Research On The Receiver Front-end Of Q-band Dual-beam Phased Array

Multi beam phased array radar is widely used in military electronic field because of its superior anti-jamming ability,ultra long detection range,multi-target tracking and survivability.With the increasing military and civil demand,manufacturing high-performance,miniaturization,high integration,low cost,light weight,high reliability products has become an important development direction in the field of electronics.In this thesis,we use microwave multi chip module(MMCM)and microwave multilayer board technology to complete the research of Q-band dual beam phased array receiver front-end.This thesis will design the receiver module from the following aspects: one is to use microwave monolithic integrated circuit(MMIC)to realize the RF front-end circuit design through gold wire interconnection;Second,the key passive circuit is designed by using microwave multilayer board technology;Third,the double-sided structure layout is adopted,and the back power supply and beam control circuit are designed through the insulator cavity.The specific research contents are as follows:Firstly,the status of multi beam phased array receiving front-end at home and abroad is investigated,focusing on the key technologies needed in this design.According to the technical specifications and design principles,the link design and simulation prediction of the system are carried out.Secondly,the front-end circuit of the receiver is designed.According to the system index,the low noise amplifier chip,multi-function amplitude and phase chip and power divider chip are selected,and the key passive circuit of the system is designed.Based on the material selection and analysis of multilayer circuit,the 4-layer microwave circuit board is realized by using Rogers 4003 substrate and bonding chip RO4450 B.On this basis,three interconnection structures are designed:(1)Quasi coaxial via vertical interconnection structure: through simulation and optimization,the return loss is less than-23 d B and insertion loss is less than0.08 d B in the range of 43.5GHz-46GHz;(2)layer coupling transition structure based on asymmetric slot line: the return loss is less than-22 d B and insertion loss is less than 0.1d B in the range of 43.5GHz-46GHz;(3)quasi coaxial via Transition structure combined with layer coupling: the transition structure can reduce the size of the circuit layout as much as possible on the basis of ensuring the best transmission characteristics.The experimental results show that the insertion loss and return loss of the transition structure are less than 3.5d B and-10 d B in the frequency range of 43.5GHz-46 GHz.Finally,the multi beam network is designed by using quasi coaxial via and layer coupling transition structure.The four in one circuit is in the frequency range of 43.5GHz-46 GHz,the insertion loss is less than 0.2d B,the return loss is less than-18 d B,and the isolation of adjacent channels is more than 32 d B.Finally,the circuit layout design,power supply and wave control circuit board design and cavity structure design of the receiving module are carried out.After processing and testing,the size of the whole machine is 73.2mm×67.5mm×14.3mm.In the frequency range of 43.5GHz-46 GHz,the channel gain is more than 45 d B,the noise figure is less than 3.3d B,the gain flatness is less than 1.5d B,the VSWR of the input port is less than 2,the phase-shifting accuracy is less than 4°and the attenuation accuracy is less than 0.4d B,which meets the design requirements.