HIGH-FREQUENCY SHIELDED HOUSING, IN PARTICULAR HIGH-FREQUENCY SHIELDED FILTER HOUSING

Abstract

An improved high-frequency shielded housing is characterized by the following features, among others: multiple contact sections (K; K.sub.G; K.sub.D) are formed or provided arranged offset to one another between the housing cover (17) and the housing (3), galvanic separating sections (T; T.sub.G; T.sub.D) are formed or provided between the contact sections (K.sub.G; K.sub.D), the housing cover (17) and the housing (3) are galvanically separated in the regions of the galvanic separating sections, and screw connections (25) are provided in the contact sections (K; K.sub.G; K.sub.D), the housing cover (17) and the housing (3) being galvanically contacted in the regions of the screw connections.

Claims

1. High-frequency-proof housing, in particular high-frequency-proof filter housing, having the following features: comprising a housing (3) comprising a housing base (5) and a housing wall (6) rising from the housing base (5) and comprising a housing cover (17), a housing cover (17) is positioned on a housing edge (15) formed on the housing wall (6) of the housing (3) to form a complete housing (2), the housing (3) and/or the housing cover (17) consist of an electrically conductive material or of a dielectric material coated with an electrically conductive layer, the housing cover (17) has a plurality of fastening holes (117), which are aligned with corresponding holes (106) in the housing wall (6), the housing cover (17) is fastened or fastenable to the housing (3) by means of a plurality of screw connections (25), the screw connections (25) comprising fastening screws (19) which penetrate fastening holes (117) in the housing cover (17) and engage in holes (109) axially aligned therewith in the housing wall (6) of the housing (3), in the mounted state the housing cover (17) and the housing (3) are galvanically contacted, characterised by the following further features: between the housing cover (17) and the housing (3), a plurality of contact portions (K; K.sub.G; K.sub.D) arranged in a mutually offset manner are formed or provided, between the contact portions (K; K.sub.G; K.sub.D), galvanic isolation portions (T; T.sub.G; T.sub.D) are formed or provided, in the regions of which the housing cover (17) and the housing (3) are galvanically isolated, and the screw connections (25) are provided in the contact portions (K; K.sub.G; K.sub.D) in the region of which the housing cover (17) is galvanically contacted with the housing (3).

2. High-frequency-proof housing according to claim 1, characterised by the following further features: the contact portions (K) are formed on the housing edge (15) of the housing (3) in the form of mutually offset housing contact portions (K.sub.G) which are positioned in succession and comprise housing edge portions (15) protruding towards the housing cover (17), and the isolation portions (T) are in the form of housing isolation portions (T.sub.G) which comprise housing edge portions (15) that are depressed or recessed with respect to the housing cover (17) and arranged between the protruding housing edge portions (15).

3. High-frequency-proof housing according to claim 2, characterised in that the housing cover (17) is provided with one or more electrically conductive contact regions positioned in a plane, via which the housing cover (17) rests on the housing contact portions (K.sub.G) and is galvanically contacted with the housing (3) in these housing contact portions (K.sub.G), a gap (27) which brings about galvanic isolation being formed between the housing wall (6) and the housing cover (17) in the region of the depressed or recessed housing edge portions (15).

4. High-frequency-proof housing according to claim 1, characterised by the following further features: the contact portions (K) are formed on the housing cover (17) in the form of housing cover contact portions (K.sub.D), which comprise mutually offset housing cover portions (18) that are positioned in succession and protrude towards the housing (3), and the isolation portions (T) are formed as housing cover isolation portions (T.sub.G) which comprise housing cover portions (18) that are depressed or recessed with respect to the housing (3) and arranged between the protruding housing cover portions (18).

5. High-frequency-proof housing according to claim 4, characterised in that the housing edge (15) is provided with one or more electrically conductive contact regions that are positioned in a plane and on which the housing cover (17) is positioned by its housing cover contact portions (K.sub.D) formed on the protruding housing cover portions (18) and is galvanically contacted with the housing (3) in these housing cover contact portions (K.sub.D), a gap (127) which brings about galvanic isolation being formed between the housing wall (6) and the housing cover (17) in the region of the depressed or recessed housing cover portions (18).

6. High-frequency-proof housing according to any of claim 1, 2 or 4, characterised in that mutually offset housing edge portions (15) protruding towards the housing cover (17) on the housing edge (15), and depressed or recessed housing edge portions (15) positioned therebetween, as well as housing cover portions (18) protruding towards the housing (3) on the housing cover (17), and depressed or recessed housing cover portions (18) positioned therebetween are formed, and in that when the housing cover (17) is positioned on the housing (3) the raised or protruding housing cover portions (18) on the raised or protruding housing edge portions (15) are positioned on top of one another in an overlapping manner at least in part, and are galvanically contacted with one another in this region, whilst isolation portions (T; T.sub.D, T.sub.G), in which the housing cover (17) is galvanically isolated from the housing (3), are provided between the recessed or depressed housing edge portions (15) and housing cover portions (18), forming a gap (227).

7. High-frequency-proof housing according to any of claims 1 to 6, characterised in that the contact portions (K; K.sub.G; K.sub.D) are square, rectangular or n-gon-shaped, in particular in the manner of a regular n-gon.

8. High-frequency-proof housing according to any of claims 1 to 7, characterised in that the housing contact portions (K.sub.G; 15) and/or the housing cover contact portions (K.sub.D; 18) are provided with corners or edges (X; Y) which are rounded.

9. High-frequency-proof housing according to any of claims 2 to 8, characterised in that the gaps (27, 127, 227) between the housing (3) and the housing cover (17) in the region of the depressed housing edge portions (15) and/or the depressed housing cover portions (18) and/or the length of the contact portions (K.sub.G; 15; K.sub.D; 18) have a length which is less than the wavelength of the average operating frequency, in particular less than the half-wavelength of the average operating frequency.

10. High-frequency-proof housing according to any of claims 2 to 9, characterised in that the length of the depressed or recessed housing edge portions (15) and/or the length of the depressed or recessed housing cover portions (18) and/or the length of the contact portions (K.sub.G; 15; K.sub.D; 18) have a length which is greater than 1/40 of the wavelength of the average operating frequency, in particular greater than 1/30 of the wavelength of the average operating frequency.

11. High-frequency-proof housing according to any of claims 2 to 10, characterised in that the length of the raised housing edge portions (15) and/or the raised housing cover portions (18) is less than the wavelength of the average operating frequency, in particular less than the half-wavelength of the average operating frequency.

12. High-frequency-proof housing according to any of claims 2 to 1, characterised in that the length of the raised housing edge portions (15) and/or the raised housing cover portions (18) is greater than 1/80 of the wavelength of the average operating frequency, in particular greater than 1/70 of the wavelength of the average operating frequency.

13. High-frequency-proof housing according to any of claims 1 to 5, characterised in that the housing cover (17) consists of a non-conductive material or a circuit board material which is coated with an electrically conductive layer, the housing cover isolation portions (T.sub.D) being formed without an electrically conductive layer or an electrically conductive layer being removed.

14. High-frequency-proof housing according to either claim 1 or claim 13, characterised in that the housing (3), including the housing edge (15), is formed of a non-conductive material or circuit board material and coated with an electrically conductive layer, the housing edge (15) being formed without an electrically conductive layer in the housing isolation portions (T.sub.G) or an electrically conductive layer being removed in this region.

15. High-frequency-proof housing according to any of claims 1 to 14, characterised in that the housing cover (17) and/or the housing edge (15) of the housing (3) consist of an electrically conductive material or are coated with an electrically conductive material, and in that the housing cover isolation portions (T.sub.D) and/or the housing isolation portions (T.sub.G) are formed by means of an electrically non-conductive coating.

16. High-frequency-proof housing according to any of the preceding claims, characterised in that the complete high-frequency-proof housing (2) forms a high-frequency-proof filter housing, in particular forming coaxial cavity resonators.

17. High-frequency-proof housing according to any of the preceding claims in conjunction with claim 3, 5 or 6, characterised in that the gaps (27, 127, 227) between the housing cover (17) and the housing edge (15) are covered by a housing cover edge or housing cover flange (17c).

18. High-frequency-proof housing according to claim 17, characterised in that the height of the housing cover edge or housing cover flange (17c) is greater than the height of the gaps (27, 127, 227).

19. High-frequency-proof housing according to either claim 17 or claim 18, characterised in that the height of the housing cover edge or housing cover flange (17c) corresponds to at least 1.5 times, preferably 2 times, 2.5 times or 3 times the material thickness of the housing cover (17) and is preferably less than 6 times, 5 times or 4 times the thickness of the housing cover (17).

20. High-frequency-proof housing according to any of claims 1 to 19, characterised in that the height of the gaps (27, 127, 227) is less than 2 times the thickness of the housing cover (17), in particular less than the thickness of the housing cover (17) or less than 0.9 times, 0.8 times, 0.7 times, 0.6 times, 0.5 times, 0.4 times, 0.3 times or 0.2 times the thickness of the housing cover (17).

21. High-frequency-proof housing according to any of claims 17 to 20, characterised in that a spacing (17e) is formed between the housing cover edge or housing cover flange (17c) and the outer face of the housing walls (6).

22. High-frequency-proof housing according to any of the preceding claims in conjunction with claim 3, 5 or 6, characterised in that the gaps (27, 127, 227) are filled with an electrically non-conductive material or dielectric.

Description

[0043] In the following, the invention will be described in greater detail by way of drawings, in which specifically:

[0044] FIG. 1 is a schematic three-dimensional drawing of an open housing of a complete HF-proof housing without the cover;

[0045] FIG. 2 is a plan view of the open housing shown in a side view in FIG. 1;

[0046] FIG. 2a is a drawing slightly modified from FIG. 2, illustrating that the individual chambers of the resonators can also be subdivided by forming apertures using boundary walls;

[0047] FIG. 3 is a three-dimensional drawing of a housing cover for sealing the open part, shown in FIG. 1, of the complete housing;

[0048] FIG. 4 is a schematic side view of the open housing shown in FIG. 1;

[0049] FIG. 5 is a schematic side view of the detail A shown in FIG. 3;

[0050] FIG. 6 is an enlarged side view of a modified cover in a partial side view;

[0051] FIG. 7 again shows a slightly modified embodiment in a side detail comparable to FIG. 5;

[0052] FIG. 8 is an embodiment slightly modified from FIG. 5 having rounded edges;

[0053] FIG. 9 again shows an embodiment slightly modified from FIGS. 5 and 8 having double-sided rounded edges;

[0054] FIG. 10 is a plan view of an embodiment modified from FIG. 2, in which the walls of the housing have a greater thickness in the region of the hole than portions therebetween;

[0055] FIG. 11 is a vertical sectional drawing in the longitudinal direction through a housing wall, showing three modifications forming raised housing edge portions;

[0056] FIG. 12 is a corresponding plan view of the embodiments according to FIG. 11;

[0057] FIG. 13 is another slightly modified embodiment having a cover provided with a peripheral edge;

[0058] FIG. 14 is a partial view from below of the housing cover in relation to a modified embodiment of the invention; and

[0059] FIG. 15 is a partial perspective view of a portion of the housing wall in relation to another modified embodiment of the invention.

[0060] FIGS. 1 to 5 show a first embodiment of a high-frequency-proof housing according to the invention preventing intermodulation problems, in particular in the form of a filter consisting of coaxial resonators. These filters are also known as coaxial cavity filters, which may in principle be in the form of band-pass filters, band-stop filters, etc. In the present case, the filter may for example be used as a duplex switch, such as are required in mobile communications technology.

[0061] In the embodiment shown, the coaxial cavity filter 1 (sometimes also simply referred to as a cavity filter or coax filter 1 in the following) comprises a chest-shaped complete housing 2, which is open on at least one face (in this case upwards). This open face OS is sealed by a cover 17 (see FIG. 3) for operation of the coax filter. The housing 2 further has a base 5, a peripheral housing wall 6 and internal conductors 7 that are provided in the interior 4 thus formed and extend vertically from the base 5 over part of the height of the housing 3.

[0062] The cavity filter shown in FIG. 1 and FIG. 2 (with the cover omitted in these drawings) is generally subdivided into chambers 101, which are defined by boundary walls, it being possible for the boundary walls each to be formed of for example two wall portions 6 protruding inwards from the housing wall 6, as is shown in FIG. 2a. Likewise, in many cases it may be sufficient for a corresponding wall portion 6 to only protrude from one inner housing wall. In both cases, in effect apertures or windows 8 are formed between either the wall portions 6 which only protrude inwards in part or the single wall portion which protrudes inward on the opposite inner housing wall, it being possible to couple the individual coaxial resonators 1 to one another via these apertures or windows 8.

[0063] In the region of provided terminals, suitable measures for coupling the signals in and out are provided in each coax filter 1, reference being made to known solutions in this regard. At the provided input or output terminals AE, AA, AS, otherwise conventional coaxial plugs can be connected to corresponding line connections.

[0064] The chest-shaped housing 3 thus constructed, comprising the housing base 5 and the internal conductor 7, may be formed from a metal milled or cast part. Preferably, aluminium is used for this purpose.

[0065] In principle, it is noted that the invention may also be implemented using a housing 3 and/or a housing cover 17 (FIG. 3) which consists of a dielectric material (in particular plastics material). In this case, the housing 3, in other words the housing wall 6, the housing base 5, the internal conductor 7 and the housing cover 17, would have to be coated with an electrically conductive layer, generally a metal layer. In this case, above all the inner walls and inner surfaces of the housing 3 have to be coated with the electrically conductive layer (which thus faces the interior), including the peripheral housing edge 15. As for the housing cover 17, the housing cover underside 17a facing the interior has to be coated with an electrically conductive layer, such that not only mechanical but also galvanic contacting is possible in the edge region 18.

[0066] A housing cover 17 is positioned on the peripheral housing edge 15, facing away from the base 5, of the housing 3, and rigidly screwed to the housing 3 by means of a plurality of screw connections 25, in this case in the form of screws 19. In FIG. 4, the housing 17 or partial housing 3, the aforementioned housing cover 17 and some of the fastening screws 19 are arranged above one another in the manner of an exploded view. By means of an arrow 17, it is further shown that the housing cover 17 is positioned on the peripheral edge 15 of the (open) housing 3, and the housing cover 17 is subsequently fastened. For this purpose, the fastening screws 19 are placed through a corresponding number of fastening holes 117 (formed in the housing cover edge 18) and screwed flush into the provided threaded holes 106 of the housing wall 15, as discussed in greater detail below.

[0067] So as to shield the individual coaxial resonators 1, in other words the interior 4 of the high-frequency cavity filter 1, towards the outside in an HF-proof manner and to prevent intermodulations, it is provided in a first embodiment, with reference to the aforementioned FIGS. 1 to 5, for the housing cover 17 to be for example flat or planar or at least to have a flat or planar peripheral edge 18, 21 or a corresponding peripheral edge surface 18, 21.

[0068] FIG. 3 is a three-dimensional drawing of the housing cover 17, specifically from the underside 17a thereof. In other words, the peripheral housing cover edge 18 of the housing cover 17 is positioned on the upwardly open chest-shaped housing 3. This peripheral edge 18, in other words this peripheral edge surface 18, is shown in dashed lines.

[0069] The housing cover edge 18 or edge surface 18 of this housing cover 17 rests (only in part as explained in the following) on the peripheral housing edge 15.

[0070] However, as can be seen from the side view of FIG. 4 and also from the enlarged detail of FIG. 5 (which shows an enlargement of a region in FIG. 4 in vertical section), the housing edge 15 does not have a consistently high level, in other words is not flat or planar overall. FIG. 5 shows that the peripheral housing edge 15 is subdivided into individual housing edge portions, specifically housing edge portions 15 that are raised, i.e. protrude towards the housing cover 17, which are followed by depressed, in other words recessed, housing edge portions 15. FIG. 5 shows in a side view (partially in section) that the housing cover 17 is formed as a plate, such that the aforementioned planar housing cover edge 18 can only rest on the raised housing edge portions 15. In this region, where the housing cover 17 thus rests on the raised housing edge portions 15 of the housing edge 15 by means of its corresponding portions of the edge surface 21, galvanic contact is thus produced between the underside 17a of the housing cover 17 and the raised housing edge portions 15 of the housing wall 6. Only in these regions 18a do the screwed-in screws 19 produce a corresponding contact pressure, which holds the cover 17 pressed against the chest-shaped housing 3.

[0071] Thus, in this embodiment, the raised housing edge portions 15 form housing-side contact portions or contact regions K.sub.G on the housing, which come into contact with the cover underside when the cover is mounted. The edge portion on the cover underside that comes into contact and thus into galvanic contact with the raised housing edge portions 15 thus forms cover-side contact regions or contact portions K.sub.D, the cover-side contact regions or contact portions being flat without projections and without depressed portions in this embodiment. Since the housing and the housing cover consist of an electrically conductive material and/or (for example if they consist of plastics material or another dielectric) are coated with an electrically conductive layer, the aforementioned housing edge portions 15, which are raised and protrude in the mounting direction (in other words towards the housing cover), form electrogalvanic bearing and/or contact portions K, on which the housing cover rests. In this case the contact portions K are thus formed by housing contact portions K.sub.G so as to bring about the desired galvanic contacting in this region.

[0072] By contrast, the housing edge portions 15 formed on the housing and recessed or depressed with respect to the housing cover 17 form galvanic isolation points, in other words contact-free isolation regions or isolation portions T, specifically isolation regions or isolation portions T.sub.G which are contact-free with respect to the housing or housing edge. The edge portions on the cover underside which are directly adjacent thereto or come to rest above the recessed housing edge portions 15 in the assembled state, and which thus come to rest at a distance from the housing edge, thus likewise form the aforementioned isolation regions or isolation portions T, in other words specifically isolation regions or isolation portions T.sub.G which are present on the cover in these regions, even if these portions are intended to be electrically conductive. This is because housing edge portions 15 slightly spaced apart from the housing cover 17, in other words depressed portions, are then located between two housing edge portions 15 raised in this manner, such that a gap 27 is formed here between this depressed housing edge portion 15 and the underside 17a of the housing cover 17. Thus, no galvanic and mechanical contact effect can occur in this region.

[0073] As a result of the correspondingly close sequence of adjacent screw connections 25 comprising the screws 19 in accordance with the spacing sequence of the holes 106, it is nevertheless ensured that the complete housing 2 with the mounted housing cover 17 is high-frequency-proof. In other words, the gaps 27, which may only be sixed extremely small in height, are not detrimental to establishing high-frequency shielding.

[0074] Above all, it is important that the screws 19 indicated in FIG. 5 can be screwed into the threaded holes 106 in the side walls 6 through the fastening holes 117 in the housing cover 17 such that the housing cover 17 can be pressed onto the housing cover edge portions 18a, which are in contact with the raised housing edge portions 15, using above-average contact pressures. In other words, in these edge portions 18 (which rest on the correspondingly raised housing edge portions 15 of the housing 3), rigid, precisely reproducible galvanic connection having high contact pressures is ensured, specifically by the defined contact surfaces which are penetrated by the screw connections 25. These defined contact surfaces are ultimately formed by the gaps 27 provided between the contact surfaces.

[0075] FIG. 6 shows a reversal of the solution disclosed thus far, in which the housing cover 17 may for example have a preferably peripheral housing cover wall 17b at a low height. In this embodiment too, the peripheral housing cover edge 18, formed on the housing cover wall 17b, of the housing cover wall 17b is subdivided into different portions, specifically into raised protruding housing cover edge portions 18 (in other words protruding towards the open housing box 3) and into depressed housing cover edge portions 18 positioned somewhat further away from the adjacent housing wall 6 by comparison.

[0076] As a result, a fully comparable solution is provided, in which a housing cover 17 correspondingly mounted on the housing edge 15 can only be mounted on the peripheral housing edge 15 of the housing 3 by means of its raised protruding housing cover edge portions 18 in regions 15a (in other words only at the housing edge portions 15a which come into contact with the raised protruding bearing surfaces of the housing cover edge portions 18). The housing cover edge portions 18, which are depressed or recessed by comparison and between which and the peripheral housing edge 15 the aforementioned gaps 127 are thus formed, are thus positioned between the raised housing cover edge portions 18.

[0077] As a result of these gaps 127, the depressed housing cover edge portions 18 are spaced apart from the housing wall 6 of the housing 3.

[0078] In this embodiment too, the holes 117 in the housing cover 17 and the holes 106 aligned therewith in the housing wall 6 are formed at the points at which the housing cover 17 rests on the housing wall 6 of the housing 3 by its raised housing cover edge portions 18. This also provides a good mechanical connection and additionally a good electrogalvanic connection in this region as a result of the high contact pressures of the screws 19, since defined contact surfaces are provided by forming the aforementioned gaps 127 in the region of the screw connections 25.

[0079] In the embodiment of FIG. 6 too, galvanic contact portions K, also referred to as housing cover contact portions K.sub.D, are thus formed on the cover underside. If a corresponding housing cover 17 is positioned on the peripheral edge of the housing, these protruding housing cover contact portions K.sub.D come into mechanical contact with the peripheral edge of the housing and bring about electrogalvanic contacting in the contact and bearing region. The housing contact portions K.sub.G are formed in the actual contact and bearing region of the housing cover contact portions K.sub.D. In these regions positioned above one another, the corresponding holes 106 for receiving the screw connections are provided, so as to be able to mechanically fasten the cover rigidly to the peripheral edge of the housing here by tightening the screws.

[0080] In the embodiment of FIG. 6, the isolation points T (also referred to herein as housing cover isolation points T.sub.D) which are recessed or positioned lower than the top of the cover are provided offset from the aforementioned contact portions K. These housing cover isolation points TD are thus directly adjacent to, galvanically isolated from and thus contact-free with respect to the corresponding portions on the housing edge of the housing, these contact-free portions thus also being referred to as housing isolation regions or housing isolation portions T.sub.G.

[0081] By contrast with the previous embodiments, FIG. 7 shows that the principle of FIG. 5 and the further principle as explained with reference to FIG. 6 can also be combined. In this case, therefore, the peripheral housing edge 15 has a series of steps, in other words the bearing and/or contact surfaces that protrude slightly further towards the housing cover 17 and have been defined as raised housing edge portions 15. In addition, the housing cover 17 is also equipped with the raised housing cover edge portions 18, as has been shown in FIG. 6. The associated raised housing cover edge portions 18 thus rest on the raised housing edge portions 15 over the entire area or so as to only overlap in part. Each depressed, in other words recessed, housing cover edge portion 18 offset therefrom and the likewise depressed, in other words recessed, housing edge portions 15 thus form an intermediate gap 227 in each case. The screws 19 again penetrate the fastening holes 117 in the housing cover 17 and are screwed into an internal thread into the threaded hole 106 in the housing. The holes 117 penetrate the housing cover 17 in the raised housing cover edge portions 18 and the holes 19 are made in the region of the raised housing edge portions 15. The arrangements and the size of the contacting surfaces on the raised housing edge portions 15 and the housing cover edge portions 18 are preferably identical, in other words preferably provided with the same surface size and at the same point, in other words in the same position, such that the associated surfaces thereof are positioned on top of one another over the whole area as far as possible. In relation to the intermodulation compatibility, it has proven particularly advantageous for the edges of the raised housing cover edge portions 18 and the raised housing edge portions 15 to be rounded or provided with a radius.

[0082] FIG. 8 therefore shows a drawing differing from FIG. 5, in which the raised housing edge portions 15 are positioned at a distance from the associated screws 19, and are provided, adjacently to the underside 17a of the cover 17, with an edge X which is rounded in section. The radius may preferably be approximately the same height as the slot 27.

[0083] In the variant of FIG. 9, the raised housing edge portions 15 actually have rounded edges not only on the sides remote from the associated screws 19, but also on the sides facing the screws 19, in other words have a rounded edge X and have a rounded edge Y opposite. In other words, the radius of these roundings X and/or Y should be at least 10% of the height of the spacing gap 27 (or 127) in the embodiment FIG. 6 or 227 in the embodiment of FIG. 7, in particular more than 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100% of the height of the spacing in question. Usually, the radius is less than or equal to the height of the spacing, in particular less than 90%, 80%, 70%, 60%, 50%, 40%, 30% or 20% of the height of the spacing gap.

[0084] It is further noted that the corresponding roundings or rounded edges X and/or Y may also be provided in the embodiments of FIG. 6, such that these roundings or rounded edges are thus formed on the raised housing cover edge portions 18, specifically again on the side remote from the screw and on the side facing the screw in each case. The same applies to the embodiment of FIG. 7, in which rounded edges could converge in each case, since they may be formed on both raised portions 15 and 18.

[0085] In this variant too, the advantages of the invention are thus accordingly achieved.

[0086] However, the embodiment in accordance with the example in FIGS. 1 to 5 is preferred, since in this case a planar material, in particular a planar metal part, can be used as the housing cover.

[0087] As shown, the aforementioned housing walls 6 of the filter may have the same wall thickness. In the embodiment shown in accordance with FIG. 10, the housing wall is formed with a varying thickness. In each of the regions in which the threaded holes 106 are formed, the housing wall 6 has a thicker material diameter 6a so as to be able to receive the housing holes 106 at an appropriate internal diameter. The housing wall portions 6b located therebetween are formed with a thinner material portion, in other words with a thinner wall portion, by comparison. This can be implemented for example in that corresponding groove-shaped depressions 6c, which generally extend perpendicularly to the base surface and may have a suitable cross section, for example in the form of a rectangular groove or a hip-roof-shaped groove provided with opposite flattened portions 6d, are preferably formed on the inner faces of the housing walls. Any modifications are possible in this regard. Further, at these points (where the threaded holes 106 are formed in the wall portions of greater thickness), a defined contact in the form of an annular bead may be provided, which in each case forms the aforementioned raised portion 15. In this case, the wall portions 6b located therebetween have a thinner wall thickness, as mentioned. However, this is not absolutely necessary for implementing the aforementioned embodiments.

[0088] In the following, reference is further made to a schematic modification with reference to FIG. 11 in a vertical sectional drawing parallel to the holes in the housing walls and with reference to FIG. 12 in the form of a plan view of the housing walls and/or an underside view of the edge 18, 21 of the lower housing cover.

[0089] FIG. 11 and the corresponding plan view of FIG. 11 show three slightly different variants side by side.

[0090] On the left in the embodiment of FIGS. 11 and 12, a corresponding raised housing wall portion 15 is formed, which encloses the corresponding hole 106 in the housing wall 6 in a disc shape or saucer shape, in other words is annular.

[0091] In the variant shown in the centre in FIGS. 11 and 12, the raised portion 15 is ridge-shaped, and thus has for example a rectangular basic shape (generally an n-gon) in a plan view in the embodiment shown, the two elongate rectangular raised housing edge portions 15 being orientated with their longitudinal extensions transverse and in particular perpendicular to the longitudinal extension of the housing wall. One raised ridge-shaped portion is offset to the left and the other to the right in the longitudinal direction of the housing wall, such that the corresponding hole 106 is received in the housing wall intermediately between this pair of raised ridge-shaped or rectangular housing edge portions 15. The vertical sectional drawing is shown in the centre in FIG. 11.

[0092] The variant on the right in FIG. 12 largely corresponds to the variant in the centre of FIGS. 11 and 12, with the difference that in the variant on the right of FIGS. 11 and 12 the ridge-shaped elevations 15 extend over the entire width (thickness) of the housing wall 6, whilst the ridge-shaped elevations 15 of the variant in the centre of FIGS. 11 and 12 are only thicker over part of the width of the housing wall, but are preferably arranged symmetrically with respect to a central plane of the housing wall so that the forces introduced by the screws can act symmetrically on these raised housing edge portions 15.

[0093] However, in a departure from the drawing, the ridge-shaped raised housing edge portions 15 could also be arranged in a manner rotated about the hole 106 in the plan view of FIG. 12, in principle at any desired angle. An arrangement in which the longitudinal extension of the individual ridge-shaped or rectangular raised housing edge portions 15 come to rest in the longitudinal direction of the associated housing wall would also be possible. Any desired modifications are possible here, in particular also as regards the surface shape of the raised housing edge portions 15, which need not necessarily be rectangular.

[0094] The variants and possibilities shown in FIGS. 11 and 12 and the discussed modifications also apply equally to raised housing cover edge portions 18. This is because the raised housing cover edge portions 18 explained with reference to the other embodiments can equally have the rounded edges X and/or Y explained with reference to FIGS. 8 and 9, but just like the embodiments disclosed with reference to FIGS. 11 and 12 in a perforated disc shape, ridge shape, etc. There are no limitations in this regard. Thus, as a result of the discussed rounded edges X and/or Y, bead-shaped raised housing edge portions and/or housing cover edge portions are generally also possible.

[0095] In the following, reference is again made to FIG. 13, which is a drawing of a modified embodiment. In this drawing, the front side wall of the housing is shown in vertical section, specifically in a plane in which the centre of the screws comes to rest.

[0096] From this, it can be seen that the cover is not planar, but rather can be provided with a peripheral housing cover edge 17c, which may also be referred to as a peripheral housing cover flange 17c. Unlike the housing cover wall 17b explained in the other embodiments, which rests on the peripheral edge of the housing, the peripheral housing cover edge or housing cover flange 17c shown in FIG. 13 is formed such that it overlaps the housing walls, preferably externally over a partial height. The formation is preferably such that the underside or inner face 17d adjacent to the housing wall 6 is positioned at a distance from the outer wall surface of the external face of the housing wall 6, and a spacing 17e is thus formed here. As a result of the aforementioned peripheral housing cover edge or flange 17c, the aforementioned gaps 27, 127, 227 are covered towards the outside, and thus are not visible from the outside when the cover is mounted.

[0097] The spacing 17d may have a width which approximately corresponds to the size of the depth or height of the gap 27, 127, 227. The corresponding gap height 27, 127, 227 and the gap width 17d may have various dimensions. It is at least sufficiently large that galvanic contact is prevented in the relevant regions described.

[0098] In a departure from the drawings, the gap height may even take on larger values, in particular when the height of the housing cover edge or housing cover flange 17c covering the gap is even greater than the corresponding gap height.

[0099] In the following, reference is made to the embodiment of FIG. 14, which is a partial view from below of the housing cover 17.

[0100] As can be seen from this, in the region of the housing edge 18, following the housing edge in the peripheral direction, in each case a contact region or contact portion K and an isolation region or isolation portion T are provided. In this regard, reference is also made to a housing cover contact region K.sub.D and a housing isolation region T.sub.G.

[0101] In this embodiment, the cover consists for example of a dielectric, in other words an electrically non-conductive body, and is preferably coated on the outer face and the inner face or underside thereof and on the peripheral end-face edge thereof connecting the top and the underside, preferably with a metal layer. This metal conductive layer is also formed in the aforementioned housing cover contact regions K.sub.D. In this case, the holes 117 in the housing cover 17 are also provided in these regions.

[0102] In this case, an electrically conductive layer is removed from the housing cover isolation regions or separating portions T.sub.D such that in this region the dielectric or another insulating layer is exposed, and is thus possibly only covered by the metal layer on the outer face of the housing cover formed of an electrically non-conductive material.

[0103] If a housing cover of this type is placed on a corresponding housing, for example by way of a peripheral housing edge 15 of a housing wall 6 (shown in chain-dotted lines in FIG. 14), which edge may for example be coated over the entire surface with an electrically conductive layer (it also being possible for the housing wall as a whole, including the edge thereof, to consist of an electrically conductive material), contact points K.sub.G and electrical isolation points T.sub.G are also formed in succession on the housing wall in each case. The contact points K.sub.G on the housing edge 15 are formed by the electrically conductive contact portions KG of the housing cover resting here, in other words creating the galvanic contacting here. The screw connections are thus provided in this region. Even if the housing edge 15 is electrically conductive, the electrical isolation points T.sub.G on the housing edge 15 are formed by regions free of an electrically conductive layer being formed adjacently on the housing cover for this purpose, in particular on the housing cover underside. Contact-free regions in which galvanic contact is not provided and is not possible are thus formed here.

[0104] The principle may also be implemented in reverse. For example, it is possible for the housing 3 to likewise consist of a dielectric or generally non-conductive material or plastics material, for example of a circuit board material, the housing 3 being coated with an electrically conductive layer on its inner face and preferably also on its outer face, as well as on its upper housing edge 15 facing the housing cover 17, including the housing contact portions K.sub.G. To form the housing isolation points T.sub.G, between these portions the dielectric wall portions, i.e. the portions consisting of non-conductive materials, may additionally be freed of an electrically conductive layer or an electrically conductive layer of this type may not be present there ex works. On a housing edge formed in this manner, it is possible to mount a housing cover which may be conductive over the entire surface on the peripheral edge region thereof mounted on the housing edge, in other words which has an electrically conductive layer extending around in a single plane. This is because galvanically effective contact portions K are only formed where the contact portions K.sub.G provided on the housing edge come into mechanical contact when the housing cover is placed on. Where the electrically conductive layers are removed on the housing edge and the electrically non-conductive material is exposed, the isolation portions T effective between the housing cover and the housing are formed, in other words the contact-free portions in which galvanic contacting is reliably prevented. This example is schematically illustrated by way of FIG. 15.

[0105] In this last case, it is also advantageous to expose the isolation point T.sub.G on the housing edge 15, which point has been freed of an electrically conductive layer, not only on the side of the housing edge 15 facing the cover, but also additionally at least to a minimal height on the inner and outer side walls 6S.

[0106] The principle illustrated by way of FIGS. 14 and 15 can also be implemented simultaneously. In this case, the position and size of the contact points K, in other words the contact portions K.sub.D on the housing cover and K.sub.G on the housing edge, as well as the isolation points T, i.e. the cover-side isolation points T.sub.D as well as the housing-side isolation points T.sub.G on the housing edge, should preferably be tailored to one another in terms of their position relative to one another and in terms of the extension size thereof such that the contact points K.sub.D on the housing cover 17 come to rest congruently or at least so as to overlap the electrically conductive contact portions K.sub.G on the housing 3, in other words come to rest on the housing edge 15. This also ensures that the corresponding isolation points T.sub.D, like the isolation points T.sub.G, come to rest adjacent one another between the protruding contact portions in each case. In terms of its functional configuration, this embodiment thus corresponds to the embodiment of FIG. 7. By contrast, the aforementioned variant in accordance with FIG. 14 corresponds in functional terms to the embodiment of FIG. 6, whilst the embodiment of FIG. 15 is comparable in functional terms to the embodiment of FIG. 5.

[0107] Finally, it should also further be mentioned that it would in principle be possible, at the desired isolation points between the spacings at which the screw connections are formed, to convert an existing electrically conductive contact layer into a galvanic isolation region or isolation portion by applying an insulating film or an insulating layer. These isolation layers may be formed both as a cover underside at the corresponding points and on the peripheral edge of the housing, potentially including a side wall portion 6s. This isolation layer can be implemented both on the cover and on the housing edge.

[0108] The preferred length of the gap or the preferred length of the defined contacts between the housing cover and the housing is preferably dependent on the operating frequency for which the housing is used. Preferably, the gap length or the contact length should be less than A and in particular less than /2 for the average operating frequency. Preferably, the corresponding values for the gap length and the contact length are less than /3, /4, /5, /6, /7, /8, /9, /10 and smaller for the average operating frequency.

[0109] Conversely, the gap length in question should preferably be greater than 1/40 or in particular greater than 1/30 of the wavelength of the average operating frequency. The preferred values for the contact length are greater than 1/80 or in particular greater than 1/70 of the wavelength of the average operating frequency. The preferred threshold values for the gap length and the contact length can be derived from the two tables below. The final column sets out preferred individual values for the gap length and the contact length for the specified band ranges.

TABLE-US-00001 Gap length Average operating Band frequency /2 /40 /30 Actual MHz MHz mm mm mm mm mm 700/800 750 400 200 10 13.3 24 800/900 800 375 188 9.4 12.5 24 1800/2200 2000 150 75 3.75 5 12

TABLE-US-00002 Contact length Average operating Band frequency /2 /80 /70 Actual MHz MHz mm mm mm mm mm 700/800 750 400 200 5 5.7 5 800/900 800 375 188 4.7 5.4 5 1800/2200 2000 150 75 1.9 2.1 5