Studies On Airship Platform Integrated Meter-wave Conformal Phased Array Antenna Based On The Theory Of Characteristic Mode

Meter-wave phased array radar is one of the most promising technologies to deal with stealth technology,and also an effective means of long-range radar detection,which has a wide range of application scenarios in different fields.The low profile and conformal design of the low frequency platform integrated antenna is also a hot demand in the antenna research field.Due to the contradiction between the antenna size and radiation performance,the phased array antenna design faces many challenges such as the miniaturization of antenna element and high gain.In thesis,An approach for the design of airship platform integrated meter-wave conformal phased array antenna based on the theory of characteristic mode（CM）is proposed.Firstly,the characteristic mode theory of metal body and the physical significance of related parameters are introduced in thesis.Because the CM is independent of excitation source and has unique properties only related to the shape and size of the electromagnetic structure itself and the properties of electromagnetic materials,it provides a clear physical explanation for studying the inherent radiation mechanism of electromagnetic structure itself.The characteristic mode analysis of the airship platform structure at the corresponding frequency is carried out to solve the radiation mode and resonance characteristics of the platform itself.Then the characteristic current and characteristic far field of significant modes are extracted,and the characteristic far field of mode contains each polarization component,which provides theoretical guidance and basic data for beam synthesis and conformal array design.Then thesis presents a method to synthesize scanning pattern using significant modes.They have the characteristics of partial orientation,but a single mode cannot meet the expected requirements of highly directional beam scanning,so the weighted combination of multiple modes is needed to achieve the target orientation graph.A multi-objective evolutionary algorithm based on decomposition（MOEA/D）is used to synthesize the direction patterns,in which the beam scanning capability and polarization characteristics are considered.In order to guide the position of the coupling line excitation structure,a set of comprehensive direction diagrams of mode current distribution in accordance with engineering design are found by selecting the solutions on the Pareto Front.Finally,the design of airship platform integrated meter-wave conformal phased array antenna is completed and verified by experiment.The scan array antenna design method based on the CM theory rationally uses part of the airship platform as the radiation aperture.The existence of the platform not only does not worsen the radiation characteristics of the antenna,but can bring beneficial effects and maximize the radiation aperture.The beam scanning range of 60° on both sides of the airship platform is realized,and the realized gain can be more than 10 d Bi at different scanning angles.