Research On Key Technology Of Front-end's Wideband And Miniaturization In Radar Reconnaissance

Radar reconnaissance front-end can receive all kinds of electromagnetic signals and find useful signals to lock and analyze.The core component is the radar reconnaissance receiver in front-end.In order to adapt to the complex electromagnetic environment,radar reconnaissance receiver must have high sensitivity,strong anti-interference ability and high survivability.Equipment's battlefield invisibility and mobility can be optimized by miniaturization design,is the important means to improve its survivability.This paper developed a wideband superheterodyne receiver in radar reconnaissance front-end based on a practical project.It is able to receive 20~3600MHz RF signal frequency and down-conversion to 70 MHz.According to different functions,IF bandwidth include 40 MHz,500k Hz,and 25 k Hz.The receiving component has two working modes of convention and low noise.Noise figure requires less than 15 dB in convention mode and less than 9d B in low noise mode.The receiving component also has high linearity requirements.It requires more than 50 dBm in out-off-band IIP2,more than 15 dBm in out-off-band IIP3,and less than-100dBc/Hz in phase noise at 10 k Hz.Mirror frequency and IF rejection requires more than 100 dB.Due to its relatively small requirements in size,this paper guarantee a high performing solution and realize miniaturization design.Frequency conversion and link circuit programme is a major feature of this article.Based on the second-frequency-conversion scheme,we suggest a double-IF1 programme to reduce local oscillator(LO)frequency and facilitate device selection.This paper using CASCADE7 software to prove the scheme,is the foundation of high-performance.Predictive selection component is the key of receiving component.This paper studied sub-octave preselected filter group,and introduce balanced amplifier and LTCC filter to replace some sub-octave filter.This method can substantially reduce the PCB area,is the critical technology of miniaturization.Moreover,this paper studied LO section,and use frequency multiplier + DDS+PLL mode to realize LO2's small step forward,low phase noise,and low spurs.LO1 uses large step forward to matching the whole frequency hopping.Finally,this paper complete the full design,adjustment and testing of the receiver component.And the receiver designed in this paper can meet the specifications.