Emulating Anisotropy to form Novel Low Cost Printed Metamaterial Antennas

Summary form only given: Simply speaking, metamaterials and periodic textures, in general, have allowed for more design degrees of freedom. Specifically, periodic media have allowed for the introduction of many more modes exhibiting different velocity and impedance characteristics. These new modes also allow for concurrent impedance matching and wave slow down for miniaturization or higher sensitivity. Such modes have been carefully examined by our group in the context of magnetic and non-magnetic photonic crystals as well as degenerate band edge crystals. We found that unit cells of these crystals can be represented by equivalent homogenized multilayered anisotropic media. That is each unit cell layer is associated with 3 (instead of one) unique permittivity tensor entries and 3 additional permeability entries for magnetic layers. These additional 2 or 4 degrees of freedoms have allow for substantial design flexibility and mode molding. Of importance is that such layer anisotropy can be realized using a pair of printed transmission lines arranged in close proximity. The voltages at each line can be thought as referring to a vector field component of the unit cell. Controlled coupling between these two lines then generates controlled anisotropy. Modes by design can then be realized and supported on the transmission line pair which can be implemented with great ease and low cost. Further, lumped elements can be printed and integrated within the lines for added control of their propagation properties, bandwidth and impedance characteristics. This paper will focus on realizing controlled anisotropy for the design of miniature antenna elements and arrays with nearly perfect aperture efficiency even the array is on-planar. We will discuss mode generation and control using metamaterials, and address the perennial issue of narrow bandwidth.