Research On Portable Detection Technology Of Surface Wave Attenuation Rate Of Absorbing Materials

With the continuous development of modern wireless communication technology and the gradual improvement of radar detection capabilities,how to avoid radar detection and improve the concealment of combat is an urgent problem to be solved.The radar detects the echo signal through the reflection and scattering of the electromagnetic wave signal by the fighter.The generation of the echo signal is mainly divided into two ways.One is specular reflection,the propagation directions of incident and reflected electromagnetic waves are symmetrical about the normal to the incident surface,the reflected signal level can be reduced by adjusting the shape of the airframe or coating absorbing materials with absorption peaks corresponding to the working frequency band of the radar.The other is traveling wave scattering.Part of the energy of the incident electromagnetic waves will generate surface traveling waves on the surface of the body.When there is a discontinuity with a large curvature,a strong non-directional scattering signal level will be generated.Therefore,traveling wave scattering has gradually become the main factor for increasing the RCS of fighter aircraft.Attenuation of traveling waves by absorbing materials is the main measure to reduce traveling wave scattering.The existing traveling wave suppression testing methods all have the shortcomings of complex testing and low testing accuracy.How to establish an effective testing method for evaluating the surface wave attenuation rate of absorbing materials is still a topic worthy of research.In this thesis,a portable detection device covering X-band for surface wave attenuation rate of absorbing materials is designed,the system is tested under near-field conditions based on surface wave transmission lines.First,a surface wave transmission line covering X-band is designed,its standing wave is less than 1.8,the integrated design of the ridge horn antenna and the slow wave surface reduces the volume and weight of the test device and improves the portability of the test.The design inherits the advantages of wide frequency band and high directivity of the double-ridged horn antenna,which greatly improves the transmission efficiency of surface waves;this thesis establishes a variety of evaluation methods for the transmission characteristics of the designed surface wave transmission line,first,the Fourier transform is used to convert the frequency domain response into the time domain response,the space wave and surface wave energy are distinguished from the propagation characteristics,the influence of the electromagnetic properties of materials on the surface wave energy is explored,then a two-dimensional amplitude-phase automatic scanning device was established to image the slow-wave surface of the surface wave transmission line,the scanning results show that the lateral phase constant of the surface wave is in good agreement with the simulation,and the surface wave is verified.The vector network module and the surface wave transmission line form the entire test system,the surface wave attenuation rate test range of the system is 0-2d B/cm,the metal plate calibration combined with the time domain gate technology is used to test the surface wave attenuation rate of absorbing materials with different electromagnetic properties,the obtained results are in good agreement with theoretical calculations,and finally the test error that may affect the test accuracy are analyzed.To sum up,the established portable detection system for surface wave attenuation rate improves the shortcomings of traditional testing methods,and greatly improves the flexibility and accuracy of testing.