Antenna system for generating multiple beams in the elevation direction

Abstract

The present application provides a system and method related to an antenna system that produces multiple beams arranged in an elevation direction. The antenna system includes a multiple beam forming network (MBFN) circuit that receives input signals and produces multiple beams adjacent to each other in a vertical direction through an antenna array. The MBFN circuit can include a Butler matrix, a Rotman lens, a Blass matrix, a Nolen matrix, or modified versions of these matrices. The modified versions of these matrices are intended to address beam squint, phase error, and even side lobe level (SLL) issues.

Description

Technical Field

[0001] This invention relates to a multi-beam antenna device. More specifically, this invention relates to an antenna system that generates multiple beams for vertical sector segmentation and generates two-dimensional multi-beams in the azimuth and elevation directions. Background Technology

[0002] To improve the communication capacity of base stations, multi-beam base station antenna arrays are needed to divide the base station's coverage area from the entire region into several smaller cells. Simultaneously, it is desirable for the coverage of each beam to remain consistent across the entire operating frequency band. However, this consistency in beam coverage can become problematic, especially with multi-beam antenna arrays.

[0003] Even when the base station coverage area is divided into smaller cells, this method still has some problems, such as insufficient or suboptimal coverage at the cell edges. Furthermore, for a given base station antenna array, increasing its capacity would be advantageous. Preferably, this capacity increase does not require a larger antenna array or any additional hardware.

[0004] When forming multiple beams in the azimuth direction for the low-frequency band (617-960MHz), similar to the mid-frequency band (1695-2690MHz) and / or C-band (3300-4200MHz), the antenna size will increase. This will increase the wind load and antenna weight of the system, which is the main challenge facing the widespread application of multi-beam antennas.

[0005] In conclusion, an innovative solution is needed that can address the edge problem of residential communities while increasing capacity without increasing hardware requirements. Summary of the Invention

[0006] This invention provides systems and methods relating to antenna systems that generate multiple beams in the elevation direction. The antenna system includes a multi-beamforming network (MBFN) circuit that receives an input signal and generates multiple beams adjacent to each other in the vertical direction via an antenna array. The MBFN circuit may include a Butler matrix, a Rotman lens, a Blass matrix, a Nolen matrix, or modified / adjusted versions of these matrices. These modified versions of the matrices are designed to address beam skew problems, phase error problems, and even sidelobe level (SLL) problems.

[0007] In a first aspect, the present invention provides an antenna system comprising: A multi-beamforming network circuit for receiving at least one input signal; An antenna array, comprising at least two antenna elements, receives the output of the circuit. in The system generates at least two output beams from the array such that the at least two output beams are adjacent to each other in the vertical direction.

[0008] On the other hand, the multi-beamforming network circuit includes a Butler matrix, a Nolen matrix, or a Blass matrix. In a further aspect, the multi-beamforming network circuit includes a modified version of one of these matrices.

[0009] In a further aspect, the present invention provides a matrix circuit for coupling multiple input signal beams to multiple output antennas, the matrix circuit comprising: This includes a matrix of directional couplers, horizontal phase delay lines, and vertical circuit element lines; The matrix is ​​configured to form: A multi-row circuit element, each row comprising a directional coupler and a horizontal phase delay line, each row receiving an input signal beam, and each directional coupler in each row being coupled to at least one other directional coupler via the horizontal delay line; and Multiple rows of circuit elements, each row of circuit elements including a directional coupler and a vertical circuit element line, each row of circuit elements being coupled between the output antenna and the load; in The matrix circuit is used to form multiple output beams based on the input signal beam; and The beamwidth of at least one of the plurality of output beams is different from the beamwidth of at least another of the plurality of output beams.

[0010] In a further aspect, the present invention provides an antenna system comprising: A multi-beamforming network circuit for receiving at least one input signal; An antenna array, comprising at least two antenna elements, receives the output of the circuit. in The system generates at least two output beams from the array such that the at least two output beams are adjacent to each other in the vertical direction.

[0011] Multibeamforming network circuits may include one or more of the following: Butler matrix; Nolen matrix; Blass matrix; modified Blass matrix; modified Nolen matrix; and modified Butler matrix.

[0012] In another aspect of the invention, the multi-beamforming network circuit includes a matrix circuit, which includes a plurality of directional couplers and delay lines, and the matrix circuit is coupled between a plurality of matched loads and an antenna array. in Each row of the matrix circuit includes multiple directional couplers coupled in series in the row-up direction, and each pair of directional couplers in the row-up direction is connected by at least one delay line. Each column of the matrix circuit includes multiple directional couplers coupled in series upwards from the column; The bottom row of the matrix circuit is coupled to multiple matched loads, such that each directional coupler in the bottom row is coupled column-up to one of the multiple matched loads between the matched load and the directional coupler in the row immediately above the matrix circuit. Each row of the matrix circuit provides a different signal beam, which has a unique elevation angle within a predetermined azimuth range, such that the antenna array provides at least three different signal beams, including at least one negative azimuth beam corresponding to the negative extreme of the azimuth range, a center azimuth beam corresponding to the center of the azimuth range, and a positive azimuth beam corresponding to the positive extreme of the azimuth range; and This matrix circuit is used to implement a method that includes providing the center azimuth beam using the bottom row of the matrix circuit.

[0013] A further aspect of the invention provides that a multi-beamforming network circuit includes a matrix circuit, the matrix circuit including a plurality of directional couplers and delay lines, the matrix circuit being coupled between a plurality of loads and an antenna array; in Each row of the matrix circuit includes multiple directional couplers coupled in series in the row-up direction, and each pair of directional couplers in the row-up direction is connected by at least one delay line. Each column of the matrix circuit includes multiple directional couplers coupled in series upwards from the column; The bottom row of the matrix circuit is coupled to multiple matched loads, such that each directional coupler in the bottom row is coupled column-up to one of the multiple matched loads between the matched load and the directional coupler in the row immediately above the matrix circuit. Each row of the matrix circuit provides a different signal beam, which has a unique azimuth angle within a predetermined elevation angle range, such that the antenna array provides at least three different signal beams, including at least one negative extreme elevation beam corresponding to the negative extreme of the elevation angle range, a center elevation beam corresponding to the center of the elevation angle range, and a positive extreme elevation beam corresponding to the positive extreme of the elevation angle range; and This matrix circuit is used to implement a method that includes providing the center pitch beam using the bottom row of the matrix circuit.

[0014] In various implementations, phase compensation is applied to each of the multiple directional couplers.

[0015] In a further aspect, the multi-beamforming network circuit includes a matrix circuit for coupling multiple input signal beams to the antenna array, the matrix circuit comprising: This includes a matrix of directional couplers, horizontal phase delay lines, and vertical circuit element lines; The matrix is ​​configured to form: A multi-row circuit element, each row comprising a directional coupler and a horizontal circuit element, each row receiving an input signal beam, and the directional coupler in each row being coupled to at least one other directional coupler via a horizontal delay line; and Multiple rows of circuit elements, each row of circuit elements including a directional coupler and a vertical circuit element line, each row of circuit elements being coupled between an output antenna in the antenna array and a load; The matrix circuit is used to form multiple output beams based on the input signal beam.

[0016] As another aspect of the invention, the input signal beam with the smallest absolute value of the pitch angle among a plurality of input signal beams is received by a specific row of the matrix circuit, which is the row closest to the load coupled to the matrix circuit.

[0017] According to another aspect of the invention, the input signal beam with the smallest absolute value of azimuth among a plurality of input signal beams is received by a specific row of the matrix circuit, which is the row closest to the load coupled to the matrix circuit.

[0018] A further aspect of the invention provides that the vertical circuit element line is implemented as one or more of the following: a phase shifter; an adjustable / variable phase shifter; and a vertical phase delay line. Similarly, the horizontal circuit element line is implemented as one or more of the following: a phase shifter; a horizontal phase delay line; and an adjustable phase shifter.

[0019] Each of the at least two antenna elements in the antenna array can be coupled to the circuit via a phase shifter. Furthermore, in a further aspect, the system also generates at least one additional output beam, which is horizontally adjacent to at least one of the output beams.

[0020] In the at least two output beams, the beamwidth of at least one of the at least two output beams is different from the beamwidth of the other of the at least two output beams.

[0021] In some respects, each of the adjustable phase shifters has an electromechanically adjustable phase shift, and at least one of the adjustable phase shifters includes: The first trace used for coupling to the first port; A second trace used for coupling to the second port; A bridging element that couples the first trace to the second trace; in The bridging element is stacked on the first and second traces, so that the bridging element provides an electrical path for signals traveling between the first and second ports; The bridging element can move mechanically between at least two positions; Moving the bridging element from one of the at least two locations to another changes the length of the electrical path between the first port and the second port.

[0022] On the other hand, the at least two positions include any of the following: First fixed position and second fixed position; Multiple fixed locations; Each fixed position is a fixed setting of a specific length of the electrical path between the first port and the second port.

[0023] In various aspects of the invention, the performance of this antenna system is equivalent to that of another antenna system with a larger antenna array. Furthermore, in some aspects, the performance of this antenna system is equivalent to that of another antenna system with more antenna columns than this antenna system. And, in some aspects, the at least two output beams provide pattern diversity to improve the wireless link implemented through this antenna system.

[0024] In some implementations, at least one input signal beam is coupled to generate at least one output beam using all the antenna elements in the antenna array. In some other implementations, at least one input signal beam is coupled to generate at least one output beam using a subset of the antenna elements in the antenna array. Attached Figure Description

[0025] Embodiments of the present invention will be described with reference to the following figures, in which the same reference numerals denote the same elements, wherein: Figure 1 This is a schematic diagram showing an antenna system that generates two beams that are adjacent to each other in the vertical direction (i.e., in the elevation direction); Figure 2 This is a block diagram of an antenna system according to one aspect of the present invention; Figure 3-7 The illustration shows an antenna array that can be used in various aspects of the present invention; Figure 8 The diagram illustrates a Blass matrix that can be used as the MBFN described in this invention; Figure 9 This is a schematic diagram of a modified Nolen matrix with an arbitrary number of radiating elements and beams that can be used in this invention; Figure 10 This is a schematic diagram of the modified Nolen matrix to compensate for phase errors; Figure 11 Is adopted with Figure 10 A schematic diagram of another modified Nolen matrix, modified using different methods to compensate for phase errors; Figure 12 This is a schematic diagram of another modified Blass matrix that generates different beams with different beamwidths; Figure 13 The illustration shows an example of generating three beams, where two beams have one beamwidth and the other beam has a narrower beamwidth; Figure 14 and Figure 16 A conventional multiport antenna is shown; Figure 15 and Figure 17 It shows the relationship with Figure 14 and Figure 16 Antennas with comparable antenna capabilities but significantly smaller physical size; Figure 18 A 4-port antenna array with a nominal 45-degree azimuth beamwidth is shown. Figure 19 It shows the relationship with Figure 18 A 4-port antenna array with comparable antenna capabilities but a much narrower configuration; Figure 20A This is a schematic diagram of a matrix circuit with a variable phase shifter in the top row; Figure 20B This is a schematic diagram of a matrix circuit where all rows have variable phase shifters; Figure 21A This is a schematic diagram of a trombone phase shifter; Figure 21B This is a schematic diagram of a variable phase shifter that uses rotational motion to adjust the phase delay; Figure 21C This is a schematic diagram of another structure of a variable phase shifter that also uses rotational motion to adjust the phase delay; Figure 21D This is a schematic diagram of a variable phase shifter structure that uses the linear motion of a high dielectric constant dielectric substrate to adjust the phase delay. Figure 21E The diagram illustrates a trombone phase shifter integrated with a coupler; Figure 21F It is used for explanation Figure 21E A schematic diagram illustrating the function and mechanism of the structure shown; Figure 21G It is used for further explanation Figure 21D A schematic diagram illustrating the function and mechanism of the structure shown; Figure 21H The diagram illustrates another structure of a variable phase shifter that utilizes rotational motion; Figure 22The illustration shows a 12-port antenna array that embodies various aspects of the present invention; Figure 23 The illustration shows a 16-port antenna array that can be used in various aspects of the present invention; Figure 24 This is a schematic diagram of a low-frequency matrix circuit according to various aspects of the present invention; Figure 25-28 It was shown as Figure 24 Four circuit boards representing different implementations of the matrix circuit shown; Figure 29 The diagram shows Figure 22 or Figure 23 An example of two beams generated by a low-frequency band array is shown. Figure 30 The illustration shows a 12-port antenna array that embodies various aspects of the present invention; Figure 31 The diagram illustrates a mid-frequency matrix circuit utilizing various aspects of the present invention; Figure 32 The diagram shows Figure 31 An example of two beams generated by the mid-frequency array shown; Figure 33 The illustration shows an example of an antenna array used for low-frequency elevation beam splitting, which can be compared with... Figure 22 and Figure 23 The antenna array shown (with a 45-degree azimuth beamwidth) has similar performance. Detailed Implementation

[0026] In one aspect of the invention, an antenna system is provided that generates multiple beams and such that the multiple beams are adjacent to each other in the vertical direction. That is, the multiple beams divide a cell into multiple cells in the elevation direction, rather than in the azimuth direction. In its simplest form, Figure 1 Two beams from a single antenna array are shown, where beam 10A (bottom beam) is a low-frequency beam that covers the area near the antenna tower, while beam 10B (top beam) is a high-gain low-frequency beam that provides coverage for the cell edge.

[0027] Reference Figure 2 The diagram illustrates a block diagram of an antenna system according to another aspect of the invention. It can be seen that the antenna system 100 includes a multi-beamforming network (MBFN) 110 that receives one or more input signals 120. The output of the MBFN is received by an antenna array 130 that generates multiple beams 140A, 140B, 140C, and 140D that are vertically adjacent to each other. In other words, multiple beams are generated in the elevation direction such that the resulting beams are vertically adjacent to each other.

[0028] For clarity, the present invention also includes generating additional beams in the azimuth direction in addition to the multiple beams in the pitch direction. That is, in addition to the multiple beams that are adjacent to each other in the vertical direction (or pitch direction), other beams are generated such that these beams are adjacent to each other in the horizontal direction or azimuth direction.

[0029] In terms of frequency bands, the multibeams generated in the elevation direction can be low-frequency, mid-frequency, C-band, or high-frequency bands, or any combination of these frequencies. Similarly, in an embodiment that combines multibeams generated in the elevation direction with multibeams generated in the azimuth direction, any beam (whether in the elevation or azimuth direction) can be low-frequency, mid-frequency, C-band, or high-frequency bands. For this combination of elevation and azimuth multibeams, in one embodiment, the elevation multibeam can be any of the aforementioned frequency bands and can be at any preferred angle in the elevation direction, while the remaining beams can be standard azimuth multibeams with an azimuth of 65 degrees, 80 degrees, or 90 degrees.

[0030] For clarity, the low-frequency band, mid-frequency band, C-band, and high-frequency band mentioned in this document should be understood as the following frequency ranges: Low frequency band: 617-960MHz Mid-frequency band: 1695-2690MHz C-band: 3300-4200MHz High frequency band: 24GHz-40GHz Furthermore, various aspects of the present invention can also be used in conjunction with cellular applications involving frequencies such as 600MHz to 2.5GHz, 450MHz to 6GHz, and 24GHz to 52GHz.

[0031] Known configurations and techniques related to antennas and antenna arrays can be used in this invention. As an example, each beam can use a 4T4R configuration, or each pair of beams can use an 8T8R wireless device. The multiple beams generated in the pitch direction can be fixed beams, or these beams can be adjusted / moved using manual electronic tuning (MET) methods and devices, or the adjustment / movement can be accomplished using remote electronic tuning (RET) methods and subsystems.

[0032] This concept of using multiple beams in elevation can be extended to generate multiple beams not only in the azimuth or elevation directions, but also at any angle combining both azimuth and elevation dimensions. For example, it's possible to generate beams with azimuth angles of +35 and -35 degrees and elevation angles of 0 degrees, or azimuth angles of 0 degrees and elevation angles of +35 and -35 degrees, as well as beams with elevation angles of +35 degrees and azimuth angles of +35 degrees, and beams with elevation angles of -35 degrees and azimuth angles of +35 degrees. Similarly, it's possible to generate beams with elevation angles of +35 degrees and azimuth angles of -35 degrees, and beams with elevation angles of -35 degrees and azimuth angles of -35 degrees.

[0033] It should also be clear that the antenna aperture size can be reduced using this invention. Furthermore, the wind load and weight of the antenna array can be reduced. In particular, when generating low-frequency multibeams in the azimuth direction using an antenna array, the antenna size increases dramatically. By generating low-frequency multibeams in the elevation direction and mid-frequency and C-band multibeams in the azimuth direction, the antenna size can be significantly reduced. Reducing the antenna size also significantly reduces antenna weight and wind load. In fact, by implementing the above improvements, large multibeam antenna arrays can be reduced to the same size as standard macro antennas. This advancement enables the widespread application of multibeam antennas in macro environments.

[0034] Conventional base station antennas or macro antennas are typically deployed as MIMO systems to mitigate channel fading and improve channel capacity and throughput. Designing such an antenna system as a MIMO system involves implementing parallel array clusters corresponding to different ports. This invention provides the same number of ports as a conventional base station antenna MIMO system; however, it requires only half the number of array clusters.

[0035] In terms of antenna array implementation, Figure 3-7 An example of an antenna array that can be used to implement aspects of the present invention is shown.

[0036] exist Figure 3 The image illustrates a 12-port macro antenna with a 4-port low-frequency band and an 8-port mid-frequency band, which is converted into a 16-port or 20-port antenna with an 8-port mid-frequency band and 8 or 12 ports for the low-frequency band. The original antenna was a multi-beam array that generated an azimuth beamwidth of 65 degrees at both the low-frequency and mid-frequency bands. In the modified antenna, the low-frequency band azimuth beamwidth is 65 degrees, but it has two or three beams in the elevation direction depending on the application. In this way, the low-frequency band antenna array can provide two or three beams in the elevation direction. It should be noted that the modified antenna array is smaller than the original antenna array (i.e., the modified antenna array is narrower), and this size reduction reduces the weight of the antenna array and alleviates wind load.

[0037] exist Figure 4 The image illustrates a 20-port macro antenna with a 4-port low-frequency band, an 8-port mid-frequency band, and an 8-port C-band. In the original antenna, the low-frequency and mid-frequency beams are generated using a standard antenna with a 65-degree azimuth beamwidth. Furthermore, for the original antenna, the C-band uses 8T8R beamforming. The modified antenna has 24 or 28 ports, including an 8-port mid-frequency band, an 8-port C-band, and an 8 or 12-port low-frequency band. The low-frequency band has a 65-degree azimuth beamwidth, but features two or three beams in the elevation direction depending on the application. The modified antenna has the same footprint as the standard macro antenna, but provides multiple low-frequency band beams in the elevation direction, thus addressing cell edge coverage issues by dividing the low-frequency band sector into two or three sectors.

[0038] exist Figure 5 The diagram illustrates another example of an antenna array that can be used in this invention. In this example, the antenna array is a mid-band array with three azimuth beams, while also generating two or three low-band beams in the elevation direction. Each beam has four ports for 4×4 MIMO. Overall, this example has a 12-port mid-band and an 8 or 12-port low-band beam, depending on whether the low-band frequencies have two or three beams. This antenna provides multiple low-band and mid-band beams within a macro antenna footprint. If the low-band multiple beams are also in the azimuth direction, the antenna width will be much larger, and the wind load and antenna weight will increase accordingly. This is an example of using a multi-beam antenna in a dense macro environment. For this antenna, the mid-band capacity is increased by multiple beams in the azimuth direction. At the same time, the low-band capacity is enhanced by two or three low-band beams in the elevation direction. This antenna can be used in applications such as inside stadiums, where the antenna is mounted on the stadium trusses and projects beams downwards.

[0039] Figure 6 The diagram illustrates the relationship between... Figure 5 A similar example, but one that integrates 3 azimuth beams in the C-band. In this example, the array has 3 azimuth beams in the mid-band and C-band, and 2 or 3 elevation beams in the low-band. This is another example of a multi-beam macro antenna also in the C-band. This antenna provides low-band, mid-band, and C-band multi-beams within the footprint of a macro antenna. If the low-band multi-beams were also in the azimuth direction, the resulting antenna width would be much larger, and the wind load and weight would increase accordingly.

[0040] exist Figure 7The image illustrates an antenna array that converts from a 3-beam azimuth to a 6-beam or 3-beam elevation. Overall, the antenna array shown achieves 9 or 18 beams using the same aperture size. The number of beams is increased by generating multiple beams in both the azimuth and elevation directions, while the antenna aperture remains within the footprint of a macro-antenna. This antenna array can be used in applications such as stadium environments, where the antenna is mounted on a truss and projects beams downwards toward the stadium stands. In this way, multiple point beams effectively divide the area in two dimensions.

[0041] In implementing an MBFN, the multi-beamforming network can employ a Butler matrix, a Nolen matrix, a Blass matrix, a variable beam directional (VBD) Blass matrix, or adjusted / modified versions of these matrices, or a Rotman lens. As described above, one aspect of the present invention generates multiple beams in the elevation direction. One or more other MBFNs may also exist that generate additional beams in the azimuth direction in addition to the multiple beams in the elevation direction. These MBFNs generating multiple beams in the azimuth direction can utilize antenna arrays different from those generating multiple beams in the elevation direction.

[0042] For MBFN Blass matrix implementations, conventional Blass matrices can cause beam skew in the resulting beams. This problem can be mitigated or even eliminated by appropriately assigning different beams to different rows of the Blass matrix circuitry. Specifically, for a set of beams within a given elevation angle range, the "center beam" is conventionally provided by the middle row of the matrix. In this embodiment of the invention, the center beam is assigned to the lowest row of the Blass matrix. This reduces the inherent degradation of large scan angle beams, which would otherwise be caused by the array aperture at lower rows.

[0043] As is well known, beam skew refers to the undesirable but unavoidable phenomenon of beam direction scanning as frequency changes. With frequency variations, the beam direction (i.e., the direction of the signal in the elevation direction) will change, while the beam should ideally maintain a constant direction. Due to beam skew, the beam coverage area will differ at different frequencies (i.e., the uplink and downlink beam coverage areas will differ), meaning that antenna arrays cannot achieve closed-loop communication. This problem becomes more severe as the relative bandwidth increases (e.g., bandwidth greater than 30%).

[0044] To effectively eliminate beam skew, it should be noted that in the Blass matrix structure, beam skew is caused by two factors: (1) The phase shift caused by each row of the Blass matrix; and (2) The pitch angle (i.e., direction) of the beam.

[0045] In other words, beams at more extreme angles inherently have greater skew. For example, a beam pointing to zero degrees (i.e., without any pitch angle and therefore pointing directly to the horizon) inherently has less skew compared to a beam located at + / -30° in the horizontal direction.

[0046] It should be noted that the first factor is unavoidable because the signal undergoes a phase shift as it moves from one row to the next, and this phase shift plays a crucial role in maintaining the beam elevation angle. However, beam skew caused by the beam elevation angle can be mitigated by allocating the rows of the matrix to specific angles.

[0047] Specifically, a standard Blass matrix design provides multiple beams within a given pitch angle range (e.g., for a 3-row matrix, the pitch angle range could be -30°, 0°, +30°). Beams pointing to extrema (i.e., the top beam, such as +30° in the example range, where the positive extremum is at the top) are provided by the top row of the matrix; beams pointing to the center of the range (e.g., at 0 degrees or directly horizontal) are provided by the middle row; and beams pointing to opposite extrema (i.e., the bottom beam, such as -30° in the example range, where the negative extremum is at the bottom of the three vertically adjacent beams) are provided by the bottom row. It should be understood that in a standard matrix, either positive or negative extrema can be placed at the top / bottom of the matrix.

[0048] However, in conventional designs, the negative extreme beam has the greatest loss and therefore the lowest gain, resulting in a higher phase shift, because it is located at the lowest row. As explained above, the beam already has significant beam skew due to its extreme angle, and this low gain and high loss will lead to further beam skew and a decrease in overall quality.

[0049] To address this beam skew issue, the center beam, instead of the positive extreme beam, is assigned to the lowest row of the Blass matrix. The center beam, inherently possessing the highest directivity due to its 0-degree elevation angle, is therefore less affected by the additional losses incurred from placing it in the bottom row compared to the extreme elevation beam conventionally assigned there. A three-beam Blass matrix configuration employing this beam allocation scheme is shown below. Figure 8 As shown.

[0050] As those skilled in the art will understand, in order to benefit from this beam allocation scheme, the Blass matrix should have at least three rows. However, it should be noted that the elevation angle range is not required to be symmetrical or centered at 0 degrees. Furthermore, there is no requirement or preference for matrices with an odd or even number of rows. Those skilled in the art will understand how this disclosure can be applied to specific desired embodiments. As a non-limiting example, in embodiments using matrices with an even number of rows, the bottom two rows of the matrix may correspond to the beam pair with the smallest absolute value and therefore the highest directivity.

[0051] Furthermore, it should be understood that the beam assignments for the other rows of the matrix may differ in different embodiments. For example, in some embodiments, the extreme pitch beam is assigned to the middle row of the matrix, while the other beam assignments are no different from the conventional assignment method. In other embodiments, multiple beam assignments differ from the conventional assignment method. For example, in some embodiments, the top two rows are assigned to provide extreme beams (i.e., the beam with the largest positive pitch angle and the beam with the largest negative pitch angle). Furthermore, in some such embodiments, for each consecutive pair of rows in the matrix, the absolute value of the beam pitch angle decreases until the last row of the matrix. Additionally, depending on the embodiment, either the top beam (positive extreme pitch angle beam) or the bottom beam (negative extreme pitch angle beam) may be assigned to the middle row.

[0052] In addition, in some embodiments, phase compensation is applied in addition to implementing the beamforming method. This phase compensation involves mitigating the phase error introduced by each of the multiple couplers. Ideally, each coupler has a phase of 90 degrees. However, when the coupling coefficient is greater than -3dB, the coupler phase varies with the coupling coefficient. Therefore, in some embodiments, phase compensation is applied to each coupler to make the phases of all couplers closer. This can be achieved by adding an additional phase factor on both the horizontal and vertical lines connecting the couplers in one row to the couplers in another row.

[0053] Based on the above, for an MBFN implemented using a Blass matrix to generate multiple beams with pitch tilt, multiple signal beams are first provided to the Blass matrix circuit. The center beam (i.e., the one with the smallest absolute pitch angle among the multiple signal beams) is assigned to the bottom row of the Blass matrix circuit. As mentioned above, this mitigates beam skew and helps balance the gain between the beams.

[0054] To mitigate phase errors, multiple signal beams are supplied to the Blass matrix circuit. Phase compensation is then applied to the directional couplers in the matrix circuit. The center beam is subsequently assigned to the bottom row of the Blass matrix circuit. It should be understood that phase compensation can be applied before or after beam assignment in the Blass matrix circuit.

[0055] For MBFNs implemented using the Nolen matrix to generate multi-beams with pitch tilt, an improved Nolen matrix can be used to address phase error and beam skew issues.

[0056] For MBFNs implemented using a Nolen matrix, phase shifters or transmission line delay lines are used between the rows of the Nolen matrix to compensate for phase errors. Alternatively, cascaded phase shifters can be used between the rows. To compensate for beam skew, as explained above regarding the Blass matrix, the input signal beam with the smallest pitch angle is assigned to the row of the Nolen matrix closest to the load (i.e., the bottom row). To achieve this, the phase error is first calculated, and then the desired phase shift used to compensate for the phase error is determined. The desired phase shift is then achieved using phase shifters / delay lines / cascaded phase shifters.

[0057] Reference Figure 9 The diagram illustrates a typical Nolen matrix. As is well known, a typical Nolen matrix is ​​composed of different components, such as directional couplers and phase delay lines. Figure 9 The Nolen matrix in the diagram has M inputs (input signal beams) and N outputs (antenna outputs / antenna elements).

[0058] like Figure 9 As shown, the Nolen matrix 10 has several columns and rows, including couplers 20, horizontal phase delay lines 30, and vertical circuit element lines 40. The Nolen matrix couples the input signal beam 50 to the output antenna element 60 through the various couplers, phase delay lines, and circuit element lines. It should be understood that each column of the Nolen matrix has a set of couplers and circuit element lines between the output antenna element and the load 70. It should also be understood that the lowest row of the Nolen matrix is ​​the row 80 closest to the load 70, and the highest row of the Nolen matrix is ​​the row 90 closest to the output antenna element 60.

[0059] For clarity, in Figure 9 In the middle, the coupler is marked with "C" xx The box indicates that the horizontal phase delay line is marked with "D". xx The rectangle indicates that the vertical circuit element lines are labeled "P". xx The circle indicated by "" shows the coupling factor and phase delay line, calculated using software. It should be noted that a conventional Nolen matrix contains some phase errors, which can degrade the matrix's performance.

[0060] One approach to solving the phase error problem is to determine the phase error of a specific antenna element and then compensate for that phase error by using engineered / designed vertical circuitry lines between rows in a particular column. The different vertical circuitry lines between rows introduce a phase shift to compensate for the phase error. As an example, according to... Figure 9 This allows us to determine the phase error of antenna element Out2 and to engineer / design vertical circuit element lines P12, P22...PM2 to compensate for this phase error of antenna element Out2.

[0061] In one aspect of the invention, only a transmission line is used between the output of a coupler in one row and the input of a coupler in the next row. The length of the transmission line is optimized to produce the desired different phases, thereby compensating for phase errors occurring at the antenna element input (i.e., the output of the Nolen matrix). An example structure with 3 beam inputs and 7 element outputs is designed using this innovation, such as... Figure 10 As shown. If implemented properly, this structure outputs multiple beams that are adjacent to each other in the pitch or vertical direction.

[0062] As shown in the figure, the phase and amplitude of the beam are optimized and adjusted to improve both beam skew and SLL performance. Because this method provides more degrees of freedom by adding different, optimized vertical transmission lines, the new Nolen matrix (shown in...) Figure 10 It can operate within a wide frequency range (wideband) of 1695-2690MHz. This new Nolen matrix configuration can also operate at other frequencies, including the low-frequency band, mid-frequency band, and even the C-band.

[0063] As an alternative, the order in which the input signal beams are assigned to each row in the matrix can also be adjusted. Figure 10 The configuration is adjusted. For a conventional three-beam configuration (beams pointing +30 degrees above the horizontal plane, 0 degrees above the horizontal plane, and -30 degrees below the horizontal plane), the conventional approach is to place the beam with the largest elevation angle at the top row, with the zero-elevation beam (pointing to the horizontal plane) in the middle row, and the -30-degree elevation beam (pointing to 30 degrees below the horizontal plane) in the bottom row, i.e., +30 degrees, 0 degrees, -30 degrees. For this aspect of the invention, the order can be -30 degrees, 0 degrees, +30 degrees. In this way, the zero-elevation beam remains in the middle row, the -30-degree elevation beam is at the top row, and the +30-degree elevation beam is at the bottom row. This novel configuration can reduce overall phase error.

[0064] Another solution to the beam skew and SLL problems is to replace the vertical phase delay line with a phase shifter between any two rows. For this innovation, a Nolen matrix configuration with 3 beam inputs and 7 outputs was designed, the block diagram of which is shown below. Figure 11 As an example, such as Figure 11 As shown, phase shifter P22 is located between coupler C12 (in the top row) and coupler C22 (in the middle row). Figure 10 In this case, a vertical delay line DV22 is used between the two couplers instead of a phase shifter P22.

[0065] As a variation of the above scheme, instead of using a single phase shifter between adjacent rows, several cascaded phase shifters (i.e., replacing...) are used. Figure 11 The circular "Pmn" boxes (using two or more phase shifters between each pair of rows) compensate for the network's phase error. As an example, in... Figure 11 Between coupler C12 and coupler C22, two or more cascaded phase shifters will be used instead of phase shifter P22. Similar to the innovations mentioned above, by adding cascaded phase shifters, beam skew is eliminated and SLL is improved compared to the conventional Nolen matrix.

[0066] Compared to the conventional Nolen matrix, the innovations described above using the modified Nolen matrix as the MBFN do not produce any beam skew, improve SLL, and allow the modified Nolen matrix to operate over a wider frequency band, covering the entire mid-band. It should also be noted that these innovations are applicable to mid-band frequencies (1695-2690MHz) as well as other frequencies such as the low-frequency band and C-band.

[0067] Reference Figure 10 and Figure 11 The circuitry in these designs generates two different Nolen matrices using two different methods. Each design has three inputs, producing three beams with different elevation directions. The resulting matrix has seven outputs, connected to seven antenna array elements. Coupler values ​​and horizontal delay line phase values ​​are obtained theoretically using appropriate software. Essentially, the phase error to be compensated is first measured / calculated, and then the compensation phase shift is designed into the relevant delay lines and / or phase shifters / cascaded phase shifters. As mentioned above, the vertical phase delay lines and phase shifters are optimized to compensate for the phase error.

[0068] Figure 12 Another configuration of the circuit elements is shown, which can be used to generate multiple beams in the azimuth and elevation directions when it is desired to generate beams with different beamwidths. For example... Figure 12 As shown, the three inputs generate three beams, one of which uses the entire array, while the other two beams use only half of the array. Still as... Figure 12 As shown, different beams have different numbers of couplers and phase shifters / vertical delay lines.

[0069] like Figure 12As shown, the circuit elements are arranged to form a matrix consisting of directional couplers, horizontal phase delay lines, and vertical circuit element lines. This matrix comprises multiple rows of circuit elements, each row having a directional coupler and a horizontal phase delay line, and each row receiving the input signal beam. Furthermore, each row includes a directional coupler coupled to at least one other directional coupler in the same row via a horizontal delay line. The matrix also consists of several columns of circuit elements, each column having a directional coupler and a vertical circuit element line. Each column of circuit elements is coupled between the output antenna and the load.

[0070] Reference Figure 13 The illustration shows an example of generating three beams, where the first beam is narrower than the other two. The wider beam can cover the area near the antenna tower, while the narrower beam can cover the area at the cell edge. It should be clear that... Figure 12 The configuration shown can be used to generate Figure 13 The three beams are shown. In this implementation, the narrow beam is generated using the input of the entire array, while the two wider beams are generated using only the two inputs of half the array.

[0071] It should be noted that, although Figure 12 The structure in the diagram is designed for a 3-beam configuration, but the overall concept allows for any number of beams and antenna array size. Furthermore, it should be understood that different beams can have different beamwidths as needed, enabling the generation of any number of beams (whether in elevation or azimuth), and any beam can have a different beamwidth. For clarity, although... Figure 12 The configuration in the example is based on the Blass matrix, but a similar configuration based on the Nolen matrix can also be used.

[0072] Various aspects of the present invention can also be used in antenna systems with a physical size significantly smaller than antenna systems with equivalent capabilities. In this aspect of the invention, multi-beaming is used in the elevation direction to achieve pattern diversity, thereby producing antenna arrays with a physical size significantly smaller than antenna arrays with equivalent capabilities.

[0073] As is well known, most base stations utilize diversity to improve signal quality by leveraging multipath propagation. Diversity can be polarization diversity, spatial diversity, or pattern diversity. Most base station antennas use polarization diversity and spatial diversity. In a 4×4 MIMO base station antenna, there are two spaced-apart dual-polarized antenna arrays to provide both polarization and spatial diversity. For clarity, to achieve spatial diversity gain, the two antenna arrays should be spaced considerably apart (the distance between arrays depends on the angular spread of the received signal) to utilize spatial diversity. This need to space the arrays apart conflicts with the desire to reduce the antenna footprint. Reducing the physical footprint or size of the antenna reduces the impact of wind load on the antenna. As an example, in a 12-port antenna array with 4-port low-frequency (LF) elements and 8-port mid-frequency (IF) elements, it is desirable to keep the total antenna width within 20 inches. Reducing the antenna width to reduce wind load results in the spacing between the two columns of LF elements approaching half a wavelength. Furthermore, when there are 4 columns of IF elements, the array spacing is also approximately half a wavelength. For many incident angle extensions, a spacing of about half a wavelength does not provide good spatial diversity.

[0074] The aspects of this invention related to elevation multibeaming can be used to provide pattern diversity and, by simultaneously using polarization diversity, to produce 4×4 or 8×8 MIMO antenna arrays with a physical size smaller than equivalent capability arrays. In the resulting antenna array, each column is fed by a multibeam network that generates at least two beams in the elevation direction (i.e., at least two beams that are adjacent or superimposed on each other in the vertical direction). As described above, the resulting antenna array is physically smaller than similar antenna arrays. In one example, a conventional 4-port low-frequency antenna array has an antenna width of approximately 20-25 inches. The equivalent array using multibeaming in the elevation direction has an antenna width of only approximately 10-15 inches. This size reduction reduces antenna wind load and antenna weight by about half. Similarly, the size reduction also reduces the overall cost of the antenna. Figure 14 A conventional 4×4 MIMO with polarization diversity and spatial diversity is shown. Figure 15 A 4×4 MIMO with polarization diversity and pattern diversity is shown, whose antenna uses dual beams in the elevation direction according to one aspect of the invention. As described above, Figure 14 and Figure 15 The antennas in these antennas have similar or comparable capabilities, while Figure 15 The antenna in the middle is physically smaller (narrower than) Figure 14 The antennas in the diagram (assuming the antenna elements of both antennas are of the same size).

[0075] It should be understood that multi-beam antenna arrays in the elevation direction can achieve pattern diversity using vertical beam splitting. This provides different paths for multipath propagation between two beams. Therefore, when a user is located at the cell edge, their equipment can travel through higher beams (e.g., Figure 1 The device communicates via a lower beam (e.g., 10B). This improves coverage at the cell edge. Similarly, when a user is near the antenna tower, their equipment communicates via a lower beam (e.g., 10B). Figure 1 The wireless device communicates using beam 10A. The signal of the same user can have multiple paths in the two beams. In this case, the wireless device will use diversity merging to optimize signal quality.

[0076] It should be clear that pattern diversity can be achieved by forming multiple beams in the elevation direction through vertical beam splitting, and the combination of polarization diversity with pattern diversity provided by multiple beams in the elevation direction can be applied to various base station antennas and small cellular antennas. These antennas and antenna arrays can be single-band or multi-band as needed. Figures 16 to 19 Examples of how these ideas are applied to different antennas are given.

[0077] Reference Figure 16 The illustration shows a 65-150 degree azimuth beamwidth antenna with a typical two-column dual-polarized antenna element to provide 4×4 MIMO. Figure 17 A 4-port antenna providing an equivalent 4×4 MIMO is shown, employing the vertical beam splitting concept described above in this invention. It can be seen that... Figure 17 The antenna in the design has only a single-row dual-polarized antenna element.

[0078] Reference Figure 18 The illustration shows a nominal 45-degree azimuth beamwidth antenna with a typical 4-column dual-polarized antenna element. Figure 19 An equivalent 4-port antenna employing the vertical beam splitting concept of the present invention is shown. It can be seen that... Figure 19 The antenna in this model has only two columns of dual-polarized antenna elements, therefore it is more powerful than... Figure 18 The antenna in it is much narrower.

[0079] As another example, a nominal 33-degree azimuth beamwidth antenna typically has six columns of dual-polarized elements to achieve 4×4 MIMO. With multi-beaming in the elevation direction, the equivalent antenna will have only three columns of dual-polarized elements.

[0080] It should be clear that the concept of vertical beam splitting, utilizing polarization diversity and pattern diversity, can be equally applied to macro antennas or small antennas. The resulting antenna's vertical array can have any number of elements. Furthermore, in multi-band antennas, some arrays or bands within the same antenna can use vertical beam splitting, while others may not. As an example, in a 12-port macro antenna with two columns of low-frequency dual-polarized antenna elements and four columns of mid-frequency dual-polarized antenna elements, only the low-frequency elements can use the vertical beam splitting concept. It should also be clear that, depending on channel requirements, the vertical beam splitting concept can be used to generate more than two beams.

[0081] As mentioned above, the vertical beam direction can be remotely controlled using a remote electronically controlled switch (RET). Figure 20A and Figure 20B The matrix architecture of a variable beam direction (VBD) Blass matrix is ​​shown, where the beam direction can be controlled by adjusting a phase shifter. Figure 20A In the architecture shown, only the top row has a variable phase shifter. In this architecture, only the first beam rotates. Figure 20B In the architecture shown, each row has a variable phase shifter. In this architecture, each beam direction can be controlled independently.

[0082] As will be clearly understood by those skilled in the art, a phase shifter can be an electromechanical phase shifter controlled by a motor. Figure 21A , 21B Figures 21C, 21D, and 21H illustrate five feasible variable phase shifter designs. Figure 21A This is a schematic diagram of a trombone-shaped phase shifter, which includes movable parts that adjust the phase shifter via linear motion. Figure 21B This is a schematic diagram of a rotary phase shifter. (Example) Figure 21B As shown, the rotating component rotates and changes the arc length to adjust the phase shifter, which can also be applied to azimuth direction. Figure 21C It is a rotary variable delay line phase shifter. Figure 21D Another example of a variable phase shifter is illustrated, which utilizes a high-dielectric-constant dielectric placed above the delay line to achieve variable phase shift. Of course, it should be understood that any suitable variable phase shifter can be used in this invention. Figure 21A , 21B 21C, 21D and 21H only depict exemplary variable phase shifter structures.

[0083] Reference Figure 21A and Figure 21F The diagram illustrates a trombone-shaped variable phase shifter. Figure 21A The front of the phase shifter is shown, while Figure 21FTwo positions of the movable portion of the variable phase shifter are shown. As shown, the phase shifter has two traces 2100-1 and 2100-2 for coupling to two ports. The first port can be coupled to trace 2100-1, and the second port can be coupled to trace 2100-2. The phase shifter also has a bridging element 2100-3, which has overlapping portions 2100-4 and 2100-5 and a connecting portion 2100-6. As shown, overlapping portion 2100-4 overlaps with trace 2100-1, while overlapping portion 2100-5 overlaps with trace 2100-2. Connecting portion 2100-6 connects overlapping portion 2100-4 to overlapping portion 2100-5. Figure 21F As can be seen, the upper image shows the first tilt position, and the lower image shows the second tilt position. The phase shifter operates by adjusting the electrical length / path between two traces, thereby lengthening the electrical distance / path the signal travels between the two ports, introducing a variable phase delay between them. The phase shifter switches between the two tilt positions by moving / sliding a movable part. Figure 21A As can be seen, when the movable part slides towards the trace direction, the phase shifter moves to the first tilt position. When the movable part slides away from the trace, the phase shifter moves to the second tilt position. At both tilt positions, the signal must traverse an electrical distance to travel between the two ports, and this distance determines the magnitude of the introduced phase delay. The electrical distance is changed by adjusting the overlap between the overlapping part and the trace. Figure 21F As can be seen, the electrical distance is longer / greater in the second tilt position than in the first tilt position, and correspondingly, a greater phase delay is introduced when the phase shifter is in the second tilt position. Therefore, the larger the overlap area between the overlapping portion and the trace, the smaller the introduced phase delay. Similarly, the smaller the overlap area (and thus the larger the electrical distance), the greater the introduced phase delay.

[0084] It should be clear that, depending on the implementation of this variable phase shifter design, the phase delay can be a continuous value between the minimum phase delay (in the first tilt position) and the maximum phase delay (in the second tilt position). Alternatively, the variable phase shifter can be set to a fixed number of phase delay values. Of course, this fixed number depends on the number of fixed tilt positions designed / implemented in the variable phase shifter. Therefore, in Figure 21F In the implementation shown, there are at least two fixed tilt positions corresponding to two phase delay values—the maximum phase delay (at the second tilt position, with the minimum overlap and the maximum electrical length) and the minimum phase delay (at the first tilt position, with the maximum overlap and the minimum electrical length). Of course, additional fixed tilt positions can be implemented between these two extreme positions to obtain additional fixed phase delay values.

[0085] Reference Figure 21B It should be clear that the implementation method of this variable phase shifter is similar to... Figure 21A The working principle of the variable phase shifter in [the context is missing]. It can be seen that... Figure 21B The variable phase shifter in the circuit does not increase / decrease the overlap between the overlapping portion and the trace (thus increasing / decrease the electrical path / length) through linear motion, but rather through rotational motion. Figure 21B As can be seen, the first port is coupled to a trace that connects to the pivot point. The pivot point connects to an arm that connects to an arc-shaped overlapping portion, which overlaps with another trace that is also arc-shaped, and this other trace is coupled to the second port. It can be seen that... Figure 21B The structure has a specific function—the transducer, which forms part of the arm, is preferably a quarter-wavelength, thus making the variable-length portion of the phase shifter open-circuited. When one end of the quarter-wavelength transmission line is short-circuited, the other end will be open-circuited, and vice versa. The first quarter-wavelength in the middle converts the open circuit at the top of the arm into an equivalent short circuit on the arc. This means that the left side of the arc will be in parallel with the short circuit. Regardless of the arc length (which changes as the phase shifter arm rotates), this will keep the left side of the arc short-circuited. The second quarter-wavelength converts the short circuit into an open circuit at the center of the bottom of the rotating arm. Thus, any part of the movable part (i.e., the arm) located on this side will always be open-circuited.

[0086] Depend on Figure 21B It is evident that there are three possible locations—in Figure 21B The diagram shows states 1, 2, and 3. States 1 and 3 represent two extremes—in state 1, the electrical length between port 1 and port 2 is the longest, while in state 3, the electrical length between these two ports is the shortest. In state 2, the electrical length between the two ports is in the middle.

[0087] Reference Figure 21C The diagram illustrates a variation of a variable phase shifter utilizing rotational motion. It can be seen that a trace is coupled to a pivot point, which connects to an arm that leads to an arc-shaped overlapping section. The overlapping section overlaps with the arc-shaped segment of a second trace. By rotating the arm / overlapping section between two extreme positions... Figure 21C The above figure shows the first extreme position. Figure 21C The diagram below shows the second extreme position, which allows adjustment of the phase delay introduced by the signal traveling between the two traces. Of course, by adjusting the position of the arm / overlap section, any delay value between the maximum delay (at one extreme position) and the minimum delay (at another extreme position) can be obtained.

[0088] It should be clear that in order to achieve Figures 21A-21C The variable phase shifter shown has its traces on a first PCB, while the overlapping / movable portion is located on a second PCB. The second PCB can move relative to the first PCB, and this relative movement capability allows for switching between tilt positions or between positions between extreme phase delay settings.

[0089] Reference Figure 21D The diagram illustrates another configuration of the variable phase shifter. It can be seen that the "cover" moves linearly, thereby achieving different amounts of coverage or overlap of the trace between the two ports. In this implementation, the cover is a high-dielectric-constant dielectric substrate, and the amount of overlap or coverage of the trace determines the phase delay between the two ports coupled by the trace. Figure 21D As can be seen, there are three phase delay settings—maximum phase delay, minimum phase delay, and an intermediate setting that provides a phase delay between the maximum and minimum. To explain the concept behind this design, [details omitted]. Figure 21G .

[0090] Depend on Figure 21G As can be seen in the left figure, a first trace 2100-100 and a second trace 2100-110 are shown, where the first trace 2100-100 is coupled to a first port 2100-120, and the second trace 2100-110 is coupled to a second port 2100-130. Both the first trace 2100-100 and the second trace 2100-110 are part of an elongated trace 2100-140. Therefore, signals traveling between the first port 2100-120 and the second port 2100-130 will pass through this elongated trace 2100-140. However, a dielectric substrate 2100-150 with a high dielectric constant can be used to overlap / overlay at least a portion of this elongated trace 2100-140. Doing so changes the propagation constant, which has the effect of lengthening the electrical path or trace length of the elongated trace. Therefore, Figure 21G The configuration on the left has minimal phase delay (the dielectric substrate does not overhang or overlap any portion of the thin trace), while Figure 21G The configuration on the right has the maximum phase delay because the dielectric overhang covers or overlaps the entire thin trace. (See reference...) Figure 21D Therefore, it can be seen that dielectric substrate 2100-150 has window 2100-160. When window 2100-160 overlaps with a thin trace, dielectric substrate 2100-150 does not overlap with the trace, thus not changing the propagation constant (see...). Figure 21D (See above), and the signal traveling between the two ports has minimal phase delay. When the dielectric substrate 2100-150 overlaps with the trace (see above). Figure 21D (See figure below). This changes the propagation constant, resulting in maximum phase delay for any signal traveling between the two ports. Of course, this also applies when the window 2100-160 only overlaps with a portion of the trace (see...). Figure 21D (See middle image) This changes the propagation constant of part of the trace, thus introducing a phase delay to the signal traveling between the two ports.

[0091] Reference Figure 21EThe diagram illustrates a variable phase shifter structure that can be incorporated into a suitable circuit. For this structure, coupler traces serve as the necessary delay lines within the variable phase shifter structure. Observe... Figure 21E As can be seen, the trace shown in the upper diagram of the trombone phase shifter is shorter than that in the lower diagram. This longer / shorter trace is achieved through... Figure 21A and Figure 21F It is achieved through linear motion similar to the structure in the middle.

[0092] Reference Figure 21H The diagram illustrates another structure of a variable phase shifter. It can be seen that the rotational movement of this structure around a central pivot point can lengthen / shorten the electrical length / distance between the ports. One port is located at the top of the image, and the other at the bottom. The left image shows the minimum phase delay setting between the ports, while the right image shows the maximum phase delay setting between the ports.

[0093] It should be clear that the architecture / structure described above for implementing a variable phase shifter can be integrated with coupler traces to improve system efficiency and minimize losses by shortening the delay line length between couplers. As can be seen, in this approach, the coupler traces themselves can serve as the required delay lines within the variable phase shifter structure.

[0094] For clarity, any of the variable phase shifter structures described above can be used with any MBFN mentioned in this document. A variable phase shifter can be used between any two horizontally adjacent directional couplers, or between any two vertically adjacent directional couplers. Similarly, a variable phase shifter can be used in place of the phase shifters schematically shown in the figures of this document.

[0095] Reference Figure 22 and Figure 23 The illustration shows an 8-port mid-frequency antenna array with a 65-degree azimuth beamwidth. These antenna arrays are equipped with a 4-port low-frequency band (see...). Figure 22 ) and 8-port low-frequency band (see Figure 23 Both low-frequency arrays perform beam splitting in the elevation direction. Figure 24 A schematic diagram of a low-frequency matrix circuit is shown. Figure 24 Different implementations of the matrix circuit shown are illustrated in the figure. Figure 25 , Figure 26 , Figure 27 and Figure 28 These different implementations use different variable phase shifter structures, which will be explained below.

[0096] Reference Figure 25As can be seen, all outputs are located on one side of the circuit board, and the variable phase shifters between the directional couplers are shown as rectangles covering the directional coupler structure. In the illustrated embodiment, all phase shifters are set to one of two extreme settings (minimum and maximum phase delay settings). The phase shifters can continuously scan the beam by linearly moving the trombone phase shifters between the minimum and maximum phase delay settings.

[0097] Reference Figure 26 , showed Figure 24 Another embodiment of the matrix circuit is schematically shown. It can be seen that the outputs are located on both sides of the circuit board. A variable phase shifter is used between the directional couplers. Figure 21F and Figure 21E The structure shown. Figure 26 The variable phase shifters shown are in the minimum phase delay setting. For a variable phase shifter in the maximum phase delay setting, its appearance will be as follows: Figure 21E As shown in the image below. Figure 26 The phase shifter in the matrix circuit can continuously scan the beam by linearly moving the integrated trombone phase shifter between the minimum phase delay setting and the maximum phase delay setting.

[0098] Reference Figure 27 , showed Figure 24 Another embodiment of the matrix circuit is schematically shown. In this embodiment, all outputs are located on one side of the circuit board, and the variable phase shifter between the directional couplers again employs... Figure 21F and Figure 21E The structure shown is implemented. For this embodiment, these variable phase shifters have two settings (with...). Figure 26 The situation is very similar in the middle) — maximum phase delay and minimum phase delay (shown in Figure 27 ).and Figure 26 As in the embodiment, the phase shifter is shown in the minimum phase delay setting. Figure 27 The phase shifter in the matrix circuit can continuously scan the beam by linearly moving between the minimum phase delay setting and the maximum phase delay setting using an integrated trombone phase shifter.

[0099] Reference Figure 28 , showed Figure 24 Another embodiment of the matrix circuit is schematically shown. In this implementation, a variable phase shifter is used between the directional couplers. Figure 21D and Figure 21G The structure explained and illustrated. (By...) Figure 28As can be seen, the phase shifter shown is in the minimum phase delay setting. In the maximum phase delay setting, the dielectric substrate will completely overlap with all the elongated traces of each directional coupler. An intermediate setting that introduces only a certain phase delay can also be used. However, it should be noted that these phase shifters can continuously scan the beam by linearly moving the dielectric substrate between the minimum and maximum phase delay settings.

[0100] Reference Figure 29 The illustration shows the use Figure 22 and Figure 23 The example shown is a low-frequency array that generates two beams in the elevation direction.

[0101] Reference Figure 30 The diagram illustrates an antenna array with an 8-port mid-band and a 4-port low-band, and an azimuth beamwidth of 65 degrees. Both the mid-band and low-band arrays are beam-splittered in the elevation direction. The low-band MBFN circuitry is... Figure 24 Same as shown.

[0102] Reference Figure 31 The diagram illustrates a mid-frequency beamforming matrix circuit. This mid-frequency beamformer is designed to generate two beams with different desired pitch angles and beamwidths. For clarity, this means generating two beams at different pitch angles and with different beamwidths. Figure 31 An MBFN with two rows of directional couplers is shown. Each directional coupler in the top row (28 directional couplers) is coupled to an adjacent directional coupler via a variable phase shifter, and each of these 28 directional couplers is coupled to an antenna output via a fixed phase shifter. The bottom row (or second row) has only 16 directional couplers; similarly, each directional coupler in the bottom row is coupled to an adjacent directional coupler via an adjustable phase shifter. For each row, the last directional coupler in the row is terminated with a matched load. Furthermore, each directional coupler in the bottom row is also terminated with a matched load. The last 12 directional couplers in the top row that are not coupled to the couplers in the bottom row are also terminated with matched loads.

[0103] Reference Figure 32 The figure shows Figure 31 An example of two beams generated by a mid-frequency array is shown.

[0104] Figure 22 and Figure 23 The low-frequency band elevation beam splitting antenna array shown can be used Figure 33 The array shown is used to achieve this, and in one implementation, it can also have a 65-degree azimuth beamwidth.

[0105] This invention provides an antenna system using an MBFN that receives at least one signal and an antenna array having at least two antenna elements. The antenna array receives the output of the MBFN, and the system generates at least two output beams from the array such that the at least two output beams are adjacent to each other in the vertical direction (i.e., in the elevation direction). In addition to multiple beams in the elevation direction, the antenna system can also generate multiple beams adjacent to each other in the horizontal direction (i.e., in the azimuth direction). Accordingly, the system can generate multiple beams adjacent to each other in the elevation direction, and can also generate other multiple beams adjacent to each other in the azimuth direction. Different beams can have different beamwidths. The MBFN can be a Butler matrix, a Nolen matrix, a Blass matrix, or a modified version of a Butler, Blass, or Nolen matrix. The MBFN can also be configured to include directional couplers in matrix form, with horizontal delay lines (which can be implemented as phase shifters or variable phase shifters) between the directional couplers in the row direction and vertical circuit elements between the directional couplers in the column direction. The MBFN can be coupled to the antenna array via phase shifters or variable phase shifters.

[0106] Regarding the allocation of each input beam to each input terminal of the MBFN, the center azimuth beam (among multiple azimuth beams) or the center elevation beam (among multiple elevation beams) can be allocated to the bottom row of the matrix circuit, or the input beam with the smallest elevation angle or the smallest azimuth angle can be allocated to the bottom row of the matrix circuit.

[0107] When a variable phase shifter is used in an MBFN, its structure can be such that the mechanical movement or positional change of an element alters the electrical path between the phase shifter ports, thereby adjusting the phase delay of the signal traveling between the ports. The mechanical movement of the element can change the phase delay from a minimum to a maximum value, and can be set to a value between the minimum and maximum values. Similarly, the mechanical movement of a dielectric substrate can also be used. Overlaying the dielectric substrate onto a thin trace coupling the variable phase shifter ports has the effect of changing the propagation constant, similar to lengthening the electrical path between the ports. Any variable phase shifter structure can be used with any MBFN (whether between vertically or horizontally adjacent directional couplers, or between a directional coupler and an antenna element). The variable phase shifter structure can be used as a vertical delay line or a horizontal delay line in an MBFN.

[0108] By employing elevation beams, and by combining elevation and azimuth beams, an antenna array with performance comparable to those of antenna arrays with a larger physical footprint, more elements / columns, or a wider physical width is provided. The use of adjacent output beams in the elevation direction also provides pattern diversity, and the system can generate its output beams using all or a subset of the antennas in the array.

[0109] Those who understand the invention will now be able to conceive of alternative structures and embodiments or variations thereof, all of which are intended to fall within the scope of the invention as defined by the following claims.

Claims

1. An antenna system, comprising: A multi-beamforming network circuit for receiving at least one input signal; An antenna array, comprising at least two antenna elements, wherein the antenna array receives the output of the multi-beamforming network circuit; in The system generates at least two output beams from the antenna array such that the at least two output beams are adjacent to each other in the vertical direction.

2. The system according to claim 1, wherein the multi-beamforming network circuit comprises one or more of the following: Butler matrix; Rotman lenses; Nolen matrix; Blass matrix; Modified Blass matrix; Modified Nolen matrix; as well as Modified Butler matrix.

3. The system of claim 1, wherein the multi-beamforming network circuit includes a matrix circuit, the matrix circuit including a plurality of directional couplers and delay lines, the matrix circuit being coupled between a plurality of matched loads and the antenna array; in Each row of the matrix circuit includes multiple directional couplers coupled in series in the row-up direction, with each pair of directional couplers connected by at least one delay line in the row-up direction. Each column of the matrix circuit includes multiple directional couplers coupled in series upwards. The bottom row of the matrix circuit is coupled to the plurality of matched loads such that each directional coupler in the bottom row is coupled column-up between one of the plurality of matched loads and the directional coupler in the row immediately above the matrix circuit. Each row of the matrix circuit provides a different signal beam, which has a unique elevation angle within a predetermined azimuth range, such that the antenna array provides at least three different signal beams. These at least three different signal beams include at least one negative azimuth beam corresponding to the negative extreme of the azimuth range, a center azimuth beam corresponding to the center of the azimuth range, and a positive azimuth beam corresponding to the positive extreme of the azimuth range. The matrix circuit is used to implement a method that includes providing the center azimuth beam using the bottom row of the matrix circuit.

4. The system of claim 1, wherein the multi-beamforming network circuit includes a matrix circuit, the matrix circuit including a plurality of directional couplers and delay lines, the matrix circuit being coupled between a plurality of matched loads and the antenna array; in Each row of the matrix circuit includes multiple directional couplers coupled in series in the row-up direction, with each pair of directional couplers connected by at least one delay line in the row-up direction. Each column of the matrix circuit includes multiple directional couplers coupled in series upwards. The bottom row of the matrix circuit is coupled to the plurality of matched loads such that each directional coupler in the bottom row is coupled column-up between one of the plurality of matched loads and the directional coupler in the row immediately above the matrix circuit. Each row of the matrix circuit provides a different signal beam, and the signal beam has a unique azimuth angle within a predetermined elevation angle range, such that the antenna array provides at least three different signal beams. These at least three different signal beams include at least one negative elevation beam corresponding to the negative extreme of the elevation angle range, a center elevation beam corresponding to the center of the elevation angle range, and a positive elevation beam corresponding to the positive extreme of the elevation angle range. The matrix circuit is used to implement a method that includes providing the center pitch beam using the bottom row of the matrix circuit.

5. The system of claim 4, wherein phase compensation is applied to each of the plurality of directional couplers.

6. The system of claim 3, wherein phase compensation is applied to each of the plurality of directional couplers.

7. The system of claim 2, wherein the multi-beamforming network circuit includes a matrix circuit for coupling multiple input signal beams to the antenna array, the matrix circuit comprising: This includes a matrix of directional couplers, horizontal phase delay lines, and vertical circuit element lines; The matrix is ​​configured to form: A multi-row circuit element, each row comprising a directional coupler and a horizontal circuit element line, each row receiving an input signal beam, and the directional coupler in each row being coupled to at least one other directional coupler via a horizontal delay line; and Multiple rows of circuit elements, each row of circuit elements including a directional coupler and a vertical circuit element line, each row of circuit elements being coupled between an antenna element in the antenna array and a load; The matrix circuit is used to form multiple output beams based on the input signal beam.

8. The system of claim 7, wherein the input signal beam with the smallest absolute value of the pitch angle among the plurality of input signal beams is received by a specific row of the matrix circuit, the specific row being the row closest to the load coupled to the matrix circuit.

9. The system of claim 7, wherein the input signal beam with the smallest absolute value of the azimuth angle among the plurality of input signal beams is received by a specific row of the matrix circuit, the specific row being the row closest to the load coupled to the matrix circuit.

10. The system of claim 7, wherein the vertical circuit element line is implemented as one or more of the following: Phase shifter; Adjustable phase shifter; and Vertical phase delay line.

11. The system of claim 7, wherein the horizontal circuit element line is implemented as one or more of the following: Phase shifter; Horizontal phase delay line; and Adjustable phase shifter.

12. The system of claim 1, wherein each of the at least two antenna elements in the antenna array is coupled to the multibeamforming network circuit via a phase shifter.

13. The system of claim 1, wherein the system further generates at least one additional output beam, the at least one additional output beam being horizontally adjacent to at least one of the output beams.

14. The system according to claim 1, wherein, In the at least two output beams, the beamwidth of at least one of the at least two output beams is different from the beamwidth of the other of the at least two output beams.

15. The system of claim 11, wherein each of the adjustable phase shifters has an electromechanically adjustable phase shift, and at least one of the adjustable phase shifters comprises: The first trace used for coupling to the first port; A second trace used for coupling to the second port; A bridging element that couples the first trace to the second trace; in The bridging element is stacked on the first trace and the second trace, such that the bridging element provides an electrical path for signals traveling between the first port and the second port; The bridging element can be mechanically moved between at least two positions; Moving the bridging element from one of the at least two locations to another changes the length of the electrical path between the first port and the second port.

16. The system of claim 15, wherein the at least two locations comprise any one of the following: First fixed position and second fixed position; Multiple fixed locations; Each fixed position is a fixed setting of a specific length of the electrical path between the first port and the second port.

17. The system of claim 1, wherein the performance of the system is equivalent to that of another antenna system having a larger antenna array.

18. The system of claim 1, wherein the performance of the system is equivalent to that of another antenna system having more antenna arrays than the system.

19. The system of claim 1, wherein the at least two output beams provide pattern diversity to improve the wireless link implemented through the system.

20. The system of claim 7, wherein at least one input signal beam is coupled to generate at least one output beam using all the antenna elements in the antenna array.

21. The system of claim 7, wherein at least one input signal beam is coupled to generate at least one output beam using a subset of the antenna elements in the antenna array.

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