A Small Meander Antenna by Magneto-dielectric Material

摘要

Nowadays, new digital multimedia broadcasting services like DVB-H and DAB/T-DMB (Terrestrial Digital Multimedia Broadcasting) have been realized through VHF/UHF band and will provide large opportunities for mobile business. The antenna size for DVB-H and DAB/T-DMB must be too large to be assembled in mobile equipments because a quarter wavelength of VHF band in vacuum (μ_r = 1, ε_r = 1) is about 40cm. To solve this problem, we have developed new small antennas consist of meander conductive metal pattern and magneto-dielectric (μ_r > 1, ε_r > 1) layers. The ferrite resin composite material and ferrite film have been used for magneto-dielectric layers. The results of electromagnetic field simulation showed that resonant length of an antenna must be 1 / (μ_r X ε_r)~(1/2), and the resonance frequency of a magneto-dielectric antenna was about 30～50% of an antenna by dielectric material. And, small volume thin film magneto-dielectric material nearby antenna conductive pattern might be able to shorten wavelength without serious radiation problem.