Radio frequency filter

1. A filter comprising:

m number of inductive components;

a metal outer tube;

n number of capacitive components, each of the n capacitive components comprising a metal inner tube, and sharing the metal outer tube, wherein the metal outer tube is grounded, the metal inner tubes of the n capacitive components are arranged in alignment, the metal inner tubes are located inside the metal outer tube, wherein n is an integer, and n=m−1;

an insulation tube located outside the m inductive components, the metal inner tubes fit around the insulation tube, the insulation tube defining n pairs of indentions allowing n conductive tabs inserting into the insulation tube therethrough, each of the n conductive tabs located between and electrically connecting a corresponding adjacent pair of the m inductive components, two opposite ends of each of the n conductive tabs exposed through a corresponding pair of indentions to connect to a corresponding one of the metal inner tubes; and

two covers detachably mounted to opposite ends of the insulation tube, and electrically connected to two of the m inductive components at the opposite ends of the insulation tube.

2. The filter of claim 1 , wherein the insulation tube comprises a hollow main body and two friction fitting portions extending from opposite end surfaces of the hollow main body, respectively, a receiving groove is defined between each friction fitting portion and a corresponding one of the opposite end surfaces, to receive a corresponding one of the two covers, and two slots are symmetrically defined in each friction fitting portion, allowing the corresponding one of the two covers to enter into the corresponding receiving groove.

3. The filter of claim 2 , wherein each of the two covers comprises a main body, each of the main bodies comprises two opposite edges and two connection portions extending out from the two opposite edges respectively, the two connection portions of each of the main bodies are depressed to a bottom of a corresponding one of the main bodies, the two connection portions of each of the main bodies are received in a corresponding one of the receiving grooves from the two slots of a corresponding one of the friction fitting portions, with the two opposite edges of a corresponding one of the main bodies resisting against a corresponding one of the friction fitting portions, the two connection portions of each of the main bodies are operable to rotatably slide in a corresponding one of the receiving grooves, with the connection portions of each of the main bodies resisting a corresponding one of the friction fitting portions and a corresponding one of the end surfaces of the hollow main body.

4. The filter of claim 2 , wherein the each of the n pairs of indentions are defined in a circumference of the insulation tube, through the insulation tube.

5. The filter of claim 1 , wherein each of the m inductive components includes a magnetic cylinder and a conductive coil, an outer surface of each of the magnetic cylinders is covered by a dielectric layer, and each of the conductive coils fits about a corresponding one of the magnetic cylinders.

6. The filter of claim 5 , wherein each of the dielectric layers is made of glass fiber oxide resin.

7. The filter of claim 6 , wherein each of the magnetic cylinders is made of magnetizable material.

8. The filter of claim 1 , wherein each of the two covers comprise a main body, an opening is defined in a center of each of the main bodies, a protrusion is formed from each of the main bodies and covers a corresponding one of the openings, to function as an input terminal and an output terminal of the filter, respectively.

9. The filter of claim 1 , wherein a length of each metal inner tube is greater than a length of each of the inductive components, while being less than a sum of the lengths of any two of the inductive components.