Design Of Microwave Imaging System Based On GDD

Glow Discharge Detector(GDD)is a good room temperature microwave detector.It has many advantages,such as low price,wide dynamic range,wide spectral range,fast response time and easy to use.It is of great significance to study the microwave imaging system based on GDD.Firstly,the volt-ampere characteristics of gas discharge and the motion characteristics of internal particles are introduced.The mechanism of GDD microwave detection is described from three aspects: the increase of electron kinetic energy,the increase of plasma ionization rate and the cascade collision gain.On this basis,the overall scheme of the microwave imaging system is designed.Secondly,based on the basic theory of gradient phase metasurface,a gradient phase metasurface structure is proposed.The structure unit consists of two similar units.The structural unit is composed of two similar unit structures.The simulation results show that the transmission coefficient is more than-3dB and the phase coverage is greater than 360? when the operating frequency is 11 GHz.Based on the designed metasurface structure,a gradient phase metasurface focusing lens with a frequency of 11 GHz and a focal length of 150 mm was constructed to realize the microwave signal focusing in the GDD microwave imaging system.Thirdly,the hardware and software needed in GDD microwave imaging system are designed and implemented.The hardware includes GDD signal conditioning circuit,twodimensional scanner platform with embedded chip STM32 as the core,and the software includes embedded software controlling two-dimensional scanner platform and upper computer software with functions of data acquisition and image processing.The construction of the system has been completed.Finally,based on the designed microwave imaging system,the imaging experiment of the object is carried out,and good imaging results are obtained.