GB2497982A - An electrically conducting interconnector between two stacked waveguides - Google Patents

Abstract

An apparatus comprising two waveguides 130, 140 adapted to be stacked at least partially upon each other, wherein an electrically conducting interconnector 160 is electrically connected to a conductor surface 135 of the first waveguide 130 receiving an electromagnetic signal and extends into the second waveguide 140 propagating said electromagnetic signal. Said interconnector 160 is electrically isolated from all the other conductor surfaces of the waveguides 130, 140 and is adapted to guide the electromagnetic signal propagating from the first waveguide 130 into the second waveguide 140. This invention realises a transition or junction between two Substrate Integrated Waveguides (SIW) having different dimensions and different directions. In particular, it may be used to implement an antenna, comprising a radio circuit and electromagnetic lens, wherein a plurality of apparatuses extend between said radio circuit and said electromagnetic lens. Each radiating waveguide of the plurality of apparatuses is locally placed in a direction that is normal to the surface of the electromagnetic lens.

Description

APPARATUS WITH TWO WAVEGUIDES STACKED UPON EACH OTHER

S The invention relates to an apparatus comprising a waveguide adapted to be stacked upon a second waveguide. It also relates to an apparatus comprising two waveguides stacked upon each other, said stack of two waveguides being designed to guide an electromagnetic signal propagating from a first waveguide into a second waveguide. The invention is also related to a method of manufacturing said apparatus.

The invention also relates to an antenna and a method of manufacturing said antenna.

The domain of the invention concerns communication devices, including digital cameras and high-definition digital camcorders that are ubiquitously used and require an increasingly higher quality of service.

There is a growing need for rehable communication devices with high recording capacities that are user friendly and offer high image quality.

When images such as video and photographs from a digital camera or DVD-Blue-Ray player are viewed on a display device including a HD (high-definition) television, the required bit rates for the transmission of data between the imaging device and the display device are in the range of several gigabits per second (Gbps).

Similar bit rates are necessary for the transmission of data between an imaging device and a storage device or physical carrier dedicated to the storage of multimedia data (audio and video data).

To prevent loss of quality during the transfer of images, a digital wire link such as an HDMI (high-definition multimedia interface) cable is at least necessary.

Indeed high-definition non-compressed multimedia data are transmitted in raw mode, it being understood that almost no processing and no compression is performed.

Raw data as recorded by the sensor of the imaging device can therefore be rendered without loss of quality.

Moreover, in home communications, raw data needs also to be transmitted almost in real time.

However, the use of a wired link in home communications systems has several drawbacks.

For example, a wired link between a camera and a television set has several limitations.

On the side of the television set, the connection systems may be difficult to access or may even not be available.

On the camera side, the connection systems have a very small size and may be concealed by covers, thereby making it difficult to connect the cable. In addition, it can be very difficult to move the camera or the screen when all devices are connected.

Similarly, in case cables are integrated in the walls of the house it is impossible to modify the installation. One approach for overcoming these drawbacks is the use of wireless connections between the communication devices.

However, said systems need to support data bit rates up to the order of several Gigabits per second (0bps). WiFi systems are operating in the 2.4 GHz and 5 0Hz radio bands (as stipulated by the 802.11.alb/g/n standard) and are not suited to reach the target bit rates. It is therefore necessary to use communications systems in a radio band of higher frequencies. The radio band around 60 GHz is a suitable candidate. When using an extensive bandwidth, 60 0Hz radio communications systems are particularly well suited to transmit data at very high bit rates. In order to obtain high quality radio communications (i.e. low error bit rate) and sufficient radio range between two communication devices without having to transmit at unauthorized power levels, it is necessary to use directional (or selective) antennas enabling line of sight (LOS) transmission. Consequently, narrow beam forming techniques are necessary for wireless transmission with high throughput bit rate.

During the discovery phase, each pair of nodes of the wireless network has to initiate the communication parameters. It is therefore necessary to configure the antenna angle in order to obtain the best quality with the radio frequency (RF) link.

Communication parameters can be transmitted with a low bit rate and therefore allow decreasing needs in the budget of the RE link (e.g. antenna gain). This in turn allows a wide antenna beam to be formed in order to detect all the nodes within reach.

Consequently, the antenna has to form both a narrow and a wide beam during subsequent phases.

The antenna needed in the above-mentioned applications shall therefore be reconfigurable so as to obtain a narrow beam in azimuth, while having a large beam in elevation.

The problems described above, mainly refer to the setting up of very high bit-rate point-to-point wireless communications between a digital camera (DVC) and an HD television set. It is clear however that the problems may be extended to any context in which it is sought to set up wireless communications between a sender device being an imaging device and a receiver device being a device for data display or data storage.

The so-called smart antennas or reconfigurable antennas are used to reach the distances required by audio and video applications. A smart antenna mainly comprises a network (e.g. an array) of radiating elements distributed on a support. Each radiating element is electronically controlled in phase and power (or gain) in order to form a narrow beam or set of beams in sending and reception mode. Each beam can be steered and controlled. Consequently, this requires a dedicated phase controller and a power amplifier for each antenna element which increases the cost of the antenna.

Furthermore, to cover several directions of radiation, a plurality of radiating elements are necessary together with separate feeding lines, phase controller and power amplifier, making the design and manufacturing very expensive.

However several technologies exist such as micro-strip lines, waveguides and substrate integrated waveguides (SIW) that allow miniaturization while being cost effective. 51W technology is to be preferred since said technology reduces cost, allows miniaturization and reduces losses.

51W technology is adapted for wavelengths corresponding to the 60 Gl-iz frequency band. This technology enables the construction of waveguides for guiding electromagnetic waves in a substrate and is very effective in terms of integration and miniaturization. SIW technology is typically indicated for guiding electromagnetic waves out of a Monolithic Microwave Integrated Circuit (MMIC) generating the electromagnetic waves and conducting these waves in the waveguides towards the electromagnetic lens of the microwave antenna.

A substrate integrated waveguide comprises a dielectric substrate such as a printed circuit board. Metal plates cover the top and bottom faces of said substrate. Instead of using solid fences or plating for the sides of the waveguide, two rows of spaced plated vias (also called posts) form the sidewalls of the waveguide. The metal plates and rows of vias form a channel throughout the dielectric substrate to guide the electromagnetic waves.

Compared to the solid fence or plating of the sides as is usually done in waveguides, 51W technology obviously allows easy manufacturing and is very cost effective.

Substrate integrated waveguides are used to connect the radio frequency (RF) electronic components with an antenna element. The height of the substrate at the antenna side may be different from t he height of the substrate fixing the MMIC circuit. Indeed, an antenna has an open output of the integrated waveguide radiating into the electromagnetic lens and consequently has a substrate that is higher than the substrate at the MMIC side.

The RF electronic components either form a RE-IC, a Elip-Chip or a MMIC. They are to be placed on a thin substrate in order to have a good ground plane and to establish the shortest possible link, being implemented here by a bonding wire. In a microwave antenna system a waveguide propagating the electromagnetic signal feeds the electromagnetic lens and is thus necessarily a high 51W. However the height of the electromagnetic lens depends on the elevation angle of the radiated beam. Therefore the corresponding radiating elements, illuminating the lens, also need to have similar high. A design problem is thus related to the implementation of a transition between a 51W receiving the electromagnetic signal and a 51W propagating said electromagnetic signal, respectively having each different sections.

Similarly, a design problem is raised about the implementation of the transition between two 51W that is to be realized whenever both substrates are made each of different m aterials or each having dif ferent permittivity. Said transition is to be implemented with a minimum of RF loss and good impedance matching. Moreover the manufacturing of the complete microwave antenna system should be easy to implement and cost effective.

More generally speaking, the implementation of transitions or junctions of a stack of integrated waveguides is an open problem. Similarly, the design of eccentric or bent waveguides in an integrated environment such as printed circuit boards (PCB) raises the same design issues as mentioned here before.

In US20080205785 an antenna system is described comprising a feeding network and radiating waveguides. Their implementation relies on SIW technology. More precisely, an implementation method for the junction or transition is described. A radiating substrate integrated waveguide is implemented on top of a feeding substrate integrated waveguide. Transverse coupling slots are implemented by cutting the wall of the radiating 51W in order to connect to the feeding 51W. These coupling slots are calibrated openings in the metal plate separating both substrate integrated waveguides. This method is well suited to connect substrate integrated waveguides having the same size and same height since the dimension of the common slot is determined by the section and the impedance of the waveguide. Therefore, two SIW with different sections or with different dielectric materials cannot be implemented by using this method.

Moreover as to the method of manufacturing of said transition, there is a potential risk of an alignment mismatch between the slots of each waveguide that may generate signal losses. The method of manufacturing is costly, difficult to put in place and has several limitations and drawbacks.

Indeed, signal leakage and a strong attenuation may appear at the electrical contact between the metal plates of the two 81W that are in contact.

Furthermore it is not possible to assembly two 81W having different directions S as is most often the case when an open-ended high 81W is used as radiating element.

As appears from the state of the art, a method is needed to realize a transition or junction between two 81W having different dimensions (size and/or sections) and different directions, while offering good quality, whose method of manufacturing is cost effective and enables miniaturization. Said connection problem is not only related to antenna systems but remains whenever waveguides are to be interconnected.

The invention has been devised with the foregoing in mind and is directed towards mitigating at least one of the aforesaid drawbacks.

According to a first aspect, t he invention concerns an apparatus comprising two waveguides stacked at least partially upon each other, a first waveguide receiving an electromagnetic signal and a second waveguide propagating said electromagnetic signal, each waveguide having at least two conductor surfaces, said conductor surfaces of both waveguides being electrically connected, wherein an electrically conducting interconnector is electrically connected to a conductor surface of the first waveguide and extends into the interior of both waveguides, said interconnector being electrically isolated from all the other conductor surfaces of the waveguides.

Thanks to said interconnector, the transition between the first waveguide and the second waveguide can be implemented with a minimum of loss, whatever the dimensions or the directions of said waveguides may be.

According to a first embodiment of the invention, the apparatus comprises an interconnector having a cylindrical shape. Said interconnector extends into the interior of the first waveguide and partially penetrates into the interior of the second waveguide. This cylindrical shaped interconnector is adapted to match the impedance of the transition between the first waveguide and the second waveguide that are stacked at least partially upon each other in the apparatus.

In another possible implementation of the apparatus according to the invention, the interconnector extends through stacked conductor surfaces of S both waveguides and insulator means are inserted between said interconnector and said stacked conductor surfaces.

According to a possible feature of the invention the apparatus may comprise a first waveguide and a second waveguide, each extending respectively along two different longitudinal directions.

In a preferred implementation of the invention both the first waveguide and the second waveguide are substrate integrated waveguides.

According to a possible feature of the preferred implementation of the invention, both substrate integrated waveguides have respectively sections each of a different size.

According to another possible feature of the preferred implementation of the invention, both substrate integrated waveguides comprise respectively dielectric materials having each a different permittivity.

In a further preferred implementation of the apparatus according to the invention, the interconnector is implemented as a metalized post in the first substrate integrated waveguide and said metalized post further extends into the second substrate integrated waveguide through an isolator ring.

The preferred implementation of the invention can advantageously be adapted so that the interconnector being a metalized post, further comprises a metallic pin inserted into said metalized post.

According to another possible feature of the preferred implementation of the invention, the rnetalized post is filled with soldering material ensuring an electrical contact between said metalized post forming the interconnector and the conductor surface of first substrate integrated waveguide receiving the electromagnetic signal.

The invention also concerns an apparatus comprising a first waveguide receiving an electromagnetic signal and being adapted to be stacked upon a second waveguide propagating the electromagnetic signal, a wherein an interconnector extends into the interior of said first waveguide and is electrically connected to a conductor surface of the first waveguide and electrically isolated from all other conductor surfaces of the first waveguide.

In a preferred embodiment of the invention, the interconnector of said apparatus extends from a first conductor surface of the first waveguide and penetrates through an aperture of a second conductor surface of said first waveguide, said second conductor surface being on the opposite side of the first conductor surface of said first waveguide.

The invention also concerns a method of manufacturing of an apparatus being composed of two stacked waveguides comprising steps of: drilling a hole throughout the first waveguide, drilling a hole on one side of the second waveguide, removing material from a common conductor surface around the hole of each of the first waveguide and of the second waveguide, creating an insulator ring at the position of the interconnector, aligning both waveguides so that the hole drilled into the first waveguide corresponds with and extends further into the hole of partial depth drilled into the second waveguide, stacking the first waveguide upon the second waveguide and inserting an electrically conducting interconnector into the hole of the first waveguide, said interconnector penetrating into the hole of the second waveguide.

In a preferred implementation of the invention, the method of manufacturing interconnected substrate integrated waveguides comprises steps of drilling a hole throughout the first substrate integrated waveguide, drilling a hole partially penetrating the second substrate integrated waveguide, removing metal from the common conductor surface around the holes of the first and second substrate integrated waveguides to create an insulator ring at the position of the interconnector, evaporating metal material (metalized coating) upon the inner surface of the drilled holes of both the first 81W and the second 81W to create a metalized post, aligning both substrate integrated waveguides so that the hole drilled into the first 81W corresponds with and extends further into the hole of partial depth drilled into the second SIW, and stacking the first 81W upon the second SIW.

In a variant of the preferred embodiment, the manufacturing method can be completed with a step of filling the metalized post with soldering material in fusion ensuring an electrical contact between the metalized post and a conductor surface of the first substrate integrated waveguide receiving the electromagnetic signal.

The preferred embodiment of the manufacturing method can further advantageously be completed with the following steps of inserting a metallic pin into the metalized post and subsequently filling said metalized post with soldering material in fusion ensuring an electrical contact between the metallic pin, the metalized post and a conductor surface of the first substrate integrated waveguide receiving the electromagnetic signal.

The apparatus according to the invention has many possible applications. In particular said apparatus is advantageously used to implement an antenna, comprising a radio circuit and an electromagnetic lens, wherein a plurality of apparatuses extend between said radio circuit and said electromagnetic lens. A first waveguide of each of the plurality of apparatuses receives an electromagnetic signal from the radio circuit and a second waveguide propagates the electromagnetic signal and radiates this electromagnetic signal into the electromagnetic lens. In said antenna, each radiating waveguide of said plurality of apparatuses is locally placed in a direction that is normal to the surface of the electromagnetic lens.

The invention also concerns a method of manufacturing an antenna comprising a step of assembling a first substrate integrating a circuit and a plurality of substrate integrated waveguides receiving electromagnetic signals, together with a second substrate comprising plurality of substrate integrated waveguides propagating said respective electromagnetic signals, wherein said method of manufacturing comprises further a step of aligning the posts of each of the second substrate integrated waveguide propagating the respective electromagnetic signals and a step of assembling the electromagnetic lens in the geometric plane formed by both substrates.

Other features and advantages will emerge from the following description given by way of a non-limiting example with reference to the accompanying drawings in which: Figure Ia illustrates the top view of a microwave antenna system according to a first embodiment of the invention; Figure lb represents the cross-section of the microwave antenna system of Figure la; Figure Ic shows in perspective a similar microwave antenna system as those represented in the figures Ia and Ib; Figure 2a represents a detailed cross-section of an apparatus with two stacked SIW according to a first embodiment of the invention; Figure 2b illustrates the assembling step of the manufacturing method according to a first embodiment of the invention; Figure 2c represents the metalized hole filled with soldering material thus forming the interconnector corresponding to a variant of the manufacturing method according to a first embodiment of the invention Figure 3a illustrates a detailed cross-section of an apparatus with two stacked SIW according to a second embodiment of the invention: Figure Sb illustrates the insertion step during which a metalized pin is introduced into the metalized hole then forming the interconnector according to the manufacturing method of the second embodiment of the invention; Figure Sc illustrates the assembling step using the metalized pin to adjust the assembling of the two 81W to be interconnected according to a variant of the manufacturing method of the second embodiment of the invention; Figures 4 a and 4 b show a real impleme ntation of a microwave antenna system according to another embodiment; Figure 4c illustrates the Si 1 parameter representing the return loss in dB of the implementation shown in figures 4a and 4b; Figure 5 represents a top view of an apparatus according to a third embodiment of the invention; and Figure 6 represents a microwave antenna system according to another embodiment of the invention.

A preferred embodiment of the interconnector connecting two waveguides is considered in the context of a microwave antenna system. Said microwave antenna system comprises a RF circuit, two connected substrate integrated waveguides and an electromagnetic lens. The electromagnetic lens is enclosed between two metallic plates. The considered microwave antenna system is represented in the figures Ia and lb. For the sake of simplicity of the drawings, the stack described in this preferred embodiment of the interconnector, comprises two waveguides respectively having each the same longitudinal direction. These waveguides are for instance implemented by using 61W technology and respectively have sections each of a different size and each having a different permittivity.

This embodiment is given by way of example and can be applied to any microwave antenna system comprising radiating antenna elements, two interconnected wave guides and a dielectric lens.

In the figures Ia and lb the RF electronic components are elements of a circuit or die 110 being either a RF-JC, a Flip-Chip or a MMIC. Said circuit is placed on a thin substrate 120. This thin substrate 120 further extends and becomes the substrate 125 of the first SIW 130 receiving the electromagnetic signal. The first 61W 130 has advantageously the same height as the die 110 (usually ± 100 pm). A second 51W 140 is the second waveguide propagating said electromagnetic signal and radiating this signal into the electromagnetic lens 150. This second 61W 140 shall have a height that roughly corresponds to the thickness of the lens, Depending on the elevation angle of the radiated beam, the electromagnetic lens has a height for example of 3.0 mm whenever an angle of elevation of 60 to 70 degrees is required. By way of example, a waveguide having a height of at least 1.5 rim is needed to radiate into a lens having a height of 3.0 mm. Therefore, an adaptation is needed between the source of the waves at the die level 110 and the transmitted waves at destination level being the electromagnetic lens 150. Consequently an adaptation is also needed between the height of the first 31W 130 and the height of the second 61W 140 that are to be connected.

Said adaptation between the first SIW 130 and the second 81W 140 is implemented according to the invention, by using an electrically conducting interconnector 160. The interconnector 160 is electrically connected to a conductor surface 135 of the first SIW 130 and extends partially into the second 81W 140. The interconnector 160 is further electrically isolated from all the other conductor surfaces of the first SIW 130 and the second SIW 140. The first 81W receives the electromagnetic signal 180 from the circuit 110. The interconnector 160 is adapted to guide this electromagnetic signal propagating from the first SIW 130 into the second SIW 140. According to the preferred embodiment, the interconnector 160 has a cylindrical shape and comprises a metal hole (or post) crossing the first 81W 130 and extending into the second 81W 140. This metal interconnector 160 allows the electromagnetic field 180 to propagate from the first 51W 130 into the second SIW 140 without discontinuity while ensuring a good adaptation.

The circuit or die 110 is fixed on a ground plane 145 of the dielectric substrate 120. The substrate 120 is further extending into the substrate 125.

The die 110 is thus part of the first 81W 130. This die 110 is linked to the first 81W 130, integrated in the substrate 125. The first 81W 130 moreover comprises two metal plates 135, 145 covering the top and bottom faces of the dielectric substrate 125 and two rows of spaced plated vias or posts 170 form the sidewalls of this first SIW 130. A bonding wire 115 connects the first 81W with the die 110. This die 110 is placed in a cavity edged in the substrate in order to have a short bonding and good ground plane connection. This mounting ensures better performance in the GHz Radiofrequency band. For this reason, the first 51W 130 has the same height as the die (i.e. ± 100 pm).

A cross-section of the antenna system is represented in the figure lb and demonstrates the principle of the interconnector 160 between the first 51W 130 and second 81W 140 according to the invention.

The scales respectively of the first 81W 130 and of the second 81W 140 as represented in the figures Ia and lb are not the same, in order to facility the reading thereof. More precise dimensions of a similar antenna system is represented in figure Ic depicting a real implementation of the first 61W 130, the second SIW 140 and of the interconnector 160.

As is further shown in figure Ib, the interconnector 160 is a metalized post that is electrically connected to the top metal plate 135 of the dielectric substrate 125 forming the first 51W 130 and moreover is electrically isolated from the common metal plate 145 of the first 61W 130 and of the second 61W 140. This interconnector 160 crosses the first SIW 130 and penetrates into the second SIW 140 without having any electrical contact therewith. Consequently the electromagnetic field 180 propagates from the first 61W 130 into the second 61W 140 by means of this interconnector 160 and finally illuminates the electromagnetic lens 150.

In figures Ia -c, the electromagnetic lens 150 has a cylindrical shape and is enclosed in between two metal plates, a top plate 190 and a bottom plate 195.

A detailed view of a first implementation of the invention is represented in the figure 2a. This figure illustrates the cross-section of the first 61W 210 receiving an electromagnetic signal and of the second SIW 220 transmitting said electromagnetic signal, together with the interconnector 230.

The implementation shown in figure 2a comprises a first 61W 210 and a second 51W 220 that can be composed each of different dielectric materials. In such case the first 51W 210 and the second 61W 220 have respectively each a different permittivity. By way of non limiting example, the substrate of the first 51W 210 has a relative permittivity Er = 2.25 whiFe the substrate of the second 51W 220 has a relative permittivity Cr = 2.94. The implementation shown in figure 2a further comprises an interconnector 230 being a metalized hole and corresponding isolator rings 240 and 245 around said metalized hole 230, in order to ensure that no electrical contact exists with the metal ground plates 250 and 260, being respectively the bottom plate of the first 51W 210 and the top plate of the second 51W 220. The end sections of both the first 61W 210 and of the second 61W 220 are implemented each by using a row of posts (metalized holes) 270. This method used to realize the end sections of the waveguides, is the same as the one used for the side walls of both SIW 210 and 220. The metalized hole 230 c an advantageously be filled with soldering material to ensure perfect electrical contact between the metallic material of the post 230 and the top plate 255 of the first SIW 210 receiving the electromagnetic signal.

The method of manufacturing the apparatus, represented in figure 2b is described as follows and comprises the steps of drilling a hole throughout the first substrate integrated waveguide 210 and drilling a hole, partially penetrating the second substrate integrated waveguide 220. Said manufacturing method further comprises a step of removing metal material from the conductor surfaces 250 and 260 around the hole respectively of the first 51W 210 and of the second 51W 220 to create insulator rings 240 and 245 at the position of the interconnector as is shown in figure 2b. In a subsequent step, metal material is evaporated (metalized coating) upon the inner surfaces respectively 230 and 235 of the drilled holes in the first 51W and the second 51W. After an alignment step of both substrate integrated waveguides, the first substrate integrated waveguide 210 is stacked upon the second substrate integrated waveguide 220 as is schematically represented in figure 2b. After stacking together the first SIW and the second SIW, the two posts 230 and 235 form the interconnector.

The method of manufacturing the apparatus represented in the figure 2a can further be completed according to the invention by a step of filling the metalized posts 230 and 235 with soldering material 290 as is illustrated in figure 2c. Said additional soldering step ensures an electrical contact between the metalized post 230, 235 forming the interconnector and the upper plate 255 of the first substrate integrated waveguide 210 receiving the electromagnetic signal.

An example of another possible implementation of the interconnected wave guides is represented in figure 3a. This figure illustrates the cross-section of the first SIW 310 receiving the electromagnetic signal and of the second 51W 320 propagating the electromagnetic signal. The implementation shown in figure 3a comprises a first 51W 310 and a second 51W 320 that can be composed each of different dielectric materials. For instance, in such case the first 81W 310 and the second 31W 320 have respectively each a different permittivity. By way of non limiting example, the substrate of the first 51W 310 has a relative permittivity Er = 2.25 while the substrate of the second 81W 320 has a relative permittivity of Er = 2.94. The implementation shown in figure 3a further comprises an interconnector being composed of the posts (metalized S hole) 330 and 335. The corresponding isolator rings 340 and 345 are represented in this figure. Said isolator rings 340 an d 34 5 en sure that no electrical contact exists with the metal ground plates 350 and 360, being respectively the bottom plate of the first SIW 310 and the top plate of the second 31W 320. The end sections of both the first 31W 310 and the second 31W 320 are implemented each by using a row of posts (metalized holes) 370.

In this implementation a metallic pin 395 is inserted into the metalized hole 330.

In addition, during the manufacturing of the interconnected waveguides, soldering material in fusion 390 is added and fills the free space between the metalized hole 330 and the metallic pin 395, thus realizing a perfect electrical contact between the metallic pin 395, the metallic material of the posts 330 and 335 and the top plate 355 of the first 81W 310 receiving the electromagnetic signal.

The manufacturing method of this embodiment further comprises a step of inserting a metallic pin 395 into the metalized posts 330 and 335 forming the interconnector as illustrated in figure 3b. Alternatively the metalized pin 395 can also be used to facilitate the alignment, assembling and stacking of both substrate integrated waveguides as is illustrated in figure 3c.

Thus, the metalized pin 395 is first inserted into the metalized post 335 of the second 31W 320, then the first 81W 310 is stacked upon the second 81W 320 by inserting the metalized pin 395 into the metalized post 330 of the first SIW 310.

Referring again to figure 3a, a subsequent step of the manufacturing method according to this embodiment is then further completed by filling the metalized posts 330 and 335 with soldering material in fusion 390 ensuring an electrical contact between the metalized posts 330 and 335 forming the interconnector, the metallic pin 395 and the top plate 355 of first substrate integrated waveguide receiving the electromagnetic signal.

A real implementation of waveguides being interconnected is shown in figures 4a and 41,. Said interconnected waveguides 410, 420 comprise an interconnector 460 according to the invention. Figure 4a shows a view of the SIW output that is radiating into the electromagnetic lens. Figure 4b shows a perspective view of the interconnected waveguides. In both figures a thin SIW 410 receiving the electromagnetic signal is on the top and the higher SIW 420 propagating said electromagnetic signal is on the bottom of the micro-wave antenna.

For instance, the first 51W 410 receiving the electromagnetic signal has a height of 0,127 mm and a width (in the plane of Figure 4a) of 2 mm. The second 51W 420 transmitting and propagating said electromagnetic signal has for example a width of 1.62 mm and a height of 1.52 mm. As further is represented in the figure 4a and in order to match the impedance of the transition, the cylindrical interconnector 460 has a diameter 0 of 0.8 mm and a depth h into the second 51W 420 of 0.26 mm. These values correspond to the particular embodiment shown in the figures 4a and 4b and are given as example of embodiment. These values are not limitative. The diameter of the interconnector 460 being 0.8 mm corresponds to the minimal possible value of a known drilling technique to implement the hole. Other drilling techniques can be used to implement the hole such as laser techniques that allow smaller diameters and greater depths to implement the cylindrical interconnector. The first SIW implemented here is a commercial product that is either of a type (Roger RO3200TMseries" or "RO373O High Frequency Laminates (PTFE/Ceramic)". The second 61W is a commercial product such as "R06002 series".

In the embodiment shown in Figure 4a, the first 51W has a relative permittivity equal to 2.23 about and the second 51W 420 has a relative permittivity equal to 2.94 about.

A graph is shown in figure 4c, illustrating the evolution of the 511 parameter, in function of the frequency. The simulated values of the Sil parameter represent the return loss of the coupling of the two 61W and shows a relative good matching in the considered bandwidth. The value of the 311 parameter is less than -8dB in the 60 GHz band.

An implementation of an interconnector between waveguides according to the invention is illustrated in figure 5. The interconnector 500 shown here connects two SIW respectively having each different longitudinal directions. In this example a cylindrical shaped metallic pin 500 is advantageously used.

This characteristic of the invention allows the configuration of a microwave antenna system as represented in the figure 6. Said microwave antenna system comprises a substrate 600 integrating a circuit 610 and a plurality of pairs of 31W receiving electromagnetic signals 620 and 51W propagating said electromagnetic signals 630 together with corresponding interconnector 640. The cylindrical shaped metallic interconnectors 640 according to the invention, allow a design where the substrate integrated waveguides 620 receiving the electromagnetic signals may have different longitudinal directions when compared to the longitudinal direction of the corresponding substrate integrated waveguides 630 propagating respective electromagnetic signals. Each of the substrate integrated waveguides 630 propagating the electromagnetic signals, radiate.

The electromagnetic signal into the cylindrical shaped electromagnetic lens 650 without any air gap in between the waveguides 630 and the lens 650, since the waveguides 630 propagating the respective electromagnetic signals are locally placed in a direction which is normal to the surface of the electromagnetic lens 650, and then can obviously be placed tangentially around the electromagnetic lens 650 as illustrated in the figure 6.

The method of manufacturing an antenna as illustrated in figure 6 comprises a step of assembling a first substrate 600 integrating a circuit 610 and a plurality of substrate integrated waveguides 620 receiving electromagnetic signals, together with a second substrate comprising plurality of substrate integrated waveguides 630 propagating respective electromagnetic signals.

The method of manufacturing comprises a step of aligning the metalizeci posts that will form the interconnectors 640 of each pair of stacked substrate integrated waveguides 620, 630 by one of the alignment methods previously described A step of assembling the electromagnetic lens 650 in the geometric plane formed by both substrates.

As appears from the preceding, the interconnection method provides excellent matching over a wide bandwidth, is cost effective and easy to perform with a classical PCB process. I0

Claims (1)

1. <claim-text>CLAIMS1. An apparatus comprising two waveguides stacked at least partially upon each other, a first waveguide receiving an electromagnetic signal and a second waveguide propagating said electromagnetic signal, each waveguide having at least two conductor surfaces, said conductor surfaces of both waveguides being electrically connected, wherein an electrically conducting interconnector is electrically connected to a conductor surface of the first waveguide and extends into the interior of both waveguides, said interconnector being electrically isolated from all the other conductor surfaces of the waveguides.</claim-text> <claim-text>2. An apparatus according to claim 1, wherein the interconnector has a cylindrical shape extending into the interior of the first waveguide and partially penetrating into the interior of the second waveguide, said cylindrical shaped interconnector being adapted to match the impedance of the transition between the first waveguide and the second waveguide.</claim-text> <claim-text>3. An apparatus according to any one of claim 1 or claim 2, wherein said interconnector extends through stacked conductor surfaces of both waveguides, insulator means being inserted between said interconnector and said stacked conductor surfaces.</claim-text> <claim-text>4. An apparatus according to any one of claims 1 to 3, wherein each of the first waveguide and of the second waveguide extends respectively along two different longitudinal directions.</claim-text> <claim-text>5. An apparatus according to any one of claims 1 to 4, wherein both the first and the second waveguide are substrate integrated waveguides.</claim-text> <claim-text>6 An apparatus according to claim 5, wherein both substrate integrated waveguides have respectively sections each of different sizes.</claim-text> <claim-text>7. An apparatus according to any one of claims 5 or 6, wherein both substrate integrated waveguides comprise respectively dielectric materials having each a different permittivity.</claim-text> <claim-text>8. An apparatus according to any one of claims 5 to 7, wherein the interconnector is implemented as a metalized post in the first substrate integrated waveguide, said metalized post further extending into the second substrate integrated waveguide through an isolator ring.</claim-text> <claim-text>9. An apparatus according to claim 8, wherein the interconnector comprises a metallic pin inserted into said metalized post.</claim-text> <claim-text>10. An apparatus according to any one of claims 8 or 9, wherein the metalized post is filled with a soldering material ensuring an electrical contact between said metalized post forming the interconnector and the conductor surface of first substrate integrated waveguide receiving the electromagnetic signal.</claim-text> <claim-text>11. An apparatus comprising a first waveguide receiving an electromagnetic signal and being adapted to be stacked upon a second waveguide propagating the electromagnetic signal, wherein an interconnector extends into the interior of said first waveguide and is electrically connected to a conductor surface of the first waveguide and electrically isolated from all other conductor surfaces of the first waveguide.</claim-text> <claim-text>12. An apparatus according to claim 11, wherein the interconnector extends from a first conductor surface of the first waveguide and penetrates through an aperture of a second conductor surface of said first waveguide, said second conductor surface being on the opposite side of the first conductor surface of said first waveguide.</claim-text> <claim-text>13. A method of manufacturing an apparatus according to any one of claims 1 to 4, comprising steps of: drilling a hole throughout the first waveguide, drilling a hole on one side of the second waveguide, removing material from a common conductor surface around the hole of each of the first waveguide and of the second waveguide, creating an insulator ring at the position of the interconnector, aligning both waveguides so that the hole drilled into the first waveguide corresponds with and extends further the hole of partial depth drilled into the second waveguide, stacking the first waveguide upon the second waveguide, and inserting an electrically conducting interconnector into the hole of the first waveguide, said interconnector penetrating into the hole of the second waveguide.</claim-text> <claim-text>14. A method of manufacturing an apparatus according to any one of claims 5 to 10 comprising steps of: drilling a hole throughout the first substrate integrated waveguicle, drilling a hole partially penetrating the second substrate integrated waveguide, removing metal material from the common cQnductor surface around the holes of the first and second substrate integrated waveguides to create an insulator ring at the position of the interconnector, evaporating metal material (metalized coating) upon the inner surface of the drilled holes of both the first and the second substrate integrated waveguide to create a metalized post, aligning both substrate integrated waveguides so that the hole drilled into the first substrate integrated waveguide corresponds with and extends further the hole of partial depth drilled into the second substrate integrated waveguide and stacking the first substrate integrated waveguide upon the second substrate integrated waveguide.</claim-text> <claim-text>15. The method of manufacturing an apparatus according to claim 14 comprising further step of: filring the metalized post with soldering material in fusion ensuring an electrical contact between the metalized post and a conductor surface of the first substrate integrated waveguide.</claim-text> <claim-text>16. The method of manufacturing according to claim 14 comprising further steps of: inserting a metallic pin into the metalized post, and filling the metalized post with soldering material in fusion ensuring an electrical contact between the metallic pin, said metalized post and a conductor surface of first substrate integrated waveguide receiving the electromagnetic signal.</claim-text> <claim-text>17. An antenna comprising a radio circuit and an electromagnetic lens, wherein a plurality of apparatuses according to any one of claims 1 to 10 extend between said radio circuit and said electromagnetic lens, each apparatus being composed of a first waveguide receiving an electromagnetic signal from the radio circuit and a second waveguide propagating said electromagnetic signal and radiating said electromagnetic signal into the electromagnetic lens, wherein each of the plurality of waveguides radiating respectively an electromagnetic signal into said electromagnetic lens is locally placed in a direction that is normal to the surface of the electromagnetic lens.</claim-text> <claim-text>18. A method of manufacturing an antenna according to claim 17, comprising steps of: assembling a first substrate integrating a circuit and a plurality of substrate integrated waveguides receiving electromagnetic signals, together with a second substrate comprising plurality of substrate integrated waveguides propagating said respective electromagnetic signals, aligning the metalized posts of each pair of stacked substrate integrated waveguides, and assembling the electromagnetic lens in the geometric plane formed by said first and second substrates.</claim-text> <claim-text>19. An apparatus substantially as hereinbefore described, with reference to, and as shown in any one of the Figures la to Ic, the Figure 2a, the Figure 3a, the Figures 4a and 4b, Figure 5 and Figure 6 of the accompanying drawings.</claim-text> <claim-text>20. A diagram representing the Si 1 parameter of the interconnector, substantially as hereinbefore described, with reference to, and as shown in, Figure 4c of the accompanying drawings 21. A method of manufacturing of a stack of two interconnected waveguides as hereinbefore described, with reference to, and as shown in any one of the Figures la to ic, the Figures 2b and 2c, the Figures 3b and 3c, the Figures 4a and 4b, the Figure 5 and the Figure 6 of the accompanying drawings.</claim-text>