To enhance an antenna Mn-Zn ferrite in permeability and quality coefficient by a method, wherein the Mn-Zn ferrite is mainly composed of a specific amount of iron sesquioxide, manganese oxide, and zinc oxide, specified in average crystal grain diameter, permeability, magnetic resonant frequency, and quality coefficient in a specific frequency band.
An antenna Mn-Zn ferrite is set to be mainly composed of 52 to 55 mol% of Fe2O3, 35 to 41 mol% of Mn, and 7 to 10 mol% of ZnO and set smaller than 3 μm in average crystal grain diameter. The antenna Mn-Zn ferrite is set at a permeability 500 in the frequency range of 500 to 1500 kHz. The magnetic resonant frequency of the antenna Mn-Zn ferrite is shifted to 3 to 12 MHz on a high-frequency side, and its quality coefficient Qm is set at a large value of 10 or above in a frequency band of 0.5 to 1.9 MHz, which includes the broadcasting frequency band of an AM radio.
HAYASHI MASATOMO
YAMAMOTO YUTAKA
HATAUCHI TAKASHI
MAKINO TERUHIRO
NAKAGAWA NOBORU
SONY CORP