Matrix circuit and better beam characteristics from MBFN generated beams

Abstract

Systems and methods are provided for mitigating beam skew and producing better beam characteristics from beams generated by an MBFN (Multi-Beamforming Network). Matrix circuits are provided that operate as MBFNs, where judiciously assigning input beams to particular rows in the matrix results in reduced or mitigated beam skew. Also, phase errors and other problems can be solved by adjusting characteristics in the circuit elements forming the matrix circuit.

Description

Technical Field

[0001] This invention relates to antenna-related circuitry. More specifically, this invention relates to circuitry for generating beams with improved characteristics using multi-beamforming networks. Background Technology

[0002] To increase the communication capacity of base stations (especially cellular 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. Furthermore, it is desirable to maintain the same coverage area for each beam across the entire operating frequency band. This beam coverage can become a problem, especially for multi-beam antenna arrays.

[0003] Multibeam antenna arrays can be divided into two categories: multibeam antennas built based on the lens principle, and multibeam antennas formed by ordinary antenna arrays fed by multibeamforming networks (MBFN).

[0004] For lens-based antennas, such as the Luneburg lens antenna, multiple beams can be generated by multiple feeds located at different positions. These positions can be calculated using principles such as lens or parabolic focus. Such multi-beam antennas typically exhibit satisfactory performance in terms of broadband matching and beam isolation. Moreover, theoretically, such lens-based antennas do not suffer from beam skew issues. However, lens-based antennas require large-volume lenses / reflectors, which are bulky, expensive, and difficult / tricky to manufacture. The large size requirement for lenses / reflectors stems from the requirement that the lens size must be larger than multiple electrical wavelengths. Therefore, it is theoretically difficult to reduce the size of such reflectors, especially for lower frequencies, such as 1 GHz - 3 GHz.

[0005] For antennas fed / generated by a multi-beamforming network (MBFN), there are two subtypes of MBFN. The first subtype is also based on the lens principle and uses lenses such as Rotman lenses. Due to the similarity in operating principle, this subtype of MBFN has the same advantages and disadvantages as lens-based multi-beam antennas; that is, these antennas offer satisfactory performance, but their physical size is quite large, and therefore they are often expensive and / or unsuitable for a given application.

[0006] The second subtype of MBFN is typically based on directional couplers, phase shifters, and crossovers. The characteristics of the components depend solely on the electrical length of the transmission lines used to construct them. Because components can be implemented using planar circuits, and because component size can be reduced by using bent lines or high-dielectric stacks, the physical size of the network is generally much smaller than that of lens-based multi-beam antennas. However, almost all antenna systems generated by MBFNs, including those using Butler, Blass, Nolen, and other similar matrices, suffer from beam skew and phase error problems.

[0007] Beam skew refers to the phenomenon where the beam direction undesirably but inevitably changes with frequency. When the frequency changes, the beam direction (i.e., the direction of the signal in the azimuth direction) will change, although the beam would preferably maintain a constant direction. Beam skew is particularly problematic in some communication systems, such as 3G, 4G, and 5G mobile communications, where the uplink and downlink operate in different frequency bands. Due to beam skew, the area of ​​beam coverage will differ across frequencies (i.e., the area of ​​beam coverage will differ for uplink and downlink), meaning that the antenna array cannot achieve closed-loop communication. This problem is exacerbated as fractional bandwidth increases, for example, exceeding 30% of the bandwidth.

[0008] Therefore, there is a need for methods and systems to solve the beam deflection problem in such MBFN-generated antenna systems. Preferably, these methods and systems also produce better beam characteristics from the beams generated by such MBFNs. Summary of the Invention

[0009] This invention provides a system and method for mitigating beam skew and generating better beam characteristics from beams generated by an MBFN (Multi-Beamforming Network). A matrix circuit is provided as an MBFN operation, wherein intelligently allocating the input beam to specific rows in the matrix results in reduced or mitigated beam skew. Furthermore, phase error is addressed by intelligently adjusting the characteristics of the circuit elements forming the matrix circuit.

[0010] In a first aspect, the present invention provides a matrix circuit for coupling multiple input signal beams to multiple output antenna elements in an antenna array, the matrix circuit comprising: - A matrix of 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 coupler and a horizontal phase delay line, each row receiving an input signal beam, and each row including a coupler series coupled to at least one horizontal phase delay line between each pair of adjacent couplers; and - Multiple rows of circuit elements, each row of circuit elements including a coupler and a vertical circuit element line, wherein the coupler is coupled in series with at least one vertical circuit element line between each pair of adjacent couplers, and each row is coupled between the output antenna and ground; in - At least one column of circuit elements also includes a load coupled between the coupler and ground; - The output of each column of circuit elements is received by the output antenna array element; - The matrix circuit is used to form multiple output beams based on the input signal beam.

[0011] In a second aspect, the present invention provides a method for improving the beam characteristics of a beam generated by an antenna array fed by a multi-beamforming network (MBFN), the method comprising: a) A matrix circuit providing rows and columns of circuit elements as the operation of the multibeamforming network; b) Provide the input signal beam to the matrix circuit such that a specific input signal beam is assigned as input to a circuit element in a specific row of the matrix circuit; c) Perform at least one of the following: c1) Assign a specific input signal beam from the input signal beam to a specific row in the matrix circuit, wherein the specific input signal beam has the smallest absolute azimuth angle in the input signal beam, and the specific row is the row closest to the ground; c2) Configure at least one specific column in the matrix circuit to compensate for errors in the antenna output of the at least one specific column; The matrix circuit mentioned above includes: - A multi-row circuit element, each row comprising a coupler and a horizontal phase delay line, each row receiving an input signal beam, and each row including a coupler series coupled along the row direction through at least one horizontal phase delay line between each pair of adjacent couplers; and - Multiple rows of circuit elements, each row of circuit elements including a coupler and a vertical circuit element line, wherein the coupler is coupled in series with at least one vertical circuit element line between each pair of adjacent couplers along the column direction, and each column is coupled between the output antenna and ground.

[0012] In a third aspect, the present invention provides a circuit for simultaneously generating multiple beams using an antenna array having multiple antenna array elements, the circuit comprising: a matrix circuit including multiple couplers and delay lines, the matrix circuit being coupled between multiple loads and the antenna array; wherein each row of the matrix circuit includes multiple couplers series-coupled along the row direction, each pair of couplers coupled along the row direction being connected by at least one delay line, each column of the matrix circuit including multiple couplers series-coupled along the column direction, and the bottom row of the matrix circuit being coupled to multiple matched loads such that each coupler of the bottom row is coupled along the column direction to the multiple matched loads. Between a matched load and a coupler in the preceding row of the matrix circuit, each row of the matrix circuit provides a different signal beam with a unique azimuth angle within a predetermined azimuth angle range, such that the antenna array provides at least three different signal beams, the at least three different signal beams including at least a negative extreme azimuth beam corresponding to the negative extreme value of the azimuth angle range, a central azimuth beam corresponding to the center of the azimuth angle range, and a positive extreme azimuth beam corresponding to the positive extreme value of the azimuth angle range, and the circuit is used to implement a method including providing the central azimuth beam with the bottom row of the matrix circuit.

[0013] In another aspect, the present invention provides a method for mitigating beam deflection in an antenna array having multiple antenna array elements, the method comprising: providing a center azimuth beam using a bottom row of a matrix circuit coupled between multiple loads and the antenna array, wherein the center azimuth beam corresponds to the center of the azimuth range in which the antenna array operates.

[0014] Another aspect of the present invention provides a method for compensating for errors in the output beam of a multi-beamforming network, the method comprising: - A matrix circuit is provided for coupling multiple input signal beams to multiple output antenna elements, the matrix circuit including a matrix of directional couplers, horizontal phase delay lines and vertical circuit element lines, and wherein the matrix circuit includes multiple columns of circuit elements, each column of circuit elements including directional couplers and vertical circuit element lines, each column of circuit elements being coupled between an output antenna and a load; - Determine the phase error at the input of the output antenna in one of the columns of the circuit elements; - Determine the phase shift to compensate for the phase error; and - Provides vertical circuit element lines that provide the phase shift. Attached Figure Description

[0015] Embodiments of the invention will now be described with reference to the following drawings, wherein the same reference numerals in the different drawings denote the same elements, and wherein: Figure 1 This is a matrix circuit diagram according to one aspect of the present invention; Figures 2A to 4B The beam quality simulation results of a 3×7 matrix circuit according to the conventional allocation method and the allocation method shown here are presented; Figures 5A to 7B The beam quality simulation results of a 9×20 matrix circuit according to the conventional allocation method and the allocation method here are shown; Figure 8 It is a graph showing the phase difference of the coupler versus frequency; Figures 9A to 9F Simulation results of beam skew for the matrix circuit with and without phase compensation are shown. Figure 10 This is a block diagram of a traditional Nolen matrix; Figure 11 This is a block diagram of a 3-beam input, 7-element Noren matrix according to one aspect of the present invention; Figure 12A This demonstrates the use without phase compensation. Figure 11 The phase of beam 2 generated by the circuit in the circuit.

[0016] Figure 12B This demonstrates the use without phase compensation. Figure 11 The amplitude of beam 2 generated by the circuit in the circuit.

[0017] Figure 13A The input of the antenna element with phase compensation is shown (i.e. Figure 11 The phase of beam 2 at the output of the Noren matrix in the matrix; Figure 13B The input of the antenna element with phase compensation is shown (i.e. Figure 11 The amplitude of beam 2 at the output of the Noren matrix in the matrix; Figure 14A The comparison of beams using a phase compensation scheme and a conventional Noren matrix is ​​shown when the beam is at different azimuth angles. Figure 14B A comparison of beams using a reordered row scheme with a conventional row allocation scheme is shown; Figure 15 A block diagram of a Noren matrix configuration using a phase shifter with 3 beam inputs and 7 element outputs according to another aspect of the present invention is shown; Figure 16A This shows the input of the antenna element without compensation. Figure 15 The phase of the middle beam in the circuit; Figure 16BThis shows the input of the antenna element with compensation. Figure 15 The phase of the middle beam in the circuit; and Figure 17 The invention illustrates the use of phase shifters to compensate for phase errors and compares the beams at different azimuth angles with respect to a conventional Noren matrix.

[0018] Figures 18A to 18F This paper illustrates a 12-element, 6-beam implementation of one aspect of the invention, showing a multi-layer configuration of the matrix circuit; and Figure 19 and Figure 20 The flowcharts are detailed illustrations of different methods according to different aspects of the present invention. Detailed Implementation

[0019] It should be understood that the systems and methods of the present invention are applicable to various frequency ranges and various wireless technologies. For clarity, the various methods and systems of the present invention are applicable to various mobile / cellular technologies / applications, including 2G, 3G, 4G, and 5G technologies. Similarly, it should be understood that the various systems and methods of the present invention are applicable to well-known cellular frequency bands, such as 617-960 MHz, 1695-2690 MHz, 3300-4200 MHz, and 5150-5925 MHz.

[0020] In one aspect, the present invention provides a method for eliminating beam skew in a plurality of resulting beams by using circuitry employed with an antenna array, based on the allocation of different beams to different rows of a matrix circuit. In particular, for a set of beams within a given azimuth angle range, the "center beam" is typically provided by the middle row of the matrix. In one aspect of the invention, the center beam is allocated to the lowest row of the matrix. This reduces the fundamental frequency attenuation of higher scan angle beams, which would otherwise be caused by the array aperture of the lower rows.

[0021] Regarding the theoretical basis of this invention, in order to achieve a given frequency f Generate at 0 with a slope from the normal direction φ A beam in a specific direction, with an asymptotic phase difference Δ between adjacent elements. Pha It should be (Equation 1): (1) in λ 0 is frequency f Wavelength in free space at 0.

[0022] It can be seen that if the beam direction φ To maintain a constant value within a specific frequency bandwidth, the phase difference must increase linearly, because... λ 0 increases linearly.

[0023] However, due to the principle of directional coupling, almost all directional couplers, such as 3-dB 90-degree orthogonal couplers, rat-race couplers, and Magic-T, cannot provide the performance of linearly increasing (or decreasing / reducing) the phase difference between the coupled port and the through port. Instead, the coupler will generate a constant phase difference between the coupled port and the through port within a given bandwidth.

[0024] According to equation (1), it should be clear that ΔPha It is a constant value, and when λ When 0 increases linearly with frequency, φ The value will be tilted accordingly. This explains the beam skew in MBFN. Since all second-subtype MBFNs are constructed based on directional couplers, beam skew is unavoidable if a linear phase difference cannot be generated.

[0025] To effectively eliminate beam deflection, please note that in a matrix circuit structure, beam deflection is caused by a combination of two factors: (1) Phase shift caused by matrix circuit rows; and (2) Azimuth angle (i.e. direction) of the beam.

[0026] In other words, beams at more extreme angles inherently have higher skew. For example, a beam pointing to zero degrees (i.e., without any azimuth tilt) inherently has less skew compared to a beam at + / -30°.

[0027] Similarly, the first factor is unavoidable because the signal undergoes a phase shift as it moves from one row to the next, which plays a crucial role in maintaining the beam angle. However, beam skew caused by the beam azimuth angle can be mitigated by allocating the rows of the matrix to provide rows at specific angles.

[0028] In particular, in one example, a conventional Blass matrix design provides multiple beams within a given azimuth range (e.g., for a 3-row matrix, the azimuth range could be (-30°, 0°, +30°)). The beam pointing to the extrema (i.e., the leftmost, e.g., +30 in the example range, where the positive extrema are on the left) is provided by the top row of the matrix; the beam pointing to the center of the range (e.g., 0) is provided by the middle rows of the matrix; and the beam pointing to the opposite extrema (i.e., the rightmost, e.g., -30 in the example range, where the negative extrema are on the left) is provided by the bottom rows of the matrix. It can be understood that in a conventional matrix, positive or negative extrema can be located at the top / bottom of the matrix.

[0029] However, due to its position in the lowest row, this conventionally designed negative extreme beam will have the greatest loss, and therefore the lowest gain, and thus a higher phase shift. As mentioned above, it already has high beam skew due to the extreme nature of its angle, and this low gain and high loss lead to further beam skew and lower overall quality.

[0030] To address this beam skew issue, the center beam, instead of the positive extreme beam, is assigned to the lowest row of the matrix. Because the center beam inherently possesses the highest directivity due to its 0 azimuth angle, it suffers less from the additional losses caused by its location in the bottom row compared to traditional extreme azimuth beams assigned to the bottom row. This configuration is as follows: Figure 1 As shown, this is applied to a Brass matrix. As those skilled in the art will understand, to observe the benefits of this configuration, the matrix circuit should have at least three rows. However, it should be noted that the azimuth range does not need to be symmetrical or centered at 0. 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 implementations. As a non-limiting example, in an implementation using a matrix with an even number of rows, the bottom two rows of the matrix may correspond to beam pairs with the smallest absolute values ​​and therefore the highest directionality.

[0031] from Figure 1 It can be seen from this that Figure 1 The matrix circuit in the invention has at least one row terminated by a matched load and at least one column also terminated by a matched load. Various aspects of the invention are applicable to matrix circuits having at least one row terminated by a matched load. Similarly, various aspects of the invention are applicable to matrix circuits having at least one column terminated by a matched load. As will be seen below, various aspects of the invention are also applicable to matrix circuits that do not have any rows terminated by a matched load (e.g., Noren or modified Noren matrix circuits).

[0032] Figure 2A , Figure 2B , Figure 3A , Figure 3B , Figure 4A and Figure 4B The simulation results of beam skew for 8 dB beam crossover and 120 degrees sector coverage are shown, using a conventional BLAS matrix and a 3×7 BLAS matrix (i.e., 7 elements in the azimuth) according to the BLAS matrix of this disclosure (i.e., where the center beam is assigned to the lowest row of the matrix). Figure 2A and Figure 2B A simulation for a negative extreme value beam (at -30 in this simulation) is shown, where Figure 2A Corresponding to the traditional beam assignment in simulation, while Figure 2BThis corresponds to a simulation of beam assignment according to this disclosure. Similarly, Figure 3A and Figure 3B The simulation for the center beam (at 0 in this simulation) is shown, while Figure 4A and Figure 4B A simulation for a positive extreme value beam (at +30 in this simulation) is shown. Similarly, Figure 3A and Figure 4A The simulation results of traditional beam assignment are shown, while Figure 3B and Figure 4B Simulation results of beam allocation according to this disclosure are shown. It can be seen that... Figure 4A The beam skew (lowest row, corresponding to the extreme azimuth beams according to traditional allocation) is significantly higher than that in the middle row. Figure 4B The beam skew (lowest row, corresponding to the center azimuth beam according to this allocation method) difference. Furthermore, Figure 3A and Figure 3B There is no beam skew difference between the middle rows of each matrix circuit. Figure 4A and Figure 4B The difference between them is large. Therefore, it can be seen that allocating the center beam to the lowest row effectively reduces the overall beam skew of the beam generated by the matrix circuit.

[0033] Similarly, Figure 5A , Figure 5B , Figure 6A , Figure 7B , Figure 7A and Figure 7B The simulation results of beam skew for a 9×20 Brass matrix (i.e., 20 elements / 9 beams in the azimuth) are shown using a conventional Brass matrix and a Brass matrix configured according to one aspect of the invention (i.e., where the center beam is assigned to the lowest row of the matrix). The Brass matrix operates in the frequency range of (1695-2690 MHz), where the azimuth beams are located at (-52, -39, -26, -13, 0, +13, +26, +39, +52). Figure 5A (Traditional) and Figure 5B (This allocation method) shows a simulation for a +52 degree beam. Figure 6A (Traditional) and Figure 6B (This allocation method) illustrates a simulation for a -52 degree beam. Figure 7A (Traditional) and Figure 7B (This allocation method) shows a simulation for a 0-degree beam.

[0034] Similarly, from Figure 6A As can be seen, using the traditional beam assignment method, there is still approximately 8 degrees of beam skew for the beam located at -52 degrees. Furthermore, the beam in this figure shows significant degradation and large sidelobes. In contrast, applying the new method… Figure 6B The beam deflection is significantly reduced, and the beam quality is significantly better.

[0035] Furthermore, it should be understood that the way beams are assigned to other rows of the matrix can differ in different embodiments. For example, in some embodiments, the extreme azimuth beams are assigned to the middle rows of the matrix, and no other beam assignments differ from conventional assignment methods. In other embodiments, multiple beam assignments differ from conventional assignment methods. For example, in some embodiments, the top two rows are assigned to provide the extreme beams (positive and negative). Furthermore, in some such embodiments, for each pair of consecutive rows, the absolute value of the beam azimuth decreases until the last row of the matrix. Additionally, according to embodiments, the leftmost or rightmost beam can be assigned to the middle row.

[0036] Compared to conventional Blass matrices, in addition to reducing beam skew, various aspects of the present invention also provide more uniform gain across different beams. Table 1 shows the gains of the Blass matrices over the azimuth range (-52, -39, -26, -13, 0, +13, +26, +39, +56) using conventional beam assignment methods and modified beam assignment methods.

[0037] Table 1

[0038] As shown in Table 1, the total gain difference across the azimuth range is 2.1 dB in the conventional BLAS. However, the maximum difference in the modified matrix with the new row allocation is only 1.3 dB. This means the new design provides a more balanced gain across the different beams in the azimuth range.

[0039] Furthermore, in some embodiments, phase compensation is applied in addition to the beamforming method. This innovation includes 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 becomes greater than -3 dB, the coupler phase varies depending on the coupler coefficient. Therefore, in some embodiments, phase compensation is applied to each coupler so that the phases of all couplers become similar. This can be achieved by adding additional phase factors on the horizontal and vertical lines that connect the couplers from one row to the next.

[0040] Figure 8 The phase difference of the coupler is shown. For example... Figure 8As shown, when the coupler value changes from 17 dB to 3.5 dB, there is a 17-degree difference. To adjust for this difference, in some embodiments, a transmission line with an electrical length of 17 degrees is added to the port of each coupler (e.g., port 4). Similarly, in some embodiments, an additional phase factor of 17 degrees is added to the delay line after each coupler. Of course, these values ​​and the methods outlined here are merely exemplary and should not be considered as limiting the scope of the invention. Those skilled in the art will recognize many suitable phase compensation methods and will be able to select appropriate methods and values ​​for a particular implementation.

[0041] The effect of this phase compensation can be achieved in Figure 9A , Figure 9B , Figure 9C , Figure 9D , Figure 9E and Figure 9F I saw it in the middle. Figure 9A (Uncompensated) and Figure 9B (The compensated version) shows a simulation for a +52 degree beam. Figure 9C (Uncompensated) and Figure 9D The (compensated) simulation shows a beamwidth of -52 degrees. Figure 9E (Uncompensated) and Figure 9F The (compensated) simulation shows a beamwidth at 0 degrees. It can be seen that... Figure 9B , Figure 9D and Figure 9F Each of the graphs in the graphs shows a tighter signal than its uncompensated counterpart (i.e., with less skew).

[0042] It should be understood that although the above discussion uses the Blass matrix circuit as an example in discussing various aspects of the invention, these aspects of the invention are equally applicable to other matrix circuits, such as the Blass matrix circuit, modified Blass matrix circuit, Noren matrix circuit, and modified Noren matrix circuit.

[0043] As mentioned above, the Blass matrix was used in the examples and explanations provided. Another matrix circuit known to be suitable for MBFN applications is the Noren matrix. Compared to the Blass matrix, the Noren matrix requires fewer couplers and delay lines. Furthermore, unlike the Blass matrix, the Noren matrix does not contain resistors at the end of each row, which helps reduce board cost and board size. However, traditional Noren matrices have several problems (much like the Blass matrix), such as beam skew and high sidelobe levels (SLL). Additionally, the operating frequency range for Noren matrices is very narrow (narrowband).

[0044] refer to Figure 10The diagram shows a schematic of a traditional Noren matrix. As is well known, a traditional Noren matrix consists of various components such as directional couplers and phase delay lines. Figure 10 The Noren matrix in the diagram has M inputs (input signal beams) and N outputs (antenna outputs / antenna elements).

[0045] from Figure 10 As can be seen, the Noren matrix 1000 has multiple columns and rows, including couplers 1020, horizontal phase delay lines 1030, and vertical circuit element lines 1040. The Noren matrix couples the input signal beam 1050 to the output antenna element 1060 through various couplers, phase delay lines, and circuit element lines. It should be clear that each column of the Noren matrix contains a set of couplers and circuit element lines between the output antenna element and the load 1070. It should also be clear that the lowest row of the Noren matrix is ​​row 1080, which is closest to the load 1070 (and closest to ground), while the highest row is row 1090, which is closest to the output antenna element 1060.

[0046] To make it clearer, in Figure 10 In the diagram, the coupler is shown as a square denoted by "C", the horizontal phase delay line as a rectangle denoted by "D", and the vertical circuit element line as a circle denoted by "P". The coupling factor and phase delay line are calculated using software. It should be noted that in traditional Noren matrices, there are some phase errors that degrade matrix performance.

[0047] For the Noren matrix, as with other matrix circuits, beam skew is caused by the phase shift of the matrix circuit rows and the azimuth angle of the beam, as described above.

[0048] As mentioned above, beams that tend to be at extreme angles inherently have more skew. For example, a beam pointing to zero degrees (without any azimuth tilt) inherently has less skew compared to a beam located at + / -30 degrees.

[0049] The problem of beam skew is mitigated by intelligently allocating the input beam to specific rows in the matrix circuit.

[0050] Another factor requiring improvement is sidelobe level (SLL). For each antenna array, there is a main beam (the desired beam) and sidelobe beams (the unwanted beams). The two main factors that have the greatest impact on sidelobe level are tapering (i.e., the power entering each antenna element) and the phase of each antenna element. Tapering is controlled by the coupling factor of the coupler. However, as mentioned above, phase is prone to error. Addressing the phase error problem will result in a better sidelobe level (SLL).

[0051] One solution to 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 circuit element lines between rows (for a specific column). The various vertical circuit element lines between rows will introduce a phase shift to compensate for the phase error.

[0052] In one aspect of the invention, only transmission lines are used between the output of each row and the input of the next row. The length of the transmission lines is optimized to produce desired different phases, thereby compensating for phase errors occurring at the inputs of the antenna elements (i.e., the outputs of the Noren matrix). Using this innovation, a sample 3-beam input, 7-element output structure was designed, which... Figure 11 As shown in the image.

[0053] exist Figure 11 In the diagram, the vertical phase delay line (shown as a rectangle marked "DVnm") is optimized to compensate for phase errors, resulting in beam skew elimination and improved sidelobe level SLL. Furthermore, some couplers are optimized and tuned to optimize the taper at the antenna element inputs. The phase and taper of the middle beam (beam 2) are shown below. Figure 12A and Figure 12B As shown.

[0054] Figure 12A The phase of beam 2 at the input of the antenna element (the output of the Noren matrix) is shown without phase compensation. Figure 12B This shows the input of the antenna element without phase compensation. Figure 11 The amplitude of beam 2 at the output of the Noren matrix in the matrix.

[0055] To compare the effects of phase compensation, the following were provided: Figure 13A and Figure 13B . Figure 13A The phase of beam 2 at the input of the antenna element (output of the Noren matrix) is shown with phase compensation. Figure 13B The amplitude of beam 2 at the input of the antenna element (output of the Noren matrix) is shown with phase compensation.

[0056] As shown in the figure, the beam phase and amplitude have been optimized and adjusted, thereby improving performance in terms of both beam skew and sidelobe level SLL. Because we have more degrees of freedom in this method (by adding different optimized vertical transmission lines), the new Noren matrix (such as...) Figure 11 (As shown) It operates over a wide frequency range of 1695-2690 MHz (wideband). The new Noren matrix should also operate at other frequencies. These improvements also apply to other matrix circuits, such as the Blass matrix circuit, the improved Blass matrix circuit, the Noren matrix circuit, and the improved Noren matrix circuit.

[0057] refer to Figure 14A The figure shows a comparison of beams using a phase compensation scheme and a traditional Noren matrix. It can be seen that the beam generated by the new method is improved in terms of beam skew, sidelobe level (SLL), and frequency range (operating in the mid-band 1695–2690 MHz).

[0058] As described above, the order of the input signal beams assigned to each row in the matrix can be adjusted. For a conventional three-beam configuration (beams at +30°, 0°, and -30°), the conventional approach is to place the highest azimuth beam in the top row, i.e., +30, 0, and -30, so that the zero azimuth beam is in the middle row, and the -30 azimuth input beam is in the bottom row. For this aspect of the invention, the order can be: -30, 0, +30. Therefore, the zero azimuth beam remains in the middle row, the -30 azimuth beam is in the top row, and the +30 azimuth beam is in the bottom row. Figure 14B The diagram shows a comparison between this beam configuration and a more conventional configuration. This novel configuration can reduce overall phase error.

[0059] Another solution to the beam skew and sidelobe level SLL problem is to use a phase shifter between any two rows instead of a vertical phase delay line. For this innovation, a Noren matrix configuration with 3 beam inputs and 7 element outputs was designed. Figure 15 The diagram presents a block diagram of this configuration.

[0060] As a variation of the above, instead of using a single phase shifter between adjacent rows, several cascaded phase shifters are used between adjacent rows (i.e., instead of...). Figure 15 The circular "Pmn" boxes (with two or more phase shifters per row pair) are used to compensate for the network's phase error. Similar to the innovations mentioned above, by adding cascaded phase shifters, beam skew is eliminated and SLL is improved compared to traditional matrices. As an example of the results obtained by using cascaded phase shifters between rows, Figure 16A and Figure 16B The phase of the middle beam (beam 2) is shown in the figure. Figure 16A The phase of the middle beam (beam 2) at the input of the antenna array element (i.e., the output of the Noren matrix) is shown without compensation. Figure 16B The phase of the middle beam (beam 2) at the input of the antenna element (i.e., the output of the Noren matrix) is shown with compensation.

[0061] refer to Figure 17The diagram shows a comparison between a scheme using a phase shifter to compensate for phase errors and a traditional Noren matrix beamforming. It can be seen that the beam skew problem is solved, the average SLL is improved, and the Noren matrix performs well in the wideband frequency range of 1695-2690MHz.

[0062] As described above, compared to the traditional Noren matrix, the innovations detailed above provide an improved Noren matrix without beam skew, with improved sidelobe levels (SLL), and the matrix operates over a wider frequency band, covering the entire mid-band frequency range. It should also be noted that although this paper only details the results for mid-band frequencies (1695-2690 MHz), the detailed innovations are also applicable to other frequencies, such as the low-band and C-band.

[0063] refer to Figure 11 and Figure 15 The circuitry in these designs generates two different Noren matrices using two different methods. Each design has three inputs, providing beams in three different directions. The resulting matrix has seven outputs, connected to seven antenna array elements. Coupler values ​​and the number of phases in the horizontal phase delay line are obtained using theoretical methods with appropriate software. Essentially, the phase error to be compensated is measured / calculated, and the compensation phase shift is designed into the associated delay line and / or phase shifter / cascaded phase shifter. As described above, the vertical phase delay line and phase shifter are optimized to compensate for the phase error.

[0064] In terms of implementation, the various types of matrix circuits discussed above can be implemented using multilayer board configurations. (Reference) Figures 18A to 18F The diagram illustrates a configuration based on this multi-layer setup. The configuration shown in the figure represents a 12-element, 6-beam MBFN with no beam deflection. Figures 18A to 18F The overall configuration, port and load locations, layout of each layer, and cross-sectional view of this example are shown. Figure 18A The overall system configuration is shown, with detailed definitions of beam ports, component ports, and loads. From Figure 18A As can be seen, a three-layer configuration of the Blass matrix is ​​implemented, consisting of a top layer, a middle layer, and a bottom layer. The substrate layer lies between the top, middle, and bottom layers. Figure 18B This is a top view of the copper layer of a system in the diagram. Figure 18C It's the underlying layout. Figure 18D It is an intermediate layer layout (a "mask" with cut-out areas or holes to allow traces on the top and bottom layers to couple with each other). Figure 18E It is a top-level layout. Figure 18F This is a cross-sectional view of the resulting circuit board used in this implementation scheme, showing in detail the top layer, middle layer, bottom layer, and substrate layer.

[0065] from Figures 18A to 18FIt can be seen that the coupler matrix and the bent lines located between the couplers form the Blass matrix. Furthermore, it can be seen that... Figure 18C The upper side of the array has 12 bent lines with curved open ends, forming a phase shifter group that will be adjacent to the input of the antenna array. In one implementation, this example is configured to operate within the 1.695 GHz - 2.69 GHz frequency band. As implemented, the phase shifter group will operate to reduce or eliminate beam skew. Of course, the various methods detailed above for various types of matrix circuits can be implemented using the methods detailed here. [The last sentence appears to be incomplete and possibly refers to a different implementation.] Figure 18C The phase shifter group shown can be used, and other methods can be used to eliminate / reduce beam skew (as described above). Similarly, in the case of a matrix circuit with or without a phase shifter group, other methods for adjusting / compensating phase errors can be applied / implemented using the implementation methods described in detail here.

[0066] For clarity, Figures 18A to 18F The configuration uses single-row phase shifters, which are placed outside the Blass matrix to eliminate beam skew. The matrix circuitry can be implemented without the phase shifter array, and various aspects of the invention can be implemented with a configuration that does not use the phase shifter array.

[0067] It should be clear that Figures 18A to 18F The implementation schemes detailed in this paper are also applicable to other matrix circuit types. The implementation schemes described in detail herein can be applied to Blass matrix circuits, modified Blass matrix circuits, Noren matrix circuits, and modified Noren matrix circuits.

[0068] As another way to achieve better beam characteristics from beams generated from matrix circuits, the apertures or gaps in the intermediate layers, as well as the circuit traces on one or both of the top and bottom layers, can be adjusted in terms of size, shape, and configuration. Apertures can have non-parallel edges, and traces can also have non-parallel shapes. Similarly, the shapes of the apertures and traces can be unconventional / irregular. This approach can be used to generate suitable matrix circuits with multi-layer configurations to produce beams with appropriate characteristics.

[0069] Figure 19 This is a flowchart illustrating in detail a method according to one aspect of the invention. In step 1100, multiple signal beams are provided to a matrix circuit. In step 1110, a center beam (i.e., the signal beam with the smallest absolute azimuth tilt among the multiple signal beams) is assigned to the bottom row of the matrix circuit. As described above, this mitigates beam skew and helps to balance gain among the beams.

[0070] Figure 20This is another flowchart illustrating in detail the method according to an embodiment of the present invention. Similarly, in step 1200, multiple signal beams are provided to the matrix circuit. In step 1210, phase compensation is applied to the couplers constituting the matrix circuit. In step 1220, the center beam is assigned to the bottom row of the matrix circuit.

[0071] It should be noted that in some embodiments, Figure 20 Steps 1200 and 1210 in the process can be reversed. That is, the order in which phase compensation is applied to the coupler and the beam is provided to the matrix depends on the implementation scheme and should not be considered as a limitation on the scope of the invention.

[0072] In one aspect, the present invention provides an MBFN that couples an input signal beam to the output antenna array of an antenna element. The MBFN is a Brass, modified Brass, Noren, or modified Noren matrix circuit. In this matrix circuit, the matrix is ​​a matrix of couplers, horizontal phase delay lines, and vertical circuit elements. In one aspect, in this matrix circuit, at least one row is coupled between the input signal beam and the load. The matrix circuit can also be implemented without rows terminating at the load. Similarly, in another aspect, at least one column is coupled between the antenna element and the load. The coupler can be a hybrid coupler or a directional coupler. The input signal beam is assigned to these rows such that the center azimuth beam is located in the lowest row of the matrix (the row closest to ground). The middle row is assigned a negative extreme azimuth beam or a positive extreme azimuth beam. This lowest row or bottom row is assigned an input beam with the highest directivity. Likewise, the cumulative effect of the characteristics of the vertical circuit elements in one or more columns compensates for errors at the input of the antenna element. Such errors may be beam skew, sidelobe level SLL, and phase error. For phase errors, this can be compensated by calculating the phase error and adjusting the characteristics of the vertical circuit elements. These vertical circuit elements can be vertical phase delay lines, phase shifters, or cascaded phase shifters. Phase delay lines can be transmission lines of a specific length. Similarly, if the vertical circuit elements are phase shifters, they are configured to compensate for the phase error of that column. A matrix circuit can be constructed using a three-layer architecture, where the middle layer is configured with vias to couple traces on the top and bottom layers. The vias and traces can have non-parallel edges or be based on a non-parallelogram shape / configuration. This matrix circuit is suitable for use with frequency bands such as, for example, 617-960 MHz, 1695-2690 MHz, 3300-4200 MHz, and 5150-5925 MHz cellular bands. This matrix circuit can also be used with other frequency bands. The methods and circuits described above are used to mitigate errors such as beam skew, sidelobe level SLL, and phase error.

[0073] Those who understand the invention will now conceive of alternative structures and embodiments or variations described above, all of which are intended to fall within the scope of the invention as defined by the appended claims.

Claims

1. A matrix circuit for coupling multiple input signal beams to multiple output antenna elements in an antenna array, the matrix circuit comprising: - A matrix of 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 coupler and a horizontal phase delay line, each row receiving an input signal beam, and each row including a coupler series coupled to at least one horizontal phase delay line between each pair of adjacent couplers; and - Multiple rows of circuit elements, each row of circuit elements including a coupler and a vertical circuit element line, wherein the coupler is coupled in series with at least one vertical circuit element line between each pair of adjacent couplers, and each row is coupled between the output antenna and ground; in - At least one column of circuit elements also includes a load coupled between the coupler and ground; - The output of each column of circuit elements is received by the output antenna array element; - The matrix circuit is used to form multiple output beams based on the input signal beam.

2. The matrix circuit according to claim 1, wherein, At least one line of circuit elements is coupled between the input signal beam and the load.

3. The matrix circuit according to claim 1, wherein, Each coupler is one of a directional coupler and a hybrid coupler.

4. The matrix circuit according to claim 1, wherein, Phase compensation is applied to at least one of the couplers.

5. The circuit according to claim 1, wherein, Each row of the matrix circuit provides a different signal beam with a unique azimuth angle within a predetermined azimuth angle range, thereby enabling the antenna array to provide at least three different signal beams, wherein the at least three different signal beams include at least a negative extreme azimuth angle beam corresponding to the negative extreme value of the azimuth angle range, a center azimuth angle beam corresponding to the center of the azimuth angle range, and a positive extreme azimuth angle beam corresponding to the positive extreme value of the azimuth angle range. in The center azimuth beam is provided to the bottom row of the matrix circuit.

6. The matrix circuit according to claim 5, wherein, The middle row of the matrix circuit is provided with one of the negative extreme azimuth beam and the positive extreme azimuth beam.

7. The matrix circuit according to claim 5, wherein, The bottom row of the matrix circuit is assigned a beam with the highest directionality.

8. The matrix circuit according to claim 1, wherein, The cumulative effect of the characteristics of the vertical circuit elements in each column compensates for the phase error at the input of the output antenna array element.

9. The matrix circuit according to claim 8, wherein, The vertical circuit element is a phase shifter.

10. The matrix circuit according to claim 8, wherein, The vertical circuit element is a vertical phase delay line.

11. The matrix circuit according to claim 9, wherein, The vertical circuit element is a cascaded phase shifter.

12. A method for improving the beam characteristics of a beam generated by an antenna array fed by a multi-beamforming network (MBFN), the method comprising: a) A matrix circuit providing rows and columns of circuit elements as the operation of the multibeamforming network; b) Provide the input signal beam to the matrix circuit such that a specific input signal beam is assigned as input to a circuit element in a specific row of the matrix circuit; c) Perform at least one of the following: c1) Assign a specific input signal beam from the input signal beam to a specific row in the matrix circuit, wherein the specific input signal beam has the smallest absolute azimuth angle in the input signal beam and the specific row is the row closest to the ground; c2) Configure at least one specific column in the matrix circuit to compensate for errors in the antenna element output of the at least one specific column; The matrix circuit includes: - A multi-row circuit element, each row comprising a coupler and a horizontal phase delay line, each row receiving an input signal beam, and each row including a coupler series coupled along the row direction through at least one horizontal phase delay line between each pair of adjacent couplers; and - Multiple columns of circuit elements, each column of circuit elements including a coupler and a vertical circuit element line, the coupler being coupled in series along the column direction through at least one vertical circuit element line between each pair of adjacent couplers, each column being coupled between the output antenna and ground.

13. The method according to claim 12, wherein, For step c1), the specific input signal beam is the center azimuth beam.

14. The method according to claim 12, wherein, Step c1) includes assigning the input signal beam with the highest absolute azimuth angle to the row of the matrix circuit closest to the output antenna coupled to the matrix circuit.

15. The method according to claim 12, wherein, Each row of the matrix circuit receives different input signal beams with unique azimuth angles within a predetermined azimuth angle range, such that at least three different input signal beams are received by the matrix circuit. These at least three different signal beams include at least a negative extreme azimuth angle beam corresponding to the negative extreme value of the azimuth angle range, a center azimuth angle beam corresponding to the center of the azimuth angle range, and a positive extreme azimuth angle beam corresponding to the positive extreme value of the azimuth angle range. Wherein, the specific input signal beam in step c1) is the center azimuth beam.

16. The method according to claim 15, wherein, Step c1) also includes providing the negative extreme azimuth beam to the middle row of the matrix circuit.

17. The method according to claim 15, wherein, Step c1) also includes providing the positive extreme azimuth beam to the middle row of the matrix circuit.

18. The method of claim 15, wherein step c1) further comprises providing the negative extreme azimuth beam and the positive extreme azimuth beam to the first and second top rows of the matrix circuit.

19. The method of claim 12, wherein step c1) further comprises assigning the rows to a signal beam such that each matrix row is adjacent to another matrix row receiving opposite azimuth values ​​having the same absolute value and opposite signs.

20. The method according to claim 12, wherein, Step c2) includes configuring the at least one specific column such that the cumulative effect of the characteristics of the vertical circuit elements of the at least one specific column compensates for the phase error at the input of the antenna array elements of the at least one specific column.

21. The method according to claim 20, wherein, The vertical circuit element is one of the phase shifter and the vertical phase delay line.

22. The method of claim 21, wherein the vertical phase delay line is a transmission line of a specific length, such that the cumulative effect of the vertical phase delay line is to compensate for the phase error.

23. The method according to claim 21, wherein, The phase shifter is constructed and arranged to compensate for the phase error.

24. The method according to claim 21, wherein, Step c2) includes calculating the phase error and adjusting the characteristics of the phase shifter to compensate for the phase error.

25. The method according to claim 12, wherein, The error in the antenna output of at least one specific column is at least one of the following: - Beam deflection; - Sidelobe level; and - Phase error.

26. The method according to claim 12, wherein, The matrix circuit is used to generate beams for use in cellular applications.

27. The matrix circuit according to claim 1, wherein, The matrix circuit is any one of the Noren matrix, the Blass matrix, the modified Noren matrix, and the modified Blass matrix.

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