Miniaturized terrestrial digital media broadcasting antenna based on low loss magneto-dielectric materials for mobile handset applications

In this paper, the low loss magneto-dielectric Co2Z ferrite has been developed for miniaturization of mobile handset antennas. The developed substrate material had almost equal permeability and permittivity of about 12, as well as low magnetic and dielectric loss tangent of about 0.047 and 0.0063 at 200 MHz, which was due to the use of a two-step sintering method. Compared with conventional final-stage sintering method, low magnetic and dielectric loss tangent were found to be a decrease of about 42% and 62%, respectively. A helical antenna operating at VHF band was fabricated on such ferrite substrate. The return loss and Smith chart of the antenna were investigated with a network analyzer. By comparing two different sintering methods, the two-step sintering samples gave better performance in loss tangent and magneto-dielectric properties, which have shown advantages in improving the antenna performance.