The new technology makes it possible to better detect moving objects, even if they rotate rapidly.
Researchers from Shanghai University of Science and Technology (USST) have developed a revolutionary new radar for detecting rotating aerial targets. They described the technology in a paper published in the journal Advanced Photonics.
Radio waves change their frequency as the signal and detector move relative to each other, making it difficult for conventional radar systems to detect objects moving at right angles to their radiation. Professor Yiming Zhu and his team found a solution to this problem with a completely different approach.
Scientists have concluded that spiral electromagnetic waves with orbital angular momentum (OAM), rather than linear, should be relied upon to detect threats. They move in a spiral, like a vortex, and when colliding with a rotating object, they create a characteristic rotational Doppler effect – a change in the frequency and wavelength of radiation perceived by the observer (receiver) due to the movement of the radiation source accordingly.
To better study this phenomenon, the team developed a device called a terahertz (THz) vortex wave emitter built into the radar. THz waves are ideal for high-resolution radar imaging because they can penetrate a variety of materials with minimal risk of damage.
“To our knowledge, this work represents the first demonstration of an integrated THz vortex beam emitter specifically designed to detect rotating targets,” said Yiming Zhu.
Using vortex emitters, scientists tested different settings and schemes for detecting objects, resulting in a new approach: using positively and negatively charged vortex beams. By adjusting the frequency of such beams, radar signals can be created to measure the speed of a rotating object with a maximum error of 2%. The echo of light waves can be received directly by a linearly polarized antenna.
According to the inventors, the new technology could have many applications. First of all, it could significantly improve object detection and lead to the creation of new military defense systems. The creation of terahertz vortex emitters is very economically beneficial and easily scalable, so they can be used in practice very soon.
They had previously written that scientists in France had created a quantum radar that works 20% faster than conventional radars. It helps detect targets even in high microwave noise environments.
Source: Focus
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