Research On RCS Reduction Technology Of Microstrip Antenna Based On Van Atta Array

With the increasing progress of radar target positioning,recognition,and combat techniques in modern electronic warfare,radar stealth technology has been rapidly developed to reduce the detectability of targets.Stealth technology of platforms including aircrafts and ships has become more and more mature,but the stealth of antenna,which is regards as the main contributor to the overall radar cross section of platforms,still faces great challenges.As a special scatterer,an antenna radiates and scatters electromagnetic wave,simultaneously.Therefore,it has become one of the most important problems in the field of antenna radar cross section reduction,because the characteristics of low radar cross section of the antenna is achieved and meanwhile its receiving and radiation characteristics are not affected.This thesis mainly studies the technology of RCS reduction for microstrip antennas.The main work is summarized as follows:1.Research on RCS reduction method of microstrip antenna based on Van Atta array.According to the principle of phase gradient inversion,a 2-by-2 Van Atta subarray is designed to convert the co-polarization component of its RCS into the cross-polarization component.Then,the total and co-polarized components of RCS are reduced by arranging the Van Atta subarrays around the microstrip antenna in the translation and rotation ways respectively.On this basis,a compact 2-by-2 RCS reduction array is designed and directly integrated with the microstrip antenna in a compact size based on the principles of polarization rotation and scattering cancellation.It is verified by the simulation and measurement that the in-band total RCS of the antenna is reduced by more than 10 dB and meanwhile the gain is increased by 1.2dB.Thus,high gain and low RCS,which are two contradictory factors of the antenna,have been successfully realized.In addition,the proposed array has a certain oblique incidence adaptability.Compared with reference antenna,the maximum value of bistatic RCS is also reduced by more than 10 dB in the range from-15o to 15 o of the incident angle.The proposed design method,provides a feasible way to design the low-RCS antennas in the stealth application.2.Application of dual-polarization mode reconfigurable OAM reflective array in RCS reduction of microstrip antenna.In this thesis,a compact OAM reflective array with a simple structure is designed according to circular antenna array.By adjusting the connection line between the elements,the radiation phase of the antenna array can be controlled,and thus the plane wave incident on the array can be converted to the OAM vortex wave.A four-element OAM reflector array is first designed.Then,in order to generate higher mode OAM beams,we design an eight-element reflector array for generating OAM vortex waves with the mode 1 and mode 2,respectively.On this basis,the RF PIN switch is introduced to realize OAM mode reconfiguration of the proposed reflector.The proposed OAM reflector array has the characteristics of polarization rotation for both horizontal-and vertical-polarizations waves.Therefore,the functions of polarization diversity and modal multiplexing are realized,which can be used to increase channel capacity in a communication system.Further,we integrate the proposed OAM reflective array with a microstrip antenna.The gain of the resultant structure is improved by 3dB,and the in-band backward RCS is reduced by more than 10 dB.Therefore,the designed reflective array is a multifunction devices in generating OAM waves and reducing RCS of the antenna.