A radio frequency interface and a waveguide module

Abstract

A waveguide module and a radio frequency interface comprising: a substrate integrated waveguide (SIW) (102, 202), a probe (103, 203), and a second waveguide (101, 201). The probe (103, 203) is arranged and / or formed at least in part to the substrate integrated waveguide (SIW) (102, 202), wherein the substrate integrated waveguide (SIW) (102, 202) comprises a coupling element and an integrated circuit (208) is arrangeable in connection with the coupling element of the substrate integrated waveguide (SIW) and the substrate integrated waveguide (SIW) (102, 202) is arranged to act as a transmission line coupling the integrated circuit (208), such as a monolithic microwave integrated circuit (MMIC), to the probe (103, 203). The substrate integrated waveguide (SIW) (102, 202) comprises at least two metallic layers and a dielectric substrate between the layers, wherein metal-plated trenches, metallized posts and / or via holes are arranged to the substrate which metal-plated trenches, metallized posts and / or via holes connect the upper and lower metal layers of the substrate integrated waveguide (102, 202), The second waveguide (101, 201) is arranged in connection with the probe (103, 203) and / or the substrate integrated waveguide (SIW) (101, 201) so that the probe (103, 203) and / or the substrate integrated waveguide (SIW) (102, 202) extends into the second waveguide (101, 201), wherein the probe (103, 203) is arranged to couple a signal coming from the integrated circuit (208) via the substrate integrated waveguide (SIW) (102, 202) to the second waveguide (101, 201) or to couple a signal coming from the second waveguide (101, 201) to the substrate integrated waveguide (SIW) (102, 202).

Description

[0001] A RADIO FREQUENCY INTERFACE AND A WAVEGUIDE MODULE

[0002] Technical Field

[0003] The invention concerns in general the technical field of electronics. Especially the invention concerns a radio frequency interface and a waveguide.

[0004] Background

[0005] Integrated circuits, also known as a microchips or ICs, are used in a wide range of electronic devices to perform various functions such as processing and storing information. Integrated circuits are small electronic devices comprising multiple interconnected electronic components such as transistors, resistors, and capacitors. These components can be e.g. etched onto a small piece of semiconductor material, e.g. silicon.

[0006] There are integrated circuits that operate in high frequency environment, e.g. with millimeter wave and THz signals. Examples of the applications and products that utilize these kinds of integrated circuits are security imaging, spectroscopy of (biological) molecules, radiometric and radar imaging, such as space and Earth observation as well as for Advanced Driver-Assistance Systems, ADAS. Therefore, there is a high demand for integrated circuits that operate with millimeter wave and THz-signals.

[0007] Monolithic microwave integrated circuits, or MMICs are one type of integrated circuit device that operate at microwave frequencies (e.g. up from 300 MHz to 300 GHz). These devices can perform functions such as microwave mixing, power amplification, low-noise amplification, and high-frequency switching. However, manufacturing and integration of millimeter wave MMICs in a cost- effective packages or modules is challenging. The challenges and frequency operating limits of the prior art solutions are related for example to lossy substrates and very narrow planar transmission lines which are difficult and expensive to manufacture. For example, if flip-chip technique is used, the operating range of the solutions of the prior art are limited to around 250 GHz which is not enough for all applications or products. Some prior art solutions require manual work and using of expensive high accuracy manufacturing that scales badly to larger manufacturing volumes.

[0008] For these reasons there is a need to develop radio frequency interfaces for integration of integrated circuits, such as monolithic microwave integrated circuits (MMICs), inside a waveguide module which are able to operate with higher frequencies than the prior art solutions and are still cost effective to manufacture.

[0009] Summary

[0010] An objective of the invention is to present a radio frequency interface for integration of integrated circuits, such as monolithic microwave integrated circuits (MMICs), inside a waveguide module which is able to perform well also with higher frequencies than the prior art solutions and which is also at the same time cost effective to manufacture.

[0011] The objectives of the invention are reached by a radio frequency interface and a waveguide module as defined by the respective independent claims.

[0012] According to a first aspect, the invention relates to a radio frequency interface comprising a substrate integrated waveguide (SIW), a probe, and a second waveguide. The probe is arranged and / or formed at least in part to the substrate integrated waveguide (SIW). The substrate integrated waveguide (SIW) comprises a coupling element and an integrated circuit is arrangeable in connection with the coupling element of the substrate integrated waveguide (SIW). The substrate integrated waveguide (SIW) is arranged to act as a transmission line coupling the integrated circuit, such as a monolithic microwave integrated circuit (MMIC), to the probe. The second waveguide is arranged in connection with the probe and / or the substrate integrated waveguide (SIW) so that the probe and / or the substrate integrated waveguide (SIW) extends into the second waveguide, wherein the probe is arranged to couple a signal coming from the integrated circuit via the substrate integrated waveguide (SIW) to the second waveguide, or to couple a signal coming from the second waveguide to the substrate integrated waveguide (SIW). In one embodiment of the invention the probe comprises a metal pattern on the substrate integrated waveguide (SIW) that extends inside the second waveguide and is parallel to the electric field of the second waveguide.

[0013] In one embodiment of the invention the probe is a radial shaped, rectangular shaped, elliptical shaped, circular shaped, triangular shaped and / or stub type probe. The probe can be an E-plane probe.

[0014] In one embodiment of the invention the metal pattern of the probe is arranged on top side, bottom side and / or at least in part inside of the substrate integrated waveguide (SIW).

[0015] In one embodiment of the invention the coupling element for the integrated circuit is arranged essentially at a first end of the substrate integrated waveguide (SIW) and the probe is arranged and / or formed essentially at a second end or second half of the substrate integrated waveguide (SIW).

[0016] In one embodiment of the invention the substrate integrated waveguide (SIW) comprises at least two metallic layers and a dielectric substrate between the layers, the dielectric substrate comprising e.g. silicon, wherein metal-plated trenches, metallized posts and / or via holes are arranged to the substrate which metal-plated trenches, metallized posts and / or via holes connect the upper and lower metal layers of the substrate integrated waveguide.

[0017] In one embodiment of the invention the at least two metallic layers are essentially uniform and / or continuous.

[0018] In one embodiment of the invention the substrate integrated waveguide (SIW) is a rectangular waveguide filled with dielectric substrate.

[0019] In one embodiment of the invention an air-filled channel is arranged at least on one side of the substrate integrated waveguide (SIW).

[0020] In one embodiment of the invention the coupling element of the substrate integrated waveguide (SIW) comprises a flip-chip connection area to which the integrated circuit is arrangeable. In one embodiment of the invention the flip-chip connection area comprises at least one pad, such as ground-signal-ground (GSG) bumps, arranged to the metal layer of the substrate integrated waveguide (SIW) to interconnect the integrated circuit to the substrate integrated waveguide (SIW) using flip-chip bonding.

[0021] In one embodiment of the invention the second waveguide comprises an opening through which at least part of the probe and / or at least part of the substrate integrated waveguide (SIW) is arrangeable.

[0022] In one embodiment of the invention the opening of the second waveguide is arranged to one side of the second waveguide, e.g. to one of the longest sides of the second waveguide.

[0023] In one embodiment of the invention at least part of the metal layer of the substrate integrated waveguide (SIW) is removed or omitted from the part of the substrate integrated waveguide (SIW) which is arrangeable inside the second waveguide, e.g. so that the dielectric material is exposed in that part of the substrate integrated waveguide (SIW).

[0024] In one embodiment of the invention at least part of the metal layer of the substrate integrated waveguide (SIW) is arranged to extend inside the second waveguide. In one embodiment of the invention the metal extension of the substrate integrated waveguide inside the second waveguide is shorter, e.g. essentially shorter, than the exposed part of the substrate integrated waveguide.

[0025] In one embodiment of the invention the second waveguide is an air-filled waveguide.

[0026] According to a second aspect, the invention relates to a waveguide module comprising a radio frequency interface according to any embodiment of the invention and an integrated circuit arranged in connection with the radio frequency interface, wherein the radio frequency interface is arranged to couple a signal coming from the integrated circuit via radio frequency interface to the second waveguide, and / or to couple a signal coming from the second waveguide to the integrated circuit. The solution of the invention can be utilized for integration of integrated circuits, such as monolithic microwave integrated circuits (MMICs), inside a waveguide module and e.g. in the following applications: as waveguides of active circuits, in the field of imaging, mm-wave communication, etc. One advantage of the solution of the invention is that with the radio frequency interface higher frequencies can be used from the integrated circuit to the second waveguide as with the prior art solutions. With prior art solutions, e.g. a flip-chip interconnection is limited to about 250 - 270 GHz, whereas in the solution of the invention the frequency operating range can be scaled at least up to 320 GHz and possibly even higher. Another benefit of the invention is the manufacturing reliability as substrate integrated waveguide (SIW) of larger size can be used instead of narrow planar transmission lines. Also the whole structure can be manufactured using e.g. silicon micromachining which enables mass production on wafer scale. Substrate integrated waveguide (SIW) which is used in the solution of the invention enables also other components, such as cavity filters or diplexers, integrated into the structure. Still another advantage of the solution of the invention is that the second waveguide, e.g. an air-filled waveguide, provides a standard interface to outside, for example to an antenna.

[0027] The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also un-recited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated.

[0028] The expression "a number of’ may herein refer to any positive integer starting from one (1 ). The expression "a plurality of’ may refer to any positive integer starting from two (2), respectively.

[0029] The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objectives and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. Brief descriptions of the drawings

[0030] The embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

[0031] Figure 1A illustrates schematically an example embodiment of a radio frequency interface from an angled view.

[0032] Figure 1 B illustrates schematically the example embodiment of the radio frequency interface of Figure 1 A from a top view.

[0033] Figure 1 C illustrates schematically the example embodiment of the radio frequency interface of Figure 1 A from a side view.

[0034] Figure 1 D illustrates schematically the example embodiment of the radio frequency interface of Figure 1 A from another side view.

[0035] Figure 2A illustrates schematically an example embodiment of a radio frequency interface from an angled view.

[0036] Figure 2B illustrates schematically the example embodiment of the radio frequency interface of Figure 2A from a top view.

[0037] Figure 2C illustrates schematically the example embodiment of the radio frequency interface of Figure 2A from a side view.

[0038] Figure 2D illustrates schematically the example embodiment of the radio frequency interface of Figure 2A from another side view.

[0039] Description of some embodiments

[0040] In the solution of the invention the radio frequency interface comprises a substrate integrated waveguide (SIW) and a probe which is arranged at least in part to the substrate integrated waveguide (SIW), e.g. on top of the substrate integrated waveguide, on bottom of the substrate integrated waveguide and / or at least partially embedded into the substrate integrated waveguide. The probe can be arranged in the middle of the substrate integrated waveguide (in a sideway direction) as in the example figures. In one embodiment the probe can be integrated to the substrate integrated waveguide (SIW). The substrate integrated waveguide (SIW) comprises a coupling element and an integrated circuit can be arranged in connection with the coupling element of the substrate integrated waveguide (SIW). The substrate integrated waveguide (SIW) is arranged to act as a transmission line coupling the integrated circuit, such as a monolithic microwave integrated circuit (MMIC), to the probe. The radio frequency interface comprises a second waveguide which is arranged in connection with the probe and / or the substrate integrated waveguide (SIW) so that the probe and / or the substrate integrated waveguide (SIW) extends into the second waveguide.

[0041] In the solution of the invention the probe is arranged to couple a signal coming from the integrated circuit via the substrate integrated waveguide (SIW) to the second waveguide, or to couple a signal coming from the second waveguide to the substrate integrated waveguide (SIW).

[0042] Figure 1 A illustrates schematically an example embodiment of a radio frequency interface 100. This example radio interface according to one embodiment of the invention comprises a substrate integrated waveguide (SIW) 102 which can e.g. be metal plated. The substrate integrated waveguide (SIW) 102 extends inside a second waveguide 101 , e.g. an air-filled waveguide (AFW), and this extension 104 into the second waveguide can be dielectric, e.g. comprising silicon. In substrate integrated waveguide (SlW)-to-second waveguide-transition area, part of the metal surrounding of the substrate integrated waveguide (SIW) is removed. At least in some embodiments there is some metal layer or extension 106 inside the second waveguide 101. A channel 107, e.g. an air-filled channel, can be arranged essentially above the substrate integrated waveguide. A probe 103, e.g. a radial stub probe, is formed or arranged to that end of the substrate integrated waveguide (SIW) 102 which is arranged in connection with the second waveguide 101 , such as an air-filled waveguide. That end of the substrate integrated waveguide can be understood to be the second end of the substrate integrated waveguide. A coupling element comprising a connection area 105 is arranged on the other end of the substrate integrated waveguide (SIW) 102 to which connection area 105 an integrated circuit, such as a MMIC, can be connected. That end of the substrate integrated waveguide can be understood to be the first end of the substrate integrated waveguide. The connection between the substrate integrated waveguide (SIW) 102 and the integrated circuit can be implemented e.g. with a flip-chip connection area which can comprises at least one pad, such as ground-signal-ground (GSG) bumps.

[0043] Figure 1 B illustrates schematically the example embodiment of the radio frequency interface of Figure 1 A from a top view. In this figure the extension of the substrate integrated waveguide (SIW) 102 into the second waveguide 101 , such as an air-filled waveguide, can be easily seen. Figure 1 C illustrates schematically the example embodiment of the radio frequency interface of Figure 1 A from a side view at the location of the extension of the substrate integrated waveguide (SIW) 102 into the second waveguide 101 . Also, the arrangement of the channel 107 above the substrate integrated waveguide can be clearly seen from this figure. Figure 1 D illustrates schematically the example embodiment of the radio frequency interface of Figure 1 A from another side view from the side where the substrate integrated waveguide (SIW) 102 enters the second waveguide 101 .

[0044] Figure 2A illustrates schematically an example embodiment of a waveguide module 200 from an angled view which waveguide module comprises a radio frequency interface which is connected to an integrated circuit 208. This example radio interface according to one embodiment of the invention comprises a substrate integrated waveguide (SIW) 202 which can e.g. be metal plated. The substrate integrated waveguide (SIW) 202 extends inside a second waveguide 201 , such as an air-filled waveguide (AFW), and this extension 204 into the second waveguide can be dielectric, e.g. comprising silicon. In substrate integrated waveguide (SlW)-to-second waveguide-transition area, part of the metal surrounding of the substrate integrated waveguide (SIW) is removed. At least in some embodiments there is some metal layer or extension 206 inside the second waveguide 201 , such as an air-filled waveguide. A channel 207, e.g. an airfilled channel, can be arranged essentially above the substrate integrated waveguide. A probe 203 is formed or arranged to that end of the substrate integrated waveguide (SIW) 202 which is arranged in connection with the second waveguide 201. That end of the substrate integrated waveguide can be understood to be the second end of the substrate integrated waveguide. A coupling element comprising a connection area 210 is arranged on the other end of the substrate integrated waveguide (SIW) 202 to which connection area 210 an integrated circuit 208, such as a MMIC, is arranged and connected. That end of the substrate integrated waveguide can be understood to be the first end of the substrate integrated waveguide. The connection between the substrate integrated waveguide (SIW) 202 and the integrated circuit can be implemented e.g. with a flip-chip connection area which can comprises at least one pad 211 , such as ground-signal-ground (GSG) bumps. In the example of Figures 2A-2D there are three pads 211 arranged to the connection area 210. In Figure 2A also a transmission line 209 of the integrated circuit 208, such as MMIC, can be seen. The transmission line of the integrated circuit can be for example a microstrip line and / or a (optionally grounded) coplanar waveguide.

[0045] Figure 2B illustrates schematically the example embodiment of the waveguide module of Figure 2A from a top view. In this figure the extension of the substrate integrated waveguide (SIW) 202 into the second waveguide 201 , such as an airfilled waveguide, can be easily seen. Also, the arrangement of the transmission line 209 to the integrated circuit 208 can be seen from Figure 2B. Figure 2C illustrates schematically the example embodiment of the waveguide module of Figure 2A from a side view. The transmission line ground plane 212 and the arrangement of the channel 207 above the substrate integrated waveguide can be clearly seen from this figure. The transmission line ground plane can be arranged e.g. essentially around 10pm distance from the transmission line of the integrated circuit. Figure 2D illustrates schematically the example embodiment of the waveguide module of Figure 2A from another side view from the side of the integrated circuit 208.

[0046] For example, the probe size, substrate integrated waveguide extension in the second waveguide and / or other dimensions or parameters are optimized for particular frequency band and therefore the Figures present example embodiments of the invention only schematically. Some example dimensions for the different components of the radio frequency interface of the invention are described in the subsequent part of the description.

[0047] In one embodiment of the invention the substrate integrated waveguide (SIW) can comprise at least two metallic layers and a dielectric substrate between the layers, the dielectric substrate comprising e.g. silicon, quartz, LTCC, and / or printed circuit material, wherein metal-plated trenches, metallized posts and / or via holes are arranged to the substrate which metal-plated trenches, metallized posts and / or via holes connect the upper and lower metal layers of the substrate integrated waveguide. The two metallic layers and the metal-plated trenches, metallized posts and / or via holes can be galvanically connected with each other. In one example embodiment the substrate integrated waveguide (SIW) can essentially have a size of 0,25 mm (width) x 0,06 mm (height).

[0048] In one embodiment of the invention the substrate integrated waveguide (SIW) is a rectangular waveguide filled with dielectric substrate, e.g. silicon, and / or the waveform travels within the area or volume defined by the two metallic layers and the metal-plated trenches, metallized posts and / or via holes. In one embodiment of the invention the at least two metallic layers are essentially uniform and / or continuous. This can mean for example that there are no holes and / or gaps in the metallic layers. Therefore, the structure of the present invention is different as the prior art solutions, which may use for example microstrip or grounded coplanar waveguide (GCPW) structure.

[0049] In one embodiment of the invention the coupling element for connecting the integrated circuit is arranged essentially at a first end of the substrate integrated waveguide (SIW) and the probe is arranged and / or formed essentially at a second end or second half of the substrate integrated waveguide (SIW).

[0050] The integrated circuit may be a Monolithic Microwave Integrated Circuit, MMIC, and in such a case the substrate integrated waveguide (SIW) may be arranged to enable a MMIC-to-second waveguide transition.

[0051] In one embodiment of the invention an air-filled channel is arranged at least on one side of the substrate integrated waveguide (SIW). In one example embodiment the air-filled channel arranged at one side of the substrate integrated waveguide can be for example 0,25 mm x 0,24 mm (e.g. arranged on top of SIW).

[0052] The probe used in the solution of the invention can extend to the second waveguide and provide a connection between the integrated circuit and the second waveguide, e.g. for enabling transitions between the integrated circuit and the second waveguide. In one embodiment of the invention the probe is a radial shaped, rectangular shaped, elliptical shaped, circular shaped, triangular shaped and / or stub type probe. The probe can be for example an E-plane probe. In one example embodiment the probe, e.g. an E-plane probe, can essentially have a size of 0,12 mm x 0,12 mm. In one embodiment of the invention the probe can comprise or be formed from a metal pattern on the substrate integrated waveguide (SIW) that extends inside the second waveguide and is parallel to the electric field of the second waveguide. In one embodiment of the invention the probe is formed by patterning the top side and / or bottom side of the substrate integrated waveguide. In one embodiment of the invention the probe can be formed and / or arranged at least in part inside of the substrate integrated waveguide (SIW). In one embodiment of the invention a bottom of the probe is without metal covering.

[0053] In one embodiment of the invention at least part of the metal layer of the substrate integrated waveguide (SIW) is removed or omitted from the part of the substrate integrated waveguide (SIW) which is arrangeable inside the second waveguide, e.g. so that the dielectric material is exposed in that part of the substrate integrated waveguide (SIW). In one example embodiment the dielectric extension inside the substrate integrated waveguide (SIW) inside the second waveguide can be for example 0,25 mm x 0,06 mm x 0,2 mm. The exposed part of the substrate integrated waveguide can be configured and sized such that it enables efficient transition (e.g. low reflection and high transmission) in the desired frequency operating range.

[0054] In one embodiment of the invention at least part of the metal layer of the substrate integrated waveguide (SIW) is arranged to extend inside the second waveguide. In one example embodiment the metal extension inside the second waveguide (before the exposed part of the substrate integrated waveguide inside the second waveguide) can be for example: 0,25 mm x 0,02 mm. The extension can be arranged for example on top and / or bottom metal layer of the substrate integrated waveguide. The metal extension is configured and sized such that it enables efficient transition in the desired frequency operating range.

[0055] The coupling element, e.g. acting as a transition structure, is arranged to the substrate integrated waveguide for coupling the integrated circuit, e.g. MMIC, to the substrate integrated waveguide. In one embodiment of the invention the coupling element of the substrate integrated waveguide (SIW) comprises a flip-chip connection area to which the integrated circuit is arrangeable. The connection area can be arranged to the substrate of the substrate integrated waveguide (SIW). In one embodiment of the invention solder balls, pillars or stud bumps may be used for the flip-chip connection. In one embodiment of the invention wire bonding technique and / or connection may be used instead of flip-chip connection in the solution of the invention for coupling the integrated circuit, e.g. MMIC, to the substrate integrated waveguide.

[0056] In one example embodiment the coupling element, e.g. a flip-chip coupling element or area, can comprise a slot pattern on top metal of the substrate integrated waveguide for providing a good impedance match for the integrated circuit to substrate integrated waveguide. In one example embodiment the connection area or area of the coupling element can be essentially 0,19 mm x 0,19 mm sized area. The flip-chip connection area can comprise at least one pad, such as ground-signal-ground (GSG) bumps, arranged to the metal layer of the substrate integrated waveguide (SIW) to interconnect the integrated circuit to the substrate integrated waveguide (SIW) using flip-chip bonding. In one example embodiment the ground-signal-ground (GSG) bumps may have the following dimensions: bump pitch in range 50...250pm, e.g. 100pm; diameter and height in range (0,02....0,1 mm), e.g. 0,04 mm.

[0057] In one embodiment of the invention the second waveguide comprises an opening through which at least part of the probe and / or at least part of the substrate integrated waveguide (SIW) is arrangeable. The opening of the second waveguide is arranged to one side of the second waveguide, e.g. to one of the longest sides of the second waveguide. In some embodiments, the second waveguide may be a vertical waveguide, i.e. the second waveguide is higher in vertical direction. The second waveguide can be metal walled.

[0058] In one embodiment of the invention the second waveguide is an air-filled waveguide. In one example embodiment the air-filled waveguide can be a WR-10 to WR-1 -waveguide, e.g. a WR-3-waveguide (0,86 mm x 0,43 mm).

[0059] In one embodiment of the invention the second waveguide can be a substrate integrated waveguide (SlW)-type of waveguide. In this case the substrate parameters of the second waveguide may be different from the substrate integrated waveguide acting as a transmission line between the integrated circuit and the probe. In one embodiment of the invention the second waveguide can comprise e.g. LTCC-material and the substrate integrated waveguide acting as a transmission line between the integrated circuit and the probe can comprise e.g. silicon.

[0060] The specific examples provided in the description given above should not be construed as limiting the applicability and / or the interpretation of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Claims

Claims1 . A radio frequency interface comprising: a substrate integrated waveguide (SIW) (102, 202), a probe (103, 203), and a second waveguide (101 , 201 ), wherein the probe (103, 203) is arranged and / or formed at least in part to the substrate integrated waveguide (SIW) (102, 202), wherein the substrate integrated waveguide (SIW) (102, 202) comprises a coupling element and an integrated circuit (208) is arrangeable in connection with the coupling element of the substrate integrated waveguide (SIW) and the substrate integrated waveguide (SIW) (102, 202) is arranged to act as a transmission line coupling the integrated circuit (208), such as a monolithic microwave integrated circuit (MMIC), to the probe (103, 203), wherein the substrate integrated waveguide (SIW) (102, 202) comprises at least two metallic layers and a dielectric substrate between the layers, wherein metal-plated trenches, metallized posts and / or via holes are arranged to the substrate which metal-plated trenches, metallized posts and / or via holes connect the upper and lower metal layers of the substrate integrated waveguide (102, 202), and wherein the second waveguide (101 , 201 ) is arranged in connection with the probe (103, 203) and / or the substrate integrated waveguide (SIW) (101 , 201 ) so that the probe (103, 203) and / or the substrate integrated waveguide (SIW) (102, 202) extends into the second waveguide (101 , 201 ), wherein the probe (103, 203) is arranged to couple a signal coming from the integrated circuit (208) via the substrate integrated waveguide (SIW) (102, 202) to the second waveguide (101 , 201 ) or to couple a signal coming from the second waveguide (101 , 201 ) to the substrate integrated waveguide (SIW) (102, 202).

2. A radio frequency interface according to claim 1 , wherein the probe (103, 203) comprises a metal pattern on the substrate integrated waveguide (SIW) (102, 202) that extends inside the second waveguide (101 , 201 ) and is parallel to the electric field of the second waveguide (101 , 201 ).

3. A radio frequency interface according to claim 1 or 2, wherein the probe (103, 203) is a radial shaped, rectangular shaped, elliptical shaped, circular shaped, triangular shaped and / or stub type probe, e.g. an E-plane probe.

4. A radio frequency interface according to any previous claim, wherein the metal pattern of the probe (103, 203) is arranged on top side, bottom side and / or at least in part inside of the substrate integrated waveguide (SIW) (102,202).

5. A radio frequency interface according to any previous claim, wherein the coupling element for the integrated circuit is arranged essentially at a first end of the substrate integrated waveguide (SIW) (102, 202) and the probe (103,203) is arranged essentially at a second end or second half of the substrate integrated waveguide (SIW) (102, 202).

6. A radio frequency interface according to any previous claim, wherein the dielectric substrate comprises silicon.

7. A radio frequency interface according to any previous claim, wherein the at least two metallic layers are essentially uniform and / or continuous.

8. A radio frequency interface according to any previous claim, wherein the substrate integrated waveguide (SIW) is a rectangular waveguide filled with dielectric substrate.

9. A radio frequency interface according to any previous claim, wherein an air-filled channel (107, 207) is arranged at least on one side of the substrate integrated waveguide (SIW) (102, 202).

10. A radio frequency interface according to any previous claim, wherein the coupling element of the substrate integrated waveguide (SIW) comprises a flip-chip connection area to which the integrated circuit is arrangeable.11 . A radio frequency interface according to claim 10, wherein the flipchip connection area (210) comprises at least one pad (211 ), such as ground- signal-ground (GSG) bumps, arranged to the metal layer of the substrate integrated waveguide (SIW) (102, 202) to interconnect the integrated circuit (208) to the substrate integrated waveguide (SIW) (102, 202) using flip-chip bonding.

12. A radio frequency interface according to any previous claim, wherein the second waveguide (101 , 201 ) comprises an opening (110, 205) through which at least part of the probe (103, 203) and / or at least part of the substrate integrated waveguide (SIW) (102, 202) is arrangeable.

13. A radio frequency interface according to claim 12, wherein the opening (110, 205) of the second waveguide (101 , 201 ) is arranged to one side of the second waveguide (101 , 201 ), e.g. to one of the longest sides of the second waveguide (101 , 201 ).

14. A radio frequency interface according to any previous claim, wherein at least part of the metal layer of the substrate integrated waveguide (SIW) (102, 202) is removed or omitted from the part of the substrate integrated waveguide (SIW) which is arrangeable inside the second waveguide (101 , 201 ), e.g. so that the dielectric material is exposed in that part of the substrate integrated waveguide (SIW).

15. A radio frequency interface according to any previous claim, wherein at least part of the metal layer (106, 206) of the substrate integrated waveguide (SIW) is arranged to extend inside the second waveguide (101 , 201 ).

16. A radio frequency interface according to any previous claim, wherein the second waveguide (101 , 201 ) is an air-filled waveguide.

17. A waveguide module (200) comprising: a radio frequency interface (100) according to any claim 1 - 16, and an integrated circuit (208) arranged in connection with the radio frequency interface, wherein the radio frequency interface (100) is arranged to couple a signal coming from the integrated circuit (208) via radio frequency interface to the second waveguide (101 , 201 ), and / or to couple a signal coming from the second waveguide (101 , 201 ) to the integrated circuit (208).

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