Magnetoelectric Composites for 1.3 GHz Antennas

A microstrip miniaturized antenna based on magnetoelectric composite has been designed and characterized. Theoretical estimates of antenna properties are given. To miniaturize UHF antennas, one needs slow-wave topologies and magneto-electric (ME) materials with equal and high permeability and permittivity. Nickel Zinc Ferrites (Ni$_{1-x}$Zn$_{x}$Fe$_{2}$O$_{4}$, x=0-0.5, NZFO) are potential candidates for use as the magnetic phase in the composite since they have high permeability, in the range 4-50, and low magnetic loss tangent. The dielectric phase use is bismuth strontium titanates (Sr$_{1-1.5x}$Bi$_{x}$TiO$_{3}$, 0.04$<$x$<$0.25, BST) that have high permittvity and low dielectric loss tangent. A sample with nickel zinc ferrite and 2{\%}~BST is used. A microstrip dipole element of 47 mm in length and 2 mm in width is placed on a composite substrate with dimensions 65 x 40 x 2.2 mm$^{3}$. The other side of the substrate has a metal ground plane. Measurements of transfer scattering parameter S$_{21}$ are made. A miniaturization factor of 5-10 is achieved. The miniaturization methodology discussed here is useful for mobile communication platforms, radar systems, and remote-controlled ground based systems.