EP3742550A1

EP3742550A1 - Multiband antenna, system and train

Info

Publication number: EP3742550A1
Application number: EP20171786.5A
Authority: EP
Inventors: Ciro De Col; Gary Parkinson
Original assignee: Siemens Mobility Ltd
Current assignee: Siemens Mobility Ltd
Priority date: 2019-05-21
Filing date: 2020-04-28
Publication date: 2020-11-25
Anticipated expiration: 2040-04-28
Also published as: GB2584170A; GB201917355D0; GB2584170B; EP3742550B1

Abstract

A multiband antenna for a train is provided, comprising a base plate and a housing. The housing comprises a base portion and a cover, removably mounted on the base plate, the cover having a footprint having a first arm and a second arm joined at a central apex. An application-specific antenna mounted on the base plate at the apex of the cover; and a cellular network antenna mounted on the base plate in each of the first and second arms of the cover. The cover comprises a continuous supporting wall and an upper portion, the continuous supporting wall extending between the base portion and the upper portion and having a maximum height h, and the upper portion extending from the apex along the first and the second arms at the maximum height h of the supporting wall and inclines to form a valley extending between the first and the second arms from proximate the apex to the base portion distal from the apex.

Description

FIELD OF INVENTION

The present invention relates to a multiband antenna and a multiband antenna system for use in a rail environment as well as to a train with such a multiband antenna system.

BACKGROUND OF INVENTION

The railway communications standard in the United Kingdom and in Europe will be updated in the near future. The current standard GSM-R (Global System for Mobile Communication - Rail) is a digital mobile communications standard which relies on the commercial GSM (2G) standard, however, has been extended specifically for the use in a rail environment. Together with the European Train Control System (ETCS) it is a basic part of the European Rail Traffic Management Systems (ERTMS). At its introduction, GSM-R had replaced many older, analogue communications technologies and it can be considered the first comprehensive digital communication standard for use in the rail environment.
The GSM (2G) standard, however, is currently subject to external pressures. In particular, the commercial GSM standard has already been widely replaced with the more recent standards UMTS (3G) and LTE (4G) which offer a much higher bandwidth and better functionality. Also, with an even newer standard 5G shortly before introduction, many commercial communication providers plan on removing GSM services within the next years. Public communication providers only guarantee the support for GSM until the year 2030. For rail communication to be working reliably by then, a new train communications standard will have to be introduced much earlier.
Thanks to these external pressures together with an increasing need for improved digital rail and transport services, the International Union of Railways (UIC) has set a new standard called the Future Rail Mobile Communications System (FRMCS) which relies largely on LTE/4G-communication. FRMCS has the objective to become the first worldwide train communications standard, conforming to European regulation as well as responding to the requirements of rail organizations all over the world.
FRMCS will offer significantly increased higher bandwidth and functionality. However, for this it will also require new technical infrastructure on the trains operating under this new standard. In particular, in the current period of transition, the trains will not only have to guarantee the use of the new LTE/4G-standard (and later 5G), but also many countries networks have to be operable under the old GSM-R standard. At the same time, additional functionalities are often required, e.g. utilizing even other communication standards, such as that of a global navigation and satellite systems, GNSS. Typical GNSS platforms for example work under the GPS, GLONASS systems.
The described communication updates require the installation of new receivers and transmitters on the trains as well as antennas on the roofs of the trains. The new antennas will require several cables to be routed through the train which potentially creates significant costs and effort due to the difficulty in obtaining installation design approvals. Also, the time for which trains will have to be taken out of service when being upgraded with the new hardware is significant and train operators would like to keep these periods as short as possible. Furthermore, train operators prefer not to have too many and too complex technical additions to their trains because they can cause future maintenance issues (e.g. leaking through the roof and snagging on branches in case of hardware upgrades on the roof of the trains).

SUMMARY OF INVENTION

Therefore, there exists a technical need to be able to deploy a solution that mitigates the impact of these train hardware updates, in particular when it comes to the antenna upgrade. The new solutions should be simple and reduce the time for upgrading and surveying the trains.
This technical problem is addressed by the matter of the independent claims of this document.
In particular, this technical problem is addressed by a multiband antenna comprising: a base plate; a housing, comprising a base portion and a cover, removably mounted on the base plate, the cover having a footprint having a first arm and a second arm joined at a central apex; an application-specific antenna mounted on the base plate at the apex of the cover; a cellular network antenna mounted on the base plate in each of the first and second arms of the cover; wherein the cover comprises a continuous supporting wall and an upper portion, the continuous supporting wall extending between the base portion and the upper portion and having a maximum height h, and the upper portion extending from the apex along the first and the second arms at the maximum height h of the supporting wall and inclines to form a valley extending between the first and the second arms from proximate the apex to the base portion distal from the apex.
By providing a multiband antenna with capabilities in different cellular or other frequencies and which has a removable cover, train communication systems may be updated easily by removal of the cover and antenna elements without major structural or other changes to existing train bodies or infrastructure.
A Global Navigation and Satellite System (GNSS) receiver may be fixed to the base plate in between the two cellular network antennas.
The base plate may have two opposing short sides and two opposing long sides forming an outer rectangle, and four fixation means, wherein the four fixation means are located such that they coincide with the corners of a smaller inner rectangle, and wherein the base plate can be divided into two halves by a half-line connecting the mid-points on the two opposing long sides such that two of the fixation means are located on a first half of the base plate and two of the fixation means are located on a second half of the base plate.
The base plate may further comprise a feed through arranged on either the first half or the second half of the base plate. The feed through in the base plate may comprise one individual feed through for each of the cellular network antennas, the application-specific antenna and the GNSS receiver fixed to the base plate.
The application-specific antenna may be mounted on the first half of the base plate and the two cellular network antennas and the GNSS receiver are mounted on the second half of the base plate.
The arms of the cover may be parallel to one another and separated by a distance d or inclined to one another at an acute angle. The arms of the cover are preferably perpendicular to the base portion. The footprint of the cover may be one of a "Y"-shape, a "V"-shape or a "U"-shape.
The application-specific antenna may be a GSM-R antenna. When mounted on a train, the apex of the cover preferably forms the leading edge of the multiband antenna when the train is in forward motion. Alternatively, when mounted on a train, the apex of the cover preferably forms the trailing edge of the multiband antenna when the train is in backward motion.
The base portion, the supporting wall and the upper portion of the cover of the housing are preferably formed integrally.
The technical problem is further addressed by a multiband antenna comprising a largely rectangular base plate with a short side and a long side, having four fixation means which are arranged on this base plate such that the locations of the four fixation means coincide with the corners of another rectangle. The base plate can be divided into two halves by a half-line connecting the mid points on the two long sides, such that two of the fixation means are arranged on the first half and two of the fixation means are arranged on the second half of the base plate. A feed-through is provided, completely or at least largely arranged on one of the first half and the second half of the base plate. The antenna further comprises two cellular network antennas fixed to the first half of the base plate in such a way that each cellular network antenna is fixed in one respective quarter of the base plate, wherein the quarters of the base plate are defined by a line connecting the mid-point of the short side of the first half of the base plate and the mid-point of the half-line of the base plate. One application specific antenna is fixed to the second half of the base plate. A global navigation and satellite system, GNSS, receiver is fixed to the base plate on the first half of the base plate, between the two cellular network antennas with a smaller distance from the cellular network antennas when compared to its distance to the application specific antenna.
The technical problem is further addressed by a multiband antenna system comprising this multiband antenna and a multiple coaxial cable, which comprises several coaxial cables in one cable jacket, wherein the multiple coaxial cables are each connected to one of the cellular network antennas, the application-specific antenna and the GNSS receiver.
The technical problem is further addressed by a train comprising either a multiband antenna system, or a multiband antenna, according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned attributes and other features and advantages of this invention and the manner of attaining them will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein

FIG. 1 shows an embodiment of a multiband antenna according to present invention in a perspective representation from the side including connecting cables;
FIG. 2 shows another embodiment of the multiband antenna in a perspective representation from above without any cables;
FIG. 3 shows an embodiment of the multiband antenna system installed on a train car in a schematic representation from the side;
FIG. 4 shows an embodiment of the multiple coaxial cable which for example has been used in the multiband antenna system depicted in Figure 3; and
FIG. 5 shows another embodiment of the multiband antenna in a perspective representation from the side without any cables.

DETAILED DESCRIPTION OF INVENTION

Figure 1 shows an embodiment of a multiband antenna 1 according to this invention in a perspective representation from the side including cables which are connected to the functional components. These functional components are two 4G-antennas 30 as cellular network antennas, a GNSS receiver 35 arranged between the two 4G-antennas 30 and a GSM-R-antenna 31 as an application-specific antenna. All of these four components are fixed to a base plate 5, which typically is made of material which does not distort the radiation characteristic of the overall the multiband antenna 1. The same is true for the housing 40, which covers all components. A material typically used for these purposes is glass fibre reinforced plastic (GRP).
The base plate 5 is rectangular in shape with a short side 6 and a long side 7. The short side 6 has two ends (edges) as does the long side 7. The base plate 5 has also four fixation means 20 which are arranged on this base plate 5 such that the locations of the four fixation means 20 coincide with the corners of another, second rectangle. Thus, one can define an outer rectangle by the shape of the base plate 5 itself and a smaller, inner rectangle by the four fixation means 20, which are holes in the embodiment. The centres of these four holes define the corners of a second rectangle which is smaller than the outer larger rectangle of the base plate 5.
The base plate 5 can be divided into two halves 8, 9 by a half-line 10 connecting the mid points 11, 12 on the two long sides 7, such that two of the fixation means 20 are arranged on the first half 8 and two of the fixation means 20 are arranged on the second half 9 of the base plate 5. This allows the base plate 5 to be attached to the roof of a train.
The functional components are arranged such that two 4G-antennas 30 are fixed to the first half 8 of the base plate 5, while the GSM-R-antenna 31 is fixed to the second half 9 of the base plate 5. This guarantees that the electromagnetic interference of the antennas is kept as small as possible. To aid a reduced electromagnetic interference, the two 4G-antennas 30 are arranged relatively closely to the outer corners of the first half 8, close to the fixation means 20. Also, both 4G-antennas are preferably aligned in parallel. Their radiation characteristics are overlapping with only a small offset resulting from the physical distance between the two 4G-antennas on the base plate 5.
As shown, the two 4G-antennas 30 are fixed to the base plate 5 in such a way that each 4G-antenna 30 is fixed in one respective quarter of the base plate 5, wherein the quarters of the base plate are defined by a line (not explicitly shown in Figure 1) connecting the mid-point 13 (not explicitly shown in Figure 1) of the short side 6 of the first half 8 of the base plate 5 and the mid-point 14 of the half-line 10 of the base plate 5. This arrangement separates the two 4G-antennas sufficiently widely from each other to not cause too much electromagnetic interference.
Further, the global navigation and satellite system, GNSS, receiver 35 is fixed to the base plate 5 in between the two 4G-antennas 30 on the first half 8 of the base plate 5. Being a receiver for signals from satellites from above, the arrangement therefore provides for clearance to receive the satellite signals sufficiently undistorted.
Further, a feed-through 15 is provided in the base plate 5 comprising one individual feed-through 15 for each cable connecting to the 4G-antenna 30, the GSM-R-antenna 31 and the GNSS receiver 35 fixed to the base plate 5. The individual feed-throughs 15 are preferably arranged in a rectangular fashion and all are located on the first half 8 of the base plate. Further, the individual feed-throughs 15 are all arranged within (a not further shown) circle of not more than 33 mm in diameter. This arrangement becomes more clear in the following Figure 2.
Figure 2 shows a schematic representation of an embodiment of the multiband antenna 1 according to this invention. The embodiment is largely identical with the one shown in figure 1. However, the base plate 5 of this embodiment has rounded corners. However, it still qualifies to fall under a rectangular shape.
The embodiment of Figure 2 also does not show any cables connecting to the functional components on the base plate 5. This, however, allows to identify the two halves 8, 9 clearly, which are defined by half-line 10 connecting the mid points 11, 12 on the two long sides 7. Further, the two quarters in which the two 4G-antennas 30 are fixed can be readily identified. Each 4G-antenna 30 is fixed in one respective quarter of the base plate 5, wherein the quarters of the base plate are defined by a line connecting the mid-point 13 of the short side 6 of the first half 8 of the base plate 5 and the mid-point 14 of the half-line 10 of the base plate 5.
The perspective also shows that all individual feed-throughs 15 are arrange within a circle 16 of not more than 33 mm in diameter. The circle 16 overlaps with another circle in the train roof (not shown) and all cables can be either fed through the individual feed-throughs 15 into the roof of the train or at least are connectible to a multiple coaxial cable 3 (not shown) which runs in the train roof area.
Figure 3 shows an embodiment of the multiband antenna system 2 installed on a train car 50 in a schematic representation from the side. The multiband antenna system 2 comprises a multiband antenna 1 which is electrically connected via a multiple coaxial cable 3 to the transceiver 51 which is located at the front of the train. From outside, the functional components of the multiband antenna 1 cannot be seen and only housing 40 is visible.
Figure 4 shows an embodiment of the multiple coaxial cable 3 which for example has been used in the multiband antenna system 2 depicted in figure 3. The multiple coaxial cable 3 comprises 4 coaxial cables which are all held together by cable jacket 4. The individual coaxial cables typically have a suitable connector (not shown) to connect individual cables to suitable connectors at either the multiband antenna 1 or at the transceiver 51.
The base plate of the multiband antenna is largely rectangular, which means that it is rectangular whereas smaller shape variations such as rounded corners can for example exist. Even an ovalized or otherwise shape adjustment is included within the meaning of rectangular here as long as a short side and a long side of this shape can be identified and sensible measures of length can be attributed to individual sides. In any case, the largely rectangular shape allows to determine a short side and a long side of the shape and the extension of these sides. This forms a first, outer rectangle.
Since the rectangular shape has two edges of identical length which are corresponding to the long side, and two edges of identical length which are corresponding to the short side, one can also speak of a rectangular shape with a long side and a short side. It has to be kept in mind that the two edges of either the long side or the short side are identical in length and this fact therefore does not have to be mentioned expressis verbis. The expression "side", here also includes the meaning of edge.
The other, second rectangular shape is defined by the four fixation means whose location on the base plate coincide with the corners of a rectangle. Typically, this rectangular shape is smaller in extent when compared to the largely rectangular shape of the base plate. The arrangement of these fixation means is mostly determined by the location of the holes in the roof of the train onto which the multiband antenna will have to be attached. These holes are already existing for the current arrangement of the GSM-R-antennas which are going to be replaced by the new multiband antenna. This forms a second, inner, rectangle.
The fixation means can be holes, studs, screws or any other type of means which are suitable to mount the base plate onto the outside of the train roof. The arrangement of the fixation means is such that when someone looks from above (i.e. the side of the base plate on which the antennas are fixed) onto the base plate, the locations of the fixation means, e.g. the centres of the holes, are arranged in a rectangular fashion. The simplest embodiment has four holes arranged in the base plate, one hole in each corner of a rectangle, outlining an overall rectangular arrangement.
Fixation means are arranged directly or indirectly on the rectangular base plate. They can e.g. be holes in the base plate itself, or they can be screws, which are fixed directly or indirectly to the base plate or any other structure on the base plate.
In the simplest embodiment, the feed-through is a hole in the base plate through which the antenna cables can be guided. Alternatively, cable connectors might be fixed to or in the feed-throughs, thus, not requiring cables to be fed through the base plate. In one embodiment, only connectors are fixed to the feed-throughs, allowing to feed an electrical signal through the base plate, but not a physical cable.
Generally, the location of technical features, such as antennas or other technical features, on the base plate is identified when looking at the base from above (perpendicularly onto the face of the base plate on which the antennas are fixed). In case of a circular hole, the location of the technical feature is identified by the location of the centre of the circle, which is a point of symmetry of the projected disk shape. The same is true for other features which appear round in two dimensions when looking from above. Other points of reference can be symmetry points or the centre of gravity of an imagined 2D-projection onto the base plate.
The technical solution according to the independent claims involves a multiband antenna which supports GSM-R and FRMCS (largely identical with 4G/5G) communication. The new multiband antenna can be fit into one antenna housing which exactly matches the size and shape of the housing of the current GSM-R antenna in use in the United Kingdom. Therefore, the multiband antenna can simply be replaced without any additional work being carried out on the train roof. The multiband antenna simply replaces the already existing GSM-R-antenna. In particular, it can be avoided that several different antennas have to be mounted individually on the train roof, thus, requiring opening up the train roof at new locations. The presented solutions rather use the already existing mounting infrastructure and only require the replacement of one device with another one. This will allow for the shortest possible repair time and avoids the renewed surveying of the train car. In addition, the height is also slightly lower than the commonly used existing GSM-R antenna on UK vehicles in order that it is not necessary to repeat vehicle gauge calculations (such as check that there is sufficient clearance for all items on the body, from railway objects such as tunnel walls). If the multiband antenna is lower in height than an existing antenna, then it will also have sufficient gauge clearance.
Additionally, the antenna elements can each be connected to the transceiver which is located inside the train typically at a different location from where the antenna cable is guided through the train roof. Using a multiple coaxial cable, which combines several coaxial cables in one cable jacket, again avoids renewed surveying of the train car. The multiple coaxial cable can simply replace the already existing coaxial cable connecting to the GSM-R antenna and transceiver. Only at the ends, the multiple coaxial cable will be separated and connected to the respective transceivers or antennas. This again means that there is no need to re-survey the train or produce a new installation design because the new cable is able to be run along the same route as the old one.
The use of a multiple coaxial cable also allows avoiding the use of combiners to combine different signals into a single cable (in which case there is a combiner loss of >3dB over one signal path).
The presented technical solution uses multiple discrete antennas in a single antenna housing, i.e. on a single base plate with multiple cables all being guided in a single combined cable assembly. This results is an installation design which is largely identical with the one currently used. Further, this means that installation design cost and time is vastly reduced since only minor changes to the existing design have to be implemented. Also, the train owner only needs a single antenna structure on the roof of their trains, which leads to a more reliable assembly which is preferred by train builders as roof access is difficult.
In a preferred embodiment of the invention, the feed-through, is completely or at least largely arranged on the first half of the base plate. First experiments have shown that this arrangement will lead to acceptably low levels of interference with the overall radiation characteristics of the 4G/5G-antennas as well as the GSM-R-antenna.
Further, in an embodiment two 4G-antennas are fixed to the first half of the base plate. The use of two antennas improves the radiation characteristics for 4G communication.
In a more specific embodiment, the two 4G-antennas are fixed to the base plate in such a way that each 4G-antenna is fixed in one respective quarter of the base plate, wherein the quarters of the base plate are defined by a line connecting the mid-point of the short side of the first half of the base plate and the mid-point of the half-line of the base plate. Thus, the interference between the two antennas can be reduced and both antennas can be accessed physically easily if necessary.
Both 4G-antennas can also be arranged so that their distance from the nearest short side is largely identical as is the distance from the nearest long side. This all provides for a desirable, homogeneous radiation pattern during communication.
In a further embodiment, a global navigation and satellite system, GNSS, receiver is also fixed to the base plate. Typically, GNSS receivers support the GPS and GLONASS systems. Other standards might also be supported. The GNSS receiver provides for further functionality, which is important in particular for a range of additional FRMCS uses. Alternatively, a train can also use GNSS receivers which are located at different other parts of the train. However, positioning the low height GNSS receiver together with the other antennas on the base plate minimises the effect on the other antenna elements.
In a more specific embodiment, the global navigation and satellite system, GNSS, receiver is fixed to the base plate with a smaller distance from the at least one 4G-antenna when compared to the distance to the GSM-R-antenna. Experiments have shown that this location allows for the least distorted communication as the 4G-antennas distort the signal of the GNSS receiver less than the GSM-R-antenna. The distances are again measured in a view from above onto the base plate, whereas the respective distances are measured between the points which are closest to each other. In another embodiment, the global navigation and satellite system, GNSS, receiver is fixed to the first half of the base plate. In another embodiment, the distance of the GNSS receiver from both 4G-antennas is not identical, but is not more different than 15%.
In an even more specific embodiment, the global navigation and satellite system, GNSS, receiver is fixed to the base plate in between two 4G-antennas on the first half of the base plate. This arrangement has shown the best radiation characteristics when testing all different communication components.
The feed-through in the base plate comprises one individual feed-through for each 4G-antenna, GSM-R-antenna and possible GNSS receiver fixed to the base plate. Thus, the connection of individual cables is less prone to errors and the arrangement of different cables can be controlled well.
In a more specific embodiment, all individual feed-throughs are arrange within a circle of not more than 33 mm in diameter. In other words, the outer edges of the feed-throughs when looking at the feed-throughs from above onto the base plate would all fit within a circle of not more than 33 mm in diameter. This allows for all cables after mounting of the base plate on the roof of the train to run without obstacle into a hole on the roof of the train, which is also 33mm in diameter. This hole is already pre-existing for the current GSM-R-antennas in use and thus, can be reutilized.
In another embodiment of the multiband antenna system, the feed-through in the base plate comprises one individual feed-through for each 4G-antenna, GSM-R-antenna and possible GNSS receiver wherein the feed-through comprises at least two first connectors which are connected to individual second connectors of the multiple coaxial cable connecting one coaxial cable with one feed-through. The connectors allow for a quick and safe connection of the multiple coaxial cable with the 4G-antenna, GSM-R-antenna and possible GNSS receiver.
In each of the embodiments described above a 4G antenna is used as an example cellular network antenna. However it should be borne in mind that as further communication standards and protocols are adopted, such as 5G, the 4G antennas may be replaced as required. Furthermore, although at present the preferred standard of communication in railways is the GSM-R system, other application-specific, in particular railway-specific, standards may be adopted.
With this in mind, the following embodiment takes into account that communication standards and protocols may change with advancing telecommunications technology and implementation.
Figure 5 shows an embodiment of the multiband antenna in a perspective view from the side without any cables. In this embodiment the housing 40 is both removable and shaped so as to have improved aerodynamic properties over existing antennas without risk of accidental engagement on overhanging branches or electrical cables. Typical antenna radome designs are often a block or a shark fin shape, which either offer little in the way of aerodynamic properties or are shaped with a long sloping leading edge and a short hook-like trailing edge to provide air flow benefits in the direction of travel of the leading edge. For trains in a reversable formation having a driver's carriage at both the front and the rear of the train the shark fin antenna on the rear driver's carriage is at risk of catching on overhead obstacles. This is because the hook-like trailing edge always forms a leading edge in one direction of travel.
The multiband antenna 1 shown in Figure 5 therefore comprises an alternative housing design to overcome these issues. The housing 41 comprises a base portion 42 on which is mounted a cover 43, the cover 43 having a footprint having a first arm 44a and a second arm 44b joined at a central apex 45. The arms 44a, 44b are perpendicular to the base portion 42, and may be parallel to each other, separated by a distance d, or inclined to one another by an acute angle (not shown). The cover 43 comprises a continuous supporting wall 46 and an upper portion 47, where the continuous supporting wall 46 extends between the base portion 42 and the upper portion 47 and has a maximum height h. The upper portion 47 extends from the apex 45 along the first 44a and the second 44b arms at the maximum height h of the supporting wall 46 and inclines to form a valley 48 extending between the first 44a and the second 44b arms from proximate the apex 45 to the base portion 42 distal the apex 45. The upper portion 47 forms a continuous upper surface over the cover within the boundary of the supporting wall 46. In the region of the valley 48 the height of the supporting wall 46 increases along the inward sides of the arms 44a, 44b from the upper end of the valley 48 proximate the apex to the ends of the arms 44a, 44b distal the apex. In the embodiment illustrated in Figure 5 the upper portion is parallel to the base portion 42 along the length of the arms 44a, 44b, but it may be desirable to also include an incline from the apex 45 to the distal ends of the arms 44a, 44b. In the embodiment shown the footprint of the cover 43 is a "Y"-shape. Alternatively the footprint of the cover may be a "V"-shape or a "U"-shape with a rounded apex 45.
The base portion 42, supporting wall 46 and upper portion 47 are formed integrally such that the housing 41 is weatherproof and completely contains the antenna components within the cover 43. The base portion 42 is rectangular in shape, having two opposing long sides of length L and two opposing short sides of length l. The supporting wall 46 has a maximum height h, where h is chosen to be marginally greater than the height of the antenna components to be contained within the cover 43. Typically l < h <L, although this need not be the case, depending on the dimensions of the antennas within the housing 41. The valley 48 is provided primarily to improve the overall aerodynamic behaviour of the housing 41 dependent upon the direction of travel of the train to which it is fitted.
The housing 41 is fixed to the base plate 5 of the multiband antenna 1 such that the apex 45 of cover 43 is positioned as the leading edge LE when the train is in forward motion. Although this leading edge LE is vertical, airflow is directed around the sides of the cover as the train moves along, removing the issues associated with block-shaped radomes. The trailing edge TE is formed by the two arms 44a, 44b of the cover, and thus is also vertical, removing the issues associated with the hook-like trailing edge of the shark fin radome. The apex 45 of the cover 43 forms the trailing edge TE of the multiband antenna when the train is in backward motion. Thus the valley 48 aids in the aerodynamic behaviour of the cover 43 when the arms 44a, 44b form the leading edge LE.
In order for the housing 41 to be removable from the base plate 5 such that antenna components within the multiband antenna 1 can be maintained or replaced a plurality of screw holes 49 are provided in the base portion 42. To improve access to screws (not shown) positioned within these screw holes 49 it may be desirable to provide notches 49a or other access features in the supporting wall 46 corresponding to the position of the screw holes 49 to enable insertion of a screwdriver along the side of the cover 43. The housing 41 is preferably formed from glass fibre reinforced plastic (GRP).
Inside the housing 41 the arrangement of antennas is similar to that shown in Figure 1. Two cellular network antennas 30 are provided in the arms 44a, 44b of the cover 43, with a GNSS receiver 35 arranged between these two cellular network antennas 30. An application-specific antenna 31 is mounted in the apex 45 of the cover 43, which in this embodiment is an antenna suitable for communication on the Global System for Mobile Communications - Railway (GSM-R) network. However, other railway application-specific antennas may be used. Both the cellular network antennas 30 and the application-specific antenna are screwed into a PCB (Printed Circuit Board) designed to provide good VSWR (Voltage Standing Wave Ratio) over a wide frequency range at 50 Ohms impedance. Replacement of the antennas may be achieved by simply unscrewing antennas that require removal and screwing in new antennas. The cellular network antennas 30 may be 4G, 5G or any other suitable cellular communication variant or protocol.
Turning back to Figure 2, the base plate 5 has two opposing short sides 6 and two opposing long sides 7 forming an outer rectangle, and four fixation means 20, wherein the four fixation means 20 are located such that they coincide with the corners of a smaller inner rectangle, and wherein the base plate 5 can be divided into two halves 8, 9 by a half-line 10 connecting the mid-points on the two opposing long sides 7 such that two of the fixation means 20 are located on a first half 8 of the base plate 5 and two of the fixation means 20 are located on a second half 9 of the base plate 5. The application-specific antenna 31 is mounted on the second half 9 of the base plate and the two cellular network antennas 30 and the GNSS receiver 35 are mounted on the first half 8 of the base plate 5. The base plate further comprises a feed through 15 arranged on either the first half 8 or the second half 9 of the base plate 5. The feed through 15 in the base plate 5 comprises one individual feed through for each of the cellular network antennas 30, the application-specific antenna 31 and the GNSS receiver 35 fixed to the base plate 5. A multiple coaxial cable 3, which comprises several coaxial cables in one cable jacket 4, where the multiple coaxial cables are each connected to one of the cellular network antennas 30, the application-specific antenna 31 and the GNSS receiver5 may be combined with the multiband antenna 1 to form a multiband antenna system. A train may be provided with either the multiband antenna 1 or the multiband antenna system.

Claims

A multiband antenna (1) comprising:
a base plate (5);

a housing (41), comprising a base portion (42) and a cover (43), removably mounted on the base plate (5), the cover (43) having a footprint having a first arm (44a) and a second arm (44b) joined at a central apex (45);

an application-specific antenna (31) mounted on the base plate (5) at the apex (45) of the cover (43);

a cellular network antenna (30) mounted on the base plate (5) in each of the first (44a) and second (44b) arms of the cover (43);

wherein the cover (43) comprises a continuous supporting wall (46) and an upper portion (47), the continuous supporting wall (46) extending between the base portion (42) and the upper portion (47) and having a maximum height h, and the upper portion (47) extending from the apex (45) along the first (44a) and the second (44b) arms at the maximum height h of the supporting wall (46) and inclines to form a valley (48) extending between the first (44a) and the second (44b) arms from proximate the apex (45) to the base portion (42) distal from the apex (45).
A multiband antenna (1) according to claim 1, wherein a Global Navigation and Satellite System (GNSS) receiver (35) is fixed to the base plate (5) in between the two cellular network antennas (30).
A multiband antenna (1) according to claim 2, wherein the base plate (5) has two opposing short sides (6) and two opposing long sides (7) forming an outer rectangle, and four fixation means (20), wherein the four fixation means (20) are located such that they coincide with the corners of a smaller inner rectangle, and wherein the base plate (5) can be divided into two halves (8, 9) by a half-line (10) connecting the mid-points on the two opposing long sides (7) such that two of the fixation means (20) are located on a first half (8) of the base plate (5) and two of the fixation means (20) are located on a second half (9) of the base plate (5).
A multiband antenna (1) according to claim 3, wherein the base plate (5) further comprises a feed through (15) arranged on either the first half (8) or the second half (9) of the base plate.
A multiband antenna (1) according to claim 4, wherein the feed through (15) in the base plate (5) comprises one individual feed through for each of the cellular network antennas (30), the application-specific antenna (31) and the GNSS receiver (35) fixed to the base plate (5).
A multiband antenna (1) according to any of claims 3 to 5, wherein the application-specific antenna (31) is mounted on the first half (8) of the base plate (5) and the two cellular network antennas (30) and the GNSS receiver (35) are mounted on the second half (9) of the base plate (5).
A multiband antenna (1) according to any preceding claim, wherein the arms (44a, 44b) of the cover (43) may be parallel to one another and separated by a distance d or inclined to one another at an acute angle.
A multiband antenna (1) according to any preceding claim, wherein the arms (44a, 44b) of the cover (43) are perpendicular to the base portion (42).
A multiband antenna (1) according to any preceding claim, wherein the footprint of the cover (43) is one of a "Y"-shape, a "V"-shape or a "U"-shape.
A multiband antenna (1) according to any preceding claim, wherein the application-specific antenna (31) is a GSM-R antenna.
A multiband antenna (1) as claimed in any preceding claim, wherein, when mounted on a train (50), the apex (45) of the cover (43) forms the leading edge LE of the multiband antenna (1) when the train (50) is in forward motion.
A multiband antenna (1) as claimed in claim 11, wherein, when mounted on a train (50), the apex (45) of the cover (43) forms the trailing edge TE of the multiband antenna (1) when the train (50) is in backward motion.
A multiband antenna (1) as claimed in any preceding claim, wherein the base portion (42), the supporting wall (46) and the upper portion (47) of the cover (43) of the housing (41) are formed integrally.
A multiband antenna (1) comprising a largely rectangular base plate (5) with a short side (6) and a long side (7), having four fixation means (20) which are arranged on this base plate (5) such that the locations of the four fixation means (20) coincide with the corners of another rectangle, and wherein the base plate (5) can be divided into two halves (8, 9) by a half-line (10) connecting the mid points (11, 12) on the two long sides (7), such that two of the fixation means (20) are arranged on the first half (8) and two of the fixation means (20) are arranged on the second half (9) of the base plate (5), a feed-through (15) being provided, completely or at least largely arranged on one of the first half (8) and the second half (9) of the base plate (5);
characterised in that
two cellular network antennas (30) are fixed to the first half (8) of the base plate (5) in such a way that each cellular network antenna (30) is fixed in one respective quarter of the base plate (5), wherein the quarters of the base plate are defined by a line connecting the mid-point (13) of the short side (6) of the first half (8) of the base plate (5) and the mid-point (14) of the half-line (10) of the base plate (5), and one application-specific antenna (31) is fixed to the second half (9) of the base plate (5).
A multiband antenna (1) according to claim 14, wherein a Global Navigation and Satellite System (GNSS) receiver (35) is fixed to the base plate (5), on the first half (8) of the base plate (5), in between the two cellular network antennas (30) with a smaller distance from the cellular network antennas (30) when compared to its distance to the application-specific antenna (31)..
A multiband antenna according to any one of claims 14-15 and any one of claims 1-13.
A multiband antenna system (2) comprising the multiband antenna (1) of any of claims 4 to 13 or claim 14 when dependent on any one of claims 4 to 13 and a multiple coaxial cable (3), which comprises several coaxial cables in one cable jacket (4), wherein the coaxial cables are each connected to one of the cellular network antennas (30), the application-specific antenna (31) and the GNSS receiver (35).
A train (50) comprising a multiband antenna (1) of any of claims 1 to 15 or the multiband antenna system (2) of claim 16.