Analysis And Synthesis Of Conformal Array Antenna With Complex Platforms

As a hot research topic of modern antenna design, conformal array antenna has the big potential to be used in the military and civil area. For the advanced aircraft such as airplane and missile, antennas should be confomal with the platforms to avoid destroying the aerodynamics performance and have the advantages of wide beam cover and low RCS. While in the common life, conformal antennas are also necessary because of the concept of beautification antenna. Apparently, performances of the antennas are related with the characteristics of platforms which are always differing, so it is necessary to study the conformal antenna with the complex platforms.By combining the ways of theory analysis, numerical simulation and experiment verification, conformal antenna with complex platforms have been studied in this thesis. This thesis focuses on the antenna miniaturization, analysis and synthesis methods of conformal antenna and following contents have been studied deeply: 1. Analysis of electromagnetic radiation using JMCFIEJMCFIE is employed to analyze the radiation property of conformal antennas with complex platform in this theis because of its reduced unknows and computation complexity. Firstly, planar and simple conformal antennas are analyzed by JMCFIE. Then JMCFIE are combined with MLFMA to study the conformal antenna with platforms, which is composed of metal and dielectric. Results calculated with JMCFIE are compared with those got from commercial software CST and good agreements are observed, which demonstrates the good performances of JMCFIE for the analysis of the conformal antenna with complex platforms. 2. Compact antenna designBecause of limited space, antenna miniaturization is a key technology for modern aircraft. By integrating a miniaturized hybrid patch coupler inside the annular ring antenna, a compact circularly polarized antenna with total size of λ0/2 × λ0/2 is designded and its performances are comparable with the conventional microstrip antenna. In addition, equivalent circuit model is also proposed to provide assistance for this antenna design. To make the antenna size more compact, concept of ring reflector and director are proposed, the proposed antenna has the size of λ0/4 × λ0/4 while the radiation performances are remained. 3. Co-aperture antenna designBy integrating the antennas that have different functions and frequencies into a common aperture, the numbers of aperture in the system will be reduced dramatically and make the system be more compact. Accroding to different frequency ratio, two dual-band coaperture antennas and one tri-band coperture antenna are designed with the compact ring structure. 4. Optimization of antenna and synthesis of array using invasive weed optimizationInvasive weed optimization are combined with commercial software HFSS for the antenna optimization. Full wave analysis is carried out in the HFSS, while the optimization process is finished in the IWO. By this way, the optimized antenna can be transferred to engineering application directly. Then concept of active element pattern(AEP) is introduced, radiation pattern of large antenna array are calculated by combine the theory of AEP and array factor(AF). With this hybrid method, radiation pattern of large antenna array can be computated very efficiently while the specific error is remaind. Lastly, a planar array antenna is synthesized by combining IWO and AEP. Compare with HFSS, good agreement is achieved. 5. Design of conformal antenna and array with complex platformsDifferent antennas and arrays are designed for different applications and platforms. Based on the conical platform, a linear array is optimized with AEP and IWO. Measured results show the effectiveness of proposed method for the conformal array synthesis. In addition, a wide beam scan array by the antenna miniaturization technology is designed either and are optimized by AEP and IWO either. The measured results demonstrate that wide beam scanning can be achieved with the proposed method. For the cylindrical platform with limited space for antenna, an antenna array is designed for omnidirectional circularly polarized beam covering in the horizontal plane. The main technology includes antenna miniaturization and hybrid series and parallel feeding structure. The proposed design has the features of compact size, easy to conformal and fabricate. For the unmanned aircraft platforms, a low profile vertical polarization antenna is designed firstly. Then EFIE-JMCFIE and MLFMA are carried out to calculate the radiaton pattern of the antenna conformal to two unmanned aircrafts that have different properties. Measured results show that good agreement is abtained for our calculated results. Lastly, a coapeture antenna array operated at X/K band is designed for unmanned aircraft either. AEP and IWO are used again to optimize this antenna array, measured results show that the proposed array has accurate beam direction with the optimized phase distribution.