Design Method Of Conformal Array Antenna Based On Quasi-Conformal Transformation

With the development of modern antenna technology,various antenna structures are applied in military,civilian and commercial.Due to its ability to be attached to the carrier,wide-angle scanning,strong anti-interference and easy to install and maintain,the conformal antenna has attracted many people’s attention.Based on the form-invariance of Maxwell equations under coordinate transformation,transform optics(TO)provides an equivalent relationship between space transformation and space medium,and the propagation trajectory of electromagnetic waves can be controlled according to it.At the same time,with the intervention and development of artificially structured metamaterials,a new method of designing electromagnetic and optical devices is provided for TO.So we can reduce the difficulty of synthesizing and designing conformal arrays by TO.Firstly,this article discusses the concepts of TO and conformal array antenna,as well as the current domestic and foreign research.Then it discusses how to reduce the complexity of required materials through conformal transformation(CT)and quasi-conformal transformation(QCT).Finally,based on QCT,some simulation examples are used to verify how to utilize the existing mature linear array antenna optimization or synthesis algorithm to design the conformal array antenna.It starts from a simple single-beam antenna and then moves to an intricate multi-beam antenna system.In the case of single-beam antennas,it includes the symmetrical Taylor beam optimized by the matrix pencil method and the asymmetric cosecant-squared beam optimized by the forward-backward matrix pencil method.They are respectively converted into corresponding conformal arrays based on QCT.The results show that the beam under the action of the conformal lens fits well with the original beam,which confirms the effectiveness of the design method on a single-beam antenna array.In the case of multi-beam antennas,it includes the multi-beam linear array antenna system obtained by the iterative weighted convex optimization algorithm and the multi-beam frequency-invariant linear array antenna system obtained by the extended generalized matrix pencil method.They are also converted into corresponding conformal array antenna system.The results show that this method is still applicable even in the current situation.Simultaneously,it is not only limited to the beam involved in this article,but also theoretically it can be extended to realize the synthesis and design of conformal array antennas of any beam.