Increased anisotropy induced by direct ion etch for telecommunications/electronics devices
View Patent ↗A microwave bandstop filter having a magnetic strip formed over dielectric material. The magnetic resonant frequency is controlled by an induced magnetic anisotropy in the magnetic strip of the microwave bandstop filter. The magnetic anisotropy field is induced by an anisotropic surface texture formed on the surface of the magnetic strip itself, or formed on an underlying layer. Alternatively, the anisotropic surface texture could be formed on both an underlying layer and on the magnetic strip itself. This induced magnetic anisotropy field allows the resonant frequency of the microwave filter to be controlled over a wide frequency range and make high frequency operation possible without reliance on the application of an externally applied magnetic field.
1. A microwave bandstop filter comprising:
a dielectric layer;
a crystalline layer disposed on top of the dielectric layer;
the crystalline layer having a surface configured with an anisotropic texture;
a magnetic strip formed on the surface of the crystalline layer.
2. A microwave bandstop filter as in claim 1 wherein the anisotropic texture results in a magnetic anisotropy field in the magnetic strip.
3. A microwave bandstop filter as in claim 1 wherein the magnetic strip has a longitudinal axis, and wherein the anisotropic texture results in a magnetic anisotropy axis oriented parallel to the longitudinal axis of the magnetic strip.
4. A microwave bandstop filter as in claim 1 wherein the magnetic strip comprises a material selected from the group consisting of Fe, Co, Ni, and their alloys.
5. A microwave bandstop filter as in claim 1 wherein the anisotropic texture comprises ripples having an average pitch of 10-200 nm.
6. A microwave bandstop filter as in claim 1 wherein the anisotropic texture comprises ripples having an average depth of 0.5-5 nm.
7. A microwave bandstop filter comprising:
a dielectric layer;
a crystalline layer disposed on top of the dielectric layer;
the crystalline layer having a surface configured with an anisotropic texture;
a magnetic strip formed on the surface of the crystalline layer and having a surface configured with an anisotropic texture.
8. A microwave bandstop filter as in claim 7 wherein the anisotropic textures comprise ripples having an average pitch of 10-200 nm.
9. A microwave bandstop filter as in claim 7 wherein the anisotropic textures comprise ripples having an average depth of 0.5-5 nm.