Waveguides and transmission lines in gaps between parallel conducting surfaces

Abstract

A microwave device, such as a waveguide, transmission line, waveguide circuit, transmission line circuit or radio frequency part of an antenna system, is disclosed. The microwave device comprises two conducting layers arranged with a gap there between, and a set of periodically or quasi-periodically arranged protruding elements fixedly connected to at least one of said conducting layers, thereby forming a texture to stop wave propagation in a frequency band of operation in other directions than along intended waveguiding paths, thus forming a so-called gap waveguide. All protruding elements are connected electrically to each other at their bases at least via the conductive layer on which they are fixedly connected, and some or all of the protruding elements are in conductive or non-conductive contact also with the other conducting layer. A corresponding manufacturing method is also disclosed.

Claims

1. A microwave device, such as a waveguide, transmission line, waveguide circuit, transmission line circuit or radio frequency part of an antenna system, the microwave device comprising two conducting layers arranged with a gap there between, and a set of periodically or quasi-periodically arranged protruding elements fixedly connected to at least one of said conducting layers, thereby forming a texture to stop wave propagation in a frequency band of operation in other directions than along intended waveguiding paths, all protruding elements being connected electrically to each other at their bases at least via said conductive layer on which they are fixedly connected, and wherein some or all of the protruding elements are in conductive contact and/or non-conductive contact also with the other conducting layer.

2. The microwave device of claim 1, wherein at least one of the conductive layers is further provided with at least one conducting element, said conducting element not being in electrical contact with the other of said two conducting layers, said conducting element(s) thereby forming said waveguiding paths, preferably for a single-mode wave.

3. The microwave device of claim 2, wherein the conducting element(s) is one of a conducting ridge and a groove with conducting walls.

4. The microwave device of claim 3, wherein the protruding elements in contact with the other conducting layer are preferably fixedly connected to the other conducting layer, and wherein the protruding elements are arranged to at least partly surround a cavity between said conducting layers, said cavity thereby forming said groove functioning as a waveguide.

5. The microwave device of claim 2, wherein the width of the conducting element is in the range 1.0 - 6.0 mm, and preferably in the range 2.0- 4.0 mm.

6. The microwave device of claim 1, wherein the microwave device is a radio frequency (RF) part of an antenna system, e.g. for use in communication, radar or sensor applications.

7. The microwave device of claim 1, wherein the distance between adjacent protruding elements in the set of periodically or quasi-periodically arranged protruding elements is in the range of 0.05 - 2.0 mm, and preferably in the range 0.1-1.0 mm.

8. The microwave device of claim 1, wherein each of the protruding elements have a maximum width dimension in the range 0.05 - 1.0 mm, and preferably in the range 0.1 - 0.5 mm.

9. The microwave device of claim 1, wherein at least some, and preferably all, of the protruding elements are in mechanical contact with said other conducting layer.

10. The microwave device of claim 9, wherein at least some of said protruding elements are fixedly attached to said other conducting layer, e.g. by means of soldering or adhesion.

11. The microwave device of claim 1, wherein said protruding elements have essentially identical heights, the maximum height difference between any pair of protruding elements being less than 0.02 mm, and preferably being less than 0.01 mm.

12. The microwave device according to claim 1, wherein the two conducting layers are connected together for rigidity by a mechanical structure at some distance outside the region with guided waves, where the mechanical structure may be integrally and preferably monolithically formed on at least one of the conducting materials defining one of the conducting layers.

13. The microwave device according to claim 1, wherein at least part of the two conducting layers are mostly planar except for the fine structure provided by the ridges, grooves and texture.

14. The microwave device according to claim 1, wherein the set of periodically or quasi-periodically arranged protruding elements are monolithically formed on one of said conducting layers, and preferably monolithically formed by coining, whereby each protruding element is monolithically fixed to the conducting layer, all protruding elements being connected electrically to each other at their bases via said conductive layer on which they are fixedly connected.

15. The microwave device according to claim 14, further comprising at least one ridge along which waves are to propagate, said ridge being arranged on the same conducting layer as the protruding elements, and also being monolithically formed on said conducting layer.

16. The microwave device of claim 1, further comprising a plurality of monolithic waveguide elements, each having a base and protruding fingers extending up from the base, thereby forming said protruding elements, wherein the waveguide elements are conductively connected with one of said conducting layers, and arranged to form a waveguide along this conducting layer.

17. The microwave device of claim 16, wherein the waveguide elements comprises flat base plates for formation of groove gap waveguides.

18. The microwave device of claim 16, wherein the waveguide elements comprises bases provided with protruding ridges, for formation of ridge gap waveguides.

19. The microwave device of claim 16, wherein the waveguide elements are made of metal.

20. The microwave device of claim 16, wherein at least one of the waveguide elements comprises a plurality of fingers arranged on two opposite sides of the base.

21. The microwave device of claim 16, wherein at least one of the waveguide elements comprises a plurality of fingers arranged along two or more parallel but separate lines along at least one of the edges.

22. The microwave device of claim 16, wherein at least one of the waveguide elements comprises a plurality of fingers arranged along a single line along at least one of the edges.

23. The microwave device of claim 16, wherein at least some of the fingers are bent-up tongues extending from the outer side of the base.

24. The microwave device of claim 16, wherein at least some of the fingers are bent-up tongues extending from interior cut-outs within the base.

25. The microwave device of claim 16, wherein the waveguide elements comprises at least one of a straight waveguide element, a curved or bent waveguide element, a branched waveguide element and a transition waveguide element.

26. The microwave device of claim 16, wherein the transition waveguide element is a transition to connect to a monolithic microwave integrated circuit module (MMIC).

27. The microwave device of claim 16, wherein the protruding height of the fingers is greater than the width and thickness of the fingers, and preferably greater than double the width and thickness.

28. The microwave device of claim 16, wherein the width of the fingers is greater than the thickness.

29. The microwave device of claim 1, wherein said protruding elements are formed as a surface mount technology grid array, such as a pin grid array, column grid array and/or a ball grid array, wherein each pin is fixed to the conducting layer by soldering, but wherein all protruding elements are connected electrically to each other at their bases via said conductive layer on which they are fixedly connected.

30. The microwave device of claim 29, further comprising a ball grid array arranged outside the protruding elements forming said texture to stop wave propagation, said ball grid array functioning as spacers between said conducting layers.

31. The microwave device according to claim 1, wherein the protruding elements have maximum cross-sectional dimensions of less than half a wavelength in air at the operating frequency, and/or wherein the protruding elements in the texture stopping wave propagation are spaced apart by a spacing being smaller than half a wavelength in air at the operating frequency.

32. The microwave device according to claim 1, wherein at least one of the conducting layers is provided with at least one opening, preferably in the form of rectangular slot(s), said opening(s) allowing radiation to be transmitted to and/or received from said microwave device.

33. The microwave device according to claim 1, further comprising at least one integrated circuit module, such as a monolithic microwave integrated circuit module, arranged between said conducting layers, the texture to stop wave propagation thereby functioning as a means of removing resonances within the package for said integrated circuit module(s).

34. The microwave device of claim 33, wherein the integrated circuit module(s) is arranged on one of said conducting layer, and wherein protruding elements overlying the integrated circuit(s) are shorter than protruding elements not overlying said integrated circuit(s).

35. The microwave device of claim 1, wherein the microwave device is adapted to form waveguides for frequencies exceeding 20 GHz, and preferably exceeding 30 GHz, and most preferably exceeding 60 GHz.

36. A flat array antenna comprising a corporate distribution network realized by a microwave device of claim 1.

37. A method for producing a microwave device, such as a waveguide, transmission line, waveguide circuit, transmission line circuit or radio frequency part of an antenna system, the method comprising: providing a conducting layer having a set of periodically or quasi-periodically arranged protruding elements fixedly connected thereto, all protruding elements being connected electrically to each other at their bases at least via said conductive layer on which they are fixedly connected; arranging another conducting layer over said conducting layer, thereby enclosing the protruding elements within the gap formed between the conducting layers; wherein protruding elements form a texture to stop wave propagation in a frequency band of operation in other directions than along intended waveguiding paths, and wherein some or all of the protruding elements are in conductive or non-conductive contact also with the other conducting layer.

38. The method of claim 37, wherein the step of providing a conducting layer having a set of periodically or quasi-periodically arranged protruding elements fixedly connected thereto comprises: providing a die being provided with a plurality of recessions forming the negative of the protruding elements; arranging a formable piece of material on the die; and applying a pressure on the formable piece of material, thereby compressing the formable piece of material to conform with the recessions of the die.

39. The method of claim 38, wherein the die is provided with a collar in which the formable piece of material is insertable.

40. The method of claim 39, wherein the die comprises a base plate and a collar, the collar being provided as a separate element, loosely arranged on the base plate.

41. The method of claim 38, wherein the die further comprises at least one die layer comprising through-holes forming said recessions.

42. The method of claim 41, wherein the die comprises at least two sandwiched die layers comprising through-holes.

43. The method of claim 41, wherein the at least one die layer is arranged within the collar.

44. The method of claim 37, wherein the step of providing a conducting layer having a set of periodically or quasi-periodically arranged protruding elements fixedly connected thereto comprises: providing a first conducting layer, e.g. arranged as a metalized layer on a substrate; providing a plurality of monolithic waveguide elements, each having a base and protruding fingers extending up from the base; and conductively connecting the waveguide elements with the first conducting layer, and arranged to form a waveguide along the first conducting layer.

45. The method of claim 44, wherein the step of conductively connecting the waveguide elements with the first conducting layer is made by pick-and-place technology.

46. The method of claim 44, wherein the step of conductively connecting the waveguide elements with the first conducting layer comprises the sub-steps of: picking and placing waveguide elements with a vacuum placement system on said first conducting layer, so that the waveguide elements becomes adhered to the first conducting layer; and heating the substrate at an elevated temperature, thereby connecting the waveguide elements to the first conducting layer by means of soldering.

47. The method of claim 37, wherein the step of providing a conducting layer having a set of periodically or quasi-periodically arranged protruding elements fixedly connected thereto comprises: providing a first conducting layer; and fixedly connecting a set of periodically or quasi-periodically arranged protruding elements to the first conducting layer, wherein said protruding elements are all electrically connected to each other via said conducting layer on which they are fixedly connected, and wherein said protruding elements are formed by surface mount technology grid array, such as a pin grid array, column grid array and/or ball grid array technology.

48. The method of claim 47, wherein the step of providing protruding elements on the first conducting layer involves the steps of: producing a pattern of the layout of the protruding elements and possible waveguide paths on the first conducting layer; arranging the parts to be connected to the first conducting layer in a jig; and connecting the parts to the first conducting layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For exemplifying purposes, the invention will be described in closer detail in the following with reference to embodiments thereof illustrated in the attached drawings, wherein:

(2) FIG. 1 is a perspective side view showing a gap waveguide in accordance with one embodiment of the present invention;

(3) FIG. 2 is a perspective side view showing a circular cavity of a gap waveguide in accordance with another embodiment of the present invention;

(4) FIGS. 3a-3c are schematic illustrations of an array antenna in accordance with another embodiment of the present invention, where FIG. 3a is an exploded view of a subarray/sub-assembly of said antenna, FIG. 3b is a perspective view of an antenna comprising four such subarrays/sub-assemblies, and FIG. 3c is a perspective view of an alternative way of realizing the antenna of FIG. 3b;

(5) FIG. 4 is a top view of an exemplary distribution network realized in accordance with the present invention, and useable e.g. in the antenna of FIGS. 3a-3c;

(6) FIG. 5 is a perspective and exploded view of three different layers of an antenna in accordance with another alternative embodiment of the present invention making use of an inverted microstrip gap waveguide;

(7) FIG. 6 is a close-up view of an input port of a ridge gap waveguide in accordance with a further embodiment of the present invention;

(8) FIGS. 7 and 8 are perspective views of partly disassembled gap waveguide filters in accordance with a further embodiments of the present invention;

(9) FIGS. 9a and 9b are illustrations of a gap waveguide packaged MMIC amplifier chains, in accordance with a further embodiment of the present invention, and where FIG. 9a is a schematic perspective view seen from the side and FIG. 9b is a side view;

(10) FIG. 10 is a schematic exploded view of a manufacturing equipment in accordance with one embodiment of the present invention;

(11) FIG. 11 is a top view of the die forming layer in FIG. 10;

(12) FIG. 12 is a perspective view of the assembled die of FIG. 10;

(13) FIG. 13 is a perspective view of the manufacturing equipment of FIG. 10 in an assembled disposition;

(14) FIG. 14 is a schematic exploded view of a manufacturing equipment in accordance with another embodiment of the present invention;

(15) FIGS. 15 and 16 are top views illustrating the two die forming layers in the embodiment of FIG. 14;

(16) FIG. 17 is a perspective view showing an RF part producible by the manufacturing equipment of FIG. 14;

(17) FIG. 18a is a perspective side view of a groove gap waveguide in accordance with another embodiment of the present invention, and FIG. 18b shows a cross-sectional view of the same waveguide;

(18) FIG. 19a is a perspective side view of a ridge gap waveguide in accordance with another embodiment of the present invention, and FIG. 19b shows a cross-sectional view of the same waveguide;

(19) FIG. 20 is a perspective side view showing a waveguide forming element according to a first embodiment, wherein the right hand figure shows the waveguide forming element, and the left hand figure shows a punched out preform for formation of the waveguide element of the right hand figure;

(20) FIG. 21 is a perspective top view of a partly assembled waveguide, made by the waveguide elements of FIG. 20;

(21) FIG. 22 is a cross-sectional view of the waveguide of FIG. 21;

(22) FIGS. 23-26 illustrate waveguide elements of a similar type as in FIG. 20, but having different geometries;

(23) FIGS. 27-30 are schematic cross-sectional views illustrating various ways of using waveguide elements to form different types of waveguides;

(24) FIGS. 31-32d illustrate different embodiments of waveguide elements having two rows of protruding fingers along each side;

(25) FIGS. 33-35 are schematic illustrations of how different waveguide elements may be combined into more complex waveguide parts;

(26) FIGS. 36, 37 and 38 are perspective top views illustrating embodiments of waveguide elements having a solid ridge, for forming ridge gap waveguides;

(27) FIG. 39 is a schematic cross-sectional view of a waveguide elements similar to the one in FIG. 31, but having the base formed into a non-solid ridge;

(28) FIG. 40 is a schematic top-view illustrating use of waveguide elements to connect to an integrated circuit;

(29) FIG. 41 is a schematic top-view illustrating the use of waveguide elements to form a grid of protruding fingers

(30) FIGS. 42a and 42b illustrate an embodiment of a passive network; and

(31) FIGS. 43a and 43b illustrate an embodiment of a realization with active components.

DETAILED DESCRIPTION

(32) In the following detailed description, preferred embodiments of the present invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known constructions or functions are not described in detail, so as not to obscure the present invention.

(33) In a first embodiment, as illustrated in FIG. 1, an example of a rectangular waveguide is illustrated. The waveguide comprises a first conducting layer 1, and a second conducting layer 2 (here made semi-transparent, for increased visibility). The conducting layers are arranged at a constant distance h from each other, thereby forming a gap there between.

(34) This waveguide resembles a conventional SIW with metallized via holes in a PCB with metal layer (ground) on both sides, upper (top) and lower (bottom) ground plane. However, here there is no dielectric substrate between the conducting layers, and the metalized via holes are replaced with a monolithic part comprising a conductive layer and protruding elements 3 extending from, and fixedly monolithically integrated with this first conducting layer. The second conducting layer 2 rest on the protruding elements 3, and is also connected to these, e.g. by means of soldering. The protruding elements 3 are made of conducting material, such as metal. They can also be made of metallized plastics or ceramics.

(35) Further, the first and second conductive layers may be attached to each other by means of a rim, extending around the periphery of one of the conducting layers. The rim is not illustrated, for increased visibility.

(36) Similar to a SIW waveguide, a waveguide is here formed between the conducting elements, here extending between the first and second ports 4.

(37) In this example, a very simple, straight waveguide is illustrated. However, more complicated paths may be realized in the same way, including curves, branches, etc.

(38) FIGS. 18a and 18b illustrate a similar realization of a groove gap waveguide, but instead of having circular protruding elements (as in FIG. 1), the protruding elements are here having a rectangular or square cross-sectional geometry.

(39) FIGS. 19a and 19b illustrate another similar realization, but here the gap waveguide forms a ridge gap waveguide, with a ridge extending from one of the conducting layers, and forming the waveguide path in the waveguide.

(40) FIG. 2 illustrates a circular cavity of a gap waveguide. This is realized in a similar way as in the above-discussed straight waveguide of FIG. 1, and comprises first and second conducting layers 1, 2, arranged with a gap there between, and protruding elements extending between the conducting layers, and connected to these layers. The protruding elements are monolithically connected to one of the conducting layers. The protruding elements 3 are here arranged along a circular path, enclosing a circular cavity. Further, in this exemplary embodiment, a feeding arrangement 6 and an X-shaped radiating slot opening 5 is provided.

(41) This circular waveguide cavity functions in similar ways as circular SIW cavity.

(42) With reference to FIGS. 3a-3c, an embodiment of a flat array antenna will now be discussed. This antenna structurally and functionally resembles the antenna discussed in [13], said document hereby being incorporated in its entirety by reference.

(43) FIG. 3a shows the multilayer structure of a sub-assembly in an exploded view. The sub-assembly comprises a lower gap waveguide layer 31 with a first ground plane/conducting layer 32, and a texture formed by protruding elements 33 and a ridge structure 34, together forming a gap waveguide between the first ground plane 32 and a second ground plane/conducting layer 35. The second ground plane 35 is here arranged on a second, upper waveguide layer 36, which also comprises a third, upper ground plane/conducting layer 37. The second waveguide layer may also be formed as a gap waveguide layer. A gap is thus formed between both the first and second ground planes and between the second and third ground planes, respectively, thereby forming two layers of waveguides. The bottom, second ground plane 35 of the upper layer has a coupling slot 38, and the upper one has 4 radiating slots 39, and between the two ground planes there is a gap waveguide cavity. FIG. 3a shows only a single subarray forming the unit cell (element) of a large array. FIG. 3b shows an array of 4 such subarrays, arranged side-by-side in a rectangular configuration. There may be even larger arrays of such subarrays to form a more directive antenna.

(44) Between the subarrays, there is in one direction provided a separation, thereby forming elongated slots in the upper metal plate. Protruding elements/pins are arranged along both sides of the slots. This forms corrugations between the subarrays in E-plane.

(45) In FIG. 3c, an alternative embodiment is shown, in which the upper conducting layer, including several sub-arrays, is formed as a continuous metal plate. This metal plate preferably has a thickness sufficient to allow grooves to be formed in it. Hereby, elongate corrugations having similar effects as the slots in FIG. 3b can instead be realized as elongate grooves extending between the unit cells.

(46) Either or both of the waveguide layers between the first and second conducting layer and the second and third conducting layer, respectively, may be formed as monolithic gap waveguides as discussed in the foregoing, without any substrate between the two metal ground planes, and with protruding elements extending between the two conducting layers. Then, the conventional via holes, as discussed in [13], will instead be metal pins or the like, which are monolithically formed between the two metal plates, within each unit cell of the whole antenna array.

(47) In FIG. 4, a top view of an example of the texture in the lower gap waveguide layer of the antenna in FIG. 3 is illustrated. This shows a distribution network 41 in ridge gap waveguide technology in accordance with [13], for waves in the gap between the two lower conducting layers. The ridge structure forms a branched so-called corporate distribution network from one input port 42 to four output ports 43. The distribution network may be much larger than this with many more output ports to feed a larger array. In contrast to the antenna of [13], the via-holes arranged to provide a stopping texture are here formed as protruding elements 44 monolithically formed in the above-described manner. Hereby, there is no or partly no substrate and the via holes are replaced by the protruding elements/pins. The ridge structure may be formed in the same way, to be monolithically arranged on the conductive layer. Hereby, the ridge becomes a solid ridge such as shown in the ridge gap waveguides in e.g. [4]. Alternatively, the ridge may be drawn as a thin metal strip, a microstrip, supported by pins.

(48) With reference to FIG. 5, another embodiment of an antenna will now be discussed. This antenna comprises three layers, illustrated separately in an exploded view. The upper layer 51 (left) comprises an array of radiating horn elements 52 formed therein. The middle layer 53 is arranged at a distance from the upper layer 51, so that a gap towards the upper layer is provided. This middle layer 53 comprises a microstrip distribution network 54 arranged on a substrate having no ground plane. The waves propagate in the air gap between the upper and middle layer, and above the microstrip paths. A lower layer 55 (right) is arranged beneath and in contact with the middle layer 53. This lower layer comprises an array of protruding elements 56, such as metal pins, monolithically manufactured in the above-discussed manner on a conducting layer 57. The conducting layer may be formed as a separate metal layer or as a metal surface of an upper ground plane of a PCB. The protruding elements are integrally connected to the conducting layer in such a way that metal contact between the bases of all protruding elements is ensured.

(49) Thus, this antenna functionally and structurally resembles the antenna disclosed in [12], said document hereby being incorporated in its entirety by reference. However, whereas this known antenna was realized by milling to form an inverted microstrip gap waveguide network, the present example provides a distribution network realized as a monolithically formed gap waveguide, which entails many advantages, as has been discussed thoroughly in the foregoing sections of this application.

(50) FIG. 6 provides a close-up view of an input port of a microstrip-ridge gap waveguide on a lower layer showing a transition to a rectangular waveguide through a slot 63 in the ground plane. In this embodiment, there is no dielectric substrate present, and the conventionally used via holes are replaced by protruding elements 61, monolithically connected to a conducting layer 62 in such a way that there is electric contact between all the protruding elements 61. Thus, a microstrip gap waveguide is provided. The upper metal surface is removed for clarity. The microstrip supported by pins, i.e. the micrtostrip-ridge, may also be replaced by a solid ridge in the same way as discussed above in connection with FIG. 4.

(51) FIG. 7 illustrates an exemplary embodiment of a gap waveguide filter, structurally and functionally similar to the one disclosed in [14], said document hereby being incorporated in its entirety by reference. However, contrary to the waveguide filter disclosed in this document, the protruding elements 71 arranged on a lower conducting layer 72 are here formed by monolithically and integrally formed protruding elements in the above-discussed fashion. An upper conducting layer 73 is arranged above the protruding elements, in the same way as disclosed in [12]. Thus, this then becomes a groove gap waveguide filter.

(52) FIG. 8 provides another example of a waveguide filter, which may also be referred to as gap-waveguide-packaged microstrip filter. This filter functionally and structurally resembles the filter disclosed in [15], said document hereby being incorporated in its entirety by reference. However, contrary to the filter disclosed in [15], the filter here is packaged by a surface having protruding elements, in which protruding elements 81 provided on a conducting layer 82 are realized in the above-described way. Two alternative lids, comprising different number and arrangement of the protruding elements 81 are illustrated.

(53) With reference to FIGS. 9a and 9b, an embodiment providing a package for integrated circuit(s) will be discussed. In this example, the integrated circuits are MMIC amplifier modules 91, arranged in a chain configuration on a lower plate 92, here realized as a PCB having an upper main substrate, provided with a lower ground plane 93. A lid is provided, formed by a conducting layer 95, e.g. made of aluminum or any other suitable metal. The lid may be connected to the lower plate 92 by means of a surrounding frame or the like.

(54) The lid is further provided with protruding elements 96, 97, protruding towards the lower plate 92. This is functionally and structurally similar to the package disclosed in [16], said document hereby being incorporated in its entirety by reference. The protruding elements are preferably of different heights, so that the elements overlying the integrated circuits 91 are of a lower height, and the elements overlying areas laterally outside the integrated circuits are of a greater height. Hereby, holes are formed in the surface presented by the protruding elements, in which the integrated circuits are inserted. The protruding elements are in electric contact with the upper layer 95, and electrically connected to each other by this layer. Further, but not shown in the figures, at least some of the protruding elements may be in contact also with the lower plate 92, and also possibly with the integrated circuit modules 91.

(55) Here, and contrary to the disclosure in [16], the protruding elements are formed on the upper layer 95 monolithically. This packaging is consequently an example of using the gap waveguide as discussed above as a packaging technology, according to the present invention.

(56) The above-discussed exemplary embodiments, such as other realizations of microwave devices in accordance with the invention, can be manufactured and produced in various ways. For example, it is possible to use conventional manufacturing techniques, such as drilling, milling and the like.

(57) However, according to one preferred line of embodiments, the microwave devices, and in particular the protruding elements, are formed by PGA, BGA, or other surface mount technology (SMT) grid arrays, such as CGA and the like.

(58) According to another preferred line of embodiments, the microwave devices may be produced by using a die forming or coining technique to be discussed in more detail in the following, thereby monolithically integrated protruding elements.

(59) According to yet another preferred line of embodiments, the microwave devices are produced by pick-and-place technology, and using standardized or customized waveguide elements. This is also discussed in more detail in the following.

(60) Notably, all of these three preferred techniques may be used not only to form the microwave devices where some or all of the protruding elements are in conductive or non-conductive contact also with the other conducting layer, but may also be used to form and produce conventional gap waveguides and the like, where a gap is provided between the protruding elements and the overlying conducting layer/surface.

(61) An equipment and method for manufacturing of monolithically formed microwave devices and RF parts will next be described in further detail, with reference to FIGS. 10-17.

(62) With reference to FIG. 10, a first embodiment of an apparatus for producing an RF part comprises a die comprising a die layer 104 being provided with a plurality of recessions forming the negative of the protruding elements of the RF part. An example of such a die layer 104 is illustrated in FIG. 11. This die layer 104 comprises a grid array of evenly dispersed through-holes, to form a corresponding grid array of protruding elements. The recessions are here of a rectangular shape, but other shapes, such as circular, elliptical, hexagonal or the like, may also be used. Further, the recessions need not have a uniform cross-section over the height of the die layer. The recessions may be cylindrical, but may also be conical, or assume other shapes having varying diameters.

(63) The die further comprises a collar 103 arranged around said at least one die layer. The collar and die layer are preferably dimensioned to that the die layer has a close fit with the interior of the collar. In FIG. 12, the die layer arranged within the collar is illustrated.

(64) The die further comprises a base plate 105 on which the die layer and the collar are arranged. In case the die comprises through-holes, the base plate will form the bottom of the cavities provided by the through-holes.

(65) A formable piece 102 of material is further arranged within the collar, to be depressed onto the die layer 104. Pressure may be applied directly to the formable piece of material, but preferably, a stamp 101 is arranged on top of the formable piece of material, in order to distribute the pressure evenly. The stamp is preferably also arranged to be insertable into the collar, and having a close fit with the interior of the collar. In FIG. 13, the stamp 101 arranged on top of the formable piece of material in the collar 103 is illustrated in an assembled disposition.

(66) The above-discussed arrangement may be arranged in a conventional pressing arrangement, such as a mechanical or hydraulic press, to apply a pressure on the stamp and the base plate of the die, thereby compressing the formable piece of material to conform with the recessions of the at least one die layer.

(67) The multilayer die press or coining arrangement discussed above can provide protruding elements/pins, ridges and other protruding structures in the formable piece of material having the same height. Through-holes are obtainable e.g. by means of drilling. In case non-through going recessions are used in the die layer, this arrangement may also be used to produce such protruding structures having varying heights.

(68) However, in order to produce protruding structures having varying heights, it is also possible to use several die layers, each having through-holes. Such an embodiment will now be discussed with reference to FIGS. 14-17.

(69) With reference to the exploded view of FIG. 14, this apparatus comprises the same layers/components as in the previously discussed embodiment. However, here two separate die layers 104a and 104b are provided. Examples of such die layers are illustrated in FIGS. 15 and 16. The die layer 104a (shown in FIG. 15) being arranged closest to the formable piece of material 102 is provided with a plurality of through-holes. The other die layer 104b (shown in FIG. 16), being farther from the formable piece of material 102 comprises fewer recessions. The recessions of the second die layer 104b are preferably correlated with corresponding recessions in the first die layer 104a. Hereby, some recessions of the first die layer will end at the encounter with the second die layer, to form short protruding elements, whereas some will extend also within the second die layer, to form high protruding elements. Hereby, by adequate formation of the die layer, it is relatively simple to produce protruding element of various heights,

(70) An example of an RF part having protruding elements of varying heights, in accordance with the embodiments of the die layers illustrated in FIGS. 15 and 16, is shown in FIG. 17.

(71) In the foregoing, the stamp 101, collar 103, die layer(s) 104 and base plate 105 are exemplified as separate elements, being detachably arranged on top of each other. However, these elements may also be permanently or detachably connected to each other, or formed as integrated units, in various combinations. For example, the base plate 105 and collar 103 may be provided as a combined unit, the die layer may be connected to the collar and/or the base plate, etc.

(72) The pressing in which pressure is applied to form the formable material in conformity with the die layer may be performed at room temperature. However, in order to facilitate the formation, especially when relatively hard materials are used, heat may also be applied to the formable material. For example if aluminum is used as the formable material, the material may be heated to a few hundred degrees C., or even up to 500 deg. C. If tin is used, the material may be heated to 100-150 deg. C. By applying heat, the forming can be faster, and less pressure is needed.

(73) To facilitate removal of the formable material from the die/die layer after the forming, the recessions can be made slightly conical or the like. It is also possible to apply heat or cold to the die and formable material. Since different materials have different coefficients of thermal expansion, the die and formable material will contract and expand differently when cold and or heat is applied. For example, tin has a much lower coefficient of thermal expansion than steel, so if the die is made of steel and the formable material of tin, removal will be much facilitated by cooling. Cooling may e.g. be made by dipping or in other way exposing the die and/or formable material to liquid nitrogen.

(74) The protruding elements/fingers 3 may also be provided in the form of monolithic waveguide elements 106, and these elements will now be discussed more thoroughly.

(75) Each waveguide element comprises a base 161, and fingers 3 protruding from the base, preferably in an essentially orthogonal direction. An example of such a waveguide element is illustrated in the right-hand figure of FIG. 20. Here, the base 161 has an elongate, rectangular form, and protruding fingers are provided at both longitudinal sides. This waveguide element can be produced by punching out a blank in the form of the rectangular centre and tongues extending out from the longitudinal sides, as illustrated in the left-hand figure of FIG. 20. The tongues can then be bent upwards, e.g. by press forming, to the erect position of the right hand figure of FIG. 20.

(76) These waveguide elements can then be picked and placed on the substrate having a conducting layer, as is schematically illustrated in FIG. 21, where six elements of the type discussed in relation to FIG. 20 have been arranged along a T-path. Picking and placing of such elements can be made by a per se known pick-and-place equipment. Preferably, the waveguide elements are provided on tapes, on trays or the like, and are picked by a pick-up arrangement, e.g. using pneumatic suction cups. The waveguide elements are then placed on the substrate. The substrate preferably has an adherent surface, to maintain the placed waveguide elements in place during assembly. When all waveguide elements have been properly placed, the connection between the waveguide elements and the substrate is fixated. For example, a soldering paste could be arranged on the substrate prior to placement, which is adherent to maintain the placed elements in the right position during assembly, and which fixates the element when the substrate is subsequently heat treated at an elevated temperature, e.g. by applying infrared heating to the substrate, or by treatment in an oven.

(77) The waveguide elements are preferably made of metal, but may also be made of e.g. plastic materials or the like, which are provided with metalized surfaces.

(78) FIG. 22 schematically illustrates a waveguide formed in this way, in a schematic cross-sectional view. The waveguide comprises a lower substrate, in this example comprising a lower substrate layer 111, an optional conductive metal layer 112 on top of said lower substrate layer and a solder or solder paste layer 113. A waveguide element 106 is arranged on top of the solder or solder paste layer 113, and consequently the waveguide element is in electric and conductive contact with the conductive layer of the substrate, and fixated to the substrate by means of soldering. The lower substrate layer can be made of metal, whereby it will in itself serve as a conductive layer. In this case, the conductive layer 112 can be omitted. On top of the waveguide element, the second conductive layer 104 is arranged, as discussed in the foregoing, in such a way that there is at least partly contact between the protruding elements and the second conductive layers, and so that a gap is formed between the conducting layers enclosing the protruding fingers of the waveguide elements there between.

(79) The waveguide element of FIG. 20 is arranged to provide a straight waveguide section. However, more complex geometries can be provided in essentially the same way. Some examples of such alternative geometries are illustrated in FIGS. 23-26.

(80) FIG. 23 illustrate a curved waveguide section, in which the base plate forms a curve, and with protruding fingers being provided along the sides.

(81) FIG. 24 is a straight waveguide section similar to the one of FIG. 20, but having fewer protruding fingers along the longitudinal sides.

(82) FIG. 25 illustrates even shorter waveguide elements. Such short waveguide elements may comprise four, six or eight protruding fingers each, with 2-4 fingers on each longitudinal side. Such short waveguide elements may be combined in various ways to provide waveguides in the centre, or be arranged along the sides of waveguides, etc. Some examples of this is provided in the following.

(83) FIG. 26 illustrates a more complex geometry, providing a divider, where one incoming waveguide is split into two outgoing waveguides, or vice versa.

(84) Forming waveguides by use of such waveguide elements can be made in various ways, and some examples are provided in the following, with reference to FIGS. 27-30.

(85) In FIG. 27, a waveguide element forms the waveguide along the base plate, with the protruding fingers being arranged on the sides of this waveguide. The waves hereby propagate along the base, and only a single row of protruding fingers is provided at each side. Such embodiments work for some embodiments, in particular if the protruding fingers are in conductive contact with both the first and second conductive layer, but often it is preferred to provide two or more rows of protruding fingers along each side.

(86) In FIG. 28, two waveguide forming elements are placed parallel to each other, and with a separation distance there between. In this embodiment, the waves propagate along the separation distance, and the waveguide elements forming double rows of protruding fingers along each side.

(87) In FIG. 29, a waveguide forming element having protruding fingers along each longitudinal side is used as a waveguide, in a similar way as in the embodiment of FIG. 27. However, in addition, additional waveguide elements having protruding fingers only at one side are arranged parallel with the center waveguide element, thereby providing double rows of protruding fingers along the waveguide. The additional waveguide elements may also have protruding fingers on each side, thereby providing three rows of protruding fingers along each side of the waveguide, as is illustrated in FIG. 30.

(88) However, the waveguide elements may also comprise two or more rows of protruding fingers. Some examples of such waveguide elements are discussed in the following, in relation to FIGS. 31 and 32.

(89) In the embodiment of FIG. 31, a waveguide similar to the one discussed in relation to FIG. 20 is provided, with tongues being formed at the edge of the base. However, in this embodiment, the tongues are bent upwards along two different folding lines at each side, so that every other tongue is situated farther away from the centre line of the waveguide element. Hereby, two rows of staggered protruding fingers are obtained.

(90) In the embodiments of FIGS. 32a-32d, the tongues are instead punched out within the perimeter of the base plate, whereby two or more rows of protruding fingers can be obtained in a staggered or non-staggered disposition. In the illustrative examples of FIGS. 32a-32d, two rows of protruding fingers are provided along each longitudinal side, and in a non-staggered disposition. In the embodiment of FIGS. 32a and 32b, the base area between the protruding fingers may serve as a lifting area when using pick-and-place assembling. However, for some applications, the base area between the fingers may be insufficient. For example, the base area may have too limited dimensions for certain pick-and-place equipment, the wave guide element may need a more stable base, etc. To this end, the base area may extend past one or both the rows of protruding fingers, to form an additional base area. Such an embodiment, where the base extends past the rows of protruding fingers are one side, is illustrated in FIGS. 32c and 32d.

(91) Such additional base areas on one or several sides may naturally be used on any of type of wave guide element, and this concept is not limited to the particular wave guide element of FIGS. 32a-32d.

(92) The waveguide elements discussed so far have protruding fingers distributed relatively evenly along the sides. However, other configurations are also feasible. For example, the protruding fingers may be arranged only at the ends of the waveguide element, as in the embodiment illustrated schematically in FIG. 33. However, many other configurations are also feasible.

(93) Further, the waveguide elements may comprise a combination of protruding fingers being provided as tongues extending from the edges, and tongues being punched out within the base plate. Further, small waveguide elements, each having a relatively simple configuration, may be assembled together to form more complex geometries.

(94) As an example, FIG. 34 is an illustration of a T power divider having three ports, wherein each port is formed by a waveguide element of the type discussed in relation to FIG. 33, and a centre waveguide element is formed by a combination of internal and external protruding fingers.

(95) As another example, FIG. 35 is an illustration of a right angle corner, having two ports, each formed by a waveguide element of the type discussed in relation to FIG. 33, and a centre waveguide element formed by a combination of internal and external protruding fingers.

(96) The above two embodiments are merely examples, and other and even more complex geometries can be obtained in the same way. For example, special antenna exciter components to be located below coupling slots can be obtained in the same way.

(97) So far, various examples of waveguide elements primarily intended for groove gap waveguides have been discussed. However, by placing such waveguide elements around a ridge, or by providing a ridge on the base of these elements, most of these waveguide elements can also be used for forming ridge gap waveguides. Further, many other examples of waveguide elements for forming ridge gap waveguides are feasible, some of which will be briefly discussed in the following.

(98) In FIG. 36, a simple waveguide forming element for forming a straight section of a ridge waveguide is illustrated. The waveguide element comprises a base 161 and protruding fingers 3, such as pins, pillars or the like. Further, a ridge 107 is provided, along which waves can propagate. The ridge is here a solid ridge. Elements such as this can e.g. be produced by etching, spark erosion, molding, such as injection molding, and the like. The waveguide element can either be made of metal, or be provided with a metalized, conducting surface.

(99) This type of ridge elements can be picked and placed in a similar way as discussed above, by using e.g. the upper surface of the ridge as a lifting surface for picking the elements, e.g. by means of pneumatic suction cups.

(100) However, the ridge need not be solid. An example of such a waveguide element, resembling the element of FIG. 36, is illustrated schematically in the cross-sectional view of FIG. 37. Here, the waveguide element is formed in a similar way as the embodiments of FIG. 31, with double rows of protruding fingers, formed as bent up tongues, along each longitudinal side. However, contrary to the embodiment of FIG. 31, the base is here formed in a bent shape, to form a rectangular shaped ridge along the centre of the base. The ridge hereby is provided with solid side walls and upper surface, but is unfilled in the middle.

(101) The embodiment of FIG. 38 is similar to the embodiment of FIG. 36, but comprises a somewhat more complex form, having a central ridge extending from one side and into an opening, functioning as a coupling port, in the substrate. The ridge is here preferably provided with a non-uniform width, thereby forming a transition towards the coupling opening. This element may be used as an input or output port of a ridge gap waveguide

(102) The embodiment of FIG. 39 is a branched distribution network formed in ridge gap waveguide technology in accordance with [13]. The ridge structure forms a branched so-called corporate distribution network from one input port to four output ports. The distribution network may be much larger than this with many more output ports to feed a larger array. In contrast to the antenna of [13], the stopping texture is here formed as protruding elements/fingers. The ridge is preferably a solid ridge such as shown in the ridge gap waveguides in e.g. [4].

(103) Some examples of waveguide elements have now been discussed. However, it should be acknowledged by the skilled addressee that many other embodiments and variations are feasible. Hereby, a range of standardized waveguide elements can be provided, and used for formation of whole or parts of essentially any type of waveguide or RF part. Since standardized elements may be used, and picked and placed by e.g. ordinary pick and place equipment, waveguides and RF parts can hereby be manufactured very cost-effectively, both in small and large series. The RF parts can even be custom made in a quick and cost-effective way.

(104) Some examples of RF parts have been discussed in the following. However, many other types of per se known RF parts can be produced by using waveguide elements in the above-discussed way. For example, a circular cavity of a rectangular waveguide can be formed in this way, e.g. using curved waveguide elements, so that the protruding fingers/elements are arranged along a circular path, enclosing a circular cavity. Further, in such an embodiment, a feeding arrangement may be provided within the cavity, as well as a radiating opening, such as a X-shaped radiating slot opening.

(105) It is also possible to produce RF parts to form flat array antennas with this technology. For example, antennas structurally and functionally resembling the antenna disclosed in [12] and/or the antenna discussed in [13] can be cost-effectively produced in this way, said documents hereby being incorporated in its entirety by reference. One or several of the waveguide layers of such an antenna may be made as a waveguide as discussed in the foregoing, without any substrate between the two metal ground planes, and with protruding fingers/elements extending between the two conducting layers, formed by waveguide elements with bases attached to the substrate. Then, the conventional via holes, as discussed in [13], will instead be fingers, such as metal pins or the like, forming a waveguide cavity between the two metal plates, within each unit cell of the whole antenna array.

(106) The RF part may also be a gap waveguide filter, structurally and functionally similar to the one disclosed in [14], said document hereby being incorporated in its entirety by reference. However, contrary to the waveguide filter disclosed in this document, the protruding fingers/elements are now then arranged on a lower conducting layer by use of the above-discussed waveguide elements. Another example of a waveguide filter producible in this way is the filter disclosed in [15], said document hereby being incorporated in its entirety by reference.

(107) The RF part may also be used to form a connection to and from an integrated circuit, and in particular MMICs, such as MMIC amplifier modules. Such an embodiment is illustrated schematically in FIG. 40. Here, an integrated circuit is arranged on a substrate, such as a PCB. Waveguide elements, as discussed in the foregoing, may then be placed to form waveguides leading to/from the integrated circuit, and to form a transition between the waveguide and the integrated circuit. In the illustrative example, a MMIC 181 is connected to waveguide elements 182 by a transition element 183. A lid may be arranged on top of the substrate, to form the upper conductive surface of the waveguides.

(108) Further, grids of protruding fingers may also be provided by waveguide elements of the general type discussed above, for use e.g. for packaging. Such grids may e.g. be formed by providing waveguide elements having one, two or more rows of protruding fingers side-by-side on a substrate. Such an embodiment is illustrated schematically in FIG. 41. In case the rows of the grid are so closely arranged that there is not sufficient space left for pneumatically lifting the waveguide elements, an extension of the base plate may extend out on one of the sides, to function as a lifting area, as schematically illustrated in FIG. 41.

(109) FIGS. 42a and 42b illustrate two different perspective views of a passive network comprising a branched waveguide, and provide an example of how various types of waveguide elements can be combined to produce more complex realizations. In the illustrative example of FIGS. 42a and 42b, the waveguide network comprises a branched waveguide element similar to the one of FIG. 26, followed by straight waveguide elements, similar to the one of FIG. 24, and subsequently followed by curved waveguide elements, similar to the one of FIG. 23. In addition, a plurality of smaller waveguide elements, similar to the ones of FIG. 25 are arranged around the perimeter of the waveguide, to provide additional protruding fingers outside the first row of protruding fingers provided by the above-discussed waveguide elements. Hereby, each waveguide section is provided with two or more rows of protruding fingers at each side at all, or at least most, positions.

(110) FIGS. 43a and 43b illustrate examples of an active component, similar to the embodiment of FIG. 40, but illustrated in greater detail. In this embodiment, two active components 181, such as MMICs, are provided. The active components 181 are at the input/output ports connected to a plurality of input/output lines, such as microstrip lines 184 for providing bias voltages to the MMIC. Further, some RF input/output ports are connected to gap waveguide transmission lines, via transition elements 183. The gap waveguides are here illustrated as straight waveguides, being formed e.g. by elements similar to the one discussed in relation to FIGS. 20 and 24. However, more complex waveguide transmission lines or networks may also be used. Further, a plurality of smaller waveguide elements, here of the type illustrated in FIG. 25, are provided around both the gap waveguides and the active components, to improve the performance of the gap waveguides and provide shielding between the components. In addition, further elements, such as passive components 186 and the like may be provided.

(111) Both the passive network illustrated in FIGS. 42a and 42b and the active component network of FIGS. 43a and 43b are merely examples, and the skilled reader will appreciate that other realizations are also feasible in a similar way, to obtain the same or other functionality.

(112) The invention has now been described with reference to specific embodiments. However, several variations of the technology of the waveguide and RF packaging in the antenna system are feasible. For example, a multitude of different waveguide elements useable to form various types of waveguides and other RF parts are feasible, either for use as standardized elements, or for dedicated purposes or even being customized for certain uses and applications. Further, even though assembly by means of pick-and-place equipment is preferred, other types of surface mount technology placement may also be used, and the waveguide elements may also be assembled in other ways. Further, the here disclosed realization of protruding elements can be used in many other antenna systems and apparatuses in which conventional gap waveguides have been used or could be contemplated. Such and other obvious modifications must be considered to be within the scope of the present invention, as it is defined by the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word comprising does not exclude the presence of other elements or steps than those listed in the claim. The word a or an preceding an element does not exclude the presence of a plurality of such elements. Further, a single unit may perform the functions of several means recited in the claims.

REFERENCES

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