CN102324601A - Tunable filter - Google Patents

Abstract

The invention provides a tunable filter comprising a cavity, a cover plate which is assembled on the cavity and a plurality of tuning screw rods; at least two resonators are arranged in the cavity; every tuning screw rod respectively penetrates through each resonator; inductor devices capable of adjusting the coupling quantity between the tuning screw rods and the cover plate and the resonators are arranged; and the inductor devices are wound on the tuning screw rods. An electromagnetic field in an inductor is changed by changing the current which flows through the inductor or the direction of the current, so that a multi-band filtering function can be realized without manual debugging, performance indexes of the filter are guaranteed under different frequency while the filter is tunable, the frequency of the filter is tunable, the product cost is greatly reduced while the same functions are realized, the size is reduced, the material cost is reduced, simultaneously the workload of debugging and assembly is reduced, the miniaturization of the product is realized, and social resources are greatly saved.

Description

A kind of tunable filter

Technical field

The present invention relates to field of wireless communication, relate in particular to a kind of improvement of tunable filter.

Background technology

In decades in the past; More and more important effect is being brought into play in wireless mobile telecommunication technology develop rapidly, filter, and existing filter generally can be crossed elimination interference signal useless in communication system; Guarantee signal operate as normal in the operating frequency range, and pass through with the loss of minimum.See also shown in Figure 1; Existing filter 1 ' be through the distributed constant principle design is realized its performance index through mechanical structure, by resonant cavity 11 ', resonator 12 ', cover plate 13 ' and tuning screw rod 14 ' form; Filter 1 ' the be equivalent to resonator of several series connection; Each resonator is made up of series capacitance and inductance, wherein inductance correspond to resonator 12 ' diameter, resonator 12 ' upper surface and cover plate 13 ' inner surface be equivalent to two pole plates of plate condenser; Filter 1 ' be through tuning screw rod 14 ' the change spacing between the capacitor accomplish to filter 1 ' debugging; And need be tuning separately to every fixing tuning screw rod 14 ' carry out, adopt that manufal tuning frequency amount is big, cost is high, also may influence simultaneously filter 1 ' performance.Therefore, realize that if desired the interior index of multi-frequency scope then must design a kind of new tunable filter again.

Summary of the invention

The objective of the invention is to overcome the defective of prior art, but provide a kind of in the certain frequency scope frequency adjustable, reduce workload, tunable filter that the low guaranteed performance of cost is stable.

The present invention realizes like this; A kind of tunable filter; Comprise cavity, be assemblied in the cover plate of said cavity, a plurality of tuning screw rod, be provided with at least two resonators in the said cavity, each said tuning screw rod runs through each said resonator respectively; Also comprise the inductance component of the coupling amount between the said tuning screw rod of scalable and said cover plate and the said resonator, said inductance component is set around on the said tuning screw rod.

Further, said inductance component electrically connects through a circuit board and external circuit.

Particularly, said cavity has a bottom surface, and said circuit board is assemblied on the said bottom surface, and said inductance component two ends are separately fixed on the said circuit board.

More specifically, said inductance component two ends are welded on respectively on the said circuit board.

Further, said inductance component is a coil.

Further, on said circuit board, be provided with the temperature sensor that detects said circuit board variations in temperature.

Further, said tuning screw rod one end runs through said resonator and runs through said bottom surface, and said tuning screw rod and said underrun screw are fixed.

Particularly, said tuning screw rod comprises the plastic cement medium that the metal magnetic core is peripheral with being covered in said metal magnetic core.

A kind of tunable filter of the present invention is outside at said tuning screw rod through the winding inductance component, and to its energising, flows through the size or the direction of said inductance component electric current through change; To change himself inner electromagnetic field, because of the electric current in the said inductance component changes in time, because electromagnetic induction; The said tuning screw rod that passes said inductance component can produce induced current (being vortex flow), and on the other hand, said tuning screw rod runs through said resonator; The equivalent electric circuit original paper of said resonator is equivalent to an inductance, and said tuning screw rod also can produce induced current (being vortex flow) down in electromagnetic induction influence, and the size or the direction that flow through inductive current through change are to change the electromagnetic field of inductance inside; And then influence the coupling amount between said tuning screw rod and said cavity and said cover plate, reaching the purpose that just can realize the multiband filter function without manual debugging, under the situation that mixes up filter frequencies in advance to said inductance component galvanization; Size of current, stable being convenient to of direction are controlled, thereby cause that each resonant cavity frequency can change synchronously, but are satisfying the filter timing simultaneously; Make filter under different frequencies, performance index are guaranteed, and have realized the frequency adjustable property of filter; Under the situation that realizes identical function, greatly reduce the cost of product, reduced volume; Material Cost reduces; Debug the assembly work amount simultaneously and reduce, realized the miniaturization of product, saved social resources in a large number.

Description of drawings

Fig. 1 is the sectional structure chart of a kind of filter of prior art;

Fig. 2 is the sectional structure chart of embodiment of the invention tunable filter;

Fig. 3 is the structural representation of embodiment of the invention Inductive component winding on tuning screw rod;

Embodiment

In order to make the object of the invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.

The present invention can be used for designing structures such as tunable filter, duplexer, mixer, multiplexer or the integrated diversity filter of duplexer, below the present invention specifically explain as embodiment with a kind of tunable filter.

Referring to Fig. 2, Fig. 3; The embodiment of the invention provides a kind of tunable filter 1; Comprise cavity 11, be assemblied in the cover plate 12 of said cavity 11, a plurality of tuning screw rod 13; Be provided with at least two resonators 14 in the said cavity 11; Each said tuning screw rod 13 runs through each said resonator 14 respectively, and said tunable filter 1 also comprises the inductance component 15 of a winding on said tuning screw rod 13, the coupling amount between the said tuning screw rod 13 of said inductance component 15 scalable and said cover plate 12 and the said resonator 14.

Like this, a kind of tunable filter 1 of the present invention through winding inductance component 15 on said tuning screw rod 13, and to its energising; Flow through the size or the direction of said inductance component 15 electric currents through change, to change himself inner electromagnetic field, because of the electric current in the said inductance component 15 changes in time; Because electromagnetic induction, the said tuning screw rod 13 that passes said inductance component 15 can produce induced current (being vortex flow), on the other hand; Said tuning screw rod 13 runs through said resonator 14, and the equivalent electric circuit original paper of said resonator 14 is equivalent to an inductance, and said tuning screw rod 13 also can produce induced current (being vortex flow) under the electromagnetic induction influence; Size or the direction that flows through inductive current through change to be changing the inner electromagnetic field of inductance, and then influence the coupling amount of 12 of said tuning screw rod 13 and said cavity 11 and said cover plates, to reach the purpose that just can realize the multiband filter function without manual debugging; To said inductance component galvanization, size of current, stable being convenient to of direction are controlled, thereby are caused that each resonant cavity frequency can change synchronously under the situation that mixes up filter frequencies in advance; But satisfying the filter timing simultaneously, making filter under different frequencies, performance index are guaranteed; Realize the frequency adjustable property of filter, under the situation that realizes identical function, greatly reduced the cost of product; Reduced volume, Material Cost reduces, and debugs the assembly work amount simultaneously and reduces; Realize the miniaturization of product, saved social resources in a large number.

See also Fig. 2, as a kind of specific embodiment of a kind of tunable filter provided by the invention, said inductance component 15 is connected with external circuit (figure does not show) through a circuit board 16.Particularly, said cavity 11 has a bottom surface 111, and said circuit board 16 is assemblied on the said bottom surface 111, and said inductance component 15 two ends are separately fixed on the said circuit board 16.In other embodiments; Said circuit board 16 can be arranged on the said cover plate 12 or any place of said tunable filter 1; As long as it can supply said inductance component 15 to be electrically connected at external circuit; Present embodiment is preferably said circuit board 16 and is assemblied on the said bottom surface 111, and is easy for installation.Particularly, said inductance component 15 two ends are welded on respectively on the said circuit board 16, make said inductance component 15 fixation on said circuit board, effective through welding; Certainly, also can be said inductance component 15 through paste or through connector with fixing or the like, but it is good all to be not so good as welding effect; What any also need be described is; On said circuit board 16, be provided with the temperature sensor (figure does not show) of said circuit board 16 variations in temperature; After the linear expansion coefficient of the material that is adopted according to said resonator 14 and the temperature change value that said temperature sensor is surveyed are calculated; Size of current and the direction that should pass through in the said inductance component 15 of control break realize the frequency automatic correction compensate function, reach from the waft realization of correcting function of dynamic temperature.

Particularly, cooperate shown in Figure 3ly, said inductance component 15 is a coil, and coil is rich to be located on the said tuning screw rod 13, and concrete winding is placed outside said tuning screw rod 13, makes said tuning screw rod 13 be equivalent to an iron core; In the present embodiment, said inductance component 15 is preferably the coil of enamelled wire coiling, and main material is a copper, and the good and low price of its conductive effect can certainly be other wire coil, but does not possess the advantage of the good and low price of conductive effect.

Further, referring to shown in Figure 2, said tuning screw rod 13 1 ends run through said resonator 14 and run through said bottom surface 111, and said tuning screw rod 13 and said bottom surface 111 are fixed through screw.Particularly; Be threaded with said resonator 14 set internal threads through said tuning screw rod 13 set external screw threads, make said tuning screw rod 13 in the set screw thread of institute's cavity bottom, to move up and down, change the spacing between said tuning screw rod 13 and the said cover plate 12; Frequency with to said filter 1 is carried out tuning; The preferred threaded engagement of present embodiment connects, because it is simple in structure, is convenient to the control debugging; In other embodiments, also can adopt axis hole to cooperate or other fit system between said tuning screw rod 13 and the said resonator 14.Also need to prove; After reaching said filter 1 a needed frequency range, said tuning screw rod 13 passes the bottom surface 111 of said cavity 11, and screw rod 13 can adopt self-locking screw rod or other fixed forms; So that said tuning screw rod 13 combines more firm with said cavity 11; Even if in transportation, also guaranteed said tuning screw rod 13 not can because of slip influence and said cover plate 12 between spacing, and then influence the frequency of filter 1.

Particularly, said tuning screw rod 13 is for having externally threaded tuning screw rod, and said tuning screw rod 13 comprises metal magnetic core 131 and the plastic cement medium 132 that is covered in said metal magnetic core 131 peripheries.Said metal magnetic core 131 passes through the integrated through injection molding moulding with said plastic cement medium 132 or suppresses together; Said metal magnetic core 131 is not limited to the strip in the present embodiment; Can also be the trapezoidal or irregular arbitrary shape of other rectangle; What need any be described is that said metal magnetic core 131 has the head 1311 of a split-type structural, can be convenient to said tuning screw rod 13 and install from top to bottom at said cavity 11.

The present invention is by the computing formula of resonant frequency:

$\mathrm{Fr}=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}---\left(1\right)$

Because field region can equivalence be an inductance L, electric field region can equivalence be an electric capacity, and the computing formula of capacitor C is:

$C=\frac{\mathrm{\ϵS}}{4\mathrm{\πkd}}---\left(2\right)$

Wherein ∈ representes the dielectric constant of electric field region filling dielectric material, and the S equivalence is the area of capacitor board, and d is equivalent to the spacing between tuning screw rod 13 and the said cover plate 12, and k is the electrostatic force constant.Can learn the size that also can change capacitance C through the change DIELECTRIC CONSTANTS from formula 2, thereby realize the purpose of filter 1 frequency adjustable.

The above is merely preferred embodiment of the present invention, and its structure is not limited to the above-mentioned shape of enumerating, and all any modifications of within spirit of the present invention and principle, being done, is equal to replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (8)

1. tunable filter; Comprise cavity, be assemblied in the cover plate of said cavity, a plurality of tuning screw rod; Be provided with at least two resonators in the said cavity, each said tuning screw rod runs through each said resonator respectively, it is characterized in that; It is outside that the inductance component that also comprises the coupling amount between the said tuning screw rod of scalable and said cover plate and the said resonator, said inductance component are set around said tuning screw rod.

2. a kind of tunable filter as claimed in claim 1 is characterized in that: said inductance component electrically connects through a circuit board and external circuit.

3. a kind of tunable filter as claimed in claim 2 is characterized in that: said cavity has a bottom surface, and said circuit board is assemblied on the said bottom surface, and said inductance component two ends are separately fixed on the said circuit board.

4. a kind of tunable filter as claimed in claim 3 is characterized in that: said inductance component two ends are welded on respectively on the said circuit board.

5. like each described a kind of tunable filter of claim 1-4, it is characterized in that: said inductance component is a coil.

6. a kind of tunable filter as claimed in claim 2 is characterized in that: on said circuit board, be provided with the temperature sensor that detects said circuit board variations in temperature.

7. a kind of tunable filter as claimed in claim 3 is characterized in that: said tuning screw rod one end runs through said resonator and runs through said bottom surface, and said tuning screw rod and said underrun screw are fixed.

8. a kind of tunable filter as claimed in claim 7 is characterized in that: said tuning screw rod comprises the plastic cement medium that the metal magnetic core is peripheral with being covered in said metal magnetic core.

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