YIG thin film microwave apparatus.

摘要

Microwave apparatus includes a YIG thin film device (1) utilising the ferrimagnetic resonance effect, and a magnetic circuit (2) having a gap of length l g in which the YIG thin film device is provided and applying a bias magnetic field perpendicular to a film surface of the YIG thin film device, the magnetic circuit (2) including a permanent magnet (4) having a thickness l m and a soft magnetic plate (5) having a thickness l x.
<??>The permanent magnet (4) satisfies the characteristics
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and the soft magnetic plate satisfies the characteristics
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wherein: fo is the resonance frequency of the YIG thin film device (1);
gamma is the gyromagnetic ratio of the YIG thin film;
NZ<Y> is the demagnetisation factor of the YIG thin film;
4 pi Mso<Y> is the saturation magnetisation of the YIG thin film at room temperature;
4 pi Mso<Y> is the saturation magnetisation of the soft magnetic plate (5);
Br DEG is the remanence of the permanent magnet (4) at room temperature;
alpha 1<B> is the first order temperature coefficient of the remanence of the permanent magnet (4) at or near room temperature;
alpha 1<Y> is the first order temperature coefficient of the saturation megnetisation of the YIG thin film at or near room temperature; and
alpha 1<x> is the first order temperature coefficient of the saturation magnetisation of the soft magnetic plate (5) at or near room temperature.
<??>The thicknesses l m and l x are selected to improve the temperature dependency of the resonance frequency of the apparatus, such that it is capable of operating stably over wide ranges of working frequencies and temperatures.