Research On Millimeter-wave Radiation Characteristics Of The Absorbing Coating With Inhomogeneous Temperature Profile

Stealth is one of the important features of modern military aircraft,one of the stealth methods is to apply absorbing materials on target's surface.It weakens the radar signal or infrared signal,consequently,reducing the detection ability of active radar and infrared detector.Recently,passive millimeter-wave radiation detection technology has drawn more and more attention of researchers.Based on the radiation characteristics of stealth target itself,it can gain information different from radar and infrared detection.Therefore,it is possible to be complement of radar,infrared and other detection methods.At present,the research on the millimeter-wave radiation characteristic of the coating mostly stays at room temperature or constant temperature.However,the temperature of coating is not constant but varying on some occasions.Thus,this thesis has carried out theoretical and experimental studies on the millimeter-wave thermal radiation characteristics of coatings with inhomogeneous temperature profile.The main work is shown as follows:Firstly,the millimeter-wave thermal radiation theory is introduced.The classical three-layer medium radiation transfer model is generalized,and the formula for calculating the brightness temperature of millimeter-wave radiation for the medium with inhomogeneous temperature profile is derived.Secondly,the heat conduction process of the coating under several boundary conditions is analyzed,and the variation law of the temperature profile is obtained.Then,some classical dielectric models are used to explain the variation of the dielectric constant of the coating with temperature.Then,the simulation of the brightness temperature of the coating under several temperature profiles is carried out.The brightness temperature of the coating with temperature gradient is calculated and compared with constant temperature,and then the influence of temperature characteristic of the dielectric constant on its brightness temperature is analyzed.Finally,the equivalent verification experiment is carried out.After solving the problems that may exist in the radiation measurement of small size plate,the brightness temperature of the coating at different temperature profiles are calculated.Compared with the experimental values at these temperature,the conclusions about the effect of temperature on the brightness temperature of the coating obtained by the simulation is verified.For the coating with inhomogeneous temperature profile,considering the temperature difference between the inner and outer surfaces of the coating,the calculation process of the bright temperature is improved.The calculated results indicate that the difference between the improved value and the experimental value is reduced.In this thesis,the research on the millimeter-wave radiation characteristics of the coating with inhomogeneous temperature profile support for passive radiation detection stealth aircraft.