| The original method of correlated imaging,is to realize the separation of detection and imaging in the imaging process through entangled photons.Nowadays,drawing on the basic principles of optical imaging,the introduction of correlated imaging technology into the microwave band has also attracted the attention and research of many people.In the research process of radar technology,high resolution has always been a very important exploration point and appeal.This graduation design thesis will design a high-gain microwave correlation imaging antenna,mainly for the purpose of improving the randomness of the radiation field.Based on the research of the reflection array,through a series of adjustments and random arrangements of the patches,in this way,low-correlation radiation fields in different time and space conditions are obtained,and imaging results are further obtained.This thesis has carried out related research work on high-gain microwave correlation imaging antennas.The main contents are as follows:This thesis first introduces the related research background of correlated imaging,shows the origin of correlated imaging antenna and its specific application in the microwave field,and expounds its development process and current research status at home and abroad.Secondly,it briefly explained the basic principles and design schemes of the research content.The related knowledge of related imaging,metamaterial unit and reflection array is described.Finally,the metamaterial unit is designed,and the effect of ground glass is realized by the change of compensation phase with the size of the unit branch(or unit rotation angle).The whole process is mainly designed based on the reflection array,and the antenna indicators are restricted and specified,so that the correlation of the radiation pattern is low enough while ensuring a certain bunching ability of the antenna,so as to achieve a higher gain.Based on the principles and introduction mentioned above,this thesis will try to design the following situations and demonstrate their effectiveness:1.Based on the reflectarray antenna of the double-ring patch,simply destroy the array unit and observe the difference in the radiation field of the array under different conditions.That is: pick a different number of cells at different positions on multiple double-ring reflection arrays,and observe and analyze the correlation between each array pattern under the target frequency band.Using the MATLAB algorithm,it can be proved that the correlation between the directional patterns at this time is about 0.9 or more,and the above pattern data can be used in the imaging algorithm to determine whether the antenna meets the conditions under this correlation.Then,the above array is further rotated and flipped in space.Analyzing the radiation correlation in the latter two cases,we can get that the correlation of the radiation pattern is between 0.8～0.9 and 0.7～0.8.2.Rotate the unit angle of the fixed-size reflector array unit.On the basis of the circularly polarized reflector array,randomize the rotation angle of the unit patch within a certain range,and obtain a 25*25 unit random array by using HFSS-MATLAB co-simulation.It is known that units with different rotation angles correspond to different compensation phases,that is,the reflection effect of the entire reflective panel on the incoming waves from the feed is concave and convex.The effective area of the feed source irradiated on the reflector is certain each time,so the use of different units to compensate for the difference in phase can make the pattern group obtained with high randomness.when the feed source and the array move relative to each other.At this time,the correlation between the directional patterns is mainly concentrated between 0.5 and 0.7,which is effectively reduced compared to before.3.Increase the complexity of the unit.Randomize the spatial distribution and phase of metamaterial units multiple times.Study the method of raising the degree of freedom of radiation field frequency.Explore the influence of the high-order resonance mode and multi-mode resonance of the metamaterial unit on the speed of radiation phase change with frequency.Randomly arrange different resonance modes many times to increase the frequency freedom of the radiation field.There are mainly two methods: one is to make the first resonance and the second resonance of the metamaterial unit alternate and randomly distribute each other,and use the faster phase change speed of the high mode to improve the frequency agility.The second is to use a dual-resonance or even multi-resonance metamaterial unit structure to quickly increase the phase change speed of the metamaterial unit in a fixed frequency band to improve frequency agility. |
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