Marine Radar Receiver Research And Design

With the rapid development of shipping industry, water transportation occupiesvery important position in the national economy. As rivers, ports and offshore watersbecome more crowded, ship collisions are occurring frequently, and become a threat topeople’s lives and property safety. Shipborne radar could help ships sailing in lowvisibility conditions and crowded waterway, effectively avoiding collision. Nowadays,cargo merchant vessels and fishing vessels have become increasingly dependent on highperformance shipborne radar. The higher the sensitivity of the radar receiver, the fartherthe radar can reach and the stronger detection ability the radar can get. Therefore,developing a high sensitivity shipborne radar receiver possesses very high value andsignificance.In this dissertation, the radar receiver is based on the X-band shipborne navigationradar. With the principle of low cost, high reliability, ease of realization and the goal ofdesigning a high sensitivity radar receiver, this dissertation focuses on the theory anddesign of low noise amplifier (LNA), image rejection mixer, IF matched filter andlogarithmic amplifier in the receiver. Sensitivity of the receiver is improved by reducingthe noise figure of system and high performance IF filter. In this dissertation, atwo-stage LNA is designed, and the noise figure is less than1.5dB, the gain is largerthan23dB. The image rejection mixer is optimized, and the conversion loss is less than6dB, image rejection is20dB. A20MHz bandwidth IF filter is designed by using5-order Chebyshev structure, realizing high rejection to interfering signals. A narrowband filter with better shape factor is designed by using a structure of high-Q resonatorscoupled by a capacitor to improve the output SNR of remote echo signals. Withrational gain allocation, the dynamic range of the logarithmic amplifier realized85dB.Finally, the radar receiver was inspected in field test, to verify the performance ofits high sensitivity. Indicators of shipborne radar receiver designed meet therequirements.