The Front-end Of 220GHz Single-transmitter Dual-receive Imaging Radar System Research On Key Technology Of Circuit Module

Terahertz(THz)radar imaging technology is a research hotspot in current imaging technology.Because the terahertz band is between microwave and infrared,terahertz radar imaging technology has many advantages such as high resolution,no radiation hazard,and no light interference.Therefore,it has a wide range of applications in medical diagnosis,safety detection,cultural heritage protection and other fields.The realization of terahertz radar imaging technology requires the support of terahertz radar imaging system,which includes front-end and back-end parts.The front-end of the imaging system is mainly composed of transmitter and receiver,so high-performance front-end key components can ensure the effectiveness of the overall link.Therefore,the research content of thesis mainly includes the following aspects:1.Research on high-performance terahertz key devices:(1)A novel dual-mode TM120 and TE101 dual-mode filter with high frequency selectivity for terahertz band is proposed.The new dual-mode resonator is analyzed theoretically.Finally,two dual-mode filters with center frequencies of 105 GHz and 340 GHz are designed and fabricated by CNC technology.This new dual-mode filter has low depth-width ratio,simple and symmetrical structure,controllable transmission zeros,and is convenient for E-plane processing in terahertz band.Therefore,the filter with this structure can meet the requirements of higher terahertz band radar or communication.(2)A 220 GHz high thermal conductivity doubler based on ALN is designed.The Al N substrate with high thermal conductivity is selected,and a new matching method is tried to match the input and output microstrip.Finally,the simulation and optimization of 220 GHz double frequency is realized.The optimum frequency doubling efficiency can reach 16 % in the range of 200GHz-220 GHz,and the output power is about 6mw in the whole bandwidth.(3)A 220 GHz sub-harmonic mixer with low conversion loss is designed.In the RF range of 190GHz-230 GHz,the conversion loss is about 11 dB,and the bilateral band noise temperature is less than 1400 k in 200GHz-220 GHz.2.A suitable 220 GHz terahertz imaging radar architecture with one transmitter and two receivers is proposed,and the front-end test of the system is completed.The transmitter power is ≥ 5m W in the bandwidth of 200GHz-220 GHz,the output flatness is ≤ 5dB,and the receiver noise coefficient is ≤ 10 dB,which meets the basic imaging indicators.