The Investigation Of The Application Of Zero Refractive-index Materials And Plasmas In Antennas

As a kind of electromagnetic metamaterial,zero refractive index material can improve the directivity of antenna effectively because of its special electromagnetic characteristics.A notable feature of plasma antenna is that the antenna parameters can be electrically adjusted.If the two are combined and the zero refractive index material is used to improve the direction of the antenna,and then the plasma discharge tube is introduced into the zero refractive index material,the dynamic regulation of the antenna direction can be realized.The main contents of this paper can be summarized as follows:In the second chapter two kinds of zero refractive-index materials were designed:metal lines zero refractive-index material and cross patch zero refractive-index material.The equivalent electromagnetic parameters were extracted by the equivalent parameter extraction method.The refractive index of the metal linear zero refractive-index material near 9.37GHz is 0.05,the imaginary part is 0.02,the refractive-index of the cross patch type zero refractive index material is 0.08 and the imaginary part is 0.04 near the 9.37GHz,and the two materials can be considered to have zero refraction in 9.37GHz.Subsequently,two kinds of plate structures made of materials were prepared,and the zero refractive index characteristics were verified practically.In the third chapter,the metal line and cross patch zero refractive-index materials were loaded to the horn antenna port to improve the directivity of horn antenna.The simulation results show that the main parameters of the horn antenna are improved after loading the metal line zero refractive index material,the half power width of the E plane is reduced by 1.1 degrees,the half power width of the H plane is reduced by 4.9 degrees,the echo loss is reduced by 2.4dB,the maximum gain is increased by 1.6dB,and the gain bandwidth is 430MHz.When the cross patch linear zero refractive index material is loaded,the half power width of the E plane is reduced by 5.5 degrees,the half power width of the H plane is reduced by 3 degrees,the echo loss is reduced by 2.8dB,the maximum gain is 2.2dB,and the gain bandwidth is 290MHz.The measurement of the refractive index material in microwave anechoic chamber also confirms the enhancement of the antenna's directivity.In the fourth chapter,two different schemes were used to combine plasma discharge tube with zero refractive index material to control the directivity of horn antenna dynamically.For the metal linear zero refractive index material,the copper wire is replaced by a fine plasma discharge tube.The transformation range of E half power width is 9.3 degrees,the conversion range of H half power width is 15.6 degrees,and the maximum gain range is 3.7dB.For cross patch zero refractive index materials,the emitted electromagnetic wave is reflected by a relatively thick plasma discharge tube.When the plasma discharge tube is in a state of power failure,the directivity of the antenna is improved,and the directivity of the antenna increases when the plasma discharge tube is in an electrified state.The transformation range of E half power width is 19.4 degrees,the conversion range of H half power width is 16.5 degrees,and the maximum gain range is 4.6dB.In the fifth chapter,plasma physics and nuclear physics are combined to build a theoretical model of plasma preionization on the inner wall of an alpha particle coated plasma discharge tube.After calculation,it is found that when the inner diameter of the discharge tube is 10mm,the 238Pu coating with uniform coating activity can produce 108/cm3 order of magnitude free electron density in the tube,which can reduce the discharge time of the plasma tube from about 500ns to about 220ns.