Antenna array module

Abstract

The present invention relates to an antenna array module for a communication system on a cargo ship, the antenna array module comprising at least a first antenna element (11), a second antenna element (12) and a third antenna element (16), each antenna element being mounted on a ground plane and comprising an antenna feed. The first antenna element (11) is tilted relative to the second antenna element (12). The first antenna element and the second antenna element are arranged to radiate along a first path along the cargo ship, and the third antenna element (16) is arranged to radiate mainly towards a second path opposite to the first path.

Description

Technical Field

[0001] The present invention generally relates to the field of antenna systems for use in systems for monitoring items. Background Art

[0002] Today, the vast majority of non-bulk cargo worldwide is transported on container ships (i.e., cargo ships that carry their entire load in standard-sized containers.) They can be loaded and unloaded, stacked, efficiently transported over long distances, and transferred from one mode of transport to another (e.g., not only container ships but also via rail or trucks) without opening.

[0003] Container ships come in a variety of sizes, with the largest measuring approximately 400 meters in length and having a capacity well over 10,000 TEUs (twenty-foot equivalent units). A typical load is a mix of 20-foot and 40-foot ISO standard containers, with the latter predominating. Container ships typically include one or more below-deck cargo holds. The cargo holds used in specialized container ships are specially constructed to speed up loading and unloading and efficiently keep containers secure at sea. Within the holds, slot guides—rigid, vertical metal structures—are installed that guide the containers into clearly defined rows during the loading process and provide some support against the ship's rolling motion at sea. The holds are covered by hatch covers, onto which more containers can be stacked.

[0004] Systems have been developed for monitoring cargo in transit without requiring any manual processes. Such prior art systems use simple antennas as base stations for the communication system. For example, US 2004 / 246104 A1 describes a solution in which each container is provided with a transponder, which is mounted, for example, on the corrugated outer wall of the container using a support element such as a plastic compound or a fabric bag. This transponder comprises the following building blocks interconnected via a communication bus system:

[0005] - a fast receiving module with corresponding antenna and another transmitting / receiving module

[0006] -Processor module and memory module

[0007] -Interface module for connecting sensors

[0008] -Battery powered

[0009] Communication with the transponder may be arranged such that the fast receive module wakes the transponder from its sleep mode with an appropriate signal.The transponder comprises a second transmit / receive module which may operate, for example, at a frequency in the range of 868 MHz.

[0010] The transponder allows two-way communication with a communication unit positioned on the deck of the vessel. However, experience in the field has shown that obtaining an acceptable level of link quality for communication between the communication unit and the transponder in a setup as described above is often troublesome, especially when the transponder is located deep in the cargo hold.

[0011] Patent application US2008 / 231459A1 relates to a cargo container monitoring system. The system includes components located on a cargo ship for collecting cargo container status information for multiple cargo containers. The components include at least one combined data logger and gateway device. The combined device includes a first antenna and a second antenna. The first antenna is included in the data logger device or can be mounted on a protective housing of the data logger device. The first antenna receives wireless communication signals from and / or transmits wireless communication signals to tags located on the containers. No further details regarding the first antenna are provided. The second antenna is configured for communication with a satellite.

[0012] US 2009 / 016308 A1 discloses an antenna system for a cargo container monitoring system. The antenna system includes a short-range wireless communication transceiver device associated with each container, at least one long-range communication device integrated into each container wall, door, or roof, a GPS element, and an antenna system. The antenna system includes antennas suitable for Bluetooth or WiFi communication and antennas for satellite communication.

[0013] In US 2007 / 188386 a solid flat antenna is presented comprising a reflecting element, a first radiating element, a second radiating element and in some configurations a third radiating element (to form a triangular strut) and a fourth radiating element (to form a square strut).

[0014] Patents and patent applications such as US10025960 Bl, US2013 / 229262A1 and US2008 / 211630A1 disclose antenna structures having a number of antennas arranged in a circular array.

[0015] WO2014 / 086452 relates to a dual-polarized omnidirectional antenna, in which a plurality of antennas are stacked to form an antenna column. Antenna elements are arranged offset relative to each other along the central axis of the sector antenna, whereby the sector antenna covers different sectors in the azimuth plane.

[0016] In US2005 / 248454, a maritime asset security and tracking system is presented, which discloses a plurality of RFID tag readers on a cargo ship with containers.

[0017] Considering the increasing size of modern container ships, there is a need for an antenna array module that ensures good link quality for communication between the deck and a transponder placed in a fixed position amidships or on board or attached to a container. Summary of the Invention

[0018] It is an object of embodiments of the present invention to provide an antenna array module for onboard communication of a cargo vessel between a communication unit and a transponder provided in or on the vessel and / or on items being transported by the vessel.

[0019] The above objects are achieved by the solution according to the present invention.

[0020] In a first aspect, the present invention relates to an antenna array module for a communications system on a cargo ship. The antenna array module includes at least a first antenna element, a second antenna element, and a third antenna element, each antenna element including an antenna feed. The first and second antenna elements are arranged to radiate primarily along a first path, and the third antenna element is arranged to radiate primarily along a second path opposite the first path. The first antenna element is tilted relative to the second antenna element.

[0021] The proposed solution actually allows to establish a communication link of acceptable quality. The two antenna elements tilted with respect to each other radiate mainly in a direction determined by the directivity pattern of these antenna elements. Applying a certain tilt angle between the first antenna element and the second antenna element allows to achieve a final radiation pattern that can cover a path including the deepest and / or farthest parts of the cargo hold where items are stored. The third antenna element is positioned so that it radiates mainly towards the opposite side (and therefore in a substantially opposite direction). Thus, the proposed antenna array module essentially acts as a sector antenna array, wherein the first antenna element and the second antenna element on the one hand and the third antenna element on the other hand each radiate mainly towards a different sector.

[0022] In a preferred embodiment, at least one of the antenna elements is a patch antenna. This offers the advantage of being smaller than other antenna types. Furthermore, patch antennas are easy to implement and low-cost. They can also support multiple frequency bands.

[0023] The first antenna element is tilted relative to the second antenna element at an angle that also allows reaching containers deep in the cargo hold and / or located in the end of the vessel. Preferably, the first antenna element and the second antenna element are tilted relative to each other at an angle in the range of 3° to 80°, in the range of 5° to 70°, or in the range of 10° to 60°, or approximately 45°.

[0024] In embodiments of the present invention, at least one of the antenna elements is configured to radiate with circular polarization. Using circular polarization can be advantageous due to its properties, such as reflectivity and absorption. Furthermore, circular polarization can be more effective than, for example, linear polarization when line-of-sight is impaired. In one embodiment, at least one antenna element is provided with a perturbation section to excite two orthogonal radiation modes to apply source polarization.

[0025] In an embodiment of the invention, the antenna element is arranged on a substrate of a dielectric material. In a preferred embodiment, air is used as the dielectric.

[0026] In an advantageous embodiment, the antenna array module comprises three antenna elements, ie two antennas are tilted at an angle relative to each other and arranged to radiate primarily towards a first path, and a third antenna is arranged to radiate primarily in a second direction opposite to said first path.

[0027] In one embodiment, the antenna array module comprises a power splitter / combiner arranged to split a signal for transmission through at least three antenna elements and to combine signals received from at least three antenna elements.

[0028] Preferably, the first antenna element is tilted relative to a vertical plane when mounted, wherein the second antenna element is positioned to improve directivity in the vertical direction. In a preferred embodiment, the antenna array module is formed when a stack of antenna elements is mounted. Except for the tilted antenna elements, the stack is substantially vertical.

[0029] In a preferred embodiment, the antenna element is made using printing techniques, as this allows for antenna elements of smaller size.

[0030] In another embodiment, the antenna array module comprises a housing for the antenna elements. This embodiment is preferred because the antenna array module is intended to be used in harsh conditions (eg, high seas).

[0031] In one embodiment, the third antenna element is not tilted relative to the second antenna element.

[0032] In another aspect, the present invention relates to a method for mounting an antenna array module on a cargo ship. The method comprises:

[0033] - obtain the antenna array module as previously described,

[0034] -The antenna array module is mounted on a platform on a bridge of a cargo ship, the bridge being positioned to divide the cargo ship along its length axis into a longer portion and a shorter portion, wherein a first antenna element is tilted relative to a second antenna element, and the first antenna element and the second antenna element are positioned so that the main lobes of their directivity patterns are directed toward a first path corresponding to the longer portion, and the third antenna element is positioned to radiate primarily toward a second path opposite to the first path.

[0035] In other words, in this aspect, the present invention relates to a method for mounting an antenna array module on a cargo ship, wherein the method comprises:

[0036] - obtaining an antenna array module of a communication system on a cargo ship, wherein the antenna array module comprises at least a first antenna element, a second antenna element, and a third antenna element, each antenna element comprising an antenna feed;

[0037] - Mounting the antenna array module on a bridge of the cargo ship, the bridge being positioned to divide the cargo ship into a longer portion and a shorter portion along its length axis, wherein the first antenna element is tilted relative to the second antenna element, and the first antenna element and the second antenna element are positioned so that the main lobes of their directivity patterns are directed toward a first path corresponding to the longer portion, and the third antenna element is positioned to radiate primarily toward a second path opposite to the first path.

[0038] Advantageously, a plurality of antenna array modules are mounted on the bridge.

[0039] In a preferred embodiment, the antenna array modules are mounted on the side of the bridge where a direct line of sight towards the longer section is available.

[0040] For the purpose of summarizing the present invention and the advantages achieved over the prior art, certain objects and advantages of the present invention have been described above. Of course, it will be understood that not all such objects or advantages may be achieved according to any particular embodiment of the present invention. Thus, for example, those skilled in the art will recognize that the present invention may be embodied or implemented in a manner that achieves or optimizes one advantage or group of advantages as taught herein, without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0041] The above and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout the various figures.

[0043] Figure 1A perspective view showing an embodiment of an antenna element of an antenna array module according to the present invention is shown.

[0044] Figure 2 Shown Figure 1 Top and side views of an embodiment of an antenna element.

[0045] Figure 3 A sketch of a cargo ship is shown with an indication of a bridge dividing the ship into two parts along the length axis.

[0046] Figure 4 An embodiment of an antenna array module is shown having two antenna elements for radiating towards the longer part of the vessel and one antenna element for radiating towards the shorter part.

[0047] 5A to 5D Some radiation patterns obtained with different tilt angles are shown.

[0048] Figure 6 The calculation of the antenna beamwidth in the vertical and horizontal planes is shown.

[0049] Figure 7 An embodiment of an antenna array module according to the present invention is shown.

[0050] Figures 8A to 8D Shows the change Figure 7 Effect of the tilt angle α of the antenna array module.

[0051] Figure 9 Different radiation mechanisms are shown for the two paths.

[0052] Figure 10 An example of a radome for protecting the antenna 7 and a mechanical support 8 for fixing the antenna to the vessel is shown. DETAILED DESCRIPTION

[0053] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not intended to be limited thereto but only by the claims.

[0054] Furthermore, the terms first, second, etc. in the description and claims are used to distinguish between similar elements and not necessarily to describe a sequence in time, space, ranking, or any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are capable of operation in different sequences than described or illustrated herein.

[0055] It should be noted that the term "comprising" used in the claims should not be construed as being limited to the components listed thereafter; it does not exclude other elements or steps. Thus, it should be interpreted as specifying the presence of the recited features, integers, steps, or components, but not excluding the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a device comprising components A and B" should not be limited to devices consisting solely of components A and B. This means that, with respect to the present invention, the only relevant components of the device are A and B.

[0056] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments, as will be apparent to one of ordinary skill in the art from this disclosure.

[0057] Similarly, it should be understood that in describing exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in order to streamline the disclosure and aid in understanding one or more of the various inventive aspects. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. On the contrary, as the appended claims reflect, inventive aspects lie in fewer than all the features of a single preceding disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the invention.

[0058] Furthermore, although some embodiments described herein include some features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of the invention and to form different embodiments, as will be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0059] It should be noted that the use of a particular term in describing certain features or aspects of the present invention should not be taken as implying that the term is repositioned herein to include any specific characteristics of the feature or aspect of the invention with which the term is associated.

[0060] In the description provided herein, numerous specific details are set forth. However, it should be understood that embodiments of the present invention may be practiced without these specific details. In other cases, well-known methods, structures, and techniques are not shown in detail in order to avoid obscuring an understanding of this specification.

[0061] In a first aspect, the present invention provides an antenna array module arranged to establish communication between sensors mounted on a cargo ship (e.g. on a container located on top of the deck or in a cargo hold below the deck of a container ship) and a communication unit typically located at the bridge of the ship.

[0062] Modern cargo ships typically have lengths of up to 300 to 400 meters or more and widths of, for example, 50 to 60 meters. Cargo holds can be as deep as 25 meters or more below deck. The antenna array module according to the present invention is designed so that its antenna elements can handle these large dimensions while providing good overall coverage. The antenna elements are designed to confine radiation to the vertical plane and cover the entire width of the ship.

[0063] The proposed antenna array module includes three or more antenna elements. Figure 1 An embodiment of a single antenna element is shown in . Figure 1 The antenna elements in the module are implemented as microstrip patch antennas. In other embodiments, the antenna elements may be, for example, monopole antennas, dipole antennas, slot antennas, or another type of primitive antenna well known to those skilled in the art. In certain embodiments, one or more antenna elements of a module may themselves be implemented as a small antenna subarray, such as an array of 2×2 slot antennas.

[0064] More specifically, Figure 1 An embodiment of a microstrip patch antenna (i.e., an antenna fabricated using microstrip technology) with circular polarization is shown. Microstrip patch antennas have been well known in the art for many years. Microstrip patch antennas have been very widely used in wireless communication systems because they offer attractive benefits such as low profile, light weight, compactness, ease of fabrication, etc.

[0065] like Figure 1 The microstrip patch antenna 1 in comprises a ground plane 2, a metallization 4 (ie a metal layer) on top of a substrate of dielectric material 3, the metallization being referred to as a patch in the following. Figure 1 The patch in the embodiment has a generally rectangular shape. In other embodiments, the patch can have a different shape, for example, a circular or annular shape. The dielectric material can be directly air or any commercially available substrate, for example, Teflon, PVC, polypropylene, FR4, etc. In an advantageous embodiment, the dielectric material is air.

[0066] As is generally known, polarization describes the orientation of the electric field strength vector of an electromagnetic wave. Figure 1 In an embodiment of the antenna element, the generally rectangular patch is provided with some perturbations 5, which allow circular polarization. In other embodiments, other ways of obtaining circular polarization may be used, for example, using two ports per antenna and feeding them using a 90° hybrid. Circular polarization is a special case of elliptical polarization (i.e., whereby the tip of the electric field vector describes an ellipse in any fixed plane that intersects and is perpendicular to the direction of propagation). Therefore, in other embodiments, the antenna element may be arranged for using elliptical polarization. An elliptically polarized wave can be decomposed into two linearly polarized waves in phase quadrature, with their polarization planes at right angles to each other. In yet other embodiments, the antenna element is configured for linear polarization, for example vertically or horizontally or rotated 45°.

[0067] The antenna element 1 is fed by capacitive coupling through a small metal portion 6, also called a patch feed, on the same layer as the patch. A coaxial connector can be provided to feed the patch antenna connected to the ground plane 2 and the small metallization 6. In other embodiments, the patch antenna can be fed directly by a coaxial connector, by a microstrip transmission line, or via an aperture in the ground plane. Embodiments with a feeding element on top of the substrate are also envisioned.

[0068] Figure 2 Provided already in Figure 1 Top and side views of the antenna element shown in FIG.

[0069] The antenna array module is advantageously mounted high on the ship, on or near the bridge of the command vessel. Preferably, the module is located on the skybridge (i.e., the highest navigation platform on the bridge) so that many sight paths are available to the containers on or below deck. In most cases, the bridge of a cargo ship is located closer to one end of the ship than the other, e.g. Figure 3 As shown. In this case, when considered along the length axis, a longer portion 20 and a shorter portion 30 of the vessel can be indicated. This terminology will be used throughout the remainder of this description. It should be noted that if the bridge were exactly in the middle, there would still be two portions 20, 30 of equal length. Conceptually, this makes no difference to the further description given below.

[0070] For the antenna array module, improved directivity towards the longer part of the ship is obtained by providing at least two antenna elements 11, 12 tilted relative to each other, which radiate mainly towards a path covering said longer part of the ship over its entire length. Figure 4 An illustration of such an antenna array module is provided. Figure 4In the embodiment of the invention, antenna element 11 is tilted from the vertical plane formed by the other two antenna elements. Radio coverage towards the shorter part of the ship is established by an antenna array module comprising at least a third antenna element 16, which is directed towards the side opposite to the side directed by the at least two antenna elements covering the longer part.

[0071] In a preferred embodiment, the antenna array module is formed by mounting a stack of antenna elements. With the exception of tilted antenna elements, the stack is substantially vertical. The various antenna elements can be interconnected with the aid of a power divider / combiner. In some embodiments, the antenna elements can be implemented on the same printed circuit board (PCB), which then preferably also includes the power divider / combiner and feed lines.

[0072] In a preferred embodiment, the antenna array module according to the present invention includes two antenna elements 11, 12 pointing toward the same side of the ship, working together as a single antenna to radiate primarily toward the longer portion of the ship. Obviously, one or more smaller sidelobes pointing in substantially opposite directions may also be present, but these are not considered further here. One of the two antenna elements 11 is tilted relative to the other antenna element by an angle α, resulting in an angle between the tilted antenna element 11 and the extension of the other antenna element 12. Since the antenna elements other than the tilted antenna element preferably form a vertical stack, the angle α is the angle between the tilted antenna element and the vertical stack. Thus, the angle α is preferably less than 90°, preferably less than 80°, or less than 70°, so that the two antenna elements, when emitting radiation (or, in other words, when the two antenna elements are located on the same side relative to their ground planes), produce a radiation pattern with a main lobe pointing toward the same side. This tilt provides good signal levels in containers that are vertically oriented relative to the antenna position, including containers located nearly below the antenna near the ship's bridge.

[0073] The optimal tilt angle α of the first antenna element relative to the second antenna element depends inter alia on the size of the vessel, in particular on the height of the container stack: the aim should be to allow communication with containers at or near the top of the stack (usually but not necessarily above deck) as well as with containers located at great depths in the cargo hold. The tilted antenna element forms an angle with the other antenna elements which is preferably between 3° and 80°. In a more preferred embodiment, the angle is in the range of 5° to 70°. In a most preferred embodiment, the angle is 45°. The array of antenna elements will be mounted on or near the bridge so that when seen from the bridge (see Figure 3 ), they can provide line-of-sight propagation (i.e., electromagnetic waves travel in a direct path from the transmitting source to the receiver) towards the longest part of the ship.

[0074] The optimal tilt angle will obviously also depend on the number of antenna elements in the antenna array module. For example, when there is an additional antenna element pointing towards the longest part of the vessel (as in the embodiments described further below), the optimal angle α may be different from the angle in the embodiment with only two antenna elements.

[0075] Given that proper tilt angle is important for obtaining good coverage in the vertical plane, it is equally important to have good coverage in the horizontal plane. Therefore, the antenna array modules are designed to provide a radiation pattern in the horizontal plane that covers the entire width of the vessel.

[0076] 5A to 5D The directivity pattern is shown to illustrate Figure 4 The effect of the angle α of the embodiment. Figure 5A In the example, the tilt angle is α = 0°. Figure 5B In the case of α=30°, Figure 5C In the equation, α = 40°, and Figure 5D α = 60°. As the inclination of antenna element 11 relative to the other antenna elements 12 increases, the radiation pattern becomes less directional and the direction of maximum radiation shifts downward relative to the horizontal. This makes it possible to reach containers below the antenna in the deepest part of the cargo hold.

[0077] Figure 6 shows an example of how to calculate the antenna beamwidth for an array of antenna elements. In this figure, h a represents the height (relative to the bottom of the ship) of the antenna elements of the antenna array module positioned on or near the bridge. The height of the nearest container (in the worst case) is h1. The distance between the bridge and the nearest container is d1. The height of the farthest container (in the worst case) is h2, and the distance from the bridge to the farthest container is d2. Then, the angle θ that needs to be covered by the antenna array module is v Can be calculated as

[0078]

[0079] Similarly, for the angle θ h , we can write the following expression:

[0080]

[0081] By way of illustration, the following values: h a =62, h1=3, d1=5, h2=40 and d2=100 to obtain

[0082] θ v =θ h =72°

[0083] In an advantageous embodiment of the antenna array module, more than two antenna elements oriented toward the longer path are present in the module. Orienting more than two antenna elements in the same direction further improves directivity. As mentioned previously, the optimal choice of the tilt angle α can also be influenced by the fact that there are more than two antenna elements. Figure 7 A setup with three antenna elements pointing towards the longer path is shown. Figures 8A to 8D Some directivity patterns of this setup obtained with different tilt angles are shown (in Figure 8A In the case of α=0°, Figure 8B In the case of α=30°, Figure 8C In the equation, α = 45°, and Figure 8D In this example, α = 60°. As the tilt of antenna element 11 relative to the other antenna elements 12 and 17 increases, the radiation pattern becomes less directional, and the direction of maximum radiation shifts downward relative to the horizontal. In other embodiments, it is also possible for third antenna element 17 to be tilted relative to antenna element 12. This depends on the specific situation, particularly the size of the vessel. Antenna elements with additional tilt may be beneficial for achieving good coverage.

[0084] Now back Figure 4 The minimal setup with three antenna elements is shown, and in addition to the two antenna elements 11, 12 covering the longer part of the ship as discussed above, this embodiment of the antenna array module further comprises an antenna element 16 which is oriented towards the side opposite to the side to which the other two antenna elements (i.e. the tilted antenna element and its adjacent antenna element) are pointing. If the latter is referred to as the forward direction (corresponding to the longer part), then the antenna element on the opposite side can be said to be pointing in the rearward direction (corresponding to the shorter part). The third antenna element radiates primarily towards a second path which is opposite to the paths along which the first and second antenna elements primarily radiate. However, this is not necessarily to be interpreted as meaning that there is a 180° difference between the first and second paths. Due to the tilt angle between the first and second antenna elements, the difference is not 180°. However, the two paths always point towards different sides of the ship, which means that their difference exceeds 90°. In an embodiment of the module, each of the antenna elements 11, 12, 16 can be implemented as Figure 1 Antenna element 1 in.

[0085] The embodiment of the antenna array module of the present invention is basically improved in the shorter part (see Figure 3) is advantageous in terms of radio coverage of the vessel. It should be noted that in this rearward direction the main radiating mechanism is different from the other antenna elements. Whereas these other antenna elements utilize line of sight propagation, the antenna elements oriented in the rearward direction rely on diffraction of the signal on horizontal edges. Due to the width of the catwalk where the antenna array modules are typically mounted on one of the railings, there is no line of sight at most locations of the containers where communications need to be established on the short side of the ship. The radiated waves see the edge of the catwalk as a metal obstacle that will cause diffraction, thus helping to obtain coverage in shadowed areas (i.e. in shorter paths). From field tests of radio coverage performed in ships and analysis of the received signal power, it was concluded that one or more antenna elements located at a height higher than the railing to which the antenna array is attached allow to obtain good coverage on the shorter parts of the ship. In a preferred embodiment, the antenna elements pointing in the rearward direction are not tilted. In case there is more than one such antenna element, in a preferred embodiment they are stacked vertically. Figure 9 Different types of propagation in the two paths are shown.

[0086] In other embodiments, the antenna array module may include four antenna elements, with two antenna elements in each direction. The two antenna elements are tilted relative to each other. Preferably, one of the antenna elements is positioned in a vertical plane. The other two antenna elements point in a rearward direction. Similarly, in one embodiment, one or more antenna elements, preferably all antenna elements, may be implemented as Figure 1 Antenna element 1 in.

[0087] Since the antenna array module is typically placed on the bridge of a ship, the antenna elements of the module will be protected from the harsh conditions that may occur in the open sea. Therefore, the antenna array module preferably includes a housing or radome 7, such as Figure 10 The figure further shows the support members 8, with which the antenna array module is fixed to the railing of the overpass.

[0088] The housing or radome 7 is designed to minimize the overall antenna array size and to reduce wind loads on the surface of the structure of the antenna array, especially in adverse weather conditions such as strong winds and especially when the vessel is at sea. The internal structure or frame supports and distributes the external influences to which the entire structure is subjected to mechanical stresses, such as wind, ship sway, shocks, vibrations, etc. The internal structure also carries the different antenna elements, power dividers / combiners, cables for connecting the antenna elements to the power dividers / combiners, and cables for connecting the power dividers / combiners to external antenna interfaces. Depending on the embodiment of the antenna array module (for example, an embodiment with two elements pointing in the forward direction (one tilted relative to the other) and a third element pointing in the rearward direction, an embodiment with more elements pointing in the rearward direction, etc.), the internal structure may vary slightly in shape and / or size, while the housing 7 and the support 8 remain the same regardless of the number of antenna elements.

[0089] Items stored in the cargo hold (e.g., containers) may be equipped with transponders or tags that allow two-way communication with a communication unit located, for example, on an antenna, via the antenna array module of the present invention. The items (e.g., containers) are also provided with one or more sensing members to keep track of one or more parameters indicating external environmental conditions inside or near the container. In addition, transponders provided with sensors may be provided in the ship so that communication is possible even in the absence of cargo, for example, with respect to conditions in the cargo hold. Commands may be exchanged between a transponder and a communication unit of a container (or another stored item) or located in the ship itself to request and transmit, for example, one or more of the following data:

[0090] -Container marking

[0091] - Temperature inside or outside the container

[0092] - Air humidity

[0093] -Ionizing radiation

[0094] - Chemical composition of ambient air

[0095] -Electromagnetic fields sensed on containers

[0096] - The impact, shock or vibration to which the container has been subjected

[0097] - exchange of information (e.g. performance indicators) required to allow remote processing on the transponder (e.g. switching on / off, upgrading the firmware by sending a command to the transponder and the transponder downloading the required file to perform the upgrade, ...)

[0098] The transponder may essentially have the same or similar building blocks as, for example, US2004 / 246104. The transponder comprises a module arranged to receive commands from a communication unit (e.g., a request to send its identification data or data about one or more parameters). The antenna in the transponder module is adapted to cooperate with the antenna array module as described above. More particularly, the antenna in the transponder module meets constraints such as size, battery, and weight. Given that the container is metal, there are also constraints on the location of the antenna. A small printed antenna is most preferred for the application under consideration.

[0099] The transponder is further arranged to transmit the requested information back to the communication unit. This can be organized in several ways. In one embodiment, the communication from the transponder to the communication unit can use the same frequency as in the opposite direction in a half-duplex manner. In another embodiment, a dedicated frequency within the same frequency range is used for communication to the communication unit, which is different from the frequency used in the direction toward the transponder.

[0100] To conserve energy, the communication system may advantageously have a low-power mode in which the container's transponders remain in sleep mode until a wake-up signal is received. The wake-up signal may be directed to a specific transponder, a group of transponders, or all transponders. The manner in which the transponders are awakened may depend on the protocol implemented in layers above the physical layer. Transponder behavior is typically programmable, for example, waking up every X minutes / hours / days, performing a set of actions, reporting the results of one or more of these actions, and then returning to sleep.

[0101] The antenna array modules of the present invention are preferably arranged to operate at a specific frequency, such as 433 MHz, 868 MHz, or 915 MHz. In certain embodiments, multiple antenna module arrays (each operating at a different frequency) are placed next to each other. For example, three antenna modules as previously described may be provided, one operating at 433 MHz, one operating at 868 MHz, and one operating at 915 MHz. In some embodiments, only one of the three may be operational at a given time. The frequency used may be automatically selected by the communication unit or manually triggered by a remote operator.

[0102] In some embodiments, the antenna array module may be arranged to switch between two or more frequencies.

[0103] In a preferred embodiment of a communication system including an antenna array module, the communication unit is implemented as part of a gateway, i.e., a networking hardware device that allows communication and interaction between, for example, a host network and a remote network. The gateway serves as an entry and exit point for the network. The gateway provides a bridge between different network components (i.e., onboard devices, the cloud, and land-based infrastructure).

[0104] When a portion of the information from the transponders of one or more containers is received via an antenna array module in a communication unit (e.g., a gateway), the communication unit can operate in a predefined manner. The communication unit (e.g., a gateway or onboard central unit) connected to the antenna array module includes a sensing mechanism to know which networks are available to relay information from sensors or containers onboard to infrastructure on land (or conversely, to collect remote commands and relay them to the relevant sensors or containers onboard). The network and the network attachment scheme used depend on the specific implementation of this type of gateway. In one example, it is possible that the gateway / central unit is suitable for landside cellular and satellite communications, and depending on the design (related or unrelated to network availability, associated business / service costs, etc.), the communication unit may choose to check cellular communications first and only check the satellite network if no landside cellular network is available. In another case, the opposite may be true. The antenna creates a kind of onboard WiFi local network, i.e., a kind of "internal" or "local" network interface, while the landside cellular, satellite, or other network is on the "external" network interface side.

[0105] In another aspect, the present invention relates to a method for mounting an antenna array module on a cargo ship. The method comprises providing an antenna array module as previously presented. Next, the antenna array module is mounted on a railing of a platform on the bridge of the cargo ship. In order to maximize the effect of the tilt angle and line-of-sight propagation towards the longer side of the ship, the antenna array module is most preferably mounted on a railing located in the side of the mounting deck (typically a skybridge) pointing towards the longer side of the ship. As already mentioned previously, the bridge of a cargo ship is typically positioned so that it divides the ship into a longer part and a shorter part along the longitudinal axis. The first antenna element 11 is tilted relative to the second antenna element 12. These antenna elements are positioned so that the main lobe of their directional pattern points to a first path corresponding to the longer part. The third antenna element 16 is positioned to radiate primarily towards a second path opposite to the first path.

[0106] Although the present invention has been shown and described in detail in the drawings and the foregoing description, such showing and description should be considered as illustrative or exemplary rather than restrictive. The foregoing description details certain embodiments of the present invention. However, it should be understood that no matter how detailed the foregoing appears in text, the present invention can be practiced in many ways. The present invention is not limited to the disclosed embodiments.

[0107] Other variations to the disclosed embodiments may be understood and effected by those skilled in the art in practicing the disclosed aspects by studying the drawings, the present 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 or other unit may perform the functions of several items recited in a claim. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be effectively used. The computer program may be stored / distributed on a suitable medium, such as an optical storage medium or solid-state medium supplied with or as part of other hardware, or may be distributed in other forms, such as via the Internet or other wired or wireless telecommunications technology. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A method for installing an antenna array module on a cargo ship, the method comprising: Obtain an antenna array module of the communication system on the cargo ship, wherein the antenna array module comprises at least a first antenna element, a second antenna element, and a third antenna element, each antenna element comprising an antenna feed source, The antenna array module is mounted on a bridge of the cargo ship, the bridge being positioned to divide the cargo ship along its length axis into a longer portion and a shorter portion, wherein the first antenna element is tilted relative to the second antenna element, and the first antenna element and the second antenna element are positioned so that the main lobe of their directivity patterns points toward a first path corresponding to the longer portion, and the third antenna element is positioned to radiate primarily toward a second path opposite to the first path.

2. The method of claim 1, wherein at least one of the antenna elements is a patch antenna. 3 . The method of claim 1 , wherein the first antenna element and the second antenna element are tilted relative to each other at an angle in the range of 5° to 70°. The method of claim 1 , wherein at least one of the antenna elements is arranged to radiate with circular polarization.

5. The method of claim 4, wherein the at least one antenna element is provided with a perturbation to excite two orthogonal radiation modes. The method of claim 1 , wherein the antenna element is disposed on a substrate of a dielectric material.

7. The method of claim 1 , wherein the antenna array module comprises a power splitter and combiner, wherein the power splitter and combiner is arranged to split a signal into signals transmitted through at least the first antenna element, the second antenna element, and the third antenna element and to combine signals received from at least the first antenna element, the second antenna element, and the third antenna element.

8. The method of claim 1, wherein the first antenna element is tilted relative to a vertical plane when mounted, and wherein the second antenna element is positioned to improve directivity in a vertical direction.

9. The method of claim 1, wherein at least the first antenna element, the second antenna element, and the third antenna element form a substantially vertical stack.

10. The method of claim 1, wherein the antenna element is fabricated using a printing technique.

11. The method of claim 1 , the antenna array module comprising a housing for the antenna elements.

12. The method of claim 1, wherein the third antenna element is not tilted relative to the second antenna element.

13. The method of claim 1, wherein a plurality of the antenna array modules are mounted on the bridge.

14. The method of claim 1, wherein the antenna array modules are mounted on a side of the bridge where a direct line of sight towards the longer portion is available.

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