Research On Abroadband Phased Array Radar RF Front End

With the rapid development of wireless communication technology,the application in radar is more and more demanding,such as ultra broadband,high gain,beam scanning and so on.In this paper the design of wideband phased array radar rf frequency range is wide,1.4-6GHZ,array number 4x4,broadband has caused difficulties for phased array radar system design,including the phase shifter bandwidth limitations,miniaturization,high reliability and so on.The design content of rf front end of broadband phased array radar is divided into two parts: antenna module and TR module.For the antenna module,the 1.4-6GHz plane helical antenna was designed through CST Microwave Studio software,and the 1.4-6GHz broadband index gradient Balun was designed to realize the balance to unbalanced feed.The high dielectric constant RF-60(40mil)is used as the base plate of the antenna,which can greatly reduce the transverse size of the antenna and improve the performance of the antenna,and the S11 is less than-8dB array antenna module.Finally,through the Proe software design antenna module cavity,complete the antenna module design.The design content of TR components is mainly divided into two parts: radio frequency circuit and digital circuit.The purpose is to test the basic characteristics of the circuit as the basis for the later work progress.The TR module of this design contains four frequency bands,and how to design the most simplified circuit is very important.In this paper,the innovation lies in the integration of four channels into three channels through reasonable design scheme,which can reduce the use of filter and switch number and simplify the circuit.In order to ensure good heat dissipation and high reliability,it is necessary to pay attention to signal routing and overall layout.In order to realize miniaturization,the digital circuit board and the rf circuit board are designed as four layers of mixing platen,effectively reducing the space feed volume.Finally re-use Proe software for cavity structure design,here in this paper,considering the practical application of the array number is very large,in order to realize the TR module components,and antenna assembly is simple,in the design of the TR cavity,especially chose SMP compact connector to use,the above completes the TR component design content.Finally work out physical antenna and TR components,because the test antenna array must be combined with the late after the completion of control system and test together just have reference meaning,currently only test antenna return loss,test results meet the design requirements.TR component testing by vector network analyzer,spectrum instrument and the use of voltage source,the final test results as follows: when the FPGA program control for each channel independently,channel power and second harmonic suppression meet the requirements of design index,circuit characteristic is good.