System Research Of Rotating Circular Array Microwave Interferometric Radiometer

Since 1990 s,the Microwave Interferometric Radiometer(MIR)has been one emerging research field in the passive microwave remote sensing.Compared with real aperture radiometer,thinned antenna array with small aperture antenna units is used to instead large aperture antenna in MIR.MIR can get better spatial resolution with this thinned antenna array.In recent years,with the improvement of interferometric synthetic aperture theory and rapid development of radio frequency receiver technology,MIR is becoming a practical passive microwave remote sensing means.Rotating circular array MIR is one of the most impotant part of MIR researching areas.Rotating circular array can be used for time-division sampling in spatial frequency domain,so rotating circular array MIR has a better aperture sparse ratio and simpler hardware system than traditional MIR.When comes to spaceborned microwave radiometer,rotating circular array can located in column carrier conformally.What's more,MIR calibration becomes easy with a rotating circular array.This paper is focused on the system design and analysis of rotating circular array MIR.The main works and conclusions are as follow:1.System architecture research of rotating circular array MIRBased on the existed research of circular array,a new rotating circular array form is proposed in this paper,which is based on cyclic subarray.Rotating cyclic subarray form has a shorter imaging cycle period than traditional rotating array.Every antenna unit has mirror backup in other subarrays,so rotating cyclic subarray has excellent system reliability.This rotating cyclic subarray form demonstrates a new method for rotating circular array MIR designing.2.Signal transmission modeling analysis of rotating circular array MIRIn rotating circular array MIR system,balanced amplifer is used in Millimeter wave frontend receivers.Signal transmission modeling is constructed for this balanced amplifer receivers and the non-ideal characteristics of the balanced amplifer is analysed in this paper.The relationship between practical visibility function and ideal visibility function is formulated in this signal transmission modeling.3.System error analysis of rotating circular array MIRBy rotating circular array MIR system simulator,kinds of hardware module error is analysed quantified.Modularity error assessment model is established in this paper,which is usefull for rotating circular array MIR modular design and system error assessment.4.Calibration and error correction of rotating circular array MIRBased on the system error analysis results,systematic calibration and error correction of rotating circular array MIR is proposed in this paper.Complete system signal link is all coverd in this calibration method.This Calibration and error correction method is combined with rotating circular array form,especially the amplitude error correction and phase error correction.Rotational symmetry of rotating circular array is used in amplitude error correction.Redundant measurement information by rotating circular array is used to design a new phase self calibration method.This phase self calibration method doesn't need any calibration hardware and can be operated with target observation synchronously.This phase self calibration method is demonstrated by both simulation and field imaging experiment.By completing calibration and error correction of rotating circular array MIR,the relashionship between the final system calibrated error and kinds of module performance parameters is achieved.This result can be used for system error assessment after system integration.