Research On Performance Of Cylindrical Conformal Dipole Array Antenna

With the development of electronic wars and information wars, excellent performances and good matches to carrier surfaces of antenna are required in the application fields of advanced aerocrafts and vehicles(aeroplane,missle,secondary planet,warship and vehicle), and conformal antenna is defined in the circumstances. Not only the traditional military affairs have a great demand for conformal antenna, but also the mobile communication does with the development of mobile communication, in which conformal antenna can be used as station antenna and portable antenna. So the research and analysis on conformal antenna is valuable in the fields of engineering and national defense.The research on conformal antenna's performance is a very active research field, and it is the important technique in the future intelligent stealth technique and weapon system. In the essence of conformal antenna, there is a kind of antenna which must consider the effect from ambience. When the modeling of antenna is closed to the natural ambience, then we can dope out the antenna performance exactly. However, there are some disadvantages in the study and application of conformal antenna technique at present: most of the studies on conformal antenna have been made in ideal condition, but few in actual working conditions; the analysis method converges slowly and the research hardly meets the requirements of the next analysis. Therefore, theoretical modeling,efficient and accurate analysis methods are done in this paper about dipole antennas conformal to electrically large cylinder. Main contents and innovation points in this paper are as follows:Firstly, the research on finite planar dipole array is presented, which discussed a hybrid method that contained RWG function and equivalent dipole moment model. In the dipole moment model the surface current distribution for each RWG edge element is replaced by the current of an infinitesimal dipole, having an equivalent dipole moment and strength. So the total radiated field is then obtained as a sum of all these contribution of infinitesimal dipoles. This method reduces computation time, and enhances the computation efficiency.Secondly, for solving convergence problem and computation precision problem, an improved integral path's Watson transformation is put forward, which based on cylindrical carrier model, to predigest the radiated field integral expression. The method based on cylindrical carrier model to use Watson transformation rebuild the path of integration along a steepest descent path on which the integrand decays most rapidly. The simulation results are presented, which indicate the representations obtained here are efficient and valid in the premise of accurate value. Because it deals with complex configuration efficiently, it has larger applicability.Thirdly, for the research on conformal antenna according to its existent theories where mutual coupling effects and mutual coupling compensating are ignored, new methods to compute mutual impedance and compensate for mutual impedance are put forward. In the computing mutual impedance: the new method applying the dipole moment character to amend the mutual coupling from the different integral region, which the hybrid method ignored. In the compensating for mutual coupling, applying receive voltage to compensate the expected voltage method is proposed, thereby the compensating impedance is obtained. Therefore, in the discussion of mutual coupling, the paper adopts double protection, which ensure the little coupling reckon in the mutual computation. The simulation results are presented, which indicate the representations obtained here made a great reduce of sidelobe of radiated pattern and RCS efficiently.Finally, for the model precision and RCS reduction to realize stealth of conformal antenna's scattering performance, new methods to compute RCS and realize RCS reduction are put forward. In the computing of RCS: it is proposed in the paper that NURBS+MOM hybrid technology should be applied to model electrically large cylinder, and the method reduced the error which comes in the planet element approximate to cylindrical carrier greatly. The method optimized computation efficiency and accuracy, which analyses scattering character reckoning in the carrier effect, and this made the method have practical meaning. In the RCS reduction: induction loop is used to control impedance value and the resonant point. The simulation results proved that the method reduced the RCS greatly in the premise of little effect on gain.Inclusion, the research on performance of dipole antennas conformal to electrically large cylinder had been simulated in this paper, and new algorithms and scheme to resolve the radiated performance,mutual coupling estimate and compensating for mutual coupling,the RCS estimate and RCS reduction have been proposed, the experimental results indicated that the algorithms and scheme can get better results.