science and Technology, we could apply this principle to sound waves. In a noisy room, a person will be able to talk to another at the other end, as if they were neighbors.
"We have, in some way, recycled the reverberating waves in a room," says Mathias Fink in an article in a Scientific Reports article published by the Nature review.
There is no amplification, so no increase in the background noise, but just a better use of the existing resource.
The signal received by an antenna is the sum of all the waves arriving on it, coming from, among others, multiple reflections from walls, furniture, etc. All these waves do not arrive in phase, some are offset. Instead of strengthening, they can even annihilate like sound waves. As these offsets are random, the resulting signal is, on average, lower.
It is nearly impossible to put all these waves in phase. But the team from the Langevin Institute realized that, by correcting only a portion, the reception improving was impressive.
For this purpose, 3 x 4.5 cm copper rectangles reflect the waves without modification, or delay them by half a period. An area of 0.4 m², with 102 of these pellets, is enough for a room.
How to choose which copper parts must be activated? Through the receiver which measures the received power: if it is too low, it controls the activation of some copper rectangles to achieve optimal focus on the antenna.
Consumption is minimal since a low signal is enough to switch a rectangle in a condition or the other.
According to Ping Sheng from the Hong Kong University of Science and Technology, we could apply this principle to sound waves. In a noisy room, a person will be able to talk to another at the other end, as if they were neighbors.
