Analysis And Design Of Monopulse Meteorological Radar System

As the main equipment of high-altitude meteorological detection, the monopulsemeteorological radar system, for a long time, has played an important role in the field ofChina’s high-altitude meteorological detection. However, with the development ofscience and technology, the detection accuracy of the monopulse meteorological radarsystem based on analog signal processing cannot meet the requirements of currenthigh-altitude meteorological detection, especially in various military activities whichdemand accurate high-altitude meteorological information. In recent years, the rapiddevelopments of high speed digital circuit and digital signal processing technologyprovided a firm foundation for the digital IF receiver in radar system. Digital IF receiverhas become an inevitable trend of the development of modern radar systems. With theconsideration of related research projects and an in-depth study of the monopulsemeteorological radar system, this research is mainly concerned with the study ofthree-channel RF receiver subsystem and signal processing subsystem in ground radarsystem and the analysis and design of new types of printed antennas for radiosonde. Themajor contributions of this dissertation can be outlined as follows:1. A detailed analysis and design of three-channel RF receiver subsystem ispresented. The requirements of RF receiver subsystem are first analyzed and discussedbased on which an integrated design is finalized. To verify its feasibility, the design issimulated and optimized by the computer simulation. Finally, the prototype of thethree-channel RF receiver subsystem is fabricated and tested. The test results show thatthe design of RF receiver subsystem in this dissertation has the advantages of low noisefigure, high dynamic range, and high isolation, which can properly meet the indicatorrequirements of the high-accuracy monopulse radar system.2. A study of channel isolation and channel consistency in RF receiver subsystemis given. The three receiver channels are designed separately and placed in threeindependent metal cavities. Combined with the method of isolating local oscillatorsignals, the isolation between the RF receive channels is greatly improved. On the basisof the same hardware designs for the three-channel RF receiver channels, the amplitudeand phase errors between channels are corrected by adding a calibration signal sourcecoordinated with the signal processing subsystem and the influence of receiving link’samplitude as well as phase errors on monopulse angle measurement is eliminated. The test results show that the method presented in this dissertation is a good solution toimprove the channel isolation and channel consistency.3. The signal processing subsystem is analyzed and designed in detail. Firstly,based on the functional requirements of the subsystem, hardware circuits are designedsystematically by combining FPGA with DSP. Digital signal processing algorithms arethen adopted to analyze detailedly and implement each function of the subsystem. Thetest results of the radar system indicate that the system detection accuracy is effectivelyenhanced by the proposed digital signal processing technology.4. In the context of the application background of radiosonde antennas inmonopulse meteorological radar system and the development trends of multi-band andwideband in radar systems, dual-band and wideband printed antennas applied forradiosonde are discussed. Firstly, two types of printed monopoles with properties ofdual-band and wideband are designed by loading slot and parasitic units on thefoundation of a conventional printed monopole. Secondly, a novel printed loop antennais proposed based on the radiosonde’s special requirements for directed radiation. Byadding parasitic resonant units separately to the inner and outer sides of the printedradiating loop, two additional resonant frequencies are yielded and the impedancebandwidth of the antenna is broadened effectively.