A Study Of Front Receiver For Meteorological Radar

In this thesis, the theory for positioning of monopulse meteorological radar isdiscussed, and the principle of amplitude sum-difference meteorological radar isanalyzed. The sum-difference network and preselect filter in the link of meteorologicalradar receiver are researched in this paper, moreover, compact sum-difference networkand compact preselect filter are manufactured.Two compact couplers are designed according to the idea of equivalent circuit,namely compact ring coupler and compact branch coupler. Then, two compactsum-difference networks named ring sum-difference network and branchsum-difference network are designed based on the two compact couplers. The twosum-difference networks are simulated and tested. The results reveal that the twosum-difference networks not only have excellent performances on insertion loss andnull depth, but also possess compact structure and low manufacturing cost. So the twosum-difference networks are capable of being used in the link of meteorological radarreceiver.In order to satisfy the requirements of the receiver system, the general Chebyshevfilter is chosen as the preselect filter. The synthesized process is described, whichcontains the synthesis of the general Chebyshev polynomial and the coupling matrix.The accuracy of synthesized process is validated through examples.In order to achieve the miniaturization of preselect filter, the stepped impedanceresonator (SIR) is chosen as the resonator of coaxial cavity. The theory as well as theproperty of SIR is depicted. The extracting ways of coupling matrix and external qualityfactor are also described. Finally, based on the theories discussed above, a four-polecoaxial SIR bandpass filter with general Chebyshev response is designed. The crosscoupling between nonadjacent resonators has been introduced to produce transmissionzeros at specified frequencies close to the passband edges. The simulated results cansatisfy the requirements. The filter is manufactured and the tested result basicallysatisfies the indexes.