The Design And Realization Of The S-band Microwave Downconverter

The subject comes from a project of my organization: Research a device that converts S-band signal to 70MHz processed by back-end equipment.First of all, the paper introduces the elements of microwave down-converter and some key poformance. Through comparison, we select the scheme of microwave down-converter of 2.2~2.7GHz. Base on this project, we analyse the way of implement and the performance index of each function module, such as local oscillation, preelection RF filter, frequency converter unit,AGC unit and so on.After reference a great lot of literature about microwave down-converter design, analyse zhe advancement, feasibility and economic cost of zhe system, combining with computer simulation and practices.Then also solve some important problems such as security, electromagnetism compatibility and caloric radiator.At last, Give test results about of the system and attach some substantiality images.By making full use of favourable narrow-band tracing filter character of PLL and by combining the merits of DDS such as super fine frequency resolution high frequency accuracy very fast frequency hoping with it,the PLL/PLL+DDS frequency synthesizer presents wide band high quality source and super small frequency hoping step.While the electronically tuned filter abates the image interference and notably improves the selectivity.The paper ends with the deep analysis this high performance microwave down-converter about security, electromagnetism compatibility and caloric radiator.