Design And Implementation Of X-band All-solid-state Fully Coherent Pulse Radar Front-end

The radar transceiver front end is the core component of radar system.Based on understanding the related theories of radar and analyzing the research status at home and abroad,this paper makes a comparison of radar system and design.According to the technical indicators of the project,this paper designs the overall scheme of the X-band all solid-state all coherent pulse radar transceiver front-end.The designed radar front end mainly includes three parts: the linear frequency source that generates the radar signal,the coherent radar transmitter and the radar receiver.The linear frequency source mainly includes reference source,PLL module and pulse signal source.Prototype test results: the phase noise of the reference source is-159.29 d Bc/Hz@10k Hz,and the spurious suppression is better than-75 d Bc.The phase noise of the PLL module is-100.57 d Bc/Hz@10k Hz,and the spurious suppression is better than-55 d Bc.Direct digital waveform synthesis technology is used in the development of the pulse signal source.The LFM signal with center frequency of 90 MHz and bandwidth of 20 MHz is generated through the scheme of "FPGA+DAC".The power flatness in the band is ± 1d B,which meets the design and development requirements.The development of coherent radar transmitters adopts the up-conversion method after mixing low-frequency modulation signals and high-frequency local oscillator signals to realize the frequency shift of low-frequency signals.The hairpin SIR narrowband bandpass filter is studied and designed to filter out the spurious components outside the band.The design simulation of this filter shows that the insertion loss is less than 2d B,the return loss is more than 15 d B,and the out-of-band suppression is more than 20 d B in the 9.4GHz～9.5GHz.The saturated output power of this radar is 34.2d Bm in the frequency band of9.4GHz～9.5GHz,which basically meets the requirements of transmitting power.The coherent radar receiver adopts superheterodyne structure,and the performance of the designed receiving link meet the project requirements.After testing,the noise figure of the receiver is less than 4d B,the dynamic range is more than 90 d B,and the sensitivity is better than-92 d Bm,which meets the design and development requirements.The X-band radar transceiver system developed in this paper has the characteristics of small size,low cost and flexible application.