WO2018010792A1

WO2018010792A1 - Antenna and system comprising an antenna

Info

Publication number: WO2018010792A1
Application number: PCT/EP2016/066724
Authority: WO
Inventors: Titos Kokkinos; Ajay Babu Guntupalli; Bruno BISCONTINI
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2016-07-14
Filing date: 2016-07-14
Publication date: 2018-01-18
Also published as: BR112018016972A2; CN109417225B; BR112018016972B1; CN109417225A

Abstract

The invention relates to an antenna base layer having a bottom side and an opposed top side having at least one through hole extending from the bottom side to the top side in a stacking direction, wherein a first section at the bottom side of the antenna base layer of each of the at least one through holes is configured to accommodate an end portion of a corresponding waveguide; an antenna main layer arranged on the top side of the antenna base layer in the stacking direction, wherein the antenna main layer comprises: a first conductive sub-layer as the lowermost layer of the antenna main layer in the stacking direction comprising at least one first non-conductive slot arranged so that each first slot at least partially overlaps with a corresponding through hole of the at least one through hole of the antenna base layer in the stacking direction; a second conductive sub-layer arranged above the first sub-layer in the stacking direction, the second sub-layer comprising at least one first circuitry configured to convert electromagnetic waves coming from the antenna base layer into electromagnetic signals for a stripline transmission, wherein each of the at least one first circuitry at least partially overlaps with a corresponding first slot of the at least one first slot, and the second sub-layerfurther comprises at least a transmission line for the stripline transmission and at least one second circuitry configured to convert transmission signals of the stripline transmission into electromagnetic waves radiated away from the second sub-layer, wherein the transmission line connects a first circuitry of the at least one first circuitry with a corresponding second circuitry of the at least one second circuitry; a third conductive sub-layer arranged above the second sub-layer in the stacking direction comprising at least one second non-conductive slot, wherein each of the at least one second slot is arranged for at least partially overlapping with a corresponding second circuitry of the at least one second circuitry in the stacking direction; an antenna wall layer arranged above the third conductive sub-layer of the antenna main layer in the stacking direction, the antenna wall layer comprising at least one cavity extending from a bottom side of the antenna wall layer to a top side of the antenna wall layer in the stacking direction, wherein each of the at least one cavity is arranged so that the cavity overlaps with a corresponding second slot of the third sub-layer in the stacking direction; a top layer comprising at least one conductive patch arranged on the antenna wall layer so that each of the at least one patch overlaps with a corresponding cavity of the antenna wall layer in the stacking direction.

Description

Antenna and System comprising an antenna

Technical Field

The present invention is directed to an antenna, a system comprising the antenna and a block comprising at least one waveguide, and a method for manufacturing the antenna. Background

Massive MIMO (mMIMO) communication systems will be deployed in the context of 5G mobile access to further increase the achieved spectral efficiency, and deliver the ever increasing throughput demanded by the users. These massive MIMO systems are envisioned to operate both at the conventional mobile access frequencies (sub-6 GHz) but also in millimeter-wave (mmW) frequencies (e.g. 30 GHz), in which there are large chunks of underused spectrums.

In mMIMO base stations, a "massive" number of RF transceivers will be integrated directly behind the antenna array, and will allow the formation and steering of very narrow antenna beams that will adaptively follow specific users (by means of digital beam forming). The antenna systems of 5G mMIMO base stations will be fairly different as compared to traditional base station antenna panels. The complete antenna arrays should be preferably manufactured through a fully automated process and be delivered as a single part for the system integration. Further, the multiple ports of the array should be interfaced to the active transceivers of the base stations in a highly simplified and miniaturized manner in order for digital beam forming schemes to be supported. Further, some basic analog beam forming might be required between smaller groups of antenna elements (fed from the same transceiver) at zero cost and zero complexity increase for the complete system.

Millimeter Wave (mmW) frequencies have been employed so far in the context of mobile communications, primarily for point to point (backhaul) links. In such systems, the employed antenna arrays are high gain antennas, electrically and physically large in size, fed primarily at a single port, and properly installed in order to achieve perfect alignment between any pairs of such systems. These antenna technologies are fairly different from the antennas that will be required in mmW 5G mMIMO systems. The antenna technologies that will be employed within the context of mmW 5G mMIMO systems resemble more the antenna technologies employed so far in active electronically scanned arrays (radar systems employed in a large range of applications), with the difference that the antenna systems for mobile access would be always required to exhibit smaller form factors, achieve the highest possible integration with the active transceivers and are to be produced reliably and

reproducibly in high volumes with the minimum possible costs.

The biggest challenge that needs to be overcome for the mmW 5G mMIMO antenna arrays is that the physical spacing between the elements of the array (preliminarily dictated by the operating wavelength and usually set to be between ο.5λ and 1 λ) is significantly smaller (1 order of magnitude) than the physical size of the available active transceivers, and the physical area required to extract the heat dissipated on these transceivers. As a result, the integration of such an antenna array (at mmW frequencies) with the multiple active transceivers has been proven extremely challenging. Therefore, large efforts and top-notch innovations will be required to address this problem.

5G mMIMO mmW mobile access systems are up to the present point of time a hot and very new topic in the 5G research area and only a limited amount of literature has been published so far on the antenna technology for such an application. For example, W. Roh, J.Y. Seol, et. al., "Millimeter- Wave Beamforming as an Enabling Technology for 5G Cellular Communications: Theoretical Feasibility and Prototype Results", IEEE Comm.Mag., Feb. 2014 refers to a PCB based antenna area employed on a 5G mmW mMIMO access node. The antenna area used in this prototyped arrangement is fully PCB based (PCB printed patches) and is located centrally in the access nodes as shown in Fig. 1, while the active circuitry has been built around the antenna system, on the same PCB. The multiple antenna ports are connected with the active circuitry of multiple transceivers using PCB based transmission lines. However, such an approach would be difficult to be adopted in a commercial system, primarily because both, the antenna system itself and the way it is interconnected to remaining parts of the system is particularly lossy. The efficiency of such an RF front end is expected to be low. Furthermore, the PCB based interconnecting lines and the antenna corporate feeding network that have been used are expected to interact with the patch radiators, parasitically radiate themselves, and eventually worsen the total radiation performance of the access node. In order to address some of the antenna performance issues of the antenna system of the above mentioned prior art document, alternative antenna technologies can be employed. Such are, for example, the antenna technology presented in Yujian Li and Kwai-Man Luk, IEEE TAP. Vol. 62, No.11, Nov. 2014, and A.B. Guntupalli and Ke Wu, IEEE AWPL. Vol 13, 2014, wherein Figs. 2 and 3 show the corresponding arrangements in these two prior art documents, respectively.

With respect to the arrangement shown in Fig. 2, an aluminum layer (aluminum plate) with embedded air-cavities has been inserted between the two PCBs in order to allow the resonant patches that form the array (located on the top PCB) to resonate (partially) in the free space, reducing in such a ways efficiency reduction caused by the dielectric losses of the array. On the bottom PCB, a PCB-based feeding network (substrate integrated waveguide technology) is used to feed the complete area from a single rectangular WG port.

In the arrangement shown in Fig. 3, the use of air cavities below the resonant patches is also proposed for the reduction of the dielectric losses of the antenna. Nevertheless, in this approach of Fig. 3, the air cavities are formed within a PCB layer, eliminating in that way the need of using the aluminum layer. The advantage of this approach in Fig. 3 is that the manufacturing process of the antenna is simplified, but the disadvantages are that the height of the cavities are preliminary dictated by the available thicknesses of dielectric cores (and not the design requirements of the patches) and that the performance is worse than the aluminum based air cavities. Summary

Accordingly, a problem to be solved by the present invention is to provide an antenna suitable for integration within 5G mMIMO mmW mobile access systems. This problem is solved by the subject matter of the independent claims. Advantageous implementations are further defined in the respective dependent claims.

In a first aspect, an antenna is provided comprising: an antenna base layer having a bottom side and an opposed top side having at least one through hole extending from the bottom side to the top side in a stacking direction, wherein a first section at the bottom side of the antenna base layer of each of the at least one through holes is configured to accommodate an end portion of a corresponding waveguide; an antenna main layer arranged on the top side of the antenna base layer in the stacking direction, wherein the antenna main layer comprises: a first conductive sub-layer as the lowermost layer of the antenna main layer in the stacking direction comprising at least one first non-conductive slot arranged so that each first slot at least partially overlaps with a corresponding through hole of the at least one through hole of the antenna base layer in the stacking direction; a second conductive sub-layer arranged above the first sub-layer in the stacking direction, the second sub-layer comprising at least one first circuitry configured to convert electromagnetic waves coming from the antenna base layer into electromagnetic signals for a stripline transmission, wherein each of the at least one first circuitry at least partially overlaps with a corresponding first slot of the at least one first slot, and the second sub-layer further comprises at least a transmission line for the stripline transmission, and at least one second circuitry configured to convert transmission signals of the stripline transmission into electromagnetic waves radiated away from the second sub-layer, wherein the transmission line connects a first circuitry of the at least one first circuitry with a corresponding second circuitry of the at least one second circuitry; a third conductive sub-layer arranged above the second sub-layer in the stacking direction comprising at least one second non-conductive slot, wherein each of the at least one second slot is arranged for at least partially overlapping with a corresponding second circuitry of the at least one second circuitry in the stacking direction; an antenna wall layer arranged above the third conductive sub-layer of the antenna main layer in the stacking direction, the antenna wall layer comprising at least one cavity extending from a bottom side of the antenna wall layer to a top side of the antenna wall layer in the stacking direction, wherein each of the at least one cavity is arranged so that the cavity overlaps with a corresponding second slot of the third sub-layer in the stacking direction; a top layer comprising at least one conductive patch arranged on the antenna wall layer, so that each of the at least one patch overlaps with a corresponding cavity of the antenna wall layer in the stacking direction.

The invention according to the first aspect provides the chance to feed the antenna with a reasonable large number of waveguide ports within a small footprint area, since all waveguides are fixed to the antenna base layer. Digital beam forming can be implemented between the parts of the antenna that are fed by different waveguide ports. Further, embodiments can implement analog/static beamforming in a PCB technology (stripline technology), which enables the miniaturization of the antenna (especially with regard to its thickness), and the synthesis of a large variety of beamforming functions (amplitude and phase tapering), and the excitation of the patches in any required polarization. This analog/static beam forming can be implemented between the antenna elements (conductive patches) that are fed from the same waveguide port. Furthermore, the feeding network of the antenna does not radiate itself, since it can be completely shielded from the outside. Furthermore, the arrangement according to the first aspect allows that the radiating resonances of the conductive patches can be supported in air filled cavities, enhancing in this way its power efficiency and suppressing parasitic effects, like surface waves. Furthermore, the arrangement according to the first aspect allows improved isolation between its individual patches, which also improves its total power efficiency, its active matching performance and its polarization purity. Furthermore, the arrangement according to the first aspect allows the usage of any single or stacked patches, of any shape, for achieving the required radiation performance. Furthermore, the arrangement according to the fist aspect is also scalable (in mmW region). Furthermore, the arrangement according to the first aspect can also be produced in high volumes in a fully automated process. Further, the embodiments of the present invention provides a high antenna integration and delivers a good radiation performance.

In a first implementation form of the antenna each through hole within the antenna base layer comprises a second section, wherein the first section of each through hole extends from the bottom side of antenna base layer to the second section of the corresponding through hole, wherein the second section of each through hole extends from its corresponding first section to the top side of the antenna base layer, wherein the dimensions of the second section of each through hole are adapted to match the impedance of the first section to the impedance of the corresponding first slot. Therewith, in a very effective and easy way, a corresponding waveguide can be attached to the antenna base layer of the antenna, wherein one end of a corresponding waveguide is provided within the first section at the bottom side of the antenna base layer. Furthermore, due to configuring the dimensions of the first and second section in such way that the impedance of the first section is matched to the impedance of the corresponding non-conductive first slot of the first conductive sublayer of the antenna main layer a very effective impedance matching necessary for the arrangement can be ensured.

In a second implementation form of the antenna, the antenna main layer comprises a first dielectric sub-layer arranged between the first and second conductive sub-layers, wherein the antenna main layer further comprises a second dielectric sub-layer arranged between the second conductive sub-layer and the third conductive sub- layer. Thereby, it is possible to freely adapt the distance between the first, second and third sub-layers by just varying the thicknesses of the first and/or second dielectric sub -layers. Further, by the provision of the first and second dielectric sub-layers the manufacturing process can also be performed in a very effective and cost efficient way, since in manufacturing the whole arrangement, and in particular the antenna main layer, each of the first, second and third conductive sub-layers can be provided onto preassembled top and bottom surfaces of a corresponding dielectric layers, that can be eventually bonded together in a fully automated and standardized process.

Furthermore, in a third implementation form of the antenna the third conductive sub-layer comprises two or more second slots and between each of two or more second slots in the third conductive sub-layer a cut out is provided, which extends along in the stacking direction at least through the second dielectric sub layer. In this arrangement cutouts are provided between the second non-conductive slots, wherein the cutouts can serve for attaching and aligning the third conductive sub-layer, by engaging with corresponding alignment pins of the antenna wall layer, to all other layers of the antenna.

In a fourth implementation form of the antenna on the bottom side of the antenna wall layer alignment pins are provided and engaged with the corresponding cutouts in the antenna main layer. Accordingly, these alignment pins can be used for being inserted into the corresponding cutouts of the third conductive sub-layer for tightly fixing and aligning the antenna wall layer to the antenna main layer. In a fifth implementation form of the antenna, between the two or more second slots of the third sub-layer at least one via is provided, which extends along the stacking direction through the antenna main layer, wherein an inner surface of the via is plated with an electrically conductive material. Thereby, it is possible that the first and/or second circuitries and/or the transmission lines of different columns of second circuitries are decoupled from each other.

In a sixth implementation form of the antenna on the top side of the antenna wall layer alignment pins are provided and engaged with corresponding cutouts in the top layer. Therewith, an attachment and fixation of the antenna wall layer to all other layers of the antenna can be ensured in an effective and easy way and at the same time the alignment of the antenna wall layer to all other layers of the antenna can be ensured. Further, the antenna wall layer serves in particular for defining a certain distance between the antenna main layer and the top layer, so that by defining a certain thickness of the antenna wall layer, the distance between the top layer and the antenna main layer can be freely adjusted.

In a seventh implementation form of the antenna, the top layer comprises a dielectric substrate, wherein the conductive patches are arranged on either the top side or the bottom side of the substrate or on both sides of the substrate. Therewith, it is possible not only to provide the patches on one surface but also, for example, on both surfaces of the dielectric substrate, thereby providing a great variety of possibilities of providing the patches on the top layer, by, for example, printing the patches on a corresponding surface of the top layer. In an eighth implementation form of the antenna the top layer comprises two or more patches and between the two or more patches cutouts are provided in the top layer. By the provision of these cutouts between the patches it is possible to attach the top layer to all other layers of the antenna and at the same time provide an alignment of the top layer to all other layers. In a ninth implementation form of the antenna the top layer comprises two or more patches and between the two or more patches vias having an inner plated surface are provided. By the provision of these vias between the patches the patches can be isolated from each other and surface waves can also be suppressed.

In a tenth implementation form of the antenna, both ends of the vias are covered with metalized pads. By providing these pads the isolation between the respective patches can be further improved.

In an eleventh implementation form of the antenna, the antenna base layer and the antenna wall layer are made from electrically conductive material, preferably aluminum. Therewith, a very light weight antenna can be provided, which is easy and cost effective to manufacture.

In a twelfth implementation form of the antenna, for each of the at least one first circuitry, the first circuitry is configured to split a signal, being the electromagnetic waves coming from the antenna base layer, into two signals, constituting the electromagnetic signal for the stripline transmission, for the two opposing sides of the first circuit within a plane perpendicular to the stacking direction, wherein each side of the two opposing sides comprises at least one second circuitry, wherein the at least two circuitries on both sides constitute together within the plane a column of second circuitries. This in particular serves for arriving at an arrangement in which in a very effective way the electromagnetic signals coming from below, that means from the waveguide via the antenna base layer, can be split up into the electromagnetic signals for the stripline transmission by a first circuitry, so that effectively the space provided by the second conductive sub-layer can be used for arranging the first and second circuitries. Therefore, it is possible to arrange the first and second circuitries in that way that there is no unused space within the second sub-layer. Furthermore, providing the first and second circuitries in that way as in this implementation form provides for a very effective and easy way to manufacture the first and second circuitries within the second conductive sub-layer. In a thirteenth implementation form the two signals after the splitting have different phases. Thereby, it is possible to provide electromagnetic waves radiated away from the second sub-layer towards the top layer having various frequencies.

According to a fourteenth implementation form within the plane more than one column of second circuitries are provided, thereby forming an array of second circuitries. In particular this arrangement of providing an array of second circuitries serves for providing a very structured arrangement of first and second circuitries, whilst a high density of first/second circuitries is possible, and the second sub-layer can be used as effectively as possible for accommodating the first and second circuitries. Furthermore, also the manufacturing of the first and second circuitries within the second sub-layer is improved due to the very structured arrangement of the second circuitries constituting such an array.

According to a second aspect, a system is provided comprising an antenna as mentioned according to the first aspect or any of the implementation forms of the first aspect, and a block comprising at least one waveguide, wherein the block is attached to the antenna and the waveguide has a body with a first end having an opening and the first end is encompassed by the corresponding through hole of the antenna base layer and a main extension direction, being a direction of a largest extension, of the waveguide coincides with a main extension direction of the corresponding through hole. Thereby, a system comprising the antenna and the corresponding waveguide is provided, which serves for a very compact arrangement of the antenna and the waveguide, enabling the advantages already mentioned with respect to the first aspect.

In a third aspect, a method for manufacturing an antenna according to the first aspect or any of the implementation forms of the first aspect is provided comprising the step of stacking in the stacking direction the antenna base layer, the antenna main layer, the antenna wall layer and the top layer and assembling these layers together by gluing theses layers together by using conductive or non-conductive epoxies or by screwing these layers together by using screws, in particular micro-screws. Thereby, a manufacturing method can be provided, which uses easy and cost effective techniques for assembling the antenna.

Brief description of drawings

The above-described aspects and the implementation forms of the present invention will be explained in the following description of specific embodiments in relation to enclosed drawings in which Fig. l refers to an arrangement in a prior art document;

Fig.2 refers to an arrangement in another prior art document;

Fig.3 refers to an arrangement in another prior art document;

Fig. 4 shows a schematic cross sectional view of the antenna according to an embodiment of the present invention;

Fig. 5 shows an exploded view of the antenna of Fig, 4;

Fig.6 shows a more detailed schematic side view of the antenna of Fig. 4;

Fig. 7 shows a perspective view of the antenna base layer of the antenna of the preceding figures;

Fig. 8a shows a top view of the first conductive sub-layer of the antenna of the preceding figures;

Fig. 8b shows a top view of the second conductive sub-layer of the antenna of the preceding figures;

Fig. 8c shows a top view of the third conductive sub-layer of the antenna of the preceding figures; Fig. 9 shows a top view of an assembled state in which the first, second and third conductive sub-layers are assembled, thereby forming the antenna main layer of the antenna of the preceding figures; Fig. loa shows a perspective view of the antenna wall layer of the antenna of the preceding figures;

Fig. 10b shows an enlarged view of the antenna wall layer according of Fig. 10a; Fig. 11 shows a side view of the antenna wall layer of Fig. 10a;

Fig. 12 shows a perspective view of the top layer of the antenna of the preceding figures; Fig. 13 shows a top view of the antenna of the preceding figures;

Fig. 14a shows a photograph of an assembled antenna according to an embodiment the present invention; Fig. 14b shows a photograph of the antenna main layer, antenna wall layer and the top layer of the antenna of Fig. 14a; and Fig. 14c shows a photograph in a cross- sectional view of the antenna of Fig. 14b.

Detailed Description

Generally, it has to be noted that all arrangement, devices, elements, units and means and so forth described in the present application could be implemented by software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionality described to be performed by the various entities are intended to mean that the respective entity is adapted to be configured to perform the respective steps and functionalities. Even if in the following description of specific embodiments a specific functionality or step is to be performed by a general entity and not reflected in the description of a specific detailed element of that entity, which performs that specific step or functionality, it should be clear for a skilled person that these elements and functionalities can be implemented in respective hardware or software elements or any kind of combination thereof. Further, the method of the present invention and its various steps are embodied in the functionalities of the various described apparatus elements.

Fig. 4 shows a cross-sectional view of an antenna according to an embodiment of the present invention. As can be seen, the antenna 10 comprises four layers, namely the antenna base layer 20, the antenna main layer 30, the antenna wall layer 60 and the top layer 70 in the stacking direction. Further, the antenna main layer 30 comprises in the stacking direction the first conductive sub-layer 32, followed by the first dielectric sub-layer 31, the second conductive sub-layer 40, the second dielectric sublayer 31', and the third conductive sub-layer 50 in the stacking direction.

Furthermore, in the embodiment of Fig. 4, on the top side and the bottom side of the top layer 70 conductive patches 72 are provided, respectively. Further, below the antenna base layer 20 a block 90 is provided, which comprises in this example eight waveguides 100, each having a body 110, indicated in Fig. 4 by the dashed lines. In this context one end of each waveguide 100 is attached to the antenna base layer 20. In this context the specific attachment by the first section/second section of the antenna base layer with the waveguide 100 is not shown in Fig. 4. Therefore, Fig. 4 just shows schematically the principle stacking order of the corresponding layers of the antenna.

Furthermore, Fig. 5 is an exploded view of the antenna shown in Fig. 4 with all four layers, namely the antenna base layer 20, the antenna main layer 30, the antenna wall layer 60 and the top layer 70. The top layer 70 is shown as a two-piece element, however, this is just optional and can of course also be a one-piece element. The antenna base layer 20 can for example be a solid conductive block (e.g. made out of a metal such as aluminum or metalized plastic) with corresponding several through holes for connecting to the waveguide 100 but also for mounting the antenna. The antenna main layer 30 can for example be a multi-layer PCB. The antenna wall layer can for example be a conductive frame (e.g. made out of a metal such as aluminum or metalized plastic) with several through holes for housing the patches of the top layer 70. The top layer 70 can for example be another PCB. Furthermore, Fig. 6 shows a schematic side view of the antenna with an emphasis on the antenna base layer 20, wherein one can clearly see that in the antenna base layer 20 a first section 27 and a second section 28 are provided. Therefore, each through hole 26 of the base layer 20 is made of two sections, namely the first section 27 and the second section 28, wherein the first section 27 of each through hole 26 extends from the bottom side 22 of the antenna base layer 20 to the second section 28 of the corresponding through hole 26, and the second section 28 of each through hole 26 extends from its corresponding section 27 to the top side 24 of the antenna base layer 20. In this context the dimensions of the second section 28 of each through hole 26 are adapted to match the impedance of the first section 27 to the impedance of the corresponding first slot 34 of the first conductive sub-layer 32. This resembles an effective method for ensuring the needed impedance matching between the wave guide and the antenna main layer 30.

Further, Fig. 7 refers to a perspective view of the antenna base layer 20. The antenna base layer 20 is a conductive element, being made, for example, of aluminum or metalized plastic. There, eight through holes 26 can be seen, which are arranged in a row, wherein on each of these through holes an end portion of a corresponding waveguide 100 can be attached, so that on the antenna base layer 20 in this example eight waveguides 100 can be attached. In the embodiment shown in Fig. 7 between each of the through holes 26 a corresponding further hole 25 (possibly threaded) can be provided for attachment purposes for attaching and aligning the antenna base layer 20 to all other antenna layers. Furthermore, further holes 25' (possibly threaded) can also be provided, which can be seen in Fig. 7 on the edges of the antenna base layer 20 into which screws, as in further holes 25, can be inserted for further fixing and aligning the antenna base layer 20 with all other layers of the antenna and the remaining RF system (i.e. incoming waveguides 100). Therefore, the antenna base layer 20 can be used to align the waveguides with the antenna (i.e. the antenna ports) and also for installing the antenna on the remaining parts of the radio unit. As already mentioned above the through holes 26 shown in Fig.7 serve as impedance transformers, which are used for interconnecting the waveguides to the antenna and transforming the impedance of the waveguide to the impedance of the antenna. It should be noted that in Fig. 7 just exemplary eight through holes 26 are shown and of course the number can also be arbitrary. Further, also the number and the size of further holes 25, 25' can be freely chosen.

Fig. 8a shows a top view of the first conductive sub-layer 32 of the antenna main layer 30. There, first non-conductive slots 34 are provided preferably, as in Fig. 8a in a row. In the implementation form of Fig. 8a, these first non-conductive slots 34 can be configured as elongated slots. The slots can extend from a bottom side of the first conductive sub-layer 32 to a top side of the first conductive sub-layer 32 in the stacking direction. Further, each of the first non-conductive slots 34 is arranged within the first conductive sub-layer 32, so that each first slot 34 at least partially overlaps with a corresponding through hole 26 of the antenna base layer 20 in the stacking direction, so that it is possible that an electromagnetic wave can be transmitted from the waveguide 100 through the first conductive sub-layer 32 to the second conductive sub-layer 40 provided above the first conductive sub-layer 32 in the stacking direction.

Further, Fig. 8b shows a top view of the second conductive sub-layer 40 arranged above the first sub-layer 32 in the stacking direction, wherein the second sub-layer 40 can comprise as in the embodiment of the Fig. 8b eight first circuitries 42 arranged in a row, wherein each of these eight first circuitries 42 can be configured to convert electromagnetic waves received from the corresponding waveguide 100 through the slots 34 into electromagnetic signals for a stripline transmission, wherein a stripline transmission refers to a transmission of currents/voltages by a signal line (wire) and two corresponding ground planes, properly arranged around the signal line. Further, each of these first circuitries 42 is provided within the second conductive sublayer 40 to at least partially overlap with a corresponding first slot 34 of the first conductive sub-layer 32. In the embodiment of Fig. 8a - 8c eight first circuitries 42 corresponding to eight first non-conductive slots 34 of the first conductive sub-layer 32 are provided, so that each first non-conductive slot 34 overlaps in the stacking direction at least partially with a corresponding first circuitry 42 of the second conductive sublayer 40. Therefore, each first non-conductive slot 34 is assigned to one corresponding first circuitry 42. Further, the second sub-layer 40 comprises in Fig. 8b transmission lines for the stripline transmission and corresponding second circuitries 46 configured to convert the transmission signals of the stripline transmission into electromagnetic waves radiated away from the second sub-layer 40 to the third conductive sub-layer 50, wherein a transmission line 44 connects a first circuitry 42 with a corresponding second circuitry 46. In the arrangement shown in Fig. 8b, for each first circuitry 42, the first circuitry 42 is configured to split an incoming electromagnetic wave coming from the corresponding waveguide 100 into two signals, constituting the electromagnetic signals for the stripline transmission for two opposing sides of the first circuitry 42 within a plane perpendicular to the stacking direction, wherein each side of the two opposing sides comprises in the embodiment of the Fig. 8b several second circuitries 46 connected in series to each other. Each of these second circuitries on one side of the first circuitry 42 are connected in series, so that all second circuitries 46 on the two sides of the first circuitry 42 together form within the plane perpendicular to the stacking direction a column 46' of second circuit 46. In the embodiment of Fig. 8b eight columns of second circuitries 46 are provided next to each other, thereby forming an array of second circuitries 46 extending across the whole plane. Thereby, in the arrangement shown in Fig. 8b a row of first circuits 42 is provided in the middle of the second conductive sub-layer 40, wherein perpendicular to the main extension direction of the row of first circuitries 42 columns of second circuitries 46 are provided. Thereby, the structure shown in Fig. 8b can be provided. In the arrangement of the second conductive sub-layer 40, the second circuitries 42 are respectively constituted by C- shaped transmission lines, which symmetrically excite a predefined polarization of the radiating patches 72 arranged in top layer 70. Further, due to the arrangement of the first circuitries 42 and the inverted arrangement of second circuitries 46 on the two sides of the first circuitries 42 the signals on the two sides of a corresponding first circuitry 42 have different phases. Thereby, it is possible to generate a certain radiation pattern in the radiating patches 72. In the arrangement of Fig. 8b, an electromagnetic wave signal is transferred to the second conductive sub-layer 40 from a corresponding waveguide 100 to a certain first circuitry 42 and converted to the stripline signal, being a signal transferred with by a certain voltage/current, to all second circuitries 46 of the corresponding column of second circuitries 46, which resembles analog (static) beamforming within each column. Further, digital beamforming can be also supported between the columns. As in the arrangement of Fig. 8b, digital beamforming is enabled in the row direction, being the main extension direction of the plurality of first circuitries 42 in Fig. 8b, and analog beamforming is enabled in the column direction being the main extension direction of the second circuitries 46 of each column. It should be noted that the number of first circuitries 42 (one per column) and second circuitries 46 can be chosen arbitrarily and fig. 8b just shows an example of an 8 columns x 14 rows arrangement.

Further, Fig. 8c shows a top view of the third conductive sub-layer 50. The third conductive sub-layer 50 comprises second non-conductive slots 52, wherein each of the second conductive slots 52 is arranged for at least partially overlapping with a corresponding second circuitry 46 in the stacking direction. Thereby, as one can clearly conclude from Fig. 8c, the second slots 52 are arranged in columns and rows, thereby forming a corresponding array as the one formed in the second conductive sub-layer 40 by the second circuitries 46. In particular, these second slots 52 can be slanted (at +/- 45⁰) as in Fig. 8c, which further enables to provide a specific polarization of the signals radiated away from the antenna 10. The exact orientation of second slots 52 defines the polarization of the radiated signal radiated from antenna 10. Furthermore, between second slots 52, cutouts 53 (preferably metalized) can be provided. These cutouts 53 can be configured as elongated slots and extend in the stacking direction at least through the third conductive sub-layer 50 and the second dielectric sub-layer 31' and can engage corresponding alignment pins 68 of the antenna wall layer 60, thereby helping in attaching and aligning the antenna main layer 30 to the other layers of the antenna 10. Further, cutouts 53 and the embedded alignment pints 68 can also help for isolating purposes for further decoupling the first/second circuitries 42/46 from each other. The metallization of the cutouts can further improve the insulating properties. In this context it is noted that of course cutouts 53 are just one possibility formed as elongated slots, but also can be formed as a plurality of through holes as long as these through holes can serve for fixation and alignment purposes. The third conductive sub-layer 50 can also be used as a ground plane for the radiating patches 72. Further, the first, second and third conductive sub-layers 32, 40 and 50 can be made from plated copper or like.

Further, Fig. 9 shows a top view of the assembled antenna main layer 30 comprising the first conductive sub-layer 32, second conductive sub-layer 40 and third conductive sub-layer 50. There, one can see that the cutouts 53 are provided in third conductive sub-layer 50. Please note, that in the assembled state of Fig. 9 not only the first, second and third conductive sublayers 32, 40 and 50 are assembled, but the antenna main layer 30 also comprises a first dielectric sublayer 31 arranged between the first conductive sublayer 32 and the second conductive sublayer 40 and the second dielectric sublayer 31' arranged between the second conductive sub-layer 40 and the third conductive sub-layer 50. Therefore, cutouts 53 can extend not only through the third conductive sub-layer 50, but also at least through the second dielectric sub-layer 31' below the third conductive sub-layer 50. Further, as in the embodiment of Fig. 9, vias 54 can be provided between second non-conductive slots 52 and also around each of first circuitries 42 for decoupling the first and second circuities 46 from each other. An inner surface of these vias 54 can be plated with a metal, for example, copper. Further, the second non-conductive slots 52 can also be seen in the top view of the antenna main layer 30 of Fig. 9, being a PCB.

Fig. 10a shows a perspective view of the antenna wall layer 60 arranged above the third conductive sub-layer 50 of the antenna main layer 30 in the stacking direction, wherein the antenna wall layer 60 can comprise as can be seen in Fig. 10a a plurality of cavities, wherein each of the cavities 62 is arranged so that the cavity 62 overlaps at least partially with the corresponding second slot 52 of the third sub-layer 50 in the stacking direction, so that an array of cavities 62 is provided corresponding to the corresponding arrays of the third conductive-sublayer 50 and the second conductive sub-layer 40. Antenna wall layer 60 can be made of an electrically conductive material, for example, aluminum or metalized plastic. Cavities 62 are used so as the resonating antenna near fields are supported in air, and the antenna operation does not suffer from side effects caused by the usage of dielectric materials (losses, surface waves etc.). The walls of cavities 62 also serve for decoupling the individual patches 72 provided in the top layer 70 from each other. In the embodiment of Fig. loa-iob cavities 62 are more like shaped in a rectangular form. Differently shaped cavities (e.g. circular or polygonal) should are of course also possible. As can be seen in the enlarged view of Fig. 10b between the cavities 62 through holes 47 and further alignment pins 67 can be provided which serve for fixation and alignment purposes of the antenna wall layer 60 to the other layers of the antenna 10. In this context, for example, through holes 47 can be configured for accepting a corresponding screw for tightly fixing the antenna wall layer 60 within the antenna 10. Further, the walls of each cavity 62 also decouple adjacent resonators and improve the radiated cross polarization purity.

Fig. 11 shows a side view of the antenna wall layer 60. Antenna wall layer 60 is configured to engage with corresponding cutouts 53 in the antenna main layer 30. Therefore, alignment pins 68 on the bottom side 64 serve for alignment purposes for aligning antenna wall layer 60 with antenna main layer 30 and serves for fixation purposes of assembling antenna wall layer 60 with the other layers. Furthermore, optionally as also in Fig. 11 further alignment pins 67 can also be provided on the opposite top side 66 of the antenna wall layer 60, which are configured for engaging with corresponding cutouts 74 provided in the top layer 70. In an assembled state, due to the engagement of further alignment pins 67 with corresponding cutouts 74 in the top layer and engagement of alignment pins 68 with corresponding cutouts 53 provided in the antenna main layer 30, a distance h_cav as also indicated in Fig. 11 between the top layer 70 and antenna main layer 30 is defined. Therefore, by using the antenna wall layer 60 the distance between the top layer 70 and the antenna main layer 30 can also be freely adjusted and defined.

Fig. 12 shows a perspective view of top layer 70. In the embodiment of the Fig. 12, a plurality of conductive patches 72 are arranged, wherein each of the conductive patches 72 is provided in that way that each of the patches overlaps with a corresponding cavity 62 of the antenna wall layer 60 in the stacking direction, thereby an array corresponding to the arrays of the antenna wall layer 60 or the second and third conductive sub-layers 40 and 50 can be formed. The patches 72 can be printed on a surface of the top layer 70. In the embodiment of Fig. 12 each of the patches 72 is a circular patch, but also any other shape is conceivable. The circular patches 72 are printed on both sides of top layer 70 on, for example, a PCB, but could also be printed only on one side or intermediate layer of the PCB. The exact dimensions of these patches 72 as well as the distance between them (thickness of the dielectric core that is being used) are usually dependent on the operational frequency requirements and are accurately determined through electromagnetic simulations. In a general case, patches 72 of any shape can be used on either the top side and/or the bottom side of top layer 70. Furthermore, since each patch 72 is provided at such a position so as to at least partially overlap with a corresponding cavity 62 of the antenna wall layer 60 it is possible that all patches 72 of one column 73 are fed by one single through hole 26 serving as a port of the antenna. Further, each patch 72 is excited by using a corresponding non-conductive slot 52 of the third conductive sublayer 50, which allows the electromagnetic fields to couple and excite the corresponding resonant cavity 62 of each patch 72. Furthermore, in the arrangement of Fig. 12, plated vias 76 are provided around patches 72 for isolating purposes between patches 72, wherein vias 76 form rectangular cavities around patches 72 for improving isolation between patches 72 and suppress any surface waves that might be supported. Further, for the same reason metalized pads 78 (for example metalized with copper) are used to further isolate all patches 72 from each other, in particular at the corners of the patches 72. The metalized pads 78 are provided below and/or above corresponding vias 76, so that each end of a corresponding via 76 can be covered by a metalized pad 78. Further, cutouts 74 are provided in the top layer 70, being a PCB, which are configured for engaging with the corresponding protrusions 67 of antenna wall layer 60. These cutouts 74 serve for arriving at a mechanical stable arrangement and also serve for alignment purposes for aligning the top layer 70 to all other layers of the antenna. In the embodiment of Fig. 12, 4 rectangular cutouts 74 are provided around each of the circular patches 72.

Fig. 13 shows a top view of the assembled antenna 10. There, the array of circular patches 72 can be clearly seen. The array in this embodiment consists of 8 columns, each being composed of 14 circular patches 72.

Fig. 14a shows a photograph of the assembled antenna, wherein Fig. 14b shows from the left side to the right side of Fig. 14b the antenna main layer 30, antenna wall layer 60 and the top layer 70. Further, Fig. 14c shows a photograph in a cross-sectional view of the whole assembled antenna according to an embodiment the present invention. Further, it should be noted that the whole assembled antenna can be manufactured by providing in the stacking direction the antenna base layer 20, the antenna main layer 30, the antenna wall layer 60 and the top layer 70 and assemble these layers together by gluing these layers together by using conductive or non-conductive epoxies or by screwing these layers together by using screws, in particular micro screws.

The invention has been described in conjunction with various embodiments herein. However, other variations to the enclosed embodiments can be readily understood and effected by those skilled in the art and practicing the claimed invention from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor of the entity may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not initiate that a

combination of these measures cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid state medium, supplied together with or as part of other hardware, but may be also distributed in other forms, such as via the internet or other wired or wireless telecommunication systems.

Claims

SET OF CLAIMS

An antenna (10) comprising:

• an antenna base layer (20) having a bottom side (22) and an opposed top side (24) having at least one through hole (26) extending from the bottom side (22) to the top side (24) in a stacking direction, wherein a first section (27) at the bottom side (22) of the antenna base layer (20) of each of the at least one through holes (26) is configured to accommodate an end portion of a corresponding waveguide (100);

• an antenna main layer (30) arranged on the top side (24) of the antenna base layer (20) in the stacking direction, wherein the antenna main layer comprises:

o a first conductive sub-layer (32) as the lowermost layer of the antenna main layer (30) in the stacking direction comprising at least one first non-conductive slot (34) arranged so that each first slot (34) at least partially overlaps with a corresponding through hole (26) of the at least one through hole (26) of the antenna base layer (20) in the stacking direction;

o a second conductive sub-layer (40) arranged above the first sub-layer (32) in the stacking direction, the second sub-layer (40) comprising at least one first circuitry (42) configured to convert electromagnetic waves coming from the antenna base layer (20) into electromagnetic signals for a stripline transmission, wherein each of the at least one first circuitry (42) at least partially overlaps with a corresponding first slot (34) of the at least one first slot (34), and the second sub-layer(4o) further comprises at least a transmission line (44) for the stripline

transmission and at least one second circuitry (46) configured to convert transmission signals of the stripline transmission into electromagnetic waves radiated away from the second sub-layer (40), wherein the transmission line (44) connects a first circuitry (42) of the at least one first circuitry (42) with a corresponding second circuitry (46) of the at least one second circuitry (46);

o a third conductive sub-layer (50) arranged above the

second sub-layer (40) in the stacking direction comprising at least one second non-conductive slot (52), wherein each of the at least one second slot (52) is arranged for at least partially overlapping with a corresponding second circuitry (46) of the at least one second circuitry (46) in the stacking direction;

• an antenna wall layer (60) arranged above the third conductive sublayer (50) of the antenna main layer (30) in the stacking direction, the antenna wall layer (60) comprising at least one cavity (62) extending from a bottom side (64) of the antenna wall layer (60) to a top side (66) of the antenna wall layer (60) in the stacking direction, wherein each of the at least one cavity (62) is arranged so that the cavity (62) overlaps with a corresponding second slot (52) of the third sub-layer (50) in the stacking direction;

• a top layer (70) comprising at least one conductive patch (72) arranged on the antenna wall layer (60) so that each of the at least one patch (72) overlaps with a corresponding cavity (62) of the antenna wall layer (60) in the stacking direction.

2. Antenna (10) according to claim 1, wherein

each through hole (26) within the antenna base layer (20) comprises a second section (28);

wherein the first section (27) of each through hole (26) extends from the bottom side (22) of the antenna base layer (20) to the second section (28) of the corresponding through hole (26);

wherein the second section (28) of each through hole (26) extends from its corresponding first section (27) to the top side (24) of the antenna base layer (20); wherein the dimensions of second section (28) of each through hole (26) are adapted to match the impedance of the first section (27) to the impedance of the corresponding first slot (34).

3. Antenna (10) according to any of the preceding claims,

wherein the antenna main layer (30) comprises a first dielectric sub-layer (31) arranged between the first conductive sub-layer (32) and the second conductive sub-layer (40);

wherein the antenna main layer (30) further comprises a second dielectric sublayer (31') arranged between the second conductive sub-layer (40) and the third conductive sub-layer (50).

4. Antenna (10) according to claim 3, wherein the third conductive sublayer (50) comprises two or more second slots (52) and between each of the two or more second slots (52) in the third conductive sub-layer (50) a cutout (53) is provided which extends along the stacking direction at least through the second dielectric sub-layer (31')·

5. Antenna (10) according to claim 4, wherein on the bottom side (64) of the antenna wall layer (60) alignment pins (68) are provided and engaged with the corresponding cutouts (53) in the antenna main layer (10).

6. Antenna (10) according to claim 4, wherein

between the two or more second slots (52) of the third sub-layer (50) at least one via (54) is provided which extends along the stacking direction through the antenna main layer (30), wherein an inner surface of the via (54) is plated with an electrically conductive material.

7. Antenna (10) according to any of the previous claims, wherein on the top side (66) of the antenna wall layer (60) alignment pins (67) are provided and engaged with corresponding cutouts (74) in the top layer (70).

8. Antenna (10) according to any of the previous claims, wherein the top layer (70) comprises a dielectric substrate wherein the conductive patches (72) are arranged on either the top side or the bottom side of the substrate or on both sides of the substrate.

9. Antenna (10) according to any of the preceding claims, wherein

the top layer (70) comprises two or more patches (72) and between the two or more patches (72) cutouts (74) are provided in the top layer (70).

10. Antenna (10) according to any of the preceding claims, wherein the top layer (70) comprises two or more patches (72) and between the two or more patches (72) vias (76) having an inner plated surface are provided.

11. Antenna (10) according to claim 10, wherein both ends of the vias (76) are covered with metalized pads (78).

12. Antenna (10) according to any of the preceding claims, wherein the

antenna base layer (20) and the antenna wall layer (60) are made from an electrically conductive material, preferably aluminium.

13. Antenna (10) according to any of the preceding claims, wherein for each of the at least one first circuitry (42) the first circuitry (42) is configured to split a signal, being the electromagnetic waves coming from the antenna base layer (20), into two signals, constituting the electromagnetic signals for the stripline transmission, for two opposing sides of the first circuitry (42) within a plane perpendicular to the stacking direction, wherein each side of the two opposing sides comprises at least one second circuitry (46), wherein the at least two second circuitries (46) on both sides constitute together within the plane a column of second circuitries (46).

14. Antenna (10) according to claim 13, wherein the two signals after the

splitting have different phases.

15. Antenna (10) according to claim 13 or 14, wherein within the plane more than one column (46') of second circuitries (46) is provided, thereby forming an array of second circuitries (46).

16. System comprising an antenna (10) according to any of claims 1 - 15 and a block (90) comprising at least one waveguide (100), wherein the block (90) is attached to the antenna (10) and the waveguide (100) has a body (110) with a first end having an opening and the first end is encompassed by the corresponding through hole (26) of the antenna base layer (20) and a main extension direction, being a direction of a largest extension, of the waveguide (100) coincides with a main extension direction of the corresponding through hole (26).

17. A method for manufacturing an antenna (10) according to any of claims 1 - 15, comprising the step of stacking in the stacking direction the antenna base layer (20), the antenna main layer (30), the antenna wall layer (60) and the top layer (70) and assembling theses layers together by gluing these layers together by using conductive or non-conductive epoxies or by screwing these layers together by using screws, in particular micro-screws.