Digital Beamforming (dbf) The Calibration Network Research

In order to enhance the useful signals and suppress the interfering signals, the Digital Beamforming (DBF) technology can achieve spatial filtering by controlling the weight vector of each array element. However, in practical work, the system usually have different kinds of errors. To achieve the desired radiation pattern, such as main beam shape and low sidelobes, it is necessary for the array to be well calibrated. So the research of array calibration technique has great significance.The main work has been concluded in the following:1) According to the project requirements, a 10×10 calibration array has been designed. Through the coupling structure in the microstrip antenna, energy can be transferred between the antenna aperture and the calibration network. Furthermore, the errors of the calibration network have been investigated in this thesis, such as the fabrication errors and the fix errors. Form the simulated results, the performances of the DBF calibration system are stable.2) From the measured results, the mutual coupling between the antenna elements and microstrip calibration network affect the accuracy of the calibration. To improve the performance of the calibration network, a series of experiments have been done. Some methods have been proposed as a guideline to guarantee the accuracy of the calibration network. Furthermore, the shielding of the T/R module is discussed. Several methods have been presented to reduce the radiation of the microstrip calibration network.