Method for manufacturing an RF filter and an RF filter

1. A method for manufacturing an RF filter having cavities, the manufacturing method comprising:

forming the cavities into shape from at least one copper plate in a first manufacturing step; and

inserting or integrating the formed cavities into a chassis material in a separate manufacturing step,

wherein the RF filter is formed without plating the cavities with an electrically conductive material.

2. The manufacturing method according to claim 1 , wherein the first manufacturing step comprises:

forming into shape a resonator cavity preform comprising at least one resonator cavity of said cavities from a copper plate of said at least one copper plate; and

machining in the wall and bottom of the formed resonator cavity preform at least one opening.

3. The manufacturing method according to claim 2 , wherein:

forming a resonator cavity preform comprises forming a plurality of mechanically separate resonator cavity preforms; and

the first manufacturing step further comprises connecting together at least two resonator cavity preforms so as to form an RF filter preform.

4. The manufacturing method according to claim 3 , wherein the second manufacturing step comprises:

mounting the RF filter preform mechanically to a base plate, and integrating the RF filter preform into a chassis material, thereby providing a chassis.

5. The manufacturing method according to claim 4 , wherein the integrating of the RF filter preform into the chassis material is accomplished by injection moulding the chassis around the RF filter preform.

6. The manufacturing method according to claim 4 or 5 , further comprising fastening a cover plate and input connector and output connector to the chassis of the RF filter.

7. The manufacturing method according to claim 1 , wherein:

the first manufacturing step comprises forming into shape at least one resonator cavity preform comprising a plurality of resonator cavities from the at least one copper plate; and

the method further comprises machining in the wall and bottom of the at least one formed resonator cavity preform at least one opening.

8. The manufacturing method according to claim 7 , wherein:

the at least one resonator cavity preform comprises a plurality of resonator cavity preforms;

the method further comprises connecting together at least two of the machined resonator cavity preforms so as to form an RF filter preform.

9. The manufacturing method according to claim 7 , wherein the second manufacturing step comprises:

inserting the at least one resonator cavity into a separately manufactured chassis of the RF filter;

mounting cavity components; and

mechanically connecting the at least one resonator cavity to a base plate.

10. The manufacturing method according to claim 9 , wherein the chassis is manufactured by injection moulding it from a proper plastic, moulding it from aluminium or machining it from a proper aluminium slab.

11. The manufacturing method according to claim 9 , wherein the cover plate and input connector and output connector are fastened to the chassis of the RF filter.

12. The method of claim 1 , wherein each of the cavities is cylindrical.

13. An RF filter comprising:

at least one resonator cavity;

a chassis of the RF filter;

a metallic bottom plate, separate from the at least one resonator cavity;

a cover plate; and

an input connector and an output connector,

wherein the resonator cavities are formed into shape from a copper plate and are configured to be inserted or integrated into the chassis of the RF filter, and wherein the resonator cavities are not plated with an electrically conductive material.

14. The RF filter according to claim 13 , wherein the resonator cavities are formed into shape to a resonator cavity preform comprising at least one resonator cavity from a copper plate by deep drawing or impact extrusion.

15. The RF filter according to claim 13 , wherein the chassis of the RF filter is manufactured into shape by injection moulding it from plastic or moulding or machining it from aluminium.

16. The RF filter according to claim 13 , wherein the resonator cavities are fastened to the base plate by a screw that fastens a resonator to the chassis and to the base plate via an opening in a bottom section of each resonator cavity.

17. The RF filter of claim 13 , wherein each of the at least one resonator cavities is cylindrical.