The Design Of Electromagnetic Devices Based On Transformation Optics

Transformation optics technology allows people to control the path of electromagnetic waves as their will.The most famous example is an"invisibility cloak,"which directs light to elude an object,making the object to be invisible.The theory of transformation optics provides a concise design method,which connects the electromagnetic parameters of materials with the space transformation,so that the propagation path of electromagnetic wave in the actual physical space and virtual space is identical.According to this design theory,we can create all kinds of new electromagnetic devices through rationally designing of physical and virtual space.However,the dielectric materials derived directly from coordinate transformation are usually anisotropic and inhomogeneous,and may be accompanied by some problems such as zero value of constitutive parameter and even infinity.Therefore,according to the characteristic that conformal transformation can greatly simplify the material,we propose the method of piecewise conformal transformation for the design of electromagnetic device of transformation optics.The main research contents of this paper are as follows:(1)First,apply the coordinate transformation of the transformation optics to design electromagnetic devices.In the beginning,we introduce the design of three-dimensional spherical invisibility cloak,and expound several two-dimensional invisibility cloak designs which simplify material's requirements to a certain extent.Then summarizing the general design specification of two-dimensional invisibility cloak,we propose a transformation function to design cylindrical invisibility cloak.In addition,based the multi-folded transformation optics realized the application of transforming the square invisibility cloak from closed type to open type,we verify the design of the open electromagnetic rotator and this paper involves the design verifications of open triangular rotator,open square rotator and open hexagon rotator.(2)Second,based on the conformal transformation optics,the design method of piecewise conformal transformation optics is proposed.According to the piecewise conformal transformation method,the four-beam directional antenna and the six-beam irregular directional antenna are designed.Generally the coordinate transformation method of transformation optics requires extremely high requirement for design material.Conformal transformation optical method can greatly simplify the material,but it is difficult to be widely applied due to its strict requirements for geometric conditions.Compared with the previous the conformal transformation method,piecewise conformal transformation proposed shows more simple,effective and has the ability to control material refractive index range.The design of electromagnetic device based on piecewise conformal transformation will has broad application prospects.