Indian Patents. 264795:AN ARRANGEMENT RELATING TO ANTENNA COMMUNICATION

Title of Invention	AN ARRANGEMENT RELATING TO ANTENNA COMMUNICATION
Abstract	The present invention relates to an arrangement (1A,1B) for providing communication between an antenna arrangement and a radio base station at a site. It comprises a waveguide arrangement (3) connected to the radio base station and to the antenna arrangement (1A,1B) supporting communication of signals between the radio base station and the antenna arrangement (1A,1B).

Full Text	FIELD OF THE INVENTION The present invention relates to an arrangement for providing communication between an antenna arrangement and a radio base station at a site. Particularly the invention relates to base station antenna feeding. The invention also relates to a base station and antenna arrangement with an arrangement for providing signal communication therebetween. STATE OF THE ART In order to provide for communication between an antenna arrangement and mobile base stations at a site coaxial feeder cables are used today. However, the losses tend to be considerable in such cables, the higher the frequency of the transmitted signals, the higher the losses. In order to reduce the losses, it is exceedingly important to use cables which are as thick as possible for the communication between the active parts of a base station and the antenna arrangement mounted on a mounting structure, for example a mast, at the base station site. The need of thick cables is also particularly of importance since the base stations generally contain all the electronics; today there is practically no electronic at all in the antenna itself. A common dimension of coaxial cables used today is 1.25 inch cables which have a loss about 0.05 dB/m for 2.2 GHz frequency signals. The fact that the losses tend to be considerable and that hence even very thick cables are needed, is a serious problem as such, among other since thick cables get bulky, heavy and require a lot of space. This problem gets even more pronounced due to the fact that, today, the antenna arrangement at a base station site mostly consist of several antennas, and generally each antenna has 2 two polarizations. It is also common to use so called sector antennas, e.g. at so called three sector sites, with three sector antennas, which hence require six (if there are two polarizations) different feeder cables between the base station and the antenna arrangement, particularly all provided along the mast on which the antenna arrangement is mounted. For a six sector site the number of cables will correspondingly be twelve. In addition thereto it is becoming common to use dual or triple frequency band antennas; this means that the number of cables that is required will be even higher, and all these cables somehow have to be bundled together. This is extremely disadvantageous, since several meters of thick, coaxial cables have to be provided on or close to a mounting structure such as a mast. For the first, it is very unsatisfactory from an aesthetic point of view. Second it is inconvenient since, due to the fact that thick cables are required, there will be a certain attenuation as well. In addition therefo installation and mounting will be time consuming and complicated and thereto also expensive, and the cables may particularly occupy a large portion of the space of the total mounting structure and hence will predominate visually. The more complicated the antenna arrangement, i.e. the more sectors, frequency bands etc, the more time consuming and difficult it will be to mount the communication arrangement consisting of a plurality of thick cables between the antenna arrangement and the base station itself, and the higher losses will have to be reckoned with. SUMMARY OF THE INVENTION What is needed is therefore an arrangement as initially referred to, which enables communication between a base 3 station and an antenna arrangement which is comparatively slim, and not complex, and which is easy to mount or install. Still further an arrangement is needed which has low losses and which is flexible, i.e. which can be used with different types of anntenna arrangements, particularly with antenna arrangements comprising several antennas which may have different polarisations and/or which may be dual or triple frequency band antennas and which may be of sector type. Particularly an arrangement is needed which is aesthetic and which has a low attenuation. Moreover an arrangement is needed which can be used in high frequency systems, i.e. in communication systems using frequencies of more than about 2 GHz. Particularly an arrangement is needed which can be made long and which can be used for a large number of signals, e.g. for sector antennas of dual polarisation type and for more than one frequency band. Still further an arrangement is needed which is easy to fabricate and to transport to the site and which can be produced and handled without high manufacturing high costs. Still further an arrangement isd needed which requires little or no maintenance, which easily can be replaced and which is robust and durable. Therefore an arrangement as initally referred to is provided which comprises a waveguide arrangement connected to a radio base station and to an antenna arrangement. In one embodiment the waveguide arrangement is connected directly to the radio base station and/or directly to the antenna arrangement. This means that it may be connected directly to the radio base station but indirectly to the antenna arrangement or vice versa. Of course it may also be connected directly to the radio base station and to the antenna arrangement. In another or in other implementations the waveguide arrangement is connected indirectly to the radio base station and/or indirectly to the antenna arrangement via intermediate connecting means such as for example jumper cables and 4 connectors disposed at the waveguide arrangement end or ends. Particularly it comprises coax-to-waveguide transitions. In another embodiment the waveguide arrangement comprises waveguide connecting portions which are connected directly to the radio base station and/or directly connected to the antenna arrangement. Particularly the waveguide arrangement is connected to or associated with an antenna mounting structure, e.g. a mast or similar. Alternative the waveguide arrangement is adapted to be incorporated in or taken up in an antenna arrangement mounting structure. Particularly it is used to provide communication with an antenna arrangement comprising several antennas, for example a multisector antenna with several sector antennas. The waveguide arrangement particularly comprises a plurality of compartments, each acting as a waveguide particularly for a signal to an antenna. Each antenna, for example the multisector antenna, or the antenna if it only comprises one antenna, may have two polarisations, the waveguide arrangement comprising one waveguide compartment for each polarisation and for each antenna, hence for a dual polarisation antenna it comprises two compartments for each sector antenna. The invention is applicable to most different kinds of antenna arrangements. In one embodiment it provides communication with an antenna arrangement comprising dual band antennas, in another embodiment with a triple band antenna arrangement. To provide communication with a sector antenna, there may be one waveguide compartment for each antenna, particularly one for each frequency band of each antenna, and/or polarization each antenna of the antenna arrangement. Particularly the waveguide arrangement comprises a longitudinal metal profile structure with a number of 5 waveguides formed by compartments, e.g. one for each antenna, particularly one for each polarisation and one for each band thereof etc. depending on what is applicable. It may be selected according to the requirements on allowed loss factor etc. In other embodiments there is/are some compartment(s) which is/are multimode compartments, others which are not. In one embodiment the metal profile structure has a circular cross-section, in other embodiments it has an oval, trapezoidal, triangular or an elliptic cross-section. In still another embodiment it has a rectangular, or particularly a square shaped, cross-section. The metal profile structure cross-section can be different from that of the respective compartments. The profile structure may e.g. be circular, the compartments rectangular or vice versa. Any combination is possible. Preferably the metal profile structure is made of some low loss conducting material e.g. aluminium (A1) or a material with similar properties. It may also be made of a material which is coated with a low conducting material e.g. aluminium. In one embodiment the waveguide arrangement comprises a. number of waveguides, each with a rectangular cross-section defined by a waveguide width and a waveguide height. In order to allow for RF signals to propagate, the width of the waveguides has to exceed λ/2 of the feed signal. The other dimension of a rectangular waveguide compartment, the height, is not restricted to a particular dimension and does actually not affect the propagation of an RF signal, and therefore it can be made low. 6 In one particular implementation the waveguide arrangement comprises one waveguide which is common for a number of signals to/from different antennas (and/or for different polarisations, frequency bands) and different signals are carried by different waveguide modes in said common waveguide. In a particular embodiment the waveguide arrangement comprises a limited number of waveguide compartments each of which carrying a number of signals to/from a given number of antennas (polarisations, frequency bands) by means of different modes. The height dimension particularly determines the loss performance of the waveguides. In one embodiment a waveguide width is approximately 0.6 λ - 1.0 λ, e.g. 0.80 λ which corresponds to 90-150, e.g. 120 mm for a 2 GHz UMTS (Universal Mobile Telecommunications System) signal. Particularly the height of the respective waveguide is about 1/4 to 1/8 of the width, particularly around 10-30 mm. Particularly the waveguide dimension, for a 2 GHz signal, is 120 x 20 mm. The typical loss will then be 0.025 dB/m. If the height of the waveguides is 10 mm, the loss will be about 0.05 dB/m. It should be clear that these figures merely are given for illustrative purposes. In one embodiment, the antenna structure comprises a single or monolithic structure. In a preferred embodiment the arrangement, or the metal profile structure, comprises a number of sections which are connected to each other such the length of the arrangement substantially corresponds to the sum of the lengths of the individual sections. In one embodiment with a common multimode waveguide, the individual sections are telescopically connected to each other. 7 The invention also relates to a base station site with a radio base station and an antenna arrangement with communication means for providing communication between the base station and the antenna arrangement, and an antenna mounting structure, for example a mast or similar. The communication means particularly comprises a waveguide arrangement, which waveguide arrangement is associated with or comprised by, or integrated in, the mounting structure. Particularly the waveguide arrangement comprises a number of parallell waveguides. Particularly the mounting structure comprises a mast with a number of legs, each leg comprising one or more waveguides of the waveguide arrangement. Particularly the waveguide arrangement comprises a number of compartments, each carrying signals to/from an antenna of the antenna arrangement. Alternatively it comprises a common waveguide supporting propagation of a number of different modes, each carrying one signal to/from one antenna of the antenna arrangement, which may comprise a plurality of antennas, e.g. being a sector antenna, dual polarised antennas, dual or triple band antennas in any combination. Particularly the invention relates to the use of an arrangement as discussed above in a cellular mobile communication system operating at about 2 GHz or more. Of course, an arrangement according to the inventive concept is applicable for other frequency ranges as well. BRIEF DESCRIPTION OF THE DRAWINGS The invention will in the following be more thoroughly described, in a non-limiting way, and with reference to the accompanying drawings in, which: 8 Fig. 1 schematically illustrates an arrangement comprising a waveguide for providing communication between two antennas and a radio base station at a site, Fig. 2 schematically illustrates an arrangement for providing communication between three antennas and a radio base station comprising a waveguide arrangement consisting of three sections and a waveguide-to-coaxial transition at each end, Fig. 3A schematically illustrates a part of a communication arrangement in the form of a waveguide with three compartments connected to one sector antenna of a three sector antenna with a a coaxial cable-to- waveguide transition, Fig. 3B is a cross-sectional view taken along lines A-A in Fig. 3A of the waveguide arrangement, Fig. 4 schematically illustrates still another embodiment of a waveguide arrangement with waveguide connections provided through direct contact with for example a sector antenna (not shown) and a radio base station, Fig. 5 is a cross-sectional view of a waveguide arrangement comprising n rectangular waveguides, Fig. 6 shows another implementation of rectangular waveguides of a waveguide arrangement with a circular cross-section but with segments forming rectangular waveguides, Fig. 7 schematically illustrates an example of a coaxial waveguide arrangement with n waveguides, 9 Fig. 8A schematically illustrates a waveguide mode fed in a rectangular waveguide, Fig. 8B is a schematical cross-sectional view of a mode fed in a circular waveguide, Fig. 8C is a schematical cross-section of the fundamental mode fed in a coaxial waveguide, Fig. 9 schematically illustrates the lower part of a waveguide arrangement with connectors for connections, forming coaxial cable-to-waveguide transitions, to a base station, and Fig. 10 schematically illustrates the connection portion (coaxial-to-waveguide transition) for a waveguide arrangement comprising one common waveguide when different waveguide modes allow for propagation of different signals. DETAILED DESCRIPTION OF THE INVENTION Fig. 1 shows an antenna arrangement 1A, 2A mounted on a mounting structure 4, here in the form of a mast, to which the two antennas 1A, 1B are mounted. For communication with the base station (not shown) a waveguide arrangement 3 is associated with the mast structure 4. In this embodiment jumper cables 2A, 2B are provided for connection to the antennas 1A, 1B. It should be clear that the waveguide arrangement 3 also is connected to the base station for example via jumper cables (not shown). Hence, in this embodiment the waveguide arrangement 3 is associated with or connected to the mast structure 4. In an alternative embodiment it may be integrated in the mast structure, or more generally in the mounting structure. In the embodiment of Fig. 10 1 the waveguide arrangement 3 is illustrated as consisting of one large section. However, preferably, it is generally divided into a plurality of sections of appropriate lengths, which is advantageous for fabrication, transportation and installation purposes. In an alternative embodiment, the waveguide arrangement or the individually waveguides provided therein, might be connected directly to the antenna and/or the base station. In case jumper cables are used, connectors are required at each end of the respective waveguides. It should be clear that the antenna arrangement may comprise more than two antennas or it could be just one antenna. Of course also different kinds of antennas may be used, for example three antennas for a three sector site or six sector antennas for a six sector site etc. Each antenna may have two polarisations and the antenna (s) additionally may be dual or triple band antennas etc. Unless waveguide connecting means are used, cf. Fig. 4, coax- to-waveguide transitions are required both for connection to the antennas and for connection to the base station. Fig. 1 only shows the basic concept of the present invention wherein a waveguide arrangement is used instead of thick cables. Fig. 2 shows another embodiment in which the waveguide arrangement comprises, here, three waveguide sections 311, 312, 313 which are interconnected by means of flanges 911, 912, 913. The uppermost waveguide section 311 is via a flange 911 connected to a waveguide feed transition 51 providing transitions to cables 2A1, 2B1, 2C1 connecting to the, here, three antennas (not shown). Similarly a waveguide feed transition 61 is connected to the lowermost waveguide section 313 via a flange 914 providing transitions to the cables 7A1, 7A2, 7A3 connecting to the base station (not shown) . The waveguide arrangement may take any of the forms as will be 11 described more thoroughly below, but also several other embodiments are possible. Fig. 3A illustrates a part of a waveguide arrangement 32 comprising three waveguide compartments (cf. illustration of waveguide arrangement cross-section taken along A-A in Fig. 3B) via a flange 92 connected to a transition arrangement 52 with coax to waveguide transitions 821, 822, 823 via cables 2A2, 2B2, 2C2 to three sector antennas of which only the first sector antenna 1A2 is shown. Fig. 3B shows an example of a cross-sectional view of a waveguide arrangement (as in Fig. 3A) comprising three waveguide compartments C1, C2, C3. The respective waveguides are rectangular waveguides with a width W32 approximately ≥ λ/2. The dimension of the width has to be such in order to enable for RF signals to propagate. The height H32 is not restricted by the wavelength and it can be made quite small. Particualarly the height determines the loss performance of the waveguide. A typical loss for an air-filled aluminium waveguide with the dimensions 120 x 20 mm is approximately 0.025 dB/m for a 2 GHz frequency signal. If the height is about 5 mm, the loss is about 0.088 dB/m, if it is about 10 mm, the loss will be about 0.045 dB/m, for a height which is about 15 mm, the loss will be approximately 0.031 dB/m, and for a height of 20 mm it will be about 0.024 dB/m. Thus, the loss is inversely proportional to H. The losses should be compared with the loss for a 1.25 Inch cable, which is about 0.05 dB/m. At high frequencies (more than 2GHz) the difference between the losses in an air-filled waveguide and a coaxial cable increases. The waveguide is in principle independent of the frequency whereas for a coaxial cable the loss in dB is proportional to the frequency due to 12 dielectric loss. Dielectrical losses can more easily be avoided in rigid waveguides. In this embodiment the rectangular waveguides C1, C2, C3 are rectangular and stacked in a common metal profile 32 comprising the waveguide arrangement. In this particular embodiment the exterior of the profile is rectangular. It may of course also be circular or of any other appropriate shape. For a 2GHz UMTS-signal, a typical size could be 0.8 λ, which is approximately 120 mm. Particularly one waveguide or one compartment acts as a waveguide for one feed signal. As will be more thoroughly discussed below, multimode implementations are also possible in which one waveguide may support propagation of more than one mode. Fig. 4 shows another embodiment of a waveguide arrangement 33 (which may have any cross-section as will be further described below, for example comprising a number of rectangular compartments etc. but it may also comprise a number of, or a single waveguide, supporting different modes, one for each feed signal). In this embodiment, however, the waveguide arrangement is via a waveguide connection 63 directly connected to the base station 10 and via a waveguide connection 53 connected directly to, here, a three sector antenna (not shown) and hence comprising three waveguide connections 531, 532, 533. The waveguide arrangement 33 is connected via flange 931 to the antenna waveguide connection 53 and via a flange 932 connected to the base station 10 via the waveguide connection 63. The flanges 931, 932 can be of any conventional kind. The waveguide connections may alternatively be soldered onto the waveguide arrangement 33. Even if the waveguide arrangement 33 in this figure is shown as comprising one 13 section only, it may of course alternatively comprise several sections as for example discussed with reference to Fig. 2. In this embodiment there are no coax-to-waveguide transitions, and hence specifically adapted or special types of antennas/base stations are required. Fig. 5 is a cross-sectional view of a waveguide arrangement 34 comprising n rectangular waveguides 1, 2,... n with a width W lager than or substantially equal to λ/2 as discussed above. The outer walls are conducting and the interior of the waveguides comprise air or a low-loss dielectric material. The supported fundamental mode is here TE10. The waveguides may also support higher order modes, in this case TE20, TE30 etc, but then they must be larger. Hence, each individual waveguide may support one or more modes, each waveguide handling one feed signal, or if multiple modes or supported, each mode holding one feed signal. Fig. 6 shows still another embodiment of a cross-section of a waveguide arrangement 35 which in principle also acts as an arrangement with a number of rectangular waveguides 1, 2, 3, 4, 5, the length of which (the outer segments 1, 2, 3) should be larger than or substantially equal to λ/2. The innermost waveguide comprises a circular waveguide for corresponding modes. Also in this case the fundamental supported mode is TE10, but the individual waveguides may also support higher order modes such as TE20, TE30 etc. Fig. 7 shows a cross-section of an embodiment of a waveguide arrangement 36 which comprises a coaxial waveguide in a multilayer implementation, comprising n layers. The fundamental supported mode is here TEM similar to a coaxial cable. The first higher order mode that might be supported is TE11 etc. According to different embodiments each waveguide compartment supports one mode, but if it is supported, i.e. if 14 the dimensions of the waveguides are larger (large enough), it is possible for multiple modes to propagate. Fig. 8A schematically illustrates the fundamental propagating mode for a rectangular waveguide with width W and height H. The walls of the waveguide are conducting and have a thickness exceeding the electrical penetration depth. As referred to above the supported fundamental mode is in such an embodiment TE10, i.e. an electrical field transversal with respect to the direction of propagation. If a larger width is used, higher order modes may be supported for feeding signals. Fig. 8B schematically illustrates the supported waveguide mode of a circular waveguide (CWG) which also has conducting walls etc., c.f. Fig. 8A. The fundamental propagating mode is here TE11. With a larger cross-section, it may also support one or more higher order modes, for example TM01. Fig. 8C is a cross-sectional view of a coaxial waveguide wherein b here corresponds to the radius of the outer conductor and a is the radius of the inner conductor. Higher order modes may be supported if a a larger radius is selected, e.g. TE11 etc. It should be clear that these figures merely show some examples on waveguide cross-sections. Fig. 9 is a very simplified view of a waveguide arrangement 36 comprising a number of waveguide compartments 371,...,376, one for each feed signal to an antenna arrangement/a base station, each waveguide comprising a connector 671,..., 676 for connection to the base station (the respective antenna) as discussed earlier in the application. Fig. 10 shows one example of a coaxial-waveguide transition for a multimode implementation according to the invention. It 15 shows a cross-section of a rectangular waveguide 37. TE10 feeding is provided by means of the central metal conductor 81 of a coaxial cable with outer conductors 87. TE20 feeding is provided by means of a phase shifted 890 which provides two signals phase shifted +/- 90° and which are fed via the central conductors 82, 83 of two coaxial-waveguide transitions 881, 882. TE10 is fed symetrically and TE20 is fed differentially. An alternative embodiment (not shown) is using a 4-port sum/delta-divider where the TE10 mode is fed to the sum-port resulting in two identical (symmetric feeding) signals fed to 82 and 83, and where the TE20 mode is fed to the delta-port resulting in two equal amplitude but 180° phase shifted (differential feeding) signals simultaneiously fed to 82 and 83. The divider is reciprocal so that the principle applies for transmission in both directions. It should be clear that different kinds of waveguides can be used. It is for example also possible to use ridge waveguides. It is an advantage of the invention that the communciation, for example all feed signals, can be collected in a slim waveguide as compared coaxial feeder cables which are thick and have large losses. Still further it is an advantages that the arrangement for providing communication between a base station and an antenna arrangement can be made more aesthetic and less optically dominating, than a large number of thick coaxial feeder cables. It is particularly advantageous that the arrangement can be integrated in a mounting structure, for example a mast, or in the legs of a mast structure. It is also advantageous that, through the use of waveguides for signal transmission, the losses will be very low. The losses are, even for low profile waveguides, lower than for thick coaxial cables. It is also an advantage that a waveguide arrangement, particularly one comprising a number of sections, can be 16 easily fabricated and installed at a low cost, and it is easy to transport and resistant to damages. It is also advantageous that such a waveguide arrangement is particularly easy and cheap to fabricate and it e.g. comprises conventional extruded aluminium profiles or a material coated with aluminium. Moreover for example for 3G (3GPP, Third Generation Partnership Project) implementations frequencies which are high are used, which means that the losses get high if cables are used, it is clearly advantageous to a use waveguide arrangement instead of very thick coaxial cables. It is also advantageous that the waveguide arrangement may fabricated in sections which simply are mounted to each other by means of flanges or similar since the mounting structure is a mast, which may be very high, even up to 20-30 meter or more. It should be clear that the invention is not limited to the specifically illustrated embodiments but that it can be varied in a number of ways without departing from the scope of the appended claims. Particularly may each waveguide in a waveguide arrangement support propagation or transmission of signals by one or more modes and the profile structure can be made with any cross- sectional shape, square-shaped, rectangular, circular, elliptic, oval etc. It should also be clear that the higher the frequency of the propagating signals is, the higher is the gain of using a waveguide arrangement. 17 CLAIMS 1. An arrangement for providing communication between an antenna arrangement and a radio base station at a site, comprising a waveguide arrangement connected to the radio base station and to the antenna arrangement supporting communication of signals between the radio base station and the antenna arrangement, characterized in that the waveguide arrangement is adapted to support communication of a plurality of signals between the radio base station and the antenna arrangement and in that it comprises a number of compartments, each compartment acting as a waveguide for a particular signal, or a number of compartments of which at least some comprise dual-, or multimode compartments wherein each mode carries one signal, or one multimode waveguide common for a number of signals. 2. An arrangement according to claim 1, characterized in that the waveguide arrangement comprises waveguide connecting means connected directly to the radio base station and/or to the antenna arrangement. 3. An arrangement according to claim 1, characterized in that the waveguide arrangement is connected indirectly to the radio base station and/or the antenna arrangement via intermediate connecting means, e.g. jumper cables and connectors disposed at the waveguide arrangement end(s). 4. An arrangement according to any one of claims 1-3, characterized in 18 that the waveguide arrangement is adapted to be associated with or connected to an antenna mounting structure, e.g. a mast or similar. 5. An arrangement according to any one of claims 1-3, characterized in that the waveguide arrangement is adapted to be incorporated, or taken up in an antenna arrangement mounting structure. 6. An arrangement according to any one of claims 1-5, characterized in that the waveguide arrangement comprises a plurality of compartments, each acting as a waveguide for a particular signal to/from an antenna of an antenna arrangement comprising several antennas e.g. a multi-sector antenna arrangement. 7. An arrangement according to claim 6, characterized in that the waveguide arrangement comprises a compartment for each polarisation of each antenna of dual polarized antennas. 8. An arrangement according to any one of the preceding claims, characterized in that each antenna of the antenna arrangement is a dual or triple band antenna, and in that there is one waveguide compartment for each band of each antenna or antenna polarization. 9. An arrangement according to any one of claims 1-5, characterized in that the waveguide arrangement comprises one multi-mode waveguide common for a number of signals to/from different antennas and/or different polarizations and/or for different 19 frequency bands and in that the different signals are carried by different waveguide modes. 10. An arrangement according to any one of the preceding claims, characterized in that the waveguide arrangement comprises a longitudinal metal profile structure with a number of waveguides. 11. An arrangement according to claim 10, characterized in that the metal profile structure has a rectangular cross- section. 12. An arrangement according to claim 10, characterized in that the metal profile structure has a circular, elliptic, oval, trapezoidial or triangular cross-section. 13. An arrangement according to claim 11 or 12, characterized in that the metal profile structure is made of a low loss conducting material, e.g. aluminium (A1) or a material with similar properties or a material which is coated with a low loss, conducting material, e.g. aluminium. 14. An arrangement according to claim 11, 12 or 13, characterized in that the waveguide arrangement comprises a number of rectangular waveguides each with a rectangular cross-section defined by a waveguide width and a waveguide height, or a number of circularly disposed segments. 15. An arrangement according to claim 14, characterized in 20 that the waveguide width (W) is larger than half the wave length (λ) (W > λm/2) . 16. An arrangement according to claim 15, characterized in that the waveguide width is approximately 0.6 λ - 1.0 λ, e.g 0.80 λ. 17. An arrangement according to claim 15 or 16, characterized in that the width is 90-150 mm for a propagating 2 GHz RF signal. 18. An arrangement according to claim 15, 16 or 17, characterized in that the height is about 1/4 - 1/8 of the width, e.g. 10-80 mm. 19. An arrangement according to any one of claims 1-13, characterized in that it comprises a circular or coaxial waveguide arrangement with a number of compartments. 20. An arrangement according to any one of the preceding claims, characterized in that it comprises one single (monolithic) structure. 21. An arrangement according to any one of claims 1-19, characterized in that it comprises a number of sections connected to each other such that the length of the arrangement substantially corresponds to the sum of the lengths of the individual sections. 21 22. A base station antenna arrangement with a base station and an antenna arrangement, communication means for providing communication of signals between the base station and the antenna arrangement, and an antenna mounting structure, e.g. a mast, the communicating means comprising a waveguide arrangement, said waveguide arrangement being associated with or comprised by the mounting structure, characterized in that the waveguide arrangement is adapted to support communication of a plurality of signals between the radio base station and the antenna arrangement and in that it comprises a number of compartments, each compartment acting as a waveguide for a particular signal, or a number of compartments of which at least some comprise dual-, or multimode compartments wherein each mode carries one signal, or one multimode waveguide common for a number of signals. 23. A base station and antenna arrangement according to claim 22, characterized in that the waveguide arrangement comprising a number of waveguides integrated in the mounting structure, e.g. a mast. 24. A base station and antenna arrangement according to claim 23, characterized in that the mounting structure comprises a mast with a number of legs, each leg comprising one or more waveguides of the waveguide arrangement. 25. A base station and antenna arrangement according to any one of claims 22-24, characterized in that the waveguide arrangement comprises a number of waveguide compartments, each carrying one or more signals to/from an 22 antenna of the antenna arrangement, that it/they support(s) propagation of a number of different modes, each carrying one, e.g. one for each polarization and/or frequency band, signal to/from an antenna of the antenna arrangement, the antenna arrangement comprising a number of antennas (e.g. a sector antenna), and/or dual polarised antennas, and/or dual or triple band antennas. 23 26. An arrangement or a base station and antenna arrangement as in any one of claims 1-25 in a cellular mobile communicating system operating at about 2 GHz or more. The present invention relates to an arrangement (1A,1B) for providing communication between an antenna arrangement and a radio base station at a site. It comprises a waveguide arrangement (3) connected to the radio base station and to the antenna arrangement (1A,1B) supporting communication of signals between the radio base station and the antenna arrangement (1A,1B).

Full Text

FIELD OF THE INVENTION
The present invention relates to an arrangement for providing
communication between an antenna arrangement and a radio base
station at a site. Particularly the invention relates to base
station antenna feeding. The invention also relates to a base
station and antenna arrangement with an arrangement for
providing signal communication therebetween.
STATE OF THE ART
In order to provide for communication between an antenna
arrangement and mobile base stations at a site coaxial feeder
cables are used today. However, the losses tend to be
considerable in such cables, the higher the frequency of the
transmitted signals, the higher the losses. In order to reduce
the losses, it is exceedingly important to use cables which
are as thick as possible for the communication between the
active parts of a base station and the antenna arrangement
mounted on a mounting structure, for example a mast, at the
base station site. The need of thick cables is also
particularly of importance since the base stations generally
contain all the electronics; today there is practically no
electronic at all in the antenna itself.
A common dimension of coaxial cables used today is 1.25 inch
cables which have a loss about 0.05 dB/m for 2.2 GHz frequency
signals.
The fact that the losses tend to be considerable and that
hence even very thick cables are needed, is a serious problem
as such, among other since thick cables get bulky, heavy and
require a lot of space.
This problem gets even more pronounced due to the fact that,
today, the antenna arrangement at a base station site mostly
consist of several antennas, and generally each antenna has
2

two polarizations. It is also common to use so called sector
antennas, e.g. at so called three sector sites, with three
sector antennas, which hence require six (if there are two
polarizations) different feeder cables between the base
station and the antenna arrangement, particularly all provided
along the mast on which the antenna arrangement is mounted.
For a six sector site the number of cables will
correspondingly be twelve. In addition thereto it is becoming
common to use dual or triple frequency band antennas; this
means that the number of cables that is required will be even
higher, and all these cables somehow have to be bundled
together.
This is extremely disadvantageous, since several meters of
thick, coaxial cables have to be provided on or close to a
mounting structure such as a mast. For the first, it is very
unsatisfactory from an aesthetic point of view. Second it is
inconvenient since, due to the fact that thick cables are
required, there will be a certain attenuation as well. In
addition therefo installation and mounting will be time
consuming and complicated and thereto also expensive, and the
cables may particularly occupy a large portion of the space of
the total mounting structure and hence will predominate
visually.
The more complicated the antenna arrangement, i.e. the more
sectors, frequency bands etc, the more time consuming and
difficult it will be to mount the communication arrangement
consisting of a plurality of thick cables between the antenna
arrangement and the base station itself, and the higher losses
will have to be reckoned with.
SUMMARY OF THE INVENTION
What is needed is therefore an arrangement as initially
referred to, which enables communication between a base
3

station and an antenna arrangement which is comparatively
slim, and not complex, and which is easy to mount or install.
Still further an arrangement is needed which has low losses
and which is flexible, i.e. which can be used with different
types of anntenna arrangements, particularly with antenna
arrangements comprising several antennas which may have
different polarisations and/or which may be dual or triple
frequency band antennas and which may be of sector type.
Particularly an arrangement is needed which is aesthetic and
which has a low attenuation. Moreover an arrangement is needed
which can be used in high frequency systems, i.e. in
communication systems using frequencies of more than about
2 GHz. Particularly an arrangement is needed which can be made
long and which can be used for a large number of signals, e.g.
for sector antennas of dual polarisation type and for more
than one frequency band. Still further an arrangement is
needed which is easy to fabricate and to transport to the site
and which can be produced and handled without high
manufacturing high costs. Still further an arrangement isd
needed which requires little or no maintenance, which easily
can be replaced and which is robust and durable.
Therefore an arrangement as initally referred to is provided
which comprises a waveguide arrangement connected to a radio
base station and to an antenna arrangement. In one embodiment
the waveguide arrangement is connected directly to the radio
base station and/or directly to the antenna arrangement. This
means that it may be connected directly to the radio base
station but indirectly to the antenna arrangement or vice
versa. Of course it may also be connected directly to the
radio base station and to the antenna arrangement. In another
or in other implementations the waveguide arrangement is
connected indirectly to the radio base station and/or
indirectly to the antenna arrangement via intermediate
connecting means such as for example jumper cables and
4

connectors disposed at the waveguide arrangement end or ends.
Particularly it comprises coax-to-waveguide transitions. In
another embodiment the waveguide arrangement comprises
waveguide connecting portions which are connected directly to
the radio base station and/or directly connected to the
antenna arrangement.
Particularly the waveguide arrangement is connected to or
associated with an antenna mounting structure, e.g. a mast or
similar. Alternative the waveguide arrangement is adapted to
be incorporated in or taken up in an antenna arrangement
mounting structure. Particularly it is used to provide
communication with an antenna arrangement comprising several
antennas, for example a multisector antenna with several
sector antennas. The waveguide arrangement particularly
comprises a plurality of compartments, each acting as a
waveguide particularly for a signal to an antenna. Each
antenna, for example the multisector antenna, or the antenna
if it only comprises one antenna, may have two polarisations,
the waveguide arrangement comprising one waveguide compartment
for each polarisation and for each antenna, hence for a dual
polarisation antenna it comprises two compartments for each
sector antenna.
The invention is applicable to most different kinds of antenna
arrangements. In one embodiment it provides communication with
an antenna arrangement comprising dual band antennas, in
another embodiment with a triple band antenna arrangement. To
provide communication with a sector antenna, there may be one
waveguide compartment for each antenna, particularly one for
each frequency band of each antenna, and/or polarization each
antenna of the antenna arrangement.
Particularly the waveguide arrangement comprises a
longitudinal metal profile structure with a number of
5

waveguides formed by compartments, e.g. one for each antenna,
particularly one for each polarisation and one for each band
thereof etc. depending on what is applicable.
It may be selected according to the requirements on allowed
loss factor etc. In other embodiments there is/are some
compartment(s) which is/are multimode compartments, others
which are not.
In one embodiment the metal profile structure has a circular
cross-section, in other embodiments it has an oval,
trapezoidal, triangular or an elliptic cross-section. In still
another embodiment it has a rectangular, or particularly a
square shaped, cross-section.
The metal profile structure cross-section can be different
from that of the respective compartments. The profile
structure may e.g. be circular, the compartments rectangular
or vice versa. Any combination is possible.
Preferably the metal profile structure is made of some low
loss conducting material e.g. aluminium (A1) or a material
with similar properties. It may also be made of a material
which is coated with a low conducting material e.g. aluminium.
In one embodiment the waveguide arrangement comprises a. number
of waveguides, each with a rectangular cross-section defined
by a waveguide width and a waveguide height. In order to allow
for RF signals to propagate, the width of the waveguides has
to exceed λ/2 of the feed signal. The other dimension of a
rectangular waveguide compartment, the height, is not
restricted to a particular dimension and does actually not
affect the propagation of an RF signal, and therefore it can
be made low.
6

In one particular implementation the waveguide arrangement
comprises one waveguide which is common for a number of
signals to/from different antennas (and/or for different
polarisations, frequency bands) and different signals are
carried by different waveguide modes in said common waveguide.
In a particular embodiment the waveguide arrangement comprises
a limited number of waveguide compartments each of which
carrying a number of signals to/from a given number of
antennas (polarisations, frequency bands) by means of
different modes. The height dimension particularly determines
the loss performance of the waveguides. In one embodiment a
waveguide width is approximately 0.6 λ - 1.0 λ, e.g. 0.80 λ
which corresponds to 90-150, e.g. 120 mm for a 2 GHz UMTS
(Universal Mobile Telecommunications System) signal.
Particularly the height of the respective waveguide is about
1/4 to 1/8 of the width, particularly around 10-30 mm.
Particularly the waveguide dimension, for a 2 GHz signal, is
120 x 20 mm. The typical loss will then be 0.025 dB/m. If the
height of the waveguides is 10 mm, the loss will be about 0.05
dB/m. It should be clear that these figures merely are given
for illustrative purposes.
In one embodiment, the antenna structure comprises a single or
monolithic structure. In a preferred embodiment the
arrangement, or the metal profile structure, comprises a
number of sections which are connected to each other such the
length of the arrangement substantially corresponds to the sum
of the lengths of the individual sections.
In one embodiment with a common multimode waveguide, the
individual sections are telescopically connected to each
other.
7

The invention also relates to a base station site with a radio
base station and an antenna arrangement with communication
means for providing communication between the base station and
the antenna arrangement, and an antenna mounting structure,
for example a mast or similar. The communication means
particularly comprises a waveguide arrangement, which
waveguide arrangement is associated with or comprised by, or
integrated in, the mounting structure.
Particularly the waveguide arrangement comprises a number of
parallell waveguides. Particularly the mounting structure
comprises a mast with a number of legs, each leg comprising
one or more waveguides of the waveguide arrangement.
Particularly the waveguide arrangement comprises a number of
compartments, each carrying signals to/from an antenna of the
antenna arrangement. Alternatively it comprises a common
waveguide supporting propagation of a number of different
modes, each carrying one signal to/from one antenna of the
antenna arrangement, which may comprise a plurality of
antennas, e.g. being a sector antenna, dual polarised
antennas, dual or triple band antennas in any combination.
Particularly the invention relates to the use of an
arrangement as discussed above in a cellular mobile
communication system operating at about 2 GHz or more. Of
course, an arrangement according to the inventive concept is
applicable for other frequency ranges as well.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will in the following be more thoroughly
described, in a non-limiting way, and with reference to the
accompanying drawings in, which:
8

Fig. 1 schematically illustrates an arrangement comprising
a waveguide for providing communication between two
antennas and a radio base station at a site,
Fig. 2 schematically illustrates an arrangement for
providing communication between three antennas and a
radio base station comprising a waveguide
arrangement consisting of three sections and a
waveguide-to-coaxial transition at each end,
Fig. 3A schematically illustrates a part of a communication
arrangement in the form of a waveguide with three
compartments connected to one sector antenna of a
three sector antenna with a a coaxial cable-to-
waveguide transition,
Fig. 3B is a cross-sectional view taken along lines A-A in
Fig. 3A of the waveguide arrangement,
Fig. 4 schematically illustrates still another embodiment
of a waveguide arrangement with waveguide
connections provided through direct contact with for
example a sector antenna (not shown) and a radio
base station,
Fig. 5 is a cross-sectional view of a waveguide arrangement
comprising n rectangular waveguides,
Fig. 6 shows another implementation of rectangular
waveguides of a waveguide arrangement with a
circular cross-section but with segments forming
rectangular waveguides,
Fig. 7 schematically illustrates an example of a coaxial
waveguide arrangement with n waveguides,
9

Fig. 8A schematically illustrates a waveguide mode fed in a
rectangular waveguide,
Fig. 8B is a schematical cross-sectional view of a mode fed
in a circular waveguide,
Fig. 8C is a schematical cross-section of the fundamental
mode fed in a coaxial waveguide,
Fig. 9 schematically illustrates the lower part of a
waveguide arrangement with connectors for
connections, forming coaxial cable-to-waveguide
transitions, to a base station, and
Fig. 10 schematically illustrates the connection portion
(coaxial-to-waveguide transition) for a waveguide
arrangement comprising one common waveguide when
different waveguide modes allow for propagation of
different signals.
DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 shows an antenna arrangement 1A, 2A mounted on a
mounting structure 4, here in the form of a mast, to which the
two antennas 1A, 1B are mounted. For communication with the
base station (not shown) a waveguide arrangement 3 is
associated with the mast structure 4. In this embodiment
jumper cables 2A, 2B are provided for connection to the
antennas 1A, 1B. It should be clear that the waveguide
arrangement 3 also is connected to the base station for
example via jumper cables (not shown). Hence, in this
embodiment the waveguide arrangement 3 is associated with or
connected to the mast structure 4. In an alternative
embodiment it may be integrated in the mast structure, or more
generally in the mounting structure. In the embodiment of Fig.
10

1 the waveguide arrangement 3 is illustrated as consisting of
one large section. However, preferably, it is generally
divided into a plurality of sections of appropriate lengths,
which is advantageous for fabrication, transportation and
installation purposes. In an alternative embodiment, the
waveguide arrangement or the individually waveguides provided
therein, might be connected directly to the antenna and/or the
base station. In case jumper cables are used, connectors are
required at each end of the respective waveguides. It should
be clear that the antenna arrangement may comprise more than
two antennas or it could be just one antenna. Of course also
different kinds of antennas may be used, for example three
antennas for a three sector site or six sector antennas for a
six sector site etc. Each antenna may have two polarisations
and the antenna (s) additionally may be dual or triple band
antennas etc.
Unless waveguide connecting means are used, cf. Fig. 4, coax-
to-waveguide transitions are required both for connection to
the antennas and for connection to the base station. Fig. 1
only shows the basic concept of the present invention wherein
a waveguide arrangement is used instead of thick cables.
Fig. 2 shows another embodiment in which the waveguide
arrangement comprises, here, three waveguide sections 311, 312,
313 which are interconnected by means of flanges 911, 912, 913.
The uppermost waveguide section 311 is via a flange 911
connected to a waveguide feed transition 51 providing
transitions to cables 2A1, 2B1, 2C1 connecting to the, here,
three antennas (not shown). Similarly a waveguide feed
transition 61 is connected to the lowermost waveguide section
313 via a flange 914 providing transitions to the cables 7A1,
7A2, 7A3 connecting to the base station (not shown) . The
waveguide arrangement may take any of the forms as will be
11

described more thoroughly below, but also several other
embodiments are possible.
Fig. 3A illustrates a part of a waveguide arrangement 32
comprising three waveguide compartments (cf. illustration of
waveguide arrangement cross-section taken along A-A in Fig.
3B) via a flange 92 connected to a transition arrangement 52
with coax to waveguide transitions 821, 822, 823 via cables 2A2,
2B2, 2C2 to three sector antennas of which only the first
sector antenna 1A2 is shown.
Fig. 3B shows an example of a cross-sectional view of a
waveguide arrangement (as in Fig. 3A) comprising three
waveguide compartments C1, C2, C3. The respective waveguides
are rectangular waveguides with a width W32 approximately ≥
λ/2. The dimension of the width has to be such in order to
enable for RF signals to propagate. The height H32 is not
restricted by the wavelength and it can be made quite small.
Particualarly the height determines the loss performance of
the waveguide. A typical loss for an air-filled aluminium
waveguide with the dimensions 120 x 20 mm is approximately
0.025 dB/m for a 2 GHz frequency signal. If the height is
about 5 mm, the loss is about 0.088 dB/m, if it is about 10
mm, the loss will be about 0.045 dB/m, for a height which is
about 15 mm, the loss will be approximately 0.031 dB/m, and
for a height of 20 mm it will be about 0.024 dB/m. Thus, the
loss is inversely proportional to H.
The losses should be compared with the loss for a 1.25 Inch
cable, which is about 0.05 dB/m. At high frequencies (more
than 2GHz) the difference between the losses in an air-filled
waveguide and a coaxial cable increases. The waveguide is in
principle independent of the frequency whereas for a coaxial
cable the loss in dB is proportional to the frequency due to
12

dielectric loss. Dielectrical losses can more easily be
avoided in rigid waveguides.
In this embodiment the rectangular waveguides C1, C2, C3 are
rectangular and stacked in a common metal profile 32
comprising the waveguide arrangement. In this particular
embodiment the exterior of the profile is rectangular. It may
of course also be circular or of any other appropriate shape.
For a 2GHz UMTS-signal, a typical size could be 0.8 λ, which
is approximately 120 mm.
Particularly one waveguide or one compartment acts as a
waveguide for one feed signal. As will be more thoroughly
discussed below, multimode implementations are also possible
in which one waveguide may support propagation of more than
one mode.
Fig. 4 shows another embodiment of a waveguide arrangement 33
(which may have any cross-section as will be further described
below, for example comprising a number of rectangular
compartments etc. but it may also comprise a number of, or a
single waveguide, supporting different modes, one for each
feed signal). In this embodiment, however, the waveguide
arrangement is via a waveguide connection 63 directly connected
to the base station 10 and via a waveguide connection 53
connected directly to, here, a three sector antenna (not
shown) and hence comprising three waveguide connections
531, 532, 533. The waveguide arrangement 33 is connected via
flange 931 to the antenna waveguide connection 53 and via a
flange 932 connected to the base station 10 via the waveguide
connection 63. The flanges 931, 932 can be of any conventional
kind. The waveguide connections may alternatively be soldered
onto the waveguide arrangement 33. Even if the waveguide
arrangement 33 in this figure is shown as comprising one
13

section only, it may of course alternatively comprise several
sections as for example discussed with reference to Fig. 2. In
this embodiment there are no coax-to-waveguide transitions,
and hence specifically adapted or special types of
antennas/base stations are required.
Fig. 5 is a cross-sectional view of a waveguide arrangement 34
comprising n rectangular waveguides 1, 2,... n with a width W
lager than or substantially equal to λ/2 as discussed above.
The outer walls are conducting and the interior of the
waveguides comprise air or a low-loss dielectric material. The
supported fundamental mode is here TE10. The waveguides may
also support higher order modes, in this case TE20, TE30 etc,
but then they must be larger. Hence, each individual waveguide
may support one or more modes, each waveguide handling one
feed signal, or if multiple modes or supported, each mode
holding one feed signal.
Fig. 6 shows still another embodiment of a cross-section of a
waveguide arrangement 35 which in principle also acts as an
arrangement with a number of rectangular waveguides
1, 2, 3, 4, 5, the length of which (the outer segments
1, 2, 3) should be larger than or substantially equal to λ/2.
The innermost waveguide comprises a circular waveguide for
corresponding modes. Also in this case the fundamental
supported mode is TE10, but the individual waveguides may also
support higher order modes such as TE20, TE30 etc.
Fig. 7 shows a cross-section of an embodiment of a waveguide
arrangement 36 which comprises a coaxial waveguide in a
multilayer implementation, comprising n layers. The
fundamental supported mode is here TEM similar to a coaxial
cable. The first higher order mode that might be supported is
TE11 etc. According to different embodiments each waveguide
compartment supports one mode, but if it is supported, i.e. if
14

the dimensions of the waveguides are larger (large enough), it
is possible for multiple modes to propagate.
Fig. 8A schematically illustrates the fundamental propagating
mode for a rectangular waveguide with width W and height H.
The walls of the waveguide are conducting and have a thickness
exceeding the electrical penetration depth. As referred to
above the supported fundamental mode is in such an embodiment
TE10, i.e. an electrical field transversal with respect to the
direction of propagation. If a larger width is used, higher
order modes may be supported for feeding signals.
Fig. 8B schematically illustrates the supported waveguide mode
of a circular waveguide (CWG) which also has conducting walls
etc., c.f. Fig. 8A. The fundamental propagating mode is here
TE11. With a larger cross-section, it may also support one or
more higher order modes, for example TM01.
Fig. 8C is a cross-sectional view of a coaxial waveguide
wherein b here corresponds to the radius of the outer
conductor and a is the radius of the inner conductor. Higher
order modes may be supported if a a larger radius is selected,
e.g. TE11 etc.
It should be clear that these figures merely show some
examples on waveguide cross-sections.
Fig. 9 is a very simplified view of a waveguide arrangement 36
comprising a number of waveguide compartments 371,...,376, one for
each feed signal to an antenna arrangement/a base station,
each waveguide comprising a connector 671,..., 676 for connection
to the base station (the respective antenna) as discussed
earlier in the application.
Fig. 10 shows one example of a coaxial-waveguide transition
for a multimode implementation according to the invention. It
15

shows a cross-section of a rectangular waveguide 37. TE10
feeding is provided by means of the central metal conductor 81
of a coaxial cable with outer conductors 87. TE20 feeding is
provided by means of a phase shifted 890 which provides two
signals phase shifted +/- 90° and which are fed via the central
conductors 82, 83 of two coaxial-waveguide transitions 881, 882.
TE10 is fed symetrically and TE20 is fed differentially.
An alternative embodiment (not shown) is using a 4-port
sum/delta-divider where the TE10 mode is fed to the sum-port
resulting in two identical (symmetric feeding) signals fed to
82 and 83, and where the TE20 mode is fed to the delta-port
resulting in two equal amplitude but 180° phase shifted
(differential feeding) signals simultaneiously fed to 82 and
83. The divider is reciprocal so that the principle applies
for transmission in both directions.
It should be clear that different kinds of waveguides can be
used. It is for example also possible to use ridge waveguides.
It is an advantage of the invention that the communciation,
for example all feed signals, can be collected in a slim
waveguide as compared coaxial feeder cables which are thick
and have large losses. Still further it is an advantages that
the arrangement for providing communication between a base
station and an antenna arrangement can be made more aesthetic
and less optically dominating, than a large number of thick
coaxial feeder cables. It is particularly advantageous that
the arrangement can be integrated in a mounting structure, for
example a mast, or in the legs of a mast structure. It is also
advantageous that, through the use of waveguides for signal
transmission, the losses will be very low. The losses are,
even for low profile waveguides, lower than for thick coaxial
cables. It is also an advantage that a waveguide arrangement,
particularly one comprising a number of sections, can be
16

easily fabricated and installed at a low cost, and it is easy
to transport and resistant to damages. It is also advantageous
that such a waveguide arrangement is particularly easy and
cheap to fabricate and it e.g. comprises conventional extruded
aluminium profiles or a material coated with aluminium.
Moreover for example for 3G (3GPP, Third Generation
Partnership Project) implementations frequencies which are
high are used, which means that the losses get high if cables
are used, it is clearly advantageous to a use waveguide
arrangement instead of very thick coaxial cables.
It is also advantageous that the waveguide arrangement may
fabricated in sections which simply are mounted to each other
by means of flanges or similar since the mounting structure is
a mast, which may be very high, even up to 20-30 meter or
more.
It should be clear that the invention is not limited to the
specifically illustrated embodiments but that it can be varied
in a number of ways without departing from the scope of the
appended claims.
Particularly may each waveguide in a waveguide arrangement
support propagation or transmission of signals by one or more
modes and the profile structure can be made with any cross-
sectional shape, square-shaped, rectangular, circular,
elliptic, oval etc. It should also be clear that the higher
the frequency of the propagating signals is, the higher is the
gain of using a waveguide arrangement.
17

CLAIMS
1. An arrangement for providing communication between an
antenna arrangement and a radio base station at a site,
comprising a waveguide arrangement connected to the radio base
station and to the antenna arrangement supporting
communication of signals between the radio base station and
the antenna arrangement,
characterized in
that the waveguide arrangement is adapted to support
communication of a plurality of signals between the radio base
station and the antenna arrangement and in that it comprises a
number of compartments, each compartment acting as a waveguide
for a particular signal, or a number of compartments of which
at least some comprise dual-, or multimode compartments
wherein each mode carries one signal, or one multimode
waveguide common for a number of signals.
2. An arrangement according to claim 1,
characterized in
that the waveguide arrangement comprises waveguide connecting
means connected directly to the radio base station and/or to
the antenna arrangement.
3. An arrangement according to claim 1,
characterized in
that the waveguide arrangement is connected indirectly to the
radio base station and/or the antenna arrangement via
intermediate connecting means, e.g. jumper cables and
connectors disposed at the waveguide arrangement end(s).
4. An arrangement according to any one of claims 1-3,
characterized in
18

that the waveguide arrangement is adapted to be associated
with or connected to an antenna mounting structure, e.g. a
mast or similar.
5. An arrangement according to any one of claims 1-3,
characterized in
that the waveguide arrangement is adapted to be incorporated,
or taken up in an antenna arrangement mounting structure.
6. An arrangement according to any one of claims 1-5,
characterized in
that the waveguide arrangement comprises a plurality of
compartments, each acting as a waveguide for a particular
signal to/from an antenna of an antenna arrangement comprising
several antennas e.g. a multi-sector antenna arrangement.
7. An arrangement according to claim 6,
characterized in
that the waveguide arrangement comprises a compartment for
each polarisation of each antenna of dual polarized antennas.
8. An arrangement according to any one of the preceding
claims,
characterized in
that each antenna of the antenna arrangement is a dual or
triple band antenna, and in that there is one waveguide
compartment for each band of each antenna or antenna
polarization.
9. An arrangement according to any one of claims 1-5,
characterized in
that the waveguide arrangement comprises one multi-mode
waveguide common for a number of signals to/from different
antennas and/or different polarizations and/or for different
19

frequency bands and in that the different signals are carried
by different waveguide modes.
10. An arrangement according to any one of the preceding
claims,
characterized in
that the waveguide arrangement comprises a longitudinal metal
profile structure with a number of waveguides.
11. An arrangement according to claim 10,
characterized in
that the metal profile structure has a rectangular cross-
section.
12. An arrangement according to claim 10,
characterized in
that the metal profile structure has a circular, elliptic,
oval, trapezoidial or triangular cross-section.
13. An arrangement according to claim 11 or 12,
characterized in
that the metal profile structure is made of a low loss
conducting material, e.g. aluminium (A1) or a material with
similar properties or a material which is coated with a low
loss, conducting material, e.g. aluminium.
14. An arrangement according to claim 11, 12 or 13,
characterized in
that the waveguide arrangement comprises a number of
rectangular waveguides each with a rectangular cross-section
defined by a waveguide width and a waveguide height, or a
number of circularly disposed segments.
15. An arrangement according to claim 14,
characterized in
20

that the waveguide width (W) is larger than half the wave
length (λ) (W > λm/2) .
16. An arrangement according to claim 15,
characterized in
that the waveguide width is approximately 0.6 λ - 1.0 λ, e.g
0.80 λ.
17. An arrangement according to claim 15 or 16,
characterized in
that the width is 90-150 mm for a propagating 2 GHz RF signal.
18. An arrangement according to claim 15, 16 or 17,
characterized in
that the height is about 1/4 - 1/8 of the width, e.g. 10-80
mm.
19. An arrangement according to any one of claims 1-13,
characterized in
that it comprises a circular or coaxial waveguide arrangement
with a number of compartments.
20. An arrangement according to any one of the preceding
claims,
characterized in
that it comprises one single (monolithic) structure.
21. An arrangement according to any one of claims 1-19,
characterized in
that it comprises a number of sections connected to each other
such that the length of the arrangement substantially
corresponds to the sum of the lengths of the individual
sections.
21

22. A base station antenna arrangement with a base station
and an antenna arrangement, communication means for providing
communication of signals between the base station and the
antenna arrangement, and an antenna mounting structure, e.g. a
mast, the communicating means comprising a waveguide
arrangement, said waveguide arrangement being associated with
or comprised by the mounting structure,
characterized in
that the waveguide arrangement is adapted to support
communication of a plurality of signals between the radio base
station and the antenna arrangement and in that it comprises a
number of compartments, each compartment acting as a waveguide
for a particular signal, or a number of compartments of which
at least some comprise dual-, or multimode compartments
wherein each mode carries one signal, or one multimode
waveguide common for a number of signals.
23. A base station and antenna arrangement according to claim
22,
characterized in
that the waveguide arrangement comprising a number of
waveguides integrated in the mounting structure, e.g. a mast.
24. A base station and antenna arrangement according to claim
23,
characterized in
that the mounting structure comprises a mast with a number of
legs, each leg comprising one or more waveguides of the
waveguide arrangement.
25. A base station and antenna arrangement according to any
one of claims 22-24,
characterized in
that the waveguide arrangement comprises a number of waveguide
compartments, each carrying one or more signals to/from an
22

antenna of the antenna arrangement, that it/they support(s)
propagation of a number of different modes, each carrying one,
e.g. one for each polarization and/or frequency band, signal
to/from an antenna of the antenna arrangement, the antenna
arrangement comprising a number of antennas (e.g. a sector
antenna), and/or dual polarised antennas, and/or dual or
triple band antennas.
23
26. An arrangement or a base station and antenna arrangement
as in any one of claims 1-25 in a cellular mobile
communicating system operating at about 2 GHz or more.

The present invention relates to an arrangement (1A,1B) for
providing communication between an antenna arrangement and a
radio base station at a site. It comprises a waveguide
arrangement (3) connected to the radio base station and to the
antenna arrangement (1A,1B) supporting communication of
signals between the radio base station and the antenna
arrangement (1A,1B).

AN ARRANGEMENT RELATING TO ANTENNA COMMUNICATION

Documents:

Inventors:

PCT Conventions: