A planar array near-field multi-point focusing system and method based on time reversal

Abstract

The invention discloses a planar array near-field multi-point focusing system and method based on time inversion, and relates to the field of electromagnetic wave control. The system includes: a signal generator, which generates channel detection signals; a transmitting module, which receives detection signals and sends TRM return signals; a control module, which regulates the return signals; and a focusing module, which transmits detection signals. The present invention uses SVD decomposition to represent the received signal of the focus field as a linear superposition of multiple orthogonal sub-signals to avoid redundancy caused by non-orthogonal signal superposition; through threshold discrimination, some sub-channels are discarded, the number of optimization variables is reduced, and optimization is accelerated Speed; set the power fluctuation threshold to improve transmission efficiency; change the power distribution ratio to realize the regulation of the energy ratio of each focal point. The invention can generate multi-point focusing according to the preset energy ratio in the near field where the intensity distribution of the electromagnetic field is extremely uneven, and can effectively solve the problems of microwave hyperthermia and multi-target selective wireless energy transmission.

Description

technical field [0001] The invention belongs to the field of space propagation and control of electromagnetic waves, and in particular relates to a planar array near-field multi-point focusing system and method based on time inversion. Background technique [0002] With the continuous expansion of the application range of electromagnetic waves, for example, microwave hyperthermia, biological effect research, wireless energy transmission, encrypted communication, microwave cutting, etc., these applications all require the ability to precisely focus electromagnetic waves at a fixed position for Act on a specific object. In the field of electromagnetism, there are a lot of researches on the propagation and regulation of electromagnetic waves. [0003] Among them, beamforming is to make the radiation pattern of the far-field area of ​​the antenna array into a specific beam by rationally designing the excitation amplitude and phase of each array element of the antenna array, the...

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Problems solved by technology

In 2014, an application for an invention patent with the patent number 201410440116.7 disclosed a space electromagnetic field shaping method based on time-reversed electromagnetic wave transmission. With the help of the space-time focusing principle of time-reversed electromagnetic waves, the electromagnetic waves are generated in the space area. Energy is concentrated in a specific shape range. Although this is the regulation of electromagnetic waves in the near field, its research cannot precisely focus energy on a target point; in 2018, an application for an invention patent with patent number 201810580750.9, A multi-target selective wireless energy transmission method and device based on focused waves is disclosed, and an optimization algorithm for realizing multi-point energy distribution is mentioned. The transmission excitation signal is linearly superimposed according to the specified weighting coefficient, so that the wireless energy is concentrated at the specified focus point according to the required ratio. This method works well in the cavity environment, but it does not consider the propagation of electromagnetic waves in free space with severe attenuation. How to improve space efficiency does not consider the correlation between superimposed signals. The superposition of non-orthogonal signals leads to redundant calculation variables, and the optimization rate is low, which cannot meet the high-efficiency requirements in engineering applications.

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