Design Of Oscillator And Mixer For X Band Ship Radar Receiver

Marine navigation radar is the security for ships,which plays an important role in such scenes as the offshore positioning of ships,navigation in and out of port,bad weather navigation and so on.Radar receiver RF front-end is an important part of radar,and the oscillator and mixer,as an important component of radar receiver RF front-end,affect the performance of the receiver.Therefore,it is of great importance to study the front-end oscillator and mixer of X-band marine radar receiver.Aimed at the design and optimization of the oscillator and mixer based on FET,the completed work mainly includes the following two aspects:(1)An NE3511S02 FET is applied to design and implement the X-band FET negative resistance oscillator.And a band-pass filter is added to lower the second harmonic suppression.Then,band-pass filter is processed and tested,and an good agreement between the simulation and the test is obtained.Finally,the oscillator is processed and tested,The final output frequency of the oscillator is 8.87GHz,the second harmonic suppression is 27.73dBc,and the phase noise is below-106dBc/Hz at 100KHz and below-131dBc/Hz at 1MHz,and the test results basically meet the design requirements.(2)An X-band FET drain mixer is designed and implemented with NE3512S02.First,the wide resistance band low pass filter,the parallel coupling band pass filter and the DC bias circuit are designed and simulated respectively.Then,ADS is used to simulate and design the whole part of the single tube FET drain mixer.Finally,the lowpass filter and the mixer are processed and tested respectively.The test results show:in the frequency range of 9.1?9.5GHz,the mixer achieved 501.3?903.3MHz output,the maximum frequency conversion gain is 1.3dB,and the isolation of each port is above 20dB,basically meet the design requirements.