The present disclosure relates to a feeding system for an array of BoR antenna elements and a BoR antenna array.

BACKGROUND ART

Antennas are known in the art and used to convert radio frequency fields into alternating current or converting alternating current into electromagnetic fields.

Antenna arrays with a set of two or more antenna elements are commonly used in various applications to combine or process signals from the antenna array in order to achieve improved performance over that of a single antenna element. For instance they are able to match a radiation pattern to a desired coverage area, changing radiation pattern, adapting to changing signal conditions and some configurations can cover a large bandwidth. Antenna arrays can be described by their radiation patterns and by the type of antenna elements in the system.

An antenna array usually comprises antenna elements and some sort of feeding system coupled to the antenna arrays. The feeding systems and the antenna arrays can have different characteristics and designs. Many antenna arrays that are currently available on the market, usually have quite complex, heavy designs being costly to manufacture. The weight of the antenna arrays limits their appliances considerably.

For instance, antennas used in small sized unmanned aerial vehicles are demanded to be of low-weight. However, in some applications the antenna array and the feeding system in particular may require small mechanical dimensions which makes it increasingly challenging to manufacture. Other, requirements in today’s antenna arrays are for them to be cost-efficient without having a trade-off for the robustness and stability of the antenna array.

There is room for antenna arrays in the present art to explore the domain of providing an antenna array with simplicity in design and manufacturing, compared to previous solutions. There is specifically a need in the present art for improved feeding systems for antenna arrays having reduced weight, being cost-efficient, flexible in design and having simplified manufacturing.

CN106785465 discloses a broadband low profile common back cavity microstrip slot array antenna comprising a dielectric substrate, a feeding microstrip line, a radiation gap, a metal back cavity and a coaxial connector, wherein the metal back cavity adopts a short cavity structure and a cavity. The cavity wall is provided with a screw mounting hole for fixing the dielectric substrate on the upper part of the metal back cavity.

Even though some currently known solutions work well in some situations it would be desirable to provide an antenna array and a feeding system that fulfils requirements related to improving the cost-efficiency, weight, flexibility in design and the manufacturing of antenna arrays and feeding systems.

SUMMARY OF THE INVENTION

It is therefore an object of the present disclosure to provide an antenna array and a feeding system for an antenna array to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages.

This object is achieved by means an antenna array and a feeding system as defined in the appended claims.

In accordance with the invention there is provided a feeding system according to claim 1 and an antenna array according to claim 13

The present disclosure provides a feeding system for an array of BoR antenna elements. The feeding system has a first axis extending in a first direction in a first plane and a second axis extending in a second direction in the first plane, the first direction being perpendicular to the second direction, the feeding system further comprising: a substrate having a connecting surface and a back surface, each of the connecting surface and the back surface being parallel to the first plane and arranged on opposite sides of the substrate, wherein the connecting surface comprises an electrically conductive pattern having a plurality of receiving portions, each receiving portion being arranged to receive a BoR antenna element extending in a third direction perpendicular to said first plane, at least one connector positioned on the back surface, wherein each connector is connected to a feeding line, each feeding line extending from the back surface to said connecting surface, wherein each feeding line is adapted to extend in the first direction or said second direction in-between two adjacent receiving portions so as to form a signal-section; at least one reflecting cavity section having a first thickness, wherein each reflecting cavity section extends in a direction opposite to said third direction from a corresponding signal-section so as to reflect a signal emitted from the corresponding signal-section.

A benefit of the feeding system is that it allows for fast manufacture, and flexibility in the design and routing of the antenna elements and other components such as the feeding lines. The electrically conductive pattern allows for the feeding lines and other active and passive components to be mounted on the substrate in a flexible manner. Further, different polarizations of the antenna can be implemented without any major modifications in the manufacturing process. Furthermore, the design of the feeding system allows for the possibility to mount the feeding line and other active and passive components in very close vicinity of the antenna elements. The connectors may be adjusted to fit the microwave electronics in direct vicinity of the antenna. Also, the weight of the feeding system can be lower since it utilizes a substrate which may have a low weight.

Moreover, the feeding line may be printed on the connecting surface by means of simple and efficient manufacturing processes thereby alleviating the need of labour intensive post processing steps for ensuring proper formation of the signal sections.

The components of the feeding system may be assembled by automatic standard pick- and-place assembly machines, allowing for a low assembly cost of the feeding system. Specifically compared to other solutions. Further, the substrate may be a flexible substrate which may be bent according to a sought contour. Further, The connecting side and the back surface

The substrate may comprise a second thickness extending from said connecting surface to said back surface, wherein said reflecting cavity section is fully incorporated within the second thickness of said substrate. A benefit of having the reflecting cavity section fully incorporated in the substrate is that it allows for the thickness of the reflecting cavity section to be smaller and consequently for reduced antenna profile.

The second thickness may be the same or greater than the first thickness. This may allow for the reflecting cavity section to be as thick as the substrate or smaller than the substrate. However, in some embodiments, the substrate comprises a second thickness extending from said connecting surface to said back surface, wherein said second thickness is smaller than said first thickness. This allows for the substrate to be thin and for the reflecting cavity section to extend beyond the thickness of the substrate, in other words to not be fully incorporated in the substrate.

The reflecting cavity section may be defined by round-shaped or polygonal-shaped shielding enclosure extending from said connecting surface in a direction opposite to said third direction, wherein said reflecting cavity section further comprises a reflecting surface, said reflecting surface being parallel to said first plane. The enclosed shape of the reflecting cavity section improves isolation between the antenna elements by restricting the propagation of waves between the antenna elements in the array. The reflecting surface allows for the signals from the signal section to be reflected towards the antenna elements.

Further, the shielding enclosure and the reflecting surface may be metallized, which allows them to efficiently reflect the emitted signals from the signal section. Furthermore, the substrate may be a printed circuit board, PCB.

The plurality of receiving portions may comprise a first receiving portion and a second receiving portion, wherein the feeding line extends from said first receiving portion to the second receiving portion, wherein the feeding line is grounded in the second receiving portion.

Further, each feeding line may comprise a portion extending from said back surface to said connecting surface in said third direction through a via in said substrate, wherein each feeding line protrudes from one of said a plurality of receiving portions along said connecting surface. By having at least one via in the substrate through which each feeding line extends, each feeding line may have a direct route from the back surface to the connecting surface. The feeding system may further comprise Surface-mount technology, SMT, components. A benefit of this is that it further increases the manufacturing speed of the feeding system since the SMT components can be mounted rapidly on the substrate. Further, a spacing may be defined between two adjacent receiving portions, wherein said signal section of each feeding line extends along a minimum distance of the spacing.

Each of said a plurality of receiving portions may comprise a feeding line extending to an adjacent receiving portion in the first direction and a feeding line extending to an adjacent receiving portion in the second direction, forming two signal sections extending perpendicular in relation to each other, allowing for vertical and horizontal polarization.

There is further provided a BoR antenna array comprising a feeding system; and a plurality of BoR antenna elements arranged on the plurality of receiving portions.

The plurality of BoR antenna elements arranged on the plurality of receiving portions may be inverted antenna elements comprising; a three dimensional block of dielectric forming a plurality of BoR-cavities on a first surface of the block of dielectric; wherein the BoR-cavities extend essentially perpendicular to the first surface into the block in a tapered manner, wherein at least the plurality of BoR-cavities on the first surface comprises an electrically conductive coating having a third thickness forming inverted BoR antenna elements; wherein, the plurality of inverted antenna elements are coupled to the feeding system. The three dimensional block of dielectric may be a flexible dielectric. The three dimensional block of dielectric may have a polygonal shape or a circular shape or any other suitable shape.

A benefit of having inverted BoR elements coupled to the feeding system is that the inverted BoR elements are fast to manufacture, requiring less manufacturing steps. Futher, inverted BoR elements are easier to mount on a feeding plate, since they are incorporated in the block of dielectric and hence a plurality of BoR elements can be handled as one piece.

The plurality of inverted antenna elements may be coupled to the feeding system by coupling of the first surface to the connecting surface. Accordingly, the first surface is adapted to be directly coupled to the connecting surface. Further, the plurality of inverted antenna elements may comprise a second surface on said block of dielectric, wherein said second surface is formed to be adapted to fit in a radome or any other type of enclosure.

The block of dielectric may have a relative permittivity within the range of 1-10, preferably within the range of 1-5. Accordingly, this allows the antenna elements to be adapted to cover a large operational bandwidth. Further, the block of dielectric may have a relative permittivity and/or permeability which varies across the body of the block of dielectric. A relative permittivity and/or permeability which varies across the body of the block of dielectric allows for static shaping of the element gain patterns. The plurality of BoR-cavities may be at least partially filled with a filler material. This allows the BoR-elements to be more robust and gives a better reliability in different environmental settings.

Further, the BoR antenna array may comprise frequency band ranges within the range of 100 MFIz-50GFIz, or within the range of 2-18 GFIz, or within the range of 2-6 GFIz. The BoR antenna array is therefore adapted to work in markets such as telecom or within electronic warfare systems.

The electrically conductive coating may comprise a minimum thickness being at least within the range of 0.2pm-8pm on a frequency band within the range of lOOMFIz- 50GFIz. Flence, the electrically conductive coating may be held with a low thickness while not suffering any current loss, avoiding harming the functioning of the inverted antenna elements. In other words, the minimal thickness of the electrically conductive coating may be at least within the range of 0.2pm-8pm on a frequency band within the range of 100MFIz-50GFIz. A benefit of having a minimum thickness being at least within the range of 0.2pm-8pm is that the weight of the inverted antenna elements may be kept low by having a lower thickness of the electrically conductive coating. The skin depth of the antenna element may be at least within the range of 0.2pm-8pm on a frequency band within the range of 100MFIz-50GFIz.

There is further provided a method for manufacturing an antenna array/BoR antenna array having inverted antenna elements, comprising the steps of: providing a three dimensional block of dielectric; forming a plurality of cavities on a first surface of the block of dielectric, wherein the cavities extend essentially perpendicular to the first surface into the block of dielectric; providing at least the plurality of cavities on the first surface with an electrically conductive coating having a third thickness, forming inverted antenna elements; assembling a feeding system on said first surface of said block of dielectric.

The cavities may be formed by any suitable hole-making operation. The electrically conductive coating may be a metal. In other words, the first surface may be metallized. The three dimensional block of dielectric may be a flexible dielectric.

A benefit of the method is that it allows for a fast and cheap manufacturing of antenna elements. Further, since the antenna elements are formed by a conductive coating a formed cavity in the block of dielectric, it allows for manufacturing of antenna elements having small dimensions without resulting in any delays in the manufacturing process. The method as disclosed herein of forming antenna elements that are incorporated in a block of dielectric further allows for a higher durability of the antenna elements compared to other solutions.

The plurality of cavities may be BoR shaped-cavities extending in a tapered manner, forming BoR-shaped antenna elements. BoR antenna elements may cover a large bandwidth. Accordingly, the method provides for a rapid manufacturing of antenna elements covering a large bandwidth. A BoR antenna element adapted to cover a high frequency will have shrinking mechanical dimensions and may be challenging to manufacture. The physical size of a BoR antenna element is determined by the frequency band of operation. Accordingly, the physical size of a BoR antenna element scale inversely with frequency. Further, a BoR antenna element adapted to high frequencies will be challenging to manufacture due to it having small mechanical dimensions. Flowever, the manufacturing method according to the disclosure allows for a fast and convenient manufacturing of BoR antenna elements also for high frequencies. Further, the inverted BoR may achieve an increased durability, in other words, by having the BoR antenna elements incorporated and manufactured in a block of dielectric, the BoR antenna elements allow for increased durability. The BoR antenna elements may be manufactured despite shrinking mechanical dimensions giving increasing manufacturing tolerances, this may open for new appliances of the BoR antenna elements allowing them to be applied to low-cost and huge-volume markets such as telecom. The weight of the inverted antenna elements may be low given that the inverted antenna elements mainly uses a dielectric, having electrically conductive coatings.

The method may further comprise the step of assembling a feeding system on the first surface of the block of dielectric. A benefit of this is that the feeding system and the antenna elements may be manufactured independently and be assembled in a last step. Further, the first surface of the block of dielectric is the surface that is modified in order to provide the block of dielectric with antenna elements. Hence, the manufacturing method as disclosed herein allows for coupling of the feeding system to the inverted antenna elements, wherein a first antenna array may adapt its first surface to a first feeding system, wherein a second antenna array may adapt its first surface to a second feeding system.

The electrically conductive coating may comprise a minimum thickness being at least within the range of 0.2pm-8pm on a frequency band within the range of 100MHz- 50GHz. Hence, the electrically conductive coating may be held with a low thickness while not suffering any current loss, avoiding harming the functioning of the inverted antenna elements. In other words, the minimal thickness of the electrically conductive coating may be within the range of 0.2pm-8pm on a frequency band within the range of 100MHz-50GHz. A benefit of having a minimum thickness being within the range of 0.2pm-8pm is that the weight of the inverted antenna elements may be kept low by having a lower thickness of the electrically conductive coating. The skin depth of the antenna element may be at least within the range of 0.2pm-8pm on a frequency band within the range of 100MHz-50GHz.

The method may further comprise the step of forming a second surface on said block of dielectric so as to fit in a radome or any other type of enclosure, wherein the second surface of said block of dielectric is the opposing surface of the first surface. Antenna arrays are often enclosed in a radome that protects the antenna from the environments. The antenna array and the radome are typically designed separately, often by different suppliers which might result in a design that is hard to put the antenna array in. Accordingly, the present disclosure provides inverted antenna elements that are incorporated in the block of dielectric, wherein the second surface of the block of dielectric may be formed to be adapted to fit in a radome. The dielectric may act as a supporting structure for a radome. Further, the dielectric may function as a radome.

Inverted antenna elements provide a benefit of in a simple manner being able to be fit in a block of dielectric.

The plurality of cavities may be formed by at least one of drilling, casting, milling or additive manufacturing. The plurality of cavities may be formed by a drill, wherein the drill comprises a drill bit having the shape of an antenna element. The drill bit may be adapted to form the shape of a BoR antenna element.

The electrically conductive coating may be deposited fully on the first surface.

However, the method may further comprise the step of removing at least a part of the electrically conductive coating in-between the plurality of cavities on the first surface of said block of dielectric. In other words, residual conductive coating deposits in between the antenna elements may be removed. According to some embodiments a part of the conductive coating deposits in-between the antenna elements may be removed. The removal of the electrically conductive coating may allow for a lower weight and for adaptation of the inverted antenna elements to the feeding system.

The inverted antenna elements may be hollow. However, the method may further comprise the step of at least partially filling the plurality of cavities with a filling material after the conductive coating has been provided. This may provide for increased rigidity and a better reliability in different environments of the inverted antenna elements.

Thus, the inverted antenna elements may avoid problems arising due to environmental factors. The inverted antenna elements may avoid deformation of the antenna elements or other implications that may arise in different environments such aschange in ambient temperature and/or pressure.

The method may further comprise a block of dielectric having a relative permittivity within the range of 1-5. The block of dielectric may have a high relative permittivity in order to reduce the physical size of the antenna elements. The higher relative permittivity of the block of dielectric, the smaller antenna elements. However, a high relative permittivity might result in reduced operational bandwidth of the antenna. The block of dielectric may have a relative permittivity and/or permeability which varies across the body of the block of dielectric. This may allow for antenna pattern optimization.

According to some embodiments, the BoR antenna array is arranged in an electronic warfare system, or a radar system, or a base station.

Further, there may be provided a vehicle comprising the BoR antenna array. Furthermore, there may be provided a base station that comprises the BoR antenna array.

It is to be understood that the herein disclosed disclosure is not limited to the particular component parts described or steps described since such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the disclosure will be described in a non-limiting way and in more detail with reference to exemplary embodiments illustrated in the enclosed drawings, in which:

Figure 1 Depicts an isometric view of a BoR antenna array

Figure 2 Depicts a top view of a feeding system

Figure 3 Depicts a top view of a schematic circuit representation of a feeding system

Figure 4 Depicts a side view of a BoR antenna array

Figure 5 Depicts a side view of a BoR antenna array where the reflecting cavity section is incorporated in the substrate Figure 6 Depicts a side view of BoR antenna array where the BoR antenna elements are inverted Figure 7 Depicts a side view of BoR antenna elements where the BoR antenna elements are inverted

Figure 8 Depicts an isometric view of a BoR antenna array with inverted antenna elements

Figure 9 Depicts an isometric view of inverted antenna elements Figure 10 Depicts a cross-sectional side-view of inverted BoR antenna elements Figure 11 Depicts a cross-sectional side-view of inverted BoR antenna elements

Figure 12 Depicts a method for manufacturing inverted antenna elements

DETAILED DESCRIPTION

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

In the following description of example embodiments, the same reference numerals denote the same or similar components.

The term “BoR” refers to Body-of-Revolution, a body that is rotational symmetric, a BoR antenna element refers to an antenna element that has a round shape extending into an oblong object. A BoR antenna may for instance have the shape of a cylinder or a cone. A benefit of having a BoR antenna is that it is mechanically robust and can be designed to cover a large bandwidth. Moreover, a BoR-element may be understood as a Vivaldi-like three-dimensional antenna element. The term “feeding line” refers to a cable or other transmission line that connects the antenna with a connector that may be transmitting and/or receiving signals. In a transmitting antenna, it feeds the radio frequency current from the transmitter to the antenna, where it is radiated as radio waves. In a receiving antenna it transfers the radio frequency voltage induced in the antenna by the radio wave to the connector. Feeding lines can be made of any type of cable that can carry radio frequency current efficiently, such as coaxial cable or a waveguide.

The term “antenna array” or “array of antenna elements” refers to a set of multiple connected antennas which work together as a single antenna. In this disclosure the term “antenna array” refers to at least two antenna elements. The term “RF” refers to radio frequency which is an electromagnetic wave having a frequency.

The term “substrate” refers to a non-conductive or dielectric substrate that may comprise conductive tracks, vias and pads, laminated on, under or between different layers of the substrate. It may further comprise electrical components such as amplifiers, switches and DC circuitry.

Figure 2 disclose top views of a feeding system 1 and Figure 3 discloses a top view of a schematic circuit representation of a feeding system 1 for an array of BoR antenna elements 2, 21 having a first axis extending in a first direction x1 in a first plane xy and a second axis extending in a second direction y1 in the first plane xy , the first direction x1 being perpendicular to the second direction y1 , said feeding system 1 further comprising: a substrate 4 having a connecting surface 5 and a back surface 6, each of the connecting surface 5 and the back surface 6 being parallel to the first plane xy and arranged on opposite sides of the substrate 4, wherein the connecting surface 5 comprises an electrically conductive pattern having a plurality of receiving portions 7, each receiving portion 7 being arranged to receive a BoR antenna element 2 extending in a third direction z1 perpendicular to said first plane xy, at least one connector 8 positioned on said back surface 6, wherein each connector 8 is connected to a feeding line 9, each feeding line 9 extending from said back surface 6 to said connecting surface 5, wherein each feeding line 9 is adapted to extend in the first direction x1 or said second direction y1 in-between two adjacent receiving portions 7 so as to form a signal-section 10; at least one reflecting cavity section 11 having a first thickness t1 , wherein each reflecting cavity section 11 extends in a direction opposite to said third direction z1 from a corresponding signal-section 10 so as to reflect a signal emitted from the corresponding signal-section 10. The emitted signal may be transmitted from the connector 8 to surrounding air. The electrically conductive pattern of the receiving portions 7 may cover (only) the circumference of each of the receiving portions 7 or the electrically conductive pattern may fill the surface of each of the receiving portions 7. A hollow BoR antenna element may be coupled to a receiving portion 7 with an electrically conductive pattern covering (only) the circumference of each receiving portion 7. The receiving portions may comprise a metallic pattern.

As disclosed in figure 2 and 3, the feeding system 1 has a rectangular shape, however it may have any suitable polygonal or round shape. Figure 2 shows the connecting surface 5 of the feeding system 1. There is disclosed in Figures 2 and 3 a plurality of receiving portions 7 each having a round shape. The receiving portions 7 are adapted to receive a BoR-element that extends perpendicular to the first plane xy in the third direction z1. The plurality of receiving portions 7 may be evenly distributed on the connecting surface 5 such as disclosed in figure 2 and 3.

As disclosed in Figure 2 and Figure 3, the feeding system 1 may comprise a plurality of feeding lines 9 extending between two adjacent receiving portions 7. Thus, the feeding lines 9 are adapted to extend between two adjacent antenna elements 2, 21 , so as to form a signal-section 10 between the two adjacent antenna elements 2, 21. Flence, in a feeding system 1 , all receiving portions 7 may be partially traversed by a feeding line

9 in the first plane xy direction as shown in Figure 2 and Figure 3. The signal-section

10 may propagate an RF wave.

There is further disclosed in Figure 4-7 a reflecting cavity section 11 extending in a direction opposite to the third direction z1 perpendicular to the first plane xy. As disclosed in Figure 4-7, the reflecting cavity sections 11 are positioned below each signal-section 10. This allows for the signals emitted from the signal-section 10 to be reflected in the reflecting cavity section 11. The reflecting cavity section 11 may allow for constructive interference of the emitted signals from the signal-section 10. The reflection of the emitted signals allow for superposition and the creation of a new wavefront which may be stronger than the original wavefront. Hence, each reflecting cavity section 11 may increase the signal strength of an antenna. The reflecting cavity section 11 may have a first thickness t1 that is substantially equal to a quarter wavelength of the highest operating radio frequency of the emitted signal from each signal-section 10. The term “substantially” as used in this context refers to that the first thickness t1 may be +-5% of a quarter wavelength of the highest operating radio frequency. The first thickness of the reflecting cavity section 11 may be adapted to reflect a wave to allow for constructive interference. Hence, the first thickness of the reflecting cavity section 11 may be adapted to have a thickness that reflects a first wave to interfere with a second wave wherein the resulting wave comprises an amplitude which is equal to the sum of the individual amplitudes of the first and the second waves, wherein the resulting wave propagates in the third direction z1.

As further disclosed in figure 2 and 3 there is at least one connector 8 positioned on the back surface 6, wherein the at least one connector 8 is connected to a feeding line 9. The connector 8 may be a RF coaxial connector 8 that is adapted to receive and/or transmit radio frequency signals. The feeding line 9 may be a micro strip line. The feeding system 1 may be implemented in an antenna adapted to transmit and/or receive signals within a frequency range (i.e. frequency band). The coaxial connector 8 may therefore be adapted to receive RF or transmit RF. The construction of the feeding system 1 as disclosed herein allows for a connector 8 to be placed with a higher degree of freedom than previously known solutions in order to match other electronics that may be connected to the feeding system 1.

As seen in Figure 5, the substrate 4 may comprise a second thickness t2 extending from said connecting surface 5 to said back surface 6, wherein said reflecting cavity section 11 is fully incorporated within the second thickness of said substrate 4. As seen in Figure 5 the first thickness is smaller than the second thickness. However, as Figure 6 discloses, the first thickness and the second thickness may be the same. The reflecting cavity section 11 is fully incorporated within the substrate 4 in both Figure 5 and Figure 6. The substrate 4 may have a permittivity in the range of 1.0-6. The incorporation of the reflecting cavity section 11 in the substrate 4 allows for the first thickness t1 of the reflecting cavity section 11 to be smaller compared to if the reflecting cavity section 11 is implemented such that it extends in a direction opposite to the third direction z1 as disclosed in Figure 4 and Figure 7, where air is the medium in the reflecting cavity section 11.

The wavelength can be calculated by the formula l = v/f, where l is the wavelength in meters, v is the velocity in m/s, and f is the frequency in Hz. Accordingly, the higher the relative per ittivity, the lower the speed of propagation of an electromagnetic wave will be. Hence, by using a substrate 4 with a relative permittivity at least slightly above 1 which is the relative permittivity for air - the wavelength will be shorter and hence the first thickness t1 can be reduced which allows for a cheaper manufacturing and decreased physical depth of the feeding system 1. !n other words, by incorporating the reflecting cavity section 11 in the substrate 4 the feeding system 1 can achieve a more slim design giving a lower profile while maintaining the equivalent performance. A lower profile of the feeding system 1 may be beneficial in hull-integrated sensors.

According to some embodiments, the second thickness t2 is the same or greater than the first thickness t1. This is further shown in Figure 5 and Figure 6. In Figure 6 the first thickness t1 and the second thickness t2 are equal. In Figure 5, the first thickness is greater than the second thickness t2. Further, in Figures 4 and 7 the reflecting cavity section 11 is not fully incorporated in the substrate 4. Figure 7, discloses that the reflecting cavity section 11 extends opposite to the third direction z1 from the connecting surface 5 beyond the back surface 6 of the feeding system 1.

As disclosed in Figures 2-6, the reflecting cavity section 11 may be defined by a polygonal-shaped shielding enclosure 12 extending from said connecting surface 5 in a direction opposite to said third direction z1, wherein said reflecting cavity section 11 further comprises a reflecting surface 13, said reflecting surface 13 being parallel to said first plane xy. The reflecting cavity section 11 may further be defined by a round shaped shielding enclosure 12.

Figure 2 discloses that the reflecting cavity section 11 is defined by a “diamond shaped” (may also be referred to as rectangular or quadratic) enclosure 12 extending opposite to the third direction z1. The reflecting cavity section 11 may have other suitable shapes such as a circular shape, a quadratic shape, a rectangular shape, a hexagonal shape or any other suitable shape. As seen in figure 2 and figures 5-7, the shielding enclosure 12 may be defined by the shape that extends opposite to the third direction z1 from the connecting surface 5, and the reflecting surface 13 is defined by a surface that extends parallel to the first plane xy and that unites the shielding enclosure 12. The figures 5-7 discloses that the reflecting surface 13 unites the shielding enclosure 12 on the end of its extension in the direction opposed to the third direction z1.

The shielding enclosure 12 and the reflecting surface 13 may comprise metal or may be metallized. By having the shielding enclosure 12 and the reflecting surface 13 comprising metal or being metallized it will allow the RF signals to reflect in an efficient manner.

The substrate 4 may be a PCB having at least one sheet layer of dielectric substrate.

As shown in Figures 2 and 3, the plurality of receiving portions 7 comprises a first receiving portion 14 and a second receiving portion 15, wherein said feeding line 9 extends from said first receiving portion 14 to said second receiving portion 15, wherein said feeding line 9 is grounded in said second receiving portion 15. As shown in Figures 2 and 3, the feeding line 9 is grounded on the second receiving portion 15, since the signal emitted from the connector 8 can be shorted after the signal-section 10. Accordingly, each feeding line 9 extends between two receiving portions 7 and a gap there-between, the gap forms the signal-section 10, and the feeding line 9 is grounded at one of the two receiving portions 7. The feeding line 9 should not come into contact with any conductive element in the first receiving portion 14 since it may short the feeding line 9 prior to its extension to the second receiving portion 15, which may result in a shorted signal-section 10. Thus, the connecting surface 5 may comprise an insulating space separating the feeding line 9 from contact with any conductive element in the first receiving portion 14.

As disclosed in Figure 5, each feeding line 9 may comprise a portion extending from said back surface 6 to said connecting surface 5 in said third direction z1 through a via 16 in said substrate 4, wherein each feeding line 9 protrudes from one of said a plurality of receiving portions 7 along said connecting surface 5. The via 16 allows for the feeding line 9 to extend a more direct route to the first receiving portion 14 without interfering with any components i.e. the current can flow unrestricted to its path. The feeding lines 9 may be adapted to not interfere with any conductive and/or non- conductive components or surfaces in its extension from the connector 8 to at least a part of the second receiving portion 15 - this may optimize the flow of the current through each feeding line 9. The connecting surface 5 may further comprise a channel on its surface in the first plane xy adapted for the feeding line 9.

The feeding system 1 may further comprise Surface-mount technology (SMT) components. SMT components may be mounted on the connecting surface 5. SMT may be passive or active components. SMT components may be components such as resistors, capacitors, transistors and diodes.

As shown in Figures 2-3, a spacing may be defined between two adjacent receiving portions 7, wherein said signal section 10 of each feeding line 9 extends a minimum distance of the spacing. The term “minimum distance” refers to the shortest distance between the edges of two adjacent receiving portions 7. In figures 2-3, all of the feeding lines 9 extend the minimum distance between two adjacent receiving portions 7. There may be equal spacing between the adjacent receiving portions 7 as disclosed in figures 2-3, however, the receiving portions may also have a varying spacing.

As seen in figure 1 the connecting surface 5 is adapted to receive BoR antenna elements 2, 21 that extend perpendicular to the first plane xy in the third direction z1. Accordingly, as shown in Figure 1 , the feeding system 1 may be coupled to a plurality of BoR antenna elements 2, 21. The BoR antenna elements 2, 21 may be adapted to avoid contact with a feeding line 9 in the first receiving portion 14 to prevent short circuit of the signal-section 10. Accordingly, the BoR antenna elements 2, 21 may comprise a groove adapted to avoid contact with the feeding line 9 on the first receiving portion 14. The groove in the BoR antenna elements 2, 21 may correspond to the form of the feeding line 9.

Figures 6-8 discloses a BoR antenna array 20 that may comprise; a plurality of inverted antenna elements 21 comprising; a three dimensional block of dielectric 22 forming a plurality of BoR-cavities 23 on a first surface 24 of the block of dielectric 22, wherein each of the plurality of BoR-cavities 23 having a first center axis c; wherein the BoR-cavities 23 extend essentially perpendicular to the first surface 24 into the block in a tapered manner, wherein at least said plurality of BoR-cavities 23 on the first surface 24 comprises an electrically conductive coating 26 having a third thickness t3 forming inverted BoR antenna elements 21; wherein, the plurality of inverted antenna elements 21 are coupled to a feeding system 1. The third thickness t3 is disclosed in figures 10 and 11.

The term “inverted” as used herein refers to that the antenna elements are created by a hole-making operation in a block of dielectric 22, becoming a part of the block of dielectric 22. A hole-making operation may be drilling. As shown in figures 6-8 the plurality of inverted antenna elements 21 may extend perpendicular to the connecting surface 5 of the feeding system 1. Further, the BoR-elements are formed by a cavity in the block of dielectric 22, wherein the cavities 23 comprise an electrically conductive coating 26. As seen in Figures 6-8, the cavities 23 are BoR-shaped, hence the antenna elements 21 are BoR antennas.

The block of dielectric 22 further comprises a second surface 25, wherein the second surface 25 may be formed to be adapted to fit in a radome or any other type of protective enclosure. This is shown in figures 10 and 11 where the second surface 25 have different shapes. In Figure 10, the second surfaces 25 has a spherical shape.

The inverted antenna elements 21 provide the advantage of having a high durability due to their design. The block of dielectric 22 may function as a protective enclosure by covering the circumference of each antenna element.

As seen in Figures 6-8, the plurality of inverted antenna elements 21 are coupled to said feeding system 1 by coupling of said first surface 24 to said connecting surface 5. The first surface 24 and the connecting surface 5 may have the same dimensions.

The block of dielectric 22 may have a relative permittivity within the range of 1-5.

The block of dielectric 22 may have a relative permittivity and/or a permeability which varies across the body of the block of dielectric 22. A benefit of this is that the antenna beam may be shaped in desired way by providing a block of dielectric 22 comprising a varying permittivity. The term “varying” refers to that the relative permittivity and/or permeability varies with at least 5% between at least two different points on the block of dielectric 22. The plurality of BoR-cavities 23 may at least partially be filled with a filler material. A benefit of this is that it strengthens the rigidity of the respective antenna elements 2, 21 in different environmental settings and reduces the risk of condensation in temperature and pressure variations. The antenna elements 2, 21 may have a hollow shape.

The BoR antenna array 20 may comprise frequency band ranges within the range of 100 MHz-50GHz, or within the range of 2-18 GHz, or within the range of 2-6 GHz. Accordingly, the BoR antenna array 20 is adapted to work within several different industrial applications

Further, the BoR antenna array 20 may be arranged in an electronic warfare system, or a radar system, or a base station or any other suitable system having a frequency band range of 100MHz-50GHz.

Further, there may be provided a vehicle comprising the BoR antenna array 20. The vehicle may be an aircraft, a vessel or a ground vehicle. Furthermore, there may be provided a base station that comprises the BoR antenna array 20.

The physical size of a BoR antenna element is determined by the frequency band of operation. Accordingly, the physical size of a BoR antenna element scale inversely with frequency. Further, a BoR antenna element adapted to high frequencies will be challenging to manufacture due to it having small mechanical dimensions. The inverted BoR antenna elements 21 as disclosed herein can be manufactured despite shrinking dimensions due to their construction. Further, they may also be manufactured if they are directed to a low frequency where they require larger mechanical dimensions. Furthermore, the construction of the feeding system 1 as disclosed herein is also easy to manufacture and can be coupled to inverted BoR elements 21 of different dimensions.

Figure 12 further discloses a method 100 for manufacturing an antenna array/BoR antenna array 20 having inverted antenna elements 2, 21 , comprising the steps of: providing 101 a three dimensional block of dielectric 22; forming 102 a plurality of cavities 23 on a first surface 24 of the block of dielectric 22, wherein the cavities 23 extend essentially perpendicular to the first surface 24 into the block of dielectric 22; providing 103 at least the plurality of cavities 23 on the first surface 24 with an electrically conductive coating 26 having a third thickness t3, forming inverted antenna elements 2, 21 ; assembling 104 a feeding system 1 on said first surface 24 of said block of dielectric 22.