The present disclosure relates to wireless communication systems and in particular to antenna arrangements for base stations, repeaters and access points operating in both sub-6-GHz frequency bands and millimeter-wave frequency bands and provides a compact arrangement by overlaying highly directive microwave antennas onto sub-6-GHz antennas.
Many services provided by the fifth generation of mobile radio systems rely on the use of frequency bands in the microwave region of the radio spectrum. Microwave radio systems have the advantage of providing very large user bandwidths and correspondingly high rates of data transmission. But the propagation characteristics of microwave radio are more similar to optical propagation and it is necessary to have an unobstructed path between user equipment and the base station that serves it. To extend microwave coverage into buildings, it is desirable to provide a small low-power relay device that receives transmissions from outside the building and re-transmit the signal inside the building.
Frequency bands in use for mobile radio services, including WiFi services have, prior to the introduction of 5th-Generation (5G) services, been below 6 GHz. The introduction of 5G has brought much higher frequencies into use at which antenna elements are far smaller than heretofore. Even complete multi-element antenna arrays are small compared with a single radiating element at lower frequencies. The term “sub-6-GHz” is used below to refer to the lower frequency bands in use for generations of mobile radio services prior to 5G.
Mobile radio services of earlier generations (2, 3 and 4) have made use of “picocells” providing local coverage in unserved areas, whereas SGNR (New Radio) utilizes microwave frequency bands. Many 5GNR services are expected to operate in frequency bands above 26 GHz, often referred to as millimeter-wave bands.
Repeaters are commonly employed to extend and add coverage to areas that are blocked by buildings/trees/obstacles. This is especially true for millimeter-wave signals where propagation losses are high and penetration through obstacles such as window glass is not possible.
European Patent Application EP2851993A1 describes an integrated window antenna for wireless communication whereby an antenna structure is printed on a glass panel/s with the window itself serving as a carrier medium. The concept is similar to printing elements on a PCB substrate and then putting them inside an antenna enclosure. The difference here is that the EP '993 application prints them on a window pane with the metal traces sandwiched between the surface of the window and a dielectric substrate on which the traces are etched. In one embodiment of the EP '993 application, a patch antenna is metalized on one side of the window pane and a reflector is metalized on their other side. In another embodiment, several window panes are used with the reflector in the middle to allow for an aperture coupled solution. U.S. Pat. No. 8,634,764 discloses a repeater system with integrated antenna in a glass pane. Similar to EP2851993A1, where the radiating elements are etched on a substrate and then applied to the glass on the window, the '764 patent goes one step further by having an outside antenna array printed on a window pane above a ground plane and then another antenna on the inside of the building on a separate ground plane. If multiple bands are used, then the occupied space for the arrangement becomes quite large.
However, as the EP '993 application points out, many glass panes are thick and have absorbing properties, both of which are detrimental to millimeter-wave antenna arrays. The window thickness needs to be small to prevent higher order transversal modes, and the glass absorbs millimeter-wave wave signals. U.S. Pat. No. 8,634,764 also discloses an outside antenna array printed on a window pane above a ground plane and a second antenna on the inside of the building on a second ground plane. If multiple bands are used, the occupied space becomes quite large.
In some embodiments millimeter-band antenna arrays, optionally together with associated electronic circuit arrangements, are positioned on planar dipole elements operating in sub-6-GHz frequency ranges. By way of example, implementations are described in which antennas operating in both frequency ranges are arranged on window panes to provide enhanced in-building service.
The direction of the beams formed by the millimeter-wave arrays may be chosen to be orthogonal to the plane of the window pane, or may be adjusted in direction by arranging appropriate phase shifts between the elements forming the arrays, as is familiar to a skilled person. This adjustment may be chosen independently by design for the external and internal arrays. If a plurality of millimeter-wave arrays is provided, the direction of beams formed by each array may be chosen to differ in order to provide separate areas of coverage within the building and/or to provide connection to more than one base station.
The shortage of available accommodation for antennas at existing base stations together with planning and other constraints on the installation of new base stations create a requirement for compact base station antennas. These must combine facilities on an increasing number of frequency ranges and must be suitable for installation in a wide variety of physical and electromagnetic environments. Examples are windows in homes and offices, urban buildings of architectural significance where installations much be small and unobtrusive, and public buildings such as airports and sports stadiums where extreme capacity must be provided to a very large number of concurrent users.
The quest for more compact base station arrangements has led to the increased integration of antennas and the inclusion therewith of electronic and other circuit devices including but not limited to power amplifiers, low-noise amplifiers, bidirectional amplifiers, signal processing devices, signal conditioning, filtering and control functionalities. Any subset of these is described herein below as electronic circuit arrangements.
Many prior art antenna arrangements providing operation in multiple frequency ranges rely on the harmonic relationship between the frequencies used for mobile radio. One object of the present disclosure is an arrangement whereby antennas for frequency ranges having a substantial and even a non-integer ratio between them can be accommodated within the space usually occupied by the antenna (or antenna array) operating in the lower of the required frequency ranges.
For the sake of clarity, the upper frequency range is referred to herein as a millimeter-wave frequency and the lower frequency as a sub-6-GHz frequency, but the disclosure is applicable wherever there is a substantial ratio between the frequencies involved. In one embodiment, sub-6 GHz can be approximately 30 kHz-6 GHz, and more typically fur the base station industry, sub-6 GHz refers to the frequency range 600 MHz-6 GHz. For millimeter wave, the range is approximately 30 GHz-300 GHz, and more specifically for 5G, millimeter wave frequencies include 26 GHz-300 GHz. Of course, the disclosure can be utilized with other suitable frequencies.
5G provides for operation of a wide variety of different services. Coverage of users will require wide area coverage in sonic frequency ranges and narrow intelligently-controlled beams in other frequency ranges. These require a wide variety of antennas having different characteristics in terms of radiation patterns, frequency and power ratings, often for the antennas forming a single base station. The disclosure is directed at solutions for such requirements.
The data connections between the fixed telecommunications network and mobile radio networks (“back-haul”) are frequently realized by using microwave radio links. The disclosure can distribute data within high-capacity millimeter-wave radio services as part of 5G systems, both as backhaul links to the fixed network and also as “front-haul” links between network switching facilities. It will also permit the development of simplified base stations having lower levels of processing capability and cost than present base stations. Some of the antenna arrangements described below are very suitable for use for relaying user data to provide extended coverage as well as for performing front-haul and back-haul functions.
In an example of the present disclosure, the window pane is used to support a repeater, in which a millimeter-wave solution for high data rate communication shares the same area as a sub-6-GHz solution used in today's mobile communications, providing a compact combined antenna solution supporting both sub-6-GHz frequency bands and new millimeter-wave bands as used by 4G and 5G radio systems.
For better understanding of the disclosure and to show how it may be carried into effect, there will now be described by way of example only, specific embodiments methods and processes according to the present disclosure, with reference to the accompanying drawings in which:
In describing the illustrative, non-limiting embodiments illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in similar manner to accomplish a similar purpose. Several embodiments are described for illustrative purposes, it being understood that the description and claims are not limited to the illustrated embodiments and other embodiments not specifically shown in the drawings may also be within the scope of this disclosure.
The operation of radio systems and antennas is bidirectional, providing for both the transmission and reception of radio signals. In the following description, references to the transmission of signals shall be taken to include their reception and vice versa.
Base stations for mobile radio services typically transmit and receive signals having 45-degree slant linear polarization. For the sake of simplicity, dipole elements are illustrated herein as having horizontal polarization, but it will be understood that by orienting dipoles appropriately they may have slant or vertical polarization. Crossed dipole or patch elements may be used in place of horizontal dipoles to provide dual slant polarization or circular polarization.
The term radiating element refers to a simple device such as a dipole or slot whose function is to transmit or receive radio waves. An antenna array comprises a plurality of radiating elements whose inputs are combined to provide increased directivity and gain relative to a single radiating
Millimeter-wave array 11 is arranged on a first face of the conductive strip 10. Millimeter-wave array 12 may be arranged on the first face or optionally on a second face (on an opposite side of the first face) of conductive strip 10 as shown in
The direction of maximum radiation (beam direction) of each of the millimeter-wave antenna arrays 11, 12 may be fixed by design or may be controlled by electronic circuit arrangements 17, optionally in response to signals from user equipment and/or by external signals provided by control circuit arrangements and transmitted to the circuit arrangements 17 by the data connection 16. The millimeter-wave arrays 11, 12, together with circuit arrangements 17 may provide MIMO or other advanced signal control and processing functionalities.
Roberts' or hairpin balun. The feed line 39 is excited at microstrip input 51. In one embodiment, the thickness can be 0.15 mm or in certain cases, it can be etched on a standard PCB material with a thickness of 0.78 mm.
As best shown in
The first lamina 37 is parallel to and aligned with the second lamina 38. Accordingly, the first outwardly-facing surface of the first lamina 37 faces in an opposite direction (away from) than the first outwardly-facing surface of the second lamina 37. And the second inwardly-facing surface of the first lamina 37 faces toward the second inwardly-facing surface of the second inwardly-facing surface of the second lamina 38.
In addition, the first and second limbs 31, 32 are sandwiched between the first and second lamina 38. Thus, the second inwardly-facing surface of the first lamina 37 contacts one side of the limbs 31, 32, and the second inwardly-facing surface of the second lamina 38 contacts a second opposite side of the limbs 31, 32. The limbs 31, 32 extend at least partially along the length and width of the lamina, and can extend the entire length and/or width of the lamina 37, 28.
A first millimeter-wave antenna array 11 and associated electronics circuit arrangements 43 are provided on the second face of lamina 37. Millimeter-wave array 11, circuit arrangements 43 and dipole limb 32 are arranged such that array 11 and circuit arrangements 43 occupy part of the same projected area as dipole limb 31. That is, the limbs 31, 32 are dimensioned to operate in a sub 6-GHz frequency range. The array 11, 12 and circuit element 43, 44 are aligned with the limbs 31, 32, respectively, and do not overhang their edges. In this way dipole limb 31 functions as a reflective groundplane behind millimeter-wave antenna array 11.
A second millimeter-wave antenna array 12 is provided on a second dielectric lamina 38 together with associated electronics circuit arrangements 44. Millimeter-wave array 12, circuit arrangements 44 and dipole limb 32 are arranged such that array 12 and circuit arrangements 44 occupy part of the same projected area as dipole limb 32. In this way dipole limb 32 functions as a reflective groundplane behind millimeter-wave antenna array 12.
One or more of each of microstrip lines 45, 50, power feeds 46, 49 or data connections 47, 48 may be made to electronic circuit arrangements 43, 44 respectively which may be integral with arrays 11, 12 or operatively connected thereto. Microstrip line 45, power feed 46 and data connection 47 may pass though lamina 38 by means of plated though holes or other connection methods.
It will be understood that the arrangement comprising dielectric laminae 37, 38 together with conductors formed on the faces thereof may be manufactured by printed circuit techniques including etching and lamination, the whole forming a 3-layer printed circuit assembly. Laminae 37, 38 are preferably formed from a low-loss dielectric material, typically between 0.3 mm and 1 mm thick but may be of the same or different dielectric material and thickness, for example a PTFE-glass laminate or a high grade resin-glass laminate such as Isola 370HR. Feed-through arrangements such as plated-through holes may be provided for conductive lines 45, 46, 47.
The millimeter antenna arrays 11, 12 may be positioned on first and second outwardly-facing sides of the dipole assembly 30 as shown in
Millimeter-wave arrays 11, 12 are independent of one another; their electrical and mechanical parameters are independently chosen by design and they may operate in the same or different frequency bands. Beams formed by the millimeter-wave arrays 11, 12 may be aligned orthogonal to the plane of the supporting lamina or may be steered to any required direction relative to the orthogonal direction in accordance with prior art methods. The steering angle may be fixed or may be varied, for example in response to traffic requirements. The dipoles may be combined in the form of crossed dipoles as shown in
A sub-6-GHz base station antenna array may comprise a plurality of dipole assemblies, at least one of which may be arranged as the dipole assembly 30 (
Feed conductors 67, 68 operate as a microstrip transmission line providing an electrically unbalanced feed to dipole limbs 61, 62 thereby creating a radiation pattern such as simulated in
As shown in
Millimeter-wave arrays 65, 66 are independent of one another, their parameters are independently chosen by design and they may operate in the same or different frequency bands. A plurality of sub-6 GHz dipoles may be configured to operate together with the first dipole, forming at least one sub-6 GHz antenna array. A plurality of millimeter-wave antenna arrays may be provided and each aligned in a corresponding manner with a sub-6 GHz dipole arm.
Substrates 63, 64 are preferably formed from low-loss dielectric material, typically 0.3 mm thick, having the dipole radiating elements formed on a first face and a millimeter-wave antenna array formed on a second face. The millimeter-wave arrays may be pre-manufactured as discrete components or formed on the substrates 63, 64 using an etching or printing process.
It will be understood that the structure here described by way of example may be realized using alternative materials and processes.
In the arrangement of
If the sub-6-GHz dipole of
Each millimeter-wave array 65, 66 operates in conjunction with a reflective groundplane formed by a conductive element of a sub-6 GHz dipole and provides a unidirectional beam. Arrays outside the window pane provide connection with a remote base station, while arrays inside the window pane provide service to users within the building.
An opening 73 is provided between an aperture 72 formed within conductive layer 90 and a proximate edge of conductive layer 90. The aperture 72 and opening 73 are preferably located substantially centrally along the long edge of conductive layer 90. The conductive layer 90 forms a continuous shunt-excited dipole, fed by a conductive strip 76 formed on a second face of lamina 71, extending from input 75 to open circuit 90 at the end of a stub extending across opening 72. The dipole is excited by the voltage across the opening 73. The feeding arrangement is related to a notch antenna and is further described in further detail in WO2015011468A1.
Conductive tracks supported on an outward-facing side of dielectric lamina 81 provide one or more of each of microstrip transmission lines 82, 83, power feeds 84, 85 and data connections 86, 87 to electronic circuit arrangements 79, 80, these being further connected to the millimeter-wave antenna arrays 77, 78 by transmission lines 88, 89. Lines 83, 84, 86, 87 are shown only in part but should be understood to extend as shown in full for lines 82, 85.
Millimeter-wave arrays 77, 78, together with associated electronic circuit arrangements 79, 80 are positioned on outwardly facing sides of laminae 71, 81. It will be understood that arrays 77, 78 may be placed on either outward sides of the arrangement and the associated electronics circuits may be positioned alongside the arrays as shown or may be positioned on the other outward face of the assembly 90. The microstrip transmission lines 82, 83, power feeds 84, 85 and data connections 86, 87 may be connected through the laminae 71, 81 by through-plated holes (vias), conductive pins or other arrangements. In this way, although lines 82-87 and feed line 76 are on first and second faces of the assembly 90, the millimeter-wave antennas and their associated electronics circuit arrangements may be positioned independently on either or both faces of the assembly 70.
The disclosure utilizes various reflective surfaces, for example the reflective groundplanes such as the conductive members 10 (
The electronic circuit arrangement required to interface to external communications circuits and to convert signals to radio frequency signals for transmission from the antennas may be contained within the structure of the antenna 160 or may be external thereto. External communication may be provided by connected coaxial cables, optical fibers and/or at least one of the sub-millimeter antennas. The arrangements may be used to provide relaying, back-haul and front-haul functionalities, as well as providing high-capacity fixed wireless access to premises not served by optical fiber or other high capacity fixed data services. In such an application the service to users may be connected through a local communications network such as Ethernet, or a wireless local area network (WLAN).
For some applications it may be advantageous to feed the sub-6 GHz and millimeter-wave antennas through a filter system (diplexer) to reduce the number of external ports on an antenna.
The foregoing description and drawings should be considered as illustrative only of the principles of the disclosure, which may be configured in a variety of shapes and sizes and is not intended to be limited by the embodiment herein described. Numerous applications of the disclosure will readily occur to those skilled in the art. Therefore, it is not desired to limit the disclosure to the specific examples disclosed or the exact construction and operation shown and described. Rather, all suitable modifications and equivalents may be resorted to, falling within the scope of the disclosure.
This application claims the benefit of U.S. Provisional Application No. 62/732,850, filed Sep. 18, 2018, the entire content of which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
62732850 | Sep 2018 | US |