| Our country is vast in territory, rich in natural resources andcomplicated in climate conditions. The meteorological factors such as rainfall,wind and temperature change greatly with recurrence. How to predict the weatherdisasters fast and effectively has a significant effect on social economy and people’s life.The meteorological radar is the most effective method to monitor and predict the burstweather disasters. Over the recent forty years, the constructions of the monitoringnetwork with meteorological radars achieved quiet great progress and play an importantrole in monitor and predict the burst weather disasters, with obvious benefits in society,economy and ecology.Combined with the urgency of the meteorological radars, a novel antenna arrayreceiving the meteorological information is studied in this paper. The antenna array canbe applied in local real-time meteorological service, outfield scientific research, andmeteorological guarantee, prevention and counteraction services for key projectconstruction. According to the specific application situation, several structures ofantenna array are presented and designed, and the antenna element is slotting dipolewhose operating frequency is1.75GHz. An omni–directional antenna model of16elements array was built, with4dB minimum and7dB maximum gains, andVSWR(Voltage Standing Wave Ratio) of the antenna is below1.5over the operatingbands. Next, another switch beam antenna of6elements array was constructed andoptimized. The maximum gain is7dB,3dB beam width can reach78°, and VSWR isless than1.5. With the use of antenna designing software, the advantages anddisadvantages of each scheme can be obtained.The LNA(Low Noise Amplifier) plays an significant role in the communicationsystems. The functions are amplifying the weak signals received by the antennas. LNAthat can be applied in the meteorological bands is studied next, based on the technicalspecifications of LNA and designing methods of the wide band amplifier. Then thenegative feedback amplifier whose operating frequency covers1-2GHz was designedwith two stage topology. The low noise E-PHEMT(Enhancement ModePseudom-orphic High Electron Mobility Transistor) ATF-54143is adopted. The biasedcircuit, negative feedback circuit, input, output and interstage match were simulated bythe commercial software. After circuit debugging, less than1.5dB NF(Noise Figure)and over32dB gain, less the2.0input and output VSWR can be achieved, which meet the requirement of the specifications. |
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