Antenna miniaturization using magneto-dielectric substrates

Abstract

Effective antenna miniaturization is a challenging problem due to the inevitable trade-off between the size and the performance of the antenna due to the fact that antenna performance is bound with the fundamental limits based on the size of the antenna. Antenna miniaturization is also a critical issue since the key component determining the size of a mobile device is usually the antenna. Recent studies on novel materials called magneto-dielectrics have raised hope to miniaturize the antenna effectively. Magneto-dielectrics are materials with both the relative permittivity (epsi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ) and the relative permeability (mu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ) of the substrate greater than unity. In this paper, several issues regarding the magneto-dielectrics and their application to the antenna miniaturization are investigated. The theoretical reason why the magneto-dielectrics are better substrates for planar antennas than the dielectric materials is investigated along with a material synthesis technique to explain how to realize these materials. Additionally, a characterization methodology to extract the frequency dependent properties (epsi', epsi" mu', and mu") of these materials is presented in this paper. Finally, the advantages and the limitations of these substrates for antenna applications are discussed in the paper.