Functionally graded magnetodielectric composite substrates for massive miniaturization of microstrip antennas

Abstract

In the present work, an axially anisotropic magnetodielectric composite, based on polymethyl methacrylate (PMMA)–NiFe₂O₄ (NFO), was designed for realizing miniaturized antennas. The structural as well as ferromagnetic properties of the developed NiFe₂O₄via a polymer pyrolysis method were studied in detail. Thin sheets of (0–3) composites were developed by adding a different volume % of NFO (5, 10, 15, and 20 vol%) in the PMMA matrix. Structural, dielectric, magnetic and magnetocapacitance measurements were investigated for individual composites. A microstrip patch antenna operating at 830 MHz was theoretically modeled by stacking differently loaded MD wafers to form a functionally graded anisotropic composite, to be used as the antenna substrate. An impressive miniaturization of 95.46% was observed for this MD antenna, when compared to normal dielectric substrates with permittivity and permeability values equal to unity.