Research On Zoom Aperture Synthesis Radiometer Antenna

Aperture synthetic radiometer is a kind of radiation measuring instrument with high resolution,which shows huge application potential in the fields of meteorological remote sensing,earth observation,target detection and social security.However,the limited field of view and sensitivity of the aperture synthetic radiometer limit the large-scale application of the aperture synthetic radiometer.Therefore,it is necessary to expand the field of view and improve the sensitivity of the aperture synthetic radiometer.The field of view of the aperture synthetic radiometer is limited by the minimum spacing of the receiving antenna.Usually the minimum spacing of the receiving antenna is the aperture size of the receiving antenna.Therefore,to obtain a larger imaging field of view,a receiving antenna with a smaller aperture must be selected.On the other hand,the sensitivity of the aperture synthetic radiometer is limited by the beam solid angle of the receiving antenna.The beam solid angle of the antenna is directly related to the aperture of the receiving antenna.In order to obtain higher measurement sensitivity,a receiving antenna with a larger aperture size must be selected.The requirements of the field of view and the sensitivity of the aperture synthetic radiometer to the antenna aperture are contradictory,making it difficult for the aperture synthetic radiometer to obtain a wide imaging field of view and high measurement sensitivity at the same time.There are two ways to solve the above problems.One is to keep the radiometer sensitivity unchanged and reduce the minimum baseline of the array to expand the imaging field of view.The other is to keep the array minimum baseline unchanged and improve the sensitivity of the radiometer.Based on the second idea,this paper proposes a "zoom" aperture synthetic radiometer.The beam width reconfigure antenna can be used to change the beam width of the unit antenna,thereby dynamically adjusting the field of view and sensitivity of the aperture synthetic radiometer,so that it has the time-sharing to obtain a wide field of view and high measure sensitivity.The specific research content is as follows:At first,the aperture synthetic radiometer with the largest imaging field of view under a fixed minimum baseline is studied.The band gap characteristics of the metal wire medium are used to match the beam width of the metal wire media antenna with the array factor beam width determined by the minimum baseline to achieve the the maximum imaging field of view under the fixed minimum baseline;secondly,to improve the sensitivity of the aperture synthetic radiometer,the reconfigurable beam width antenna is used to change the beam solid angle,so that the sensitivity of the aperture synthetic radiometer can be changed and the zoom imaging of the synthetic aperture radiometer is realized;at last,the problem of excessively large longitudinal size of the aperture synthetic radiometer during large-scale zooming is proposed,and an improved zoom aperture synthetic radiometer is proposed,which utilizes the characteristics of the double-layer metal wire media antenna with a smaller cross section to make the zoom synthetic aperture radiometer have a smaller longitudinal size.The zoom aperture synthetic radiometer proposed in this paper can dynamically adjust the field of view and sensitivity of the system,so that the fixed parameter measurement of traditional aperture synthetic radiometer transition to the adjustable parameter measurement of a new type aperture synthetic radiometer,makes the synthetic aperture radiometer can face more complex measurement tasks,and the research of fully parameter adjustable imaging and variable parameter adaptive imaging of aperture synthetic radiometer are promoted.