Study And Implimentation Of X-Band Frequency Synthesizer Used In A Weapon Location Radar

High-performance frequency synthesizer plays a critical role in the performances of modern microwave and MMW communication systems. As an important part of radar, frequency synthesizer is especially critical to military applications. This article studies X-band frequency synthesizer with low phase noise, frequency agility, wide band and multiple modes based on its application in a weapon locating radar, and gives out new design plan and makes engineering implementations.The article begins with the development of modern frequency synthesis techniques, and based on theoretical analysis of basic principles, describes applications and key specifications of synthesis techniques, makes detailed comparison of how direct analogue synthesis, digital direct synthesis (DDS) and phased-locked-loop synthesis realize low-phase-noise frequency agility, and discusses the advantages and disadvantages and applications of these means. Then a hybrid synthesis plan is put forward which combines the direct analogue synthesis and DDS, makes use of many synthesis techniques, is based on complexity and flexibility of implementation, application commonality and flexibility, and specifications of concrete applications. This plan leads to realization of X-band frequency synthesizer with low phase noise, frequency agility and multiple modes.This article also details the working principle of the X-band frequency synthesizer used in a weapon locating radar and engineering implementation scheme. This synthesizer has been successfully developed and features good interchangeability, autonomous functions, flexible control, realization of non-linear frequency modulation (NLFM) signals, single-frequency signals and dual-frequency signals, stable operation and good economy.Experiments show that the plan proposed in this article is feasible, is helpful in theory and implementation to engineering design of frequency synthesizer system. This frequency synthesizer is capable to generate X-band signals with a bandwidth of1.2GHz and a step of XXMHz, has agility time of <0.7μs, phase noise of<-100dBc/Hz@1kHz and spurious rejection of≤-70dBc.