Research On Antenna Radar Cross Section Reduction And Polarization Rotation Reflective Surface

Radar had a rapid development in the Second World War and today becomes a typical case which represents the advanced level of the military industry of a country.Antenna is closely related to the radiation and scattering characteristics of radar system as the system front end.With the rapid development of stealth and anti-stealth technologies,the radar cross section(RCS)reduction of antenna has drawn more and more attentions and been widely researched.As a special scattering structure,antenna has different scattering principles from common scattering structures.Moreover,antenna has to maintain good radiation performance when it is designed for low RCS applications.Therefore,the researches focusing on the RCS reduction of antenna are with important theoretical and practical value.Being associated with the above background and national natural science foundation of China,this dissertation mainly focuses on the antenna RCS reduction.In addition,the wideband polarization rotation reflective surfaces(PRRSs)and their application to RCS reduction is investigated.The major contribution of this dissertation can be summarized as the following five aspects:1.The scattering characteristic of Vivaldi antenna is studied in detail.Different methods for single layer and bilateral layer Vivaldi antennas are used to reduce the RCS.For the single layer Vivaldi antenna,its scattering principle is analyzed using the surface current induced by the incident plane wave.On this basis,the RCS of single layer Vivaldi is reduced by shaping the edges of the antenna.Then for the bilateral Vivaldi antenna,two half-mode substrate integrated waveguides(HMSIWs)are formed by adding two rows of metallic vias.The HMSIWs can guide the incident wave to the end of the antenna.As a result,the backward scattering is significantly reduced.2.The application of the frequency selective surface(FSS)to in-band antenna RCS reduction is investigated.The polarization-dependent band-pass FSS based on complement split resonant ring(CSRR)and quasi self-complementary FSS are designed and used for RCS reduction of microstrip antennas,respectively.By etching the FSSs in two orthogonal directions on the ground of microstrip antenna,the antenna can have both good radiation performance and low RCS.For the case of band-pass FSS based on CSRR,the in-band RCS of microstrip antenna can be reduced.For the case of quasi self-complementary FSS,both in-band and out-of-band RCS of microstrip antenna can be reduced at the same time.3.The radiation and scattering characteristics of slotted coupled antenna based on metamaterial are studied.Taking advantages of the periodic structure of metamaterial,more resonant modes can be generated in a relatively narrow frequency band.Then,the operating band of antenna can be broadened by combining the different resonant frequencies with each other.What's more,the periodic structure of metamaterial can reflect the incident wave with a zero phase.As a result,the RCS of antenna based on metamaterial can be reduced.4.The method of designing wideband high-efficiency polarization rotation reflective surface(PRRS)is investigated.By loading two asymmetric metallic vias,the working band of PRRS based on artificial magnetic conductor(AMC)is improved from 28% to 49%.When the square patch is replaced by an L-shaped patch,the working band of 103.6% can be obtained.However,the polarization conversion radio(PCR)is relatively low.In order to get the high-efficiency wideband PRRS,a dual patch PRRS are designed by using the square and L-shaped patches.The operating band of the dual patch PRRS is broadened to 98% when the PRRS is covered by a superstrate.Furthermore,the PRRS covered by metasurface superstrate is studied.When covered by the metasurface superstrate,the PRRS which is formed by pairs of L-shaped patches can achieve a working band of 126%.5.The PRRS is used to reduce RCS and design wideband circularly polarized(CP)with high gain and low RCS.The characteristics of RCS reduction of PRRS arranged in different configuration are investigated.When the unit cells of PRRS are arranged in the same direction,only the co-polarization RCS can be reduced.Moreover,the RCS reduction can be obtained when the polarization of the incident plane wave is in special direction.However,when the unit cells of PRRS are arranged in orthogonal directions,the total RCS can be reduced under arbitrary polarized incident plane waves.A 4×4 array of PRRS fed by a slot can be designed as a wideband high-gain CP antenna.What's more,the antenna RCS can be reduced by adding AMC structure.