Design of a Pyramidal Horn Antenna With Low E-Plane Sidelobes Using Transformation Optics

Abstract

Abstract-Transformation optics is a convenient way to control the pattern of electromagnetic fields. In this paper, using a novel transformation, we propose the design procedure of a horn antenna having low backlobe and sidelobe levels in its E-plane. By applying conformal transformation, the rectangular horn proposed in this paper can be realized with isotropic materials. This proposed antenna can be easily implemented by both ordinary dielectric materials and isotropic graded refractive index (GRIN) materials. In the first proposed design, in addition to the isotropy, homogeneity is furthermore introduced into the horn, and only four kinds of isotropic materials are required throughout. In the second design, it is demonstrated that the designed structure can also be implemented by graded photonic crystals (GPCs) operating in metamaterial regime. They have low loss as well as broad frequency band and are easy to implement. Simulation results are presented to validate the design approach.

Improvement of Radiation Characteristics of Balanced Antipodal Vivaldi Antenna Using Trasformation Optics

“…Optical conformal transformation is employed to realize this idea. The main advantage of conformal mapping is that the obtained media will be isotropic and can be implemented by graded refractive index (GRIN) materials [13]. Figure 1 illustrates the geometry and parameter values of the copper pattern of a typical BAVA.…”

“…For designing the desired media using GRIN materials, we consider [13]. In order to simplify the mapping from virtual space to physical space, a rectangular shape with the same conformal module (M ) is considered as an intermediate region.…”

“…This design procedure (using TO) usually leads to non-isotropic materials whose implementation is complicated. Metamaterials are a prominent candidate for realizing these complex materials, however, usually suffer from limited operation bandwidth and intrinsic losses [13]. It may be possible to achieve a simpler medium by limiting the transformation to the cases satisfying Cauchy-Riemann equations [13,14], in which, the transformation is called conformal [10,12,15].…”

“…In this method, the paths of electromagnetic waves inside a material are controlled by introducing a prescribed spatial variation in the constitutive parameters (the electric permittivity and magnetic permeability) [11]. As an interesting application, for example, using this powerful method can improve the radiation characteristics of the antenna [13,14]. TO relies on the form-invariance of Maxwell's equations under a spatial coordinate transformation [10,12].…”

“…Metamaterials are a prominent candidate for realizing these complex materials, however, usually suffer from limited operation bandwidth and intrinsic losses [13]. It may be possible to achieve a simpler medium by limiting the transformation to the cases satisfying Cauchy-Riemann equations [13,14], in which, the transformation is called conformal [10,12,15]. Using this method, the obtained material can be realized by natural dielectrics, and therefore, the problems regarding the difficult implementation, narrow bandwidth and intrinsic losses are solved [12].…”