Pristupačnost
As a part of the project prof. Anthnony Grbic visited the electromagnetic group at FER in Zagreb (14th -22nd October 2014). During the visit, partners defined forthcoming activities in modeling of metastructures and their experimental characterization. Prof. Grbic also gave an IEEE talk with the title “Metasurfaces for Manipulating Electromagnetic Waves.” The summary of the talk is given below.
Abstract:
Metamaterials have provided unprecedented control over electromagnetic fields. However, their notable thickness has often led to fabrication challenges and added loss. This has motivated the development of metasurfaces: the two dimensional analog of metamaterials. Metasurfaces are surfaces textured at a subwavelength scale to achieve tailored electromagnetic properties. They fall into two broad categories. The first class of metasurfaces manipulate electromagnetic wavefronts incident from free space. This type of metasurface tailors the wave transmitted through it, or reflected from it. The second class of metasurfaces guide or radiate waves. The metasurface acts as either a waveguiding structure or supports leaky waves that radiate directive far-field patterns. This talk will describe the development of both types of metasurfaces.
Reflectionless metasurfaces (Huygens’ metamaterial surfaces) that can steer, focus and manipulate the polarization of transmitted electromagnetic waves will be described. These metasurfaces possess both electric and magnetic responses, which allow them to be impedance-matched to the surrounding space. Different metasurfaces that allow polarization control, beam deflection and focusing will be presented. Bianisotropic metasurfaces with enhanced field tailoring properties will also be touched upon. A systematic approach to designing these new metasurfaces will be introduced, and a few experimental devices reported to demonstrate the capabilities of this technology. Next, a new approach to designing 2D inhomogeneous, anisotropic media will be described. The design methodology allows the design of 2D media that support desired spatial distributions of the wave vector and Poynting vector direction. Its utility in the design of metasurfaces will be demonstrated through different design examples. The proposed method allows arbitrary control of electromagnetic fields within a 2D medium. Such spatial control of phase and power flow allows one to mold the phase and amplitude of an aperture field. Preliminary results of a beamformer designed using the proposed methodology will be shown. Finally, the synthesis of radiation patterns using conductor-backed metasurfaces (impedance surfaces) will be explored. A synthesis procedure enabling the design of low-profile, leaky-wave antennas with prescribed far-field patterns will be demonstrated.