Design And Research Of Conformal Antenn

As compared with planar antennas,conformal antennas have unparalleled advantages of wide-angle coverage,increased radiation aperture and low antenna radar cross section(RCS),which are widely used in many fields such as aviation,aerospace and electronic communication.However,most of the existing conformal antennas suffer from narrow bandwidth and manufacturing complexity.In order to solve the above problems,this paper focuses on the analysis and research of microstrip antenna and tightly coupled dipole.The dissertation is arranged as follows:1、Design and fabrication of wideband planar microstrip array and wideband conformal microstrip arrayA unit cell of the wideband planar microstrip array is designed and it achieves the cross-polarization level below-20 dB over the whole X-band(8-12 GHz),which is realized by a cavity-backer proximity-coupled method.In addition,a thin PCB dielectric layer is applied to the bent Teflon dielectric layer aim at conformal processing.Then a planar array and a conformal array is implemented using the 4 × 4 elements,and the conformal units are axially mounted onto a cylindrical surface with a radius of 100 mm.Furthermore,the parasitic structure was introduced to reduce the isolation below-15 dB,which mitigates the deterioration caused by coupling,and achieves pretty matching.Finally,the simulation,machining and testing of the two array were completed.According to the measurement,the VSWR of the planar array remains less than 2 and the measured gain is greater than 17 dB across the entire frequency band(8-12 GHz),which presents a pretty radiation performance.The measured maximum gain reaches 18.17 dB.The impedance bandwidth of the conformal array is the same as that of the planar array.The measured gain is greater than 15.4 dB across the entire frequency band and the measured maximum gain reaches 16.3 dB,and furthermore,maintaining similar radiation performance of planar array.There are good agreements in the measured and simulated results.Compared with the existing conformal microstrip array,the bandwidth of our antenna can be increased from about 10% to 40% while maintaining the radiation performance.2、Design and fabrication of broadband dual-polarized planar tightly coupled dipole array and broadband dual-polarized conformal tightly coupled dipole arrayIn order to meet the dual-polarization requirement of conformal antenna,a unit cell of the wideband dual-polarized planar tightly coupled dipole array is designed.The unit is composed of two pairs of orthogonally dipoles to achieve dual-polarization.In addition,by optimizing the feed system and loading the matching layer,the infinite array achieves VSWR less than 2.4 over a bandwidth of 6–10 GHz(50% bandwidth),within a wide-scanning range of ±45° in two principal planes while taking the conformal machining feasibility into account.Then a planar array and a conformal array is implemented using the 4 × 4 elements,and the conformal units are axially mounted onto a cylindrical surface with a radius of 100 mm.Two arrays were simulated,fabricated and measured as folllow.According to the measurement,the VSWR of the planar array remains less than 2 across the entire frequency band(6-10 GHz),and the cross-polarized is less than-20 dB and the measured gain is greater than 17 dB,respectively,which present a pretty radiation performance.The measured maximum gain reaches 16.6 dB.Conformal arrays can maintain the same impedance bandwidth and low cross-polarization performance as planar arrays.The measured gain is greater than 12 dB across the entire frequency band and the measured maximum gain reaches 15 dB,maintaining similar radiation performance of planar array.There are good agreements in the measured and simulated results.Compared with the existing conformal array,it not only realizes dual-polarization,but also achieves 50% bandwidth.