Design Of Near-Field Adaptive Focusing Antenna

With the rise of applications such as microwave imaging,microwave sensing,RFID card reading systems,and microwave thermotherapy systems,focusing antenna arrays working in the near field have received more and more attention.At present,the near-field focusing antenna is usually designed for energy focusing under known conditions of the focusing position,which cannot meet the application requirements of certain scenarios with unknown target positions,such as RFID identification of conveyor belt goods.In this paper,the scattering of the nearfield target of the array antenna is used as feedback,and the maximum power transmission efficiency between the array transmitting antenna and the local receiving antenna is optimized.A near-field adaptive focusing antenna with unknown target position is proposed to realize the antenna.Focus positioning of near-field targets.The maximum power transmission process also considers the material and shape factors of the unknown target.The adaptive focusing antenna can achieve adaptive focusing when the target position,shape and material parameters are unknown.The main research contents of this article include:1.Two adaptive focusing antenna arrays with a working center frequency of 2.45 GHz were designed,one-dimensional linear array antenna and two-dimensional planar array antenna,respectively,to achieve adaptive focus positioning of near-field targets.In the design of the adaptive focusing antenna,the center antenna unit is used as the local test receiving antenna to obtain the target scattered feedback electromagnetic signal.Load a single scattering target at a random position above the array antenna.By optimizing the maximum power transmission between the transmitting antenna and the receiving antenna unit,the transmitting array antenna can effectively focus its radiated energy to the target position.The simulation and actual measurement results show that within the target recognition area,the shape and material of the target can be changed,and the transmitting array antenna can achieve the focused positioning at the target.2.Based on the target positioning of the adaptive focusing antenna,the measurement antenna is further transplanted to the positioning area to design a near-field focusing antenna.The performance of the antenna focusing under the conditions of adaptive focusing and unknown target is compared.The results show that a secondary design of the focusing antenna excitation based on the detected target position of the adaptive focusing antenna array can achieve better focusing performance.