SE1950509A1

SE1950509A1 - Sheet metal rf cavity filter

Info

Publication number: SE1950509A1
Application number: SE1950509A
Authority: SE
Inventors: Markku Tiihonen; Marko Määttä; Mattias Aquilon; Pasi Tiitto
Original assignee: Microdata Telecom Innovation Stockholm Ab
Priority date: 2019-04-26
Filing date: 2019-04-26
Publication date: 2020-10-06
Also published as: CN212209713U; SE543086C2

Abstract

There is provided a sheet metal RF cavity filter 100 comprising: a housing 110; a plurality of resonators 120 arranged within the housing 110; and input 180 and output 190 means arranged on the exterior of the housing. The sheet metal RF cavity filter 100 is characterized in that it further comprises an in-coupling 310, having a shape that low-pass filters an incoming signal, arranged within the housing 110 to connect the input means 180 to the resonators 120 on the input side, and/or an out-coupling 320, having a shape that low-pass filters an outgoing signal, arranged within the housing 110 to connect the resonators 120 on the output side to the output means 190.

Description

lO SHEET METAL RF CAVITY FILTER TECHNICAL FIELD The present disclosure relates to a sheet metal RF cavity filter and a method of manufacturing a sheet metal RF cavity filter.

BACKGROUND Radio frequency (RF) cavity filters are widely used in telecommunication applications. RF cavity filters are generally designed by arranging aplurality of resonators, where each resonator is tuned to a particularfrequency to achieve a combined filter characteristic, in a housing. Theresonators within the housing will interact to form a resulting filter characteristic acting on an input signal to generate an output signal.

Traditional RF cavity filters are quite bulky, but there is an increasing need in new applications such as e.g. 5G for smaller RF cavity filters.One way of producing small RF cavity filters is by manufacturing thefilters from sheet metal. Such a sheet metal RF cavity filter is e.g.described in US 2017/0084972. However, other necessary components may Still be buiky.

PROBLEMS WITH THE PRIOR ART In order to suppress high frequency noise in the signal before and/or after the signal is filtered in the sheet metal RF cavity filter, one ormore low-pass filters may be needed. Such low-pass filters are oftenquite bulky, and it may be difficult to find room for them in an installation.

There is thus a need for a sheet metal RF cavity filter that does notrequire the use of bulky low-pass filters to suppress high frequency noise in the signal. lO SUMMARY One of the objects of the present disclosure is to address the problemmentioned above. This is achieved by the sheet metal RF cavity filter andthe method of manufacturing a sheet metal RF cavity filter defined in the claims.

In embodiments, there is provided a sheet metal RF cavity filter that may comprise: a housing; a plurality of resonators arranged within the housing; and input and output means arranged on the exterior of the housing. The sheet metal RF cavity filter may further comprise an in-coupling, having a shape that low-pass filters an incoming signal,arranged within the housing to connect the input means to the resonatorsand/or an out-coupling, on the input side, having a shape that low-pass filters an outgoing signal, arranged within the housing to connect theresonators on the output side to the output means. This makes thearrangement very compact, since no external low-pass input and/or output filter is needed.

In embodiments, the sheet metal RF cavity filter further comprises aplurality of coupling lines arranged between adjacent resonators, whereina number of the resonators and coupling lines are in one piece,manufactured from a single metal sheet. This simplifies the assembly of the sheet metal RF cavity filter.

In embodiments, the in-coupling/out-coupling is one piece with the resonators and coupling lines on the input/output side, manufactured froma single metal sheet. This simplifies the assembly of the sheet metal RFcavity filter, since the whole input/output piece may then be attached tothe bottom of the housing, after folding the in-coupling/out-coupling into position.

In embodiments, at least some of the resonators each have an upper section that extends out from a lower section in a direction towards atleast one adjacent resonator, wherein at least one integrated capacitivecoupling tuning member, arranged for tuning a capacitive coupling between 2 (l8) lO adjacent resonators, extends downwards from the upper section,substantially in parallel with the extension of the lower section of theresonator. Such a sheet metal RF cavity filter fits into small places while still being easily tunable.

The sheet metal RF cavity filter may comprise at least one cross-couplingbetween the resonators on the input side and the resonators on the outputside. In embodiments, the sheet metal RF cavity filter comprises at leasttwo cross-couplings integrated into a single part between the resonatorson the input side and the resonators on the output side. This simplifiesthe assembly of the sheet metal RF cavity filter. The cross-couplings maye.g. be arranged on an interior wall in the housing, which interior wallseparates the resonators on the input side from the resonators on the output side.

In embodiments, the housing has a bottom, four side walls, and a cover,and the resonators are attached to the bottom of the housing and extendfrom the bottom towards the top of the housing, so that they extendsubstantially in parallel with the side walls of the housing. Theresonators may e.g. be inserted through openings in the bottom of theThis housing and then fixed in place by e.g. soldering or welding. simplifies the assembly of the sheet metal RF cavity filter.

In embodiments, the cover of the housing comprises a plurality of frequency tuning tabs, arranged to be positioned above at least some ofthe resonators when the cover is attached to the side walls of thehousing. The provision of such frequency tuning tabs enables an efficient tuning of the frequency.

In embodiments, the bottom and the side walls of the housing are in one piece, manufactured from a single metal sheet. If the bottom and sidewalls of the housing are manufactured in the form of a flat piece, thisenables an easy assembly of the housing by folding up the side walls fromthe bottom. However, the bottom and side walls of the housing may also bemanufactured directly into the desired shape by being e.g. deep-drawn, punched, extruded or die-casted. lO In embodiments, there is provided a method of manufacturing a sheet metal RF cavity filter. The method may comprise: manufacturing a housing fromsheet metal; arranging a plurality of resonators manufactured from sheetmetal within the housing; and arranging input and output means on theexterior of the housing. The method may comprise manufacturing an in-from coupling, having a shape that low-pass filters an incoming signal, sheet metal; and arranging the in-coupling between the input means andthe resonators, so that the in-coupling connects the input means to theresonators on the input side; and/or manufacturing an out-coupling,having a shape that low-pass filters an outgoing signal, from sheetmetal; and arranging the out-coupling between the output means and theresonators, so that the out-coupling connects the resonators on theoutput side to the output means. A sheet metal RF cavity filtermanufactured in this way will be a very compact arrangement, since no external low-pass input/output filter is needed.

In embodiments, the method further comprises arranging a plurality ofcoupling lines manufactured from sheet metal between adjacent resonators,wherein the manufacturing of the resonators further comprisesmanufacturing a number of the resonators and coupling lines from a singlemetal sheet, so that they are in one piece. This simplifies the assembly of the sheet metal RF cavity filter.

In embodiments, the in-coupling/out-coupling is in one piece with the resonators and coupling lines on the input/output side, manufactured froma single metal sheet. This simplifies the assembly of the sheet metal RFcavity filter, since the whole input/output piece may then be attached tothe bottom of the housing, after folding the in-coupling/out-coupling into position.

In embodiments, the method further comprises manufacturing at least someof the resonators from sheet metal so that they each have an upper section that extends out from a lower section in a direction towards atleast one adjacent resonator, wherein at least one integrated capacitive coupling tuning member, arranged for tuning a capacitive coupling between 4 (l8) lO adjacent resonators, extends downwards from the upper section,substantially in parallel with the extension of the lower section of theresonator. A sheet metal RF cavity filter manufactured in this way fits into small places while still being easily tunable.

The method may comprise arranging at least one cross-coupling between theresonators on the input side and the resonators on the output side. Inembodiments, the method comprises arranging at least two cross-couplingsintegrated into a single part between the resonators on the input sideand the resonators on the output side. This simplifies the assembly ofthe sheet metal RF cavity filter. The cross-couplings may e.g. bearranged on an interior wall in the housing, which interior wallseparates the resonators on the input side from the resonators on the output side.

In embodiments, the housing has a bottom, four side walls, and a cover,wherein the arranging of the resonators further comprises attaching theresonators to the bottom of the housing so that they extend from the bottom of the housing towards the top of the housing, substantially inparallel with the side walls of the housing. This simplifies the assembly of the sheet metal RF cavity filter.

In embodiments, the arranging of the resonators further comprisesinserting the resonators through openings in the bottom of the housing.

This further simplifies the assembly of the sheet metal RF cavity filter.

In embodiments, the manufacturing of the cover of the housing comprises manufacturing a plurality of frequency tuning tabs in the cover, arrangedto be positioned above at least some of the resonators when the cover isattached to the side walls of the housing. The provision of such frequency tuning tabs enables an efficient tuning of the frequency.

In embodiments, the manufacturing of the bottom and the side walls of thehousing comprises manufacturing them from a single metal sheet, so thatthey are in one piece. If the bottom and side walls of the housing are manufactured in the form of a flat piece, this enables an easy assembly (l8) lO of the housing by folding up the side walls from the bottom. However, thebottom and side walls of the housing may also be manufactured directlyextruded or into the desired shape by being e.g. deep-drawn, punched, die-casted.

In embodiments, the upper section of the resonators is a short but widetop section that extends out from a much longer but narrower lower section. The resonators may e.g. be T-shaped, with the capacitivecoupling tuning members extending downwards from both edges of the T.However, the resonators may also e.g. be shaped like an upside down L,with just one capacitive coupling tuning member extending downwards fromthe edge of the upside down L. Other shapes are also possible, as well as combinations of resonators of different shapes.

The sheet metal RF cavity filter may be manufactured from any type ofmetal sheet or metal plate, and may comprise pieces or componentsmanufactured from different types of metal sheets or metal plates, e.g. metal sheets or metal plates of different thickness.

The scope of the invention is defined by the claims, which areincorporated into this section by reference. A more completeunderstanding of embodiments of the invention will be afforded to thoseskilled in the art, as well as a realization of additional advantagesthereof, by a consideration of the following detailed description of oneor more embodiments. Reference will be made to the appended drawings that will first be described briefly.

BRIEF DESCRIPTION OF THE DRAWINGS Figs. la and lb show the exterior of a sheet metal RF cavity filter, in accordance with one or more embodiments of the disclosure.

Figs. 2a and 2b show the interior of a sheet metal RF cavity filter, in accordance with one or more embodiments of the disclosure. lO Fig. 3a is shows an out-coupling, in accordance with one or more embodiments of the disclosure.

Fig. 3b shows resonators, coupling lines and in-coupling integrated into one piece, as well as resonators, coupling lines and out-coupling integrated into one piece, in accordance with one or more embodiments of the disclosure.

Figs. 4a and 4b show two different embodiments of resonators, in accordance with one or more embodiments of the disclosure.

Fig. 5 shows a flow diagram for a method of manufacturing a sheet metal RF cavity filter, in accordance with one or more embodiments of the disclosure.

Embodiments of the present invention and their advantages are bestunderstood by referring to the detailed description that follows. Itshould be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures.

DETAILED DESCRIPTION There is an increasing need in new applications such as e.g. 5G forsmaller RF cavity filters. One way of producing small RF cavity filtersis by manufacturing the filters from sheet metal. However, in order tosuppress high frequency noise in the signal before and/or after thesignal is filtered in the sheet metal RF cavity filter, one or more low-pass filters may be required. Such low-pass filters are often quitebulky, and it may be difficult to find room for them in an installation.If one or more low-pass filters are integrated into a sheet metal RFcavity filter, such bulky external low-pass filters may no longer be needed.

Figs. la and lb show the exterior of a sheet metal RF cavity filter l00, in accordance with one or more embodiments of the disclosure. Fig. la is a perspective view of the exterior of the housing ll0, where the side 7 (18) lO walls W1, W4 and the cover T can be seen. Fig. lb is a bottom view of the exterior of the housing ll0, where the bottom B can be seen. The bottom Bmay comprise openings l60 where interior components of the sheet metal RF cavity filter l00 may be inserted.

In the housing ll0 shown in Figs. la and lb, the bottom B and the side walls W1, W2, W3, W4 of the housing ll0 are in one piece, manufactured from a single metal sheet. If the bottom B and side walls Wh vb, W3, W4of the housing ll0 are manufactured in the form of a flat piece, thisenables an easy assembly of the housing ll0 by folding up the side wallsW1, W” Uh, W4 from the bottom B. However, the bottom B and side walls WhW2, W3, W4 of the housing ll0 may also be manufactured directly into thedesired shape by being e.g. deep-drawn, punched, extruded or die-casted.

Alternatively, the bottom B and the side walls W1, W2, W3, W4 of the housing ll0 are separate pieces that are e.g. soldered or welded together.

As shown in Fig. la, the cover T may comprise a number of frequency tuning tabs l50, arranged to be positioned above at least some of theresonators l20 when the cover T is attached to the side walls W1, W2, WyW4 of the housing ll0. The provision of such frequency tuning tabs l50 enables an efficient tuning of the frequency.

The sheet metal RF cavity filter l00 shown in Figs. la and lb furthercomprises input and output means in the form of an input connector l80 and an output connector l90 arranged on the exterior of the housing ll0.The connectors l80, l90 may e.g. be coaxial cable connectors. However, other types of input/output means may alternatively be used, such as e.g. direct surface mounting via e.g. soldering.

Figs. 2a and 2b show the interior of a sheet metal RF cavity filter l00, in accordance with one or more embodiments of the disclosure. As shown in Figs. 2a and 2b, an interior wall ll5 may be arranged in the interior ofthe housing ll0 to separate the resonators l20 on the input side from theresonators l20 on the output side. Such an interior wall ll5 may be inserted into openings l60 in the bottom B of the housing, but it may 8 (l8) also be attached to the bottom B entirely by e.g. soldering or welding.

On the interior wall 115, one or more cross-couplings 170 betweenresonators 120 on the input side and resonators 120 on the output sideIn embodiments, may be arranged. the sheet metal RF cavity filter 100 comprises at least two cross-couplings 170 integrated into a single part.

A plurality of resonators 120 may be arranged within the housing 110, anda plurality of coupling lines 140 may be arranged between adjacentresonators 120. The resonators 120 and coupling lines 140 on each side ofthe interior wall 115 may be in one piece, manufactured from a singlemetal sheet, since this simplifies the assembly of the sheet metal RFcavity filter 100. The resonators 120 and/or coupling lines 140 may however also be separate pieces.

The resonators 120 may extend from the bottom B of the housing 110towards the top T of the housing 110, so that they extend substantiallyin parallel with the side walls W1, W2, W3, W4 of the housing 110. Theresonators 120 are preferably attached to the bottom B of the housing110, e.g. by soldering or welding. The resonators 120 may be insertedthrough openings 160 in the bottom B of the housing 110, since this simplifies the assembly of the sheet metal RF cavity filter 100.

At least some of the resonators 120 may comprise integrated capacitivecoupling tuning members 130 arranged for tuning a capacitive coupling2a are between adjacent resonators 120. The resonators 120 shown in Fig.

T-shaped, with capacitive coupling tuning members 130 extending downwardsfrom both edges of the T. However, other shapes are also conceivable, aslong as each resonator 120 that comprises at least one integratedcapacitive coupling tuning member 130 has an upper section 124 thatextends out from a lower section 122 in a direction towards at least oneadjacent resonator 120, as illustrated in Figs. 4a and 4b. This enablesthe at least one capacitive coupling tuning member 130 to extenddownwards from the upper section 124 towards the bottom B of the housing110, substantially in parallel with the extension of the lower section 122 of the resonator 120. This provides for an efficient tuning of the 9 (18) capacitive coupling between the resonators 120. The upper section 124 ofthe resonators 120 may e.g. be a short but wide top section 124 that extends out from a much longer but narrower lower section 122.

The sheet metal RF cavity filter 100 may also comprise one or more integrated low-pass filters. Figs. 2a and 2b illustrate such integrated low-pass input and output filters in the form of an in-coupling 310 and190 with the an out-coupling 320, arranged to connect the connectors 180, resonators 120. This makes the arrangement even more compact, since no external low-pass input or output filters are needed.Fig. 3a shows an out-coupling 320 that has a shape that low-pass filtersan outgoing signal. Such a shape could e.g. be in the form of alternatingsections of different characteristic impedance lines, and/or resonatingline sections forming attenuation notches to desired frequencies. In theout-coupling 320 shown in Fig. 3a, there is a section 330 of highimpedance between two sections 340 of low impedance. Such filters are often referred to as stepped impedance filters.

Fig. 3b shows resonators 120, coupling lines 140 and in-coupling 310 integrated into one input piece, which may be manufactured from a single metal sheet, as well as resonators 120, coupling lines 140 and out- coupling 320 integrated into one output piece, which may be manufacturedfrom a single metal sheet, in accordance with one or more embodiments ofthe disclosure. This simplifies the assembly of the sheet metal RF cavityfilter 100, since the whole input piece may then be attached to thebottom B of the housing 110, after folding the in-coupling 310 intoposition, and the whole output piece may also be attached to the bottom Bof the housing 110, after folding the out-coupling 320 into position.

However, as shown in Fig. 4b, there does not have to be coupling lines 140 between adjacent resonators.

Fig. 5 shows a flow diagram for a method 500 of manufacturing a sheet metal RF cavity filter 100. In accordance with one or more embodiments of the disclosure, the method comprises the following steps: (18) Step 510: manufacturing a housing 110 from sheet metal.

Step 540: arranging a plurality of resonators 120 manufactured from sheet metal within the housing 110.

Step 580: arranging input 180 and output 190 means on the exterior of the housing 110.

The method may further comprise the following steps: Step 525: manufacturing an in-coupling 310, having a shape that low-pass filters an incoming signal, from sheet metal.

Step 560: arranging the in-coupling 310 between the input means 180 and the resonators 120, so that the in-coupling 310 connects the input means 180 to the resonators 120 on the input side.

The method may additionally, or alternatively, comprise the following steps: Step 530: manufacturing an out-coupling 320, having a shape that low-pass filters an outgoing signal, from sheet metal.

Step 565: arranging the out-coupling 320 between the output means 190 and the resonators 120, so that the out-coupling 320 connects the resonators 120 on the output side to the output means 190.

A sheet metal RF cavity filter 100 manufactured in this way will be avery compact arrangement, since no external low-pass input/output filter is needed.

In embodiments, the method further comprises arranging, in a step 550, aplurality of coupling lines 140 manufactured from sheet metal betweenadjacent resonators 120, wherein the manufacturing 520 of the resonators120 further comprises manufacturing a number of the resonators 120 andcoupling lines 140 from a single metal sheet, so that they are in onepiece. This simplifies the assembly of the sheet metal RF cavity filter 100. 11 (18) l0 In embodiments, the in-coupling/out-coupling 3l0/320 is in one piece withthe resonators l20 and coupling lines l40 on the input/output side, manufactured from a single metal sheet. This simplifies the assembly ofthe sheet metal RF cavity filter l00, since the whole input/output piecemay then be attached to the bottom B of the housing ll0, after folding the in-coupling/out-coupling 3l0/320 into position.

In embodiments, in a step 520, the method further comprises manufacturing,at least some of the resonators l20 from sheet metal so that theyeach have an upper section l24 that extends out from a lower section l22in a direction towards at least one adjacent resonator l20, wherein atleast one integrated capacitive coupling tuning member l30, arranged fortuning a capacitive coupling between adjacent resonators l20, extendsdownwards from the upper section l24, substantially in parallel with theextension of the lower section l22 of the resonator l20. A sheet metal RFcavity filter l00 manufactured in this way fits into small places while still being easily tunable.

The method may comprise arranging at least one cross-coupling l70 betweenthe resonators l20 on the input side and the resonators l20 on the outputside. In embodiments, the method comprises arranging, in a step 570, atleast two cross-couplings l70 integrated into a single part between theresonators l20 on the input side and the resonators l20 on the output side. This simplifies the assembly of the sheet metal RF cavity filterl00. The cross-couplings l70 may e.g. be arranged on an interior wall ll5in the housing, which interior wall ll5 separates the resonators l20 on the input side from the resonators l20 on the output side.

In embodiments, the housing ll0 has a bottom B, four side walls W1, W” W3, W4, and a cover T, and the arranging 540 of the resonators l20 furthercomprises attaching the resonators l20 to the bottom B of the housing ll0so that they extend from the bottom B of the housing ll0 towards the top T of the housing ll0, substantially in parallel with the side walls Wh W2, W3, W4 of the housing ll0. This simplifies the assembly of the sheet metal RF cavity filter l00. l2 (l8) In embodiments, the arranging 540 of the resonators 120 further comprisesinserting the resonators 120 through openings 160 in the bottom B of thehousing 110. This further simplifies the assembly of the sheet metal RF cavity filter 100.

In embodiments, the manufacturing 510 of the cover T of the housing 110comprises manufacturing a plurality of frequency tuning tabs 150 in thecover T, arranged to be positioned above at least some of the resonators120 when the cover T is attached to the side walls W1, W2, W3, W4 of thehousing 110. The provision of such frequency tuning tabs 150 enables an efficient tuning of the frequency.

In embodiments, the manufacturing 510 of the bottom B and the side wallsW1, W” Uh, W4 of the housing 110 comprises manufacturing them from asingle metal sheet, so that they are in one piece. If the bottom B andside walls W1, W” Uh, W4 of the housing 110 are manufactured in the formof a flat piece, this enables an easy assembly of the housing 110 byfolding up the side walls W1, Wü Uh, W4 from the bottom B. However, thebottom B and side walls W1, W2, W3, W4 of the housing 110 may also bemanufactured directly into the desired shape by being e.g. deep-drawn, punched, extruded or die-casted.

The foregoing disclosure is not intended to limit the present inventionto the precise forms or particular fields of use disclosed. It iscontemplated that various alternate embodiments and/or modifications tothe present invention, whether explicitly described or implied herein,are possible in light of the disclosure. Accordingly, the scope of the invention is defined only by the claims. 13 (18)

Claims

1. A sheet metal radio frequency (RF) cavity filter (100) comprising: a housing (110); a plurality of resonators (120) arranged within the housing(110); andinput (180) and output (190) means arranged on the exterior of the housing (110); characterized in that the sheet metal RF cavity filter (100) further comprises an in-coupling (310), having a shape that low-pass filters anincoming signal, (110)(180) (320), arranged within the housing (120) to connect the input means to the resonators on the input side, and/or an out- coupling having a shape that low-pass filters an outgoing signal,(110) (120) (190). arranged within the housing to connect the resonators on the output side to the output means

2. The sheet metal RF cavity filter (100) further (140) of claim 1,comprising a plurality of coupling lines arranged between adjacentresonators (120) (140) (120), wherein a number of the resonators and coupling lines are in one piece, manufactured from a single metal sheet.

3. The sheet metal RF cavity filter(120) (100) of claim 1 or 2, wherein at least some of the resonators each have an upper section (124) that extends out from a lower section (122) in a direction towards at(120),(130), (120), least one adjacent resonator wherein at least one integrated capacitive coupling tuning member arranged for tuning a capacitivecoupling between adjacent resonators extends downwards from the(124), (122) substantially in parallel with the extension of the (120). upper section lower section of the resonator 14 (18) lO

4. The sheet metal RF cavity filter (l00) of any one of claims l- 3, further comprising at least two cross-couplings (l70) integrated into a single part between the resonators (l20) on the input side and the resonators (l20) on the output side.

5. The sheet metal RF cavity filter4, wherein the housing (ll0) (T), of the housing (lOO)(B),(l20) of any one of claims l-has a bottom four side walls (W1, W” W3, W4), and the resonators are attached to the (llO) and a cover bottom (B) and extend from the bottom (B) towards the top (T) so that they extend substantially in parallel (ll0). of the housing, with the side walls (W1, W2, W3, W4) of the housing

6. The sheet metal RF cavity filter(l20)(ll0). (l00) of claim 5, wherein the resonators are inserted through openings (l60) in the bottom (B) of the housing

7. The sheet metal RF cavity filter(ll0) (l00) of claim 5 or 6, wherein the cover (T) of the housing comprises a plurality of frequency tuning tabs (l50), arranged to be positioned above at least some of theresonators (l20) when the cover (T) is attached to the side walls (W1, W”W3, W4) of the housing (ll0).

8. The sheet metal RF cavity filter (l00) and the side walls (Wi, W2, W3, WM of any one of claims 5- 7, wherein the bottom (B) of the housing (ll0) are in one piece, manufactured from a single metal sheet.

9. A method (500) of manufacturing a sheet metal radio frequency (RF) cavity filter (l00), wherein the method comprises:manufacturing (5l0) a housing (ll0) from sheet metal;arranging (540) a plurality of resonators (l20) manufactured from sheet metal within the housing (ll0); and l5 (l8) arranging (580) input (180) and output (190) means on the exterior of the housing (110);characterized in: manufacturing (525) an in-coup1ing (310), having a shape that 5 1ow-pass filters an incoming signa1, from sheet meta1; and arranging (560) the in-coup1ing (310) between the input means(180) and the resonators (120), so that the in-coup1ing (310)connects the input means (180) to the resonators (120) on the input side;10 and/or manufacturing (530) an out-coup1ing (320), having a shape that 1ow-pass fi1ters an outgoing signa1, from sheet meta1; and arranging (565) the out-coup1ing (320) between the output means(190) and the resonators (120), so that the out-coup1ing (320)15 connects the resonators (120) on the output side to the output means (190).

10. The method (500) of c1aim 9, further comprising arranging (550)a p1ura1ity of coup1ing 1ines (140) manufactured from sheet meta1 betweenadjacent resonators (120), wherein the manufacturing (520) of the20 resonators (120) further comprises manufacturing a number of theresonators (120) and coup1ing 1ines (140) from a sing1e meta1 sheet, so that they are in one piece.

11. The method (500) of c1aim 9 or 10, further comprisingmanufacturing (520) at 1east some of the resonators (120) from sheet25 meta1 so that they each have an upper section (124) that extends out from a 1ower section (122) in a direction towards at 1east one adjacentresonator (120), wherein at 1east one integrated capacitive coup1ingtuning member (130), arranged for tuning a capacitive coup1ing between adjacent resonators (120), extends downwards from the upper section 16 (18) (124),(122) substantially in parallel with the extension of the lower section of the resonator (120).

12. The method(570) (500) of any one of claims 9-11, (170) further comprisingarranging at least two cross-couplings (120) integrated into asingle part between the resonators (120) on the input side and the resonators on the output side.

13. The method (500)(B), and wherein the arranging of any one of claims 9-12, wherein the housing (T),further comprises (110) so (110) has a bottom four side walls (W1, W2, W3, W4), and a cover (540) (120)(120) of the resonators attaching the resonators to the bottom (B) of the housing that they extend from the bottom (B) of the housing (110) towards the top (T) of the housing, substantially in parallel with the side walls (Wi, WL W3, W4) of the housing (110).

14. The method (500) of claim 13, wherein the arranging (540) ofthe resonators (120) further comprises inserting the resonators (120)through openings (160) in the bottom (B) of the housing (110).

15. The method (500) claim 13 or 14, wherein the manufacturingof the housing (110) (150) (510) of the cover (T) comprises manufacturing a (T),when the cover (T) (110). in the cover (120) plurality of frequency tuning tabs arranged to bepositioned above at least some of the resonators is attached to the side walls (W1, W2, W3, W4) of the housing

16. The method(510)(110) (500)of the bottom (B) of any one of claims 13-15, wherein the manufacturing and the side walls (W1, W2, W3, Wmof the housing comprises manufacturing them from a single metal sheet, so that they are in one piece. 17 (18)