Key Technology Analysis For Antenna Array Of Aperture Synthesis Microwave Radiometer

In order to meet the spatial resolution requirement of passive microwave remote sensing from space, aperture synthesis radiometer (ASR) is used. An antenna array is an important part in ASR, the performance of which strongly influences performance of a radiometer. Various types of antenna arrays were implemented in present ASR instruments.Slotted waveguide arrays remain an attractive option for one-dimensional ASR for several good reasons including their extremely high antenna efficiency, mechanical simplicity, and high-reliability. The fundamental of slotted waveguide antenna was presented.Based on the principle of slotted waveguide antenna, several Ka band resonant edge-slot waveguide arrays were designed. Parametric models and design curves created by HFSS were used instead of costly empirical laboratory techniques which required a program of fabricating and measuring numerous prototypes. Preliminary simulation results show that the performance of each slotted waveguide array element achieved all the initial requirements.Since the theoretical analysis and instrument construction for antenna array of ASR are both complicated, simulation becomes a very useful method, and is of much help in the performance validation and optimization design.A simulation module for antenna array of Synthetic Aperture Microwave Radiometric Detection System was designed and validated. The process that antenna array collecting thermal radiation and transforming thermal radiation signal into radio frequency signal was simulated. Mechanical scan of antenna array was accomplished by rotation transform to form two-dimensional image with linear array. Considering that amplitude of mutual coupling coefficient is in inverse proportion to physical distance between each pair of antennae and the impact of antenna position errors on antenna coupling, detailed methods for fabricating antenna imperfections were presented. Simulation results show that magnitude, not the position of target brightness temperature is affected by antenna imperfections, especially the antenna coupling. A preliminary analysis showing that antenna coupling has a significant impact on reconstructed image quality and the accuracy of ASR target observation is also presented. The fact that the impact of antenna element pattern errors can be decreased by enlarging the size of antenna pattern matrix is validated by a control experiment.