Electromagnetic Properties of Dielectric and Magnetic Composite Material for Antenna

Electromagnetic properties of dielectric and magnetic composite materials were studied with various weight fractions and particle sizes of ferrite. The composite materials were prepared through Ni-Zn spinel ferrite and silicon elastomer, and were characterized with regard to permittivity, permeability, loss tangent(e), and loss tangent(u). Those properties of Ni-Zn spinel ferrite were approximately 7.0, 8.4, 0.01 and 0.1 MHz to 150 MHz, respectively; loss tangent(u), in particular, increased nearly exponentially with frequency above 80 MHz. Increase of loss tangent(u) was overcome by composite with polymer. The 40 wt. % loaded composite material changed these properties (approximately 3.8, 2.2, 0.003 and 0.1 at 161 MHz.); therefore, a higher frequency can be used. This material was optimized by particle size distribution. Composite material with smaller particle size is most useful because it shows similar magnetic loss of up to 211 MHz. Magneto-dielectric composite materials are more useful for antenna because they have lower values of complex permittivity and permeability, and higher application frequency. These results are certificated by simulation of antennas.