Millimeter-wave Butler Matrix Beamforming Network

Abstract

The invention discloses a millimeter wave Butler matrix beamforming network, comprising a top layer and a ridge layer, wherein the ridge layer comprises a millimeter wave Butler matrix, and the millimeter wave Butler matrix comprises a first broadband directional coupler, a second broadband directional coupler, a first 90° phase shifter, a first frequency divider, a second 90° phase shifter, a third broadband directional coupler, a fourth broadband directional coupler, a first 45° phase shifter, a second frequency divider, and a second 45° phase shifter. The network has the advantages of wide bandwidth, small size, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of array antennas, and in particular to a millimeter-wave Butler matrix beamforming network. Background Art

[0002] Spatial multiplexing is of great significance in millimeter wave communication and imaging systems. For communication systems, it is used to overcome multipath fading and co-channel interference. For imaging systems, it can be used to improve the resolution of radar images by concentrating the power in the imaged area, thereby reducing the error from the surrounding areas (such as beamforming radar). There are several techniques used for spatial multiplexing, such as Ruzelens, Rotman lens, Blass matrix, Nolen matrix, and Butler matrix. Ruze and Rotman lenses are a time-delay beamforming technique. It is used for broadband signals and the direction of the beam produced is independent of the operating frequency. However, they have some problems such as the large size required to form the lens and the high loss of the lens area and dummy load. On the other hand, Blass, Nolen, and Butler matrices are matrix-based beamforming networks that use a set of couplers, dividers, and phase shifters to form the beamforming network. Compared with lens-based beamforming methods, their advantages are small size and low loss, except that the Blass matrix uses a dummy load and is therefore lossy. This type of Butler matrix-based beamforming can achieve a wide operating bandwidth; however, the use of fixed phase shifters results in frequency-dependent beam tilt, which limits its application.

[0003] Compared with other beamforming networks, the Butler matrix has advantages. Compared with other matrix-based beamforming networks, it is the matrix with the least number of components, so its size is small. In addition, compared with lens-based beamforming networks where the signal passes through a large area, the signal passes through a small area (component area), which reduces dielectric loss and metal loss. In the millimeter wave band, the Butler matrix has been implemented in several technologies. In microstrip technology, an 8×8 Butler matrix has a bandwidth of 4% around 25GHz, a phase variation of ±7.7°, and an output amplitude variation of no more than 1dB around 10dB. Another 4×4 microstrip Butler matrix appeared, with a bandwidth of 4.9% at 60GHz. A 4×4 one-dimensional Butler matrix is ​​implemented using substrate integrated waveguide (SIW) technology, with a bandwidth of 6.67% around 60GHz. Moreover, its phase error is ±24° and the insertion loss is as high as 2.5dB. Another 4×4 substrate integrated waveguide Butler matrix has a bandwidth of 7.15% around 28GHz. Two stacked substrate integrated waveguide Butler matrices with vertical couplers are 8×8 Butler matrices. The main limitation of these structures is the high insertion loss and electrical losses in substrate integrated waveguides (SIW). In addition, the area through which the signal passes is very small (component area), which reduces the electrical losses compared to lens-based beamforming networks.

[0004] In the millimeter wave band, Butler matrices have been implemented in some technologies. In microstrip technology, an 8×8 Butler matrix appears with a bandwidth of 4% around 25GHz and a phase variation of ±7. Another 4×4 microstrip Butler matrix appears with a bandwidth of 4.9% around 60GHz. A 4×41-D Butler matrix is ​​implemented in substrate integrated waveguide (SIW) technology with a bandwidth of 6. Another 4×4 substrate integrated waveguide Butler matrix appears with a bandwidth of 7.15% at 28GHz. A two-layer substrate integrated waveguide Butler matrix with vertically oriented couplers is used to have an 8×8 Butler matrix. The main limitation of these structures is the high insertion loss due to the electrical losses of the substrate integrated waveguide (SIW) technology. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to provide a millimeter-wave Butler matrix beamforming network with broadband performance.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a millimeter wave Butler matrix beamforming network, characterized in that it includes a top layer and a ridge layer, the ridge layer includes a millimeter wave Butler matrix, the millimeter wave Butler matrix includes a first broadband directional coupler and a second broadband directional coupler, the first broadband directional coupler and the second broadband directional coupler are respectively provided with two input ports, an output port of the first broadband directional coupler is connected to the input end of the first 90° phase shifter, the other output end of the first broadband directional coupler is connected to an input end of the first frequency divider, an output port of the second broadband directional coupler is connected to the input end of the second 90° phase shifter, the other output end of the second broadband directional coupler is connected to the other input end of the first frequency divider, the output end of the first 90° phase shifter is connected to an input end of the third broadband directional coupler. An input end of the first wideband directional coupler is connected, an output end of the first frequency divider is connected to another input end of the third wideband directional coupler, an output end of the second 90° phase shifter is connected to an input end of a fourth wideband directional coupler, another output end of the first frequency divider is connected to another input end of the fourth wideband directional coupler, an output end of the third wideband directional coupler is connected to a first output port via a first 45° phase shifter, another output end of the third wideband directional coupler is connected to an input end of the second frequency divider, an output end of the second frequency divider is connected to a second output port, an output end of the fourth wideband directional coupler is connected to a third output port via a second 45° phase shifter, another output end of the fourth wideband directional coupler is connected to another input end of the second frequency divider, and another output end of the second frequency divider is connected to a fourth output port.

[0007] A further technical solution is that: the broadband directional coupler includes a coupler spine layer, the coupler spine layer includes a first dielectric layer, a coupler metallization pattern is formed on the first dielectric layer, the coupler metallization pattern includes two printed metal input segments and two printed metal output segments, the two input segments and the two input segments are connected together by a printed circular metal connecting disk, the outer diameters of the two input segments and the two output segments are smaller than the inner diameters, two fan-shaped grooves are formed in the center of the connecting disk, the dielectric layer in the fan-shaped groove is exposed, and the two fan-shaped grooves are connected by a connecting portion; the diameter of the connecting disk between the input segment and the output segment is larger than the diameter of the connecting disk between the input segment and the input segment and larger than the diameter of the connecting disk between the output segment and the output segment, and a metallized circular disk is formed around the coupler metallization pattern.

[0008] A further technical solution is that: the divider includes a divider spine layer, the divider spine layer includes a first dielectric layer, a divider metallization pattern is formed on the upper surface of the first dielectric layer, the divider metallization pattern includes two printed metal input segments and two printed metal output segments, the input segments and the output segments are connected together through rectangular metal connecting plates, and the input segments and the output segments are respectively located at the four corners of the rectangular metal connecting plates, three rectangular grooves are formed on the rectangular metal connecting plates, the rectangular grooves are not connected to each other and the dielectric layer in the rectangular grooves is exposed; a metallized disc is formed around the divider metallization pattern.

[0009] A further technical solution is that: the 90° phase shifter includes a 90° phase shifter ridge layer, the 90° phase shifter ridge layer includes a first dielectric layer, a 90° phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 90° phase shifter metallization pattern includes a printed metal input segment, one end of the input segment is connected to one end of the first bending portion, the other end of the first bending portion is connected to one end of the second bending portion, the other end of the second bending portion is connected to one end of the printed metal output segment, the input segment is 90° to the first bending portion, the first bending portion and the second bending portion are parallel to each other, and the input segment and the output segment are on a straight line; a metallized disk is formed around the 90° phase shifter metallization pattern.

[0010] A further technical solution is that: the 45° phase shifter includes a 45° phase shifter ridge layer, the 45° phase shifter ridge layer includes a first dielectric layer, a 45° phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 45° phase shifter metallization pattern includes a metal input segment formed by printing, the metal input segment is connected to one end of the third bending portion, the other end of the third bending portion is connected to one end of the metal output segment formed by printing, the metal input segment is arranged in parallel with the metal output segment, and the third bending portion is perpendicular to the metal input segment; a metallization disk is formed around the 45° phase shifter metallization pattern.

[0011] A further technical solution is that: the output port of the millimeter-wave Butler matrix is ​​connected to an antenna array layer, the top layer covers the ridge layer and the antenna array layer, the antenna array layer includes a plurality of antenna units, the antenna unit includes a dielectric layer, a front antenna unit is formed on the upper surface of the dielectric layer, the front antenna unit includes a first longitudinal rectangular radiating plate, the outer side of the first longitudinal rectangular radiating plate is connected to a second longitudinal rectangular radiating plate, and the length of the second longitudinal rectangular radiating plate is less than the length of the first longitudinal rectangular radiating plate; the outer side of the second longitudinal rectangular radiating plate is connected to a first transverse rectangular radiating plate perpendicular to it, the outer end of the first transverse rectangular radiating plate is connected to a second transverse rectangular radiating plate, a third longitudinal rectangular radiating plate is connected to one side between the first transverse rectangular radiating plate and the second transverse rectangular radiating plate, a fourth longitudinal rectangular radiating plate is formed at the end of the second transverse rectangular radiating plate, a fifth longitudinal rectangular radiating plate is formed on the outer side of the fourth longitudinal rectangular radiating plate, and the second transverse rectangular radiating plate is arranged opposite to the center of the fifth longitudinal rectangular radiating plate, a sixth longitudinal rectangular radiating plate is formed on the outer side of the fifth longitudinal rectangular radiating plate, and the length of the sixth longitudinal rectangular radiating plate is less than the length of the fifth longitudinal radiating plate;

[0012] A back antenna unit is formed on the lower surface of the dielectric layer, and the back antenna unit includes a seventh longitudinal rectangular radiating plate, the outer side of the seventh longitudinal rectangular radiating plate is connected to the third transverse rectangular radiating plate, the outer side of the third transverse rectangular radiating plate is connected to the fourth transverse rectangular radiating plate, an eighth longitudinal rectangular radiating plate connected to the third transverse rectangular radiating plate and the fourth transverse rectangular radiating plate is formed at the connection between the third transverse rectangular radiating plate and the fourth transverse rectangular radiating plate, and the end of the fourth transverse rectangular radiating plate is connected to the ninth longitudinal rectangular radiating plate.

[0013] The beneficial effects of adopting the above technical solution are: in the Butler matrix of the network described in this application, first, a broadband directional coupler is designed using S11 and 7.35GHz bandwidth, S41<-15dB, and the output phase difference is 90.9°±1.62°. Compared with other couplers in metal RGW and PRGW, it has the advantages of broadband and small phase difference. Second, the broadband divider with a bandwidth from 26.8 to 33.9GHz, the return loss and isolation are better than 14dB, and the insertion loss is better than 0.5dB. Compared with others, the design is small in size and maintains a wider bandwidth. Third, the broadband phase shifter concept based on the coupled line coupler is designed using the same technology, with a bandwidth of 27 to 33.6GHz, a return loss better than 15dB, and an output phase difference of 45°±2°. All developed components are combined to construct a 4×4 Butler matrix and simulation, in which a bandwidth of 21.25% is achieved, and the return loss and isolation are greater than 10dB. The Butler matrix is ​​combined with a designed semi-log periodic antenna array and a coaxial to PRGW transition. The resulting beams are ±13° and ±36° at the center frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0015] Figure 1a is a schematic structural diagram of a ridge layer of a broadband directional coupler in a network according to an embodiment of the present invention;

[0016] Figure 1b is the phase difference between the S parameter and the output port of the PRGW 3-dB coupler proposed in the embodiment of the present invention;

[0017] Figure 2a is a schematic structural diagram of the ridge layer of the frequency divider in an embodiment of the present invention;

[0018] Figure 2b is an S parameter diagram of the frequency divider described in an embodiment of the present invention;

[0019] Figure 3a is a schematic structural diagram of a ridge layer of a phase shifter in an embodiment of the present invention;

[0020] Figure 3b is an S parameter diagram of the phase shifter in an embodiment of the present invention;

[0021] Figure 4 is a schematic structural diagram of the ridge layer of the millimeter wave Butler matrix described in an embodiment of the present invention;

[0022] Figure 5 is a diagram of the S parameters (fed from port 1) of the millimeter wave Butler matrix described in an embodiment of the present invention;

[0023] Figure 6 is a diagram of the S parameters (fed from port 2) of the millimeter wave Butler matrix described in an embodiment of the present invention;

[0024] Figure 7 is the phase difference between the output ports of each excitation of the input port of the millimeter-wave Butler matrix described in the embodiment of the present invention;

[0025] Figure 8a is a schematic diagram of the decomposed structure of an antenna array (radiating element), a ridge layer (part), and a top layer (part) in an embodiment of the present invention;

[0026] Figure 8b is a front structural schematic diagram of an antenna unit in an embodiment of the present invention;

[0027] Figure 8c is a schematic diagram of the back structure of the antenna unit in an embodiment of the present invention;

[0028] Fig. 9 is a diagram of the S parameters (fed from port 1) of the antenna array in an embodiment of the present invention;

[0029] Fig.10 The radiation pattern diagram of the antenna array when fed from port 2 at different frequencies (28 GHz, 30 GHz, 32 GHz);

[0030] Fig.11 is a principle block diagram of the Butler rectangle described in an embodiment of the present invention;

[0031] Wherein: 1. first broadband directional coupler; 2. second broadband directional coupler; 3. first 90° phase shifter; 4. first frequency divider; 5. second 90° phase shifter; 6. third broadband directional coupler; 7. fourth broadband directional coupler; 8. first 45° phase shifter; 9. second frequency divider; 10. second 45° phase shifter; 11. circular metal connection plate; 12. fan-shaped groove; 13. metallized circular plate; 14. rectangular metal connection plate; 15. rectangular groove; 16. first bending portion; 17. second bending portion; 18. third bending portion; 1 9. The first longitudinal rectangular radiating plate; 20. The second longitudinal rectangular radiating plate; 21. The first transverse rectangular radiating plate; 22. The second transverse rectangular radiating plate; 23. The third longitudinal rectangular radiating plate; 24. The fourth longitudinal rectangular radiating plate; 25. The fifth longitudinal rectangular radiating plate; 26. The sixth longitudinal rectangular radiating plate; 27. The seventh longitudinal rectangular radiating plate; 8. The third transverse rectangular radiating plate; 29. ​​The fourth transverse rectangular radiating plate; 30. The eighth longitudinal rectangular radiating plate; 31. The ninth longitudinal rectangular radiating plate; 32. The ridge layer; 33. The top layer; 34. The antenna array layer. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] The present invention discloses a millimeter wave Butler matrix beamforming network, comprising a top layer 33 and a ridge layer 32, wherein the ridge layer 32 comprises a millimeter wave Butler matrix, wherein the components of the 4×4 Butler matrix are a 3-dB coupler, a 45° phase shifter and a frequency divider, specifically, Fig.11 and Figure 4 As shown, the millimeter-wave Butler matrix includes a first broadband directional coupler 1 and a second broadband directional coupler 2, wherein the first broadband directional coupler 1 and the second broadband directional coupler 2 are respectively provided with two input ports, an output port of the first broadband directional coupler 1 is connected to an input end of a first 90° phase shifter 3, another output end of the first broadband directional coupler 1 is connected to an input end of a first frequency divider 4, an output port of the second broadband directional coupler 2 is connected to an input end of a second 90° phase shifter 5, another output end of the second broadband directional coupler 2 is connected to another input end of the first frequency divider 4, an output end of the first 90° phase shifter 3 is connected to an input end of a third broadband directional coupler 6, and an output end of the first frequency divider 4 is connected to another input end of the third broadband directional coupler 6. An input end of the second 90° phase shifter 5 is connected to an input end of a fourth broadband directional coupler 7, another output end of the first frequency divider 4 is connected to another input end of the fourth broadband directional coupler 7, one output end of the third broadband directional coupler 6 is connected to the first output port via a first 45° phase shifter 8, another output end of the third broadband directional coupler 6 is connected to an input end of a second frequency divider 9, one output end of the second frequency divider 9 is connected to the second output port, one output end of the fourth broadband directional coupler 7 is connected to the third output port via a second 45° phase shifter 10, another output end of the fourth broadband directional coupler 7 is connected to another input end of the second frequency divider 9, and another output end of the second frequency divider 9 is connected to the fourth output port.

[0035] In order to realize a broadband Butler matrix, each component should be broadband and the output phase should be stable. Therefore, the present application proposes to design a broadband component in a printed circuit board using ridge gap technology. For directional couplers, conventional branch couplers have relatively narrow bandwidth. In the present application, modifications are introduced to have wide bandwidth, low amplitude imbalance and low phase deviation. The goal is to build a suitable broadband Butler matrix to achieve a 20% bandwidth. The proposed coupler has higher performance than other RGW and PRGW couplers. Regarding the divider, it has a built-in layer of guide structure and uses a three-quarter wavelength band with sufficient design variables, resulting in broadband performance. The proposed divider has a broadband width (≥20%) and a compact size. However, the proposed device size is much smaller than that proposed (5.18λ0×2.14λ0). Phase shifters are key components in Butler matrices and matrix-based beamforming networks. This patent designs a passive fixed phase shifter for PRGW technology. Passive phase shifters have implemented irrelevant technology in millimeter wave bands. The structure has a stable phase difference and has a 20% bandwidth around 36GHz. However, due to some radiation loss, the insertion loss is about 0.7dB. The RGW 90° phase shifter uses ferrite material and has a bandwidth of 16.67% around 30GHz and a phase change of 10°.

[0036] The coupler design depends on the addition of quarter-wavelength baluns at all ports of a normal branch line coupler. Uniform and multi-dimensional analysis of the coupler has been used to build a complete circuit model. This is achieved by having the two coupled outputs intersect at two points, rather than just one point as in a conventional coupler. The PRGW unit, whose material is Roger RT 6002 (ε r =2.94, tanδ=0.0012), and the band gap is from 22.3GHz to 43.1GHz. Figure 1a The geometry of the coupler is shown, showing the dimensions of the coupler. Figure 1b The S parameters and output phase difference are shown. The output amplitude imbalance of the coupler is 3.38±0.43dB, the output phase difference is 90.9°±1.62°, and the output loss and isolation are better than 15dB in the operating frequency band (26.4-33.8GHz).

[0037] like Figure 1aAs shown, the broadband directional coupler includes a coupler spine layer, the coupler spine layer includes a first dielectric layer, a coupler metallization pattern is formed on the first dielectric layer, the coupler metallization pattern includes two printed metal input segments and two printed metal output segments, the two input segments and the two input segments are connected together by a printed circular metal connection plate 11, the outer diameters of the two input segments and the two output segments are smaller than the inner diameters, two fan-shaped grooves 12 are formed in the center of the connection plate, the dielectric layer in the fan-shaped groove 12 is exposed, and the two fan-shaped grooves 12 are connected by a connecting portion; the diameter of the connection plate between the input segment and the output segment is larger than the diameter of the connection plate between the input segment and the input segment and larger than the diameter of the connection plate between the output segment and the output segment, and a metallized circular plate 13 is formed around the coupler metallization pattern.

[0038] The proposed coupler design relies on adding a quarter-wavelength balun to all the ports of a normal branch line coupler. Even and odd analysis of the proposed coupler has been used to build a complete circuit model. Afterwards, a genetic algorithm is used to obtain the optimal parameters of the proposed coupler, where the objective function is to have low amplitude imbalance over a wide bandwidth. This is achieved by making the two coupled outputs intersect at two points instead of only one point in the conventional coupler. Finally, the proposed coupler is designed in PRGW technology and computer simulations are performed using the unit cell of PRGW, where the material is Roger RT 6002 (εr=2.94, tanδ=0.0012) with a band gap of 22.3-43.1GHz. Figure 1a ) shows the geometry of the coupler, and Table I shows the dimensions of the coupler. For S parameters, the simulation results are shown in Figure 1b ) is shown in Figure 2. The output amplitude imbalance of the proposed coupler is -3.38±0.43dB, and the output phase difference is 90.9°±1.62°. The return loss and isolation are better than 15dB in the working frequency band (26.4 to 33.8GHz).

[0039] Table 1 Dimensions of the proposed 3dB coupler

[0040] Parameter <![CDATA[W line ]]> <![CDATA[W match ]]> <![CDATA[L match ]]> Value(mm) 1.38 1.582 3.14 Parameter <![CDATA[r center ]]> <![CDATA[W ring1 ]]> <![CDATA[W ring1 ]]> Value(mm) 1.753 1.595 3.05

[0041] The proposed coupler is planar and has broadband, low insertion loss, and low amplitude imbalance. Moreover, it is compatible with PCB technology. Compared with other works in metal and printed RGW, the proposed coupler has the widest bandwidth of 24.5% and its phase error (±1.62°).

[0042] like Figure 2bAs shown, the divider includes a divider spine layer, and the divider spine layer includes a first dielectric layer. A divider metallization pattern is formed on the upper surface of the first dielectric layer. The divider metallization pattern includes two printed metal input segments and two printed metal output segments. The input segments and the output segments are connected together through a rectangular metal connecting plate 14, and the input segments and the output segments are respectively located at the four corners of the rectangular metal connecting plate 14. Three rectangular grooves 15 are formed on the rectangular metal connecting plate 14. The rectangular grooves 15 are not connected to each other and the dielectric layer in the rectangular grooves 15 is exposed. A metallization disc 13 is formed around the divider metallization pattern.

[0043] The bandwidth of the resulting divider is limited by the 3-dB coupler bandwidth. In this work, three-quarter wavelength sections are cascaded to obtain more design variables and the ability to achieve broadband performance. The proposed divider is designed in the PRGW technique. The geometry is as follows Figure 2a The dimensions are shown in Table II. A bandwidth of 26.8 to 33.9 GHz (23.4%) is achieved with return loss and isolation better than 14 dB. In addition, the insertion loss is better than 0.5 dB over the entire bandwidth, as shown in Table II. Figure 2b shown.

[0044] Table 2 Dimensions of PRGW divider

[0045] Parameter <![CDATA[W line ]]> <![CDATA[W1]]> <![CDATA[W2]]> <![CDATA[W3]]> Value(mm) 1.38 1.56 1.49 0.52 Parameter <![CDATA[W4]]> <![CDATA[L1]]> <![CDATA[L2]]> <![CDATA[L3]]> Value(mm) 1.23 3.65 3.65 3.65

[0046] The proposed frequency divider has a planar structure, compact size (1.1λ0×0.5λ0) and wide bandwidth with a bandwidth of 13.33% and a size of 1.5λ0×1.5λ0.

[0047] like Figure 3a As shown, the 90° phase shifter includes a 90° phase shifter ridge layer, the 90° phase shifter ridge layer includes a first dielectric layer, a 90° phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 90° phase shifter metallization pattern includes a metal input segment formed by printing, one end of the input segment is connected to one end of a first bending portion 16, the other end of the first bending portion 16 is connected to one end of a second bending portion 17, the other end of the second bending portion 17 is connected to one end of a metal output segment formed by printing, the input segment is 90° to the first bending portion 16, the first bending portion 16 and the second bending portion 17 are parallel to each other, and the input segment and the output segment are on a straight line; a metallization disk 13 is formed around the 90° phase shifter metallization pattern.

[0048] The 45° phase shifter includes a 45° phase shifter ridge layer, the 45° phase shifter ridge layer includes a first dielectric layer, a 45° phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 45° phase shifter metallization pattern includes a metal input segment formed by printing, the metal input segment is connected to one end of the third bending portion 18, the other end of the third bending portion 18 is connected to one end of the metal output segment formed by printing, the metal input segment is arranged in parallel with the metal output segment, and the third bending portion 18 is perpendicular to the metal input segment; a metallization disk 13 is formed around the 45° phase shifter metallization pattern.

[0049] The design of the phase shifter is based on a coupled line coupler with ports 2 and 3 interconnected. This gives a device with only two ports, with a phase shift between the input and output ports. Analysis of a 90° phase shifter gives a Schiffman phase shifter. Design of a 45° phase shifter for a standard 4×4 Butler matrix, therefore using the analysis of the coupled line coupler to determine the initial value of the coupling length and the coupling coefficient to produce a broadband 45° phase shift. The structure is as follows Figure 3a The dimensions are listed in Table III. The resulting S parameters and output phase difference are shown in Figure 3(b). The proposed phase shifter has a wide bandwidth of 27 to 33.6 GHz, an output phase shift of 45°±2°, a return loss better than 15 dB, and S21>-0.4 dB.

[0050] Table 3 Phase shifter dimensions

[0051] Parameter <![CDATA[W line ]]> <![CDATA[W line2 ]]> <![CDATA[W1]]> <![CDATA[W2]]> <![CDATA[W3]]> Value(mm) 1.38 1.35 1.49 1.28 0.88 Parameter <![CDATA[W4]]> <![CDATA[L1]]> <![CDATA[L2]]> S Value(mm) 1.4 5.99 10.64 0.15

[0052] The geometric structure of the proposed Butler matrix is ​​as follows Figure 4 The key point is the consistency of the geometric length and the required phase. Table 4 shows the parameters of the Butler matrix to guide the output ports, which are equally spaced.

[0053] Table 4 Dimensions of the Butler matrix structure

[0054] Parameter <![CDATA[L cP ]]> <![CDATA[L pn ]]> <![CDATA[L cc ]]> <![CDATA[L cx ]]> <![CDATA[L xt ]]> <![CDATA[L c ]]> Value(mm) 6.1 12.73 19.78 6.5 10.95 9.88 Parameter <![CDATA[L o1 ]]> <![CDATA[L o2 ]]> <![CDATA[L o3 ]]> <![CDATA[L oH ]]> <![CDATA[W x ]]> d Value(mm) 9.8 16.85 4.24 4.64 3.65 6

[0055] Figure 5 and Figure 6 The s-parameters of the Butler matrix for the excitation from ports 1 and 2 are shown respectively. The output phase difference between the output ports for each excitation of the input port is shown as Figure 7As shown. The proposed Butler matrix has many advantages over other reported Butler matrices because it has a wide bandwidth of 21.25% around 30 GHz. The amplitude imbalance is about ±1.6 dB over the entire frequency band. When fed from port 1 and port 4, the phase error is about ±10° over the entire frequency band. The phase error when fed from ports 2 and 3 is within ±10° in the frequency range of 28 to 33 GHz, while the phase error is higher in the frequency range of 27 to 28 GHz.

[0056] The top layer 33 is located on the upper side of the ridge layer 32. The top layer 33 includes a second dielectric layer, and a first metal layer is formed on the upper surface of the second dielectric layer. A second metal layer is formed on the back side of the ridge layer 32 (the back side of the first dielectric layer), and the second metal layer is connected to the metallized disc through a metallized via.

[0057] like Figure 8a-8c As shown, the output port of the millimeter-wave Butler matrix is ​​connected to an antenna array layer 34, the top layer 33 covers the ridge layer and the antenna array layer, the antenna array layer 34 includes a plurality of antenna units, and a front antenna unit is formed on the upper surface of the dielectric layer, and the front antenna unit includes a first longitudinal rectangular radiation plate 19, and the outer side of the first longitudinal rectangular radiation plate 19 is connected to a second longitudinal rectangular radiation plate 20, and the length of the second longitudinal rectangular radiation plate 20 is less than the length of the first longitudinal rectangular radiation plate 19; the outer side of the second longitudinal rectangular radiation plate 20 is connected to a first transverse rectangular radiation plate 21 perpendicular thereto, and the first transverse rectangular radiation plate 21 is A second transverse rectangular radiation piece 22 is connected to the outer end, a third longitudinal rectangular radiation piece 23 is connected to one side between the first transverse rectangular radiation piece 21 and the second transverse rectangular radiation piece 22, a fourth longitudinal rectangular radiation piece 24 is formed at the end of the second transverse rectangular radiation piece 22, a fifth longitudinal rectangular radiation piece 25 is formed on the outer side of the fourth longitudinal rectangular radiation piece 24, and the second transverse rectangular radiation piece 22 is arranged opposite to the center of the fifth longitudinal rectangular radiation piece 25, a sixth longitudinal rectangular radiation piece 26 is formed on the outer side of the fifth longitudinal rectangular radiation piece 25, and the length of the sixth longitudinal rectangular radiation piece 26 is less than the length of the fifth longitudinal radiation piece 25;

[0058] A back antenna unit is formed on the lower surface of the dielectric layer, and the back antenna unit includes a seventh longitudinal rectangular radiation plate 27, the outer side of the seventh longitudinal rectangular radiation plate 27 is connected to the third transverse rectangular radiation plate 28, the outer side of the third transverse rectangular radiation plate 28 is connected to the fourth transverse rectangular radiation plate 29, and an eighth longitudinal rectangular radiation plate 30 connected to the third transverse rectangular radiation plate 28 and the fourth transverse rectangular radiation plate 29 is formed at the connection between the third transverse rectangular radiation plate 28 and the fourth transverse rectangular radiation plate 29, and the end of the fourth transverse rectangular radiation plate 29 is connected to the ninth longitudinal rectangular radiation plate 31.

[0059] A modified version of the semi-log periodic dipole antenna was implemented using Roger RT 6002 (εr = 2.94, tanδ = 0.0012) with a thickness of 0.254 mm and a copper cladding of 0.017 mm. The geometry of the antenna PRGW input is shown in Figure 8. The antenna is designed within a four-unit array fed by a 4×4 Butler matrix. Two virtual antenna elements are used so that all array elements have symmetrical radiation patterns. They are connected to open-ended transmission lines and since the coupling between the antennas is small (≤-24 dB), the effect of the power reflected from them on the radiation pattern is negligible. In addition, rectangular cuts are introduced between the antenna elements to potentially reduce the coupling between them. The simulated S-parameters of the antenna array are shown as follows Fig. 9 As shown, it is used for the excitation of port 1. The radiation patterns at different frequencies are shown in Fig.10 As shown, the 3-dB beamwidth ranges from 117° at 27 GHz to 92° at 33 GHz.

[0060] In this application, first, a broadband directional coupler is designed using S11 and 7.35GHz bandwidth, S41<-15dB, and an output phase difference of 90.9°±1.62°. It has broadband and small phase difference compared to other couplers in metal RGW and PRGW. Second, a broadband divider with bandwidth from 26.8 to 33.9GHz, return loss and isolation better than 14dB, and insertion loss better than 0.5dB. Compared with others, this design is small in size and maintains a wide bandwidth. Third, a broadband phase shifter concept based on coupled line couplers is designed using the same technology with a bandwidth of 27 to 33.6GHz, return loss better than 15dB, and an output phase difference of 45°±2°. All the developed components are combined to build a 4×4 Butler matrix and simulation, in which a bandwidth of 21.25% is achieved, with return loss and isolation greater than 10dB. The Butler matrix is ​​combined with the designed semi-log periodic antenna array and coaxial to PRGW transition. The resulting beams are ±13° and ±36° at the center frequency.

Claims

1. A millimeter wave Butler matrix beamforming network, characterized in that: The invention comprises a top layer (33) and a ridge layer (32), wherein the ridge layer (32) comprises a millimeter wave Butler matrix, wherein the millimeter wave Butler matrix comprises a first broadband directional coupler (1) and a second broadband directional coupler (2), wherein the first broadband directional coupler (1) and the second broadband directional coupler (2) are respectively provided with two input ports, wherein an output port of the first broadband directional coupler (1) is connected to an input end of a first 90° phase shifter (3), another output end of the first broadband directional coupler (1) is connected to an input end of a first frequency divider (4), an output port of the second broadband directional coupler (2) is connected to an input end of a second 90° phase shifter (5), another output end of the second broadband directional coupler (2) is connected to another input end of the first frequency divider (4), an output end of the first 90° phase shifter (3) is connected to an input end of a third broadband directional coupler (6), and an output end of the first frequency divider (4) is connected to an input end of a third broadband directional coupler (6). connected to the other input end of the third broadband directional coupler (6), the output end of the second 90° phase shifter (5) is connected to an input end of a fourth broadband directional coupler (7), the other output end of the first frequency divider (4) is connected to the other input end of the fourth broadband directional coupler (7), one output end of the third broadband directional coupler (6) is connected to the first output port via a first 45° phase shifter (8), the other output end of the third broadband directional coupler (6) is connected to an input end of a second frequency divider (9), one output end of the second frequency divider (9) is connected to the second output port, one output end of the fourth broadband directional coupler (7) is connected to the third output port via a second 45° phase shifter (10), the other output end of the fourth broadband directional coupler (7) is connected to the other input end of the second frequency divider (9), and the other output end of the second frequency divider (9) is connected to the fourth output port; The 90° phase shifter comprises a 90° phase shifter ridge layer, the 90° phase shifter ridge layer comprises a first dielectric layer, a 90° phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 90° phase shifter metallization pattern comprises a metal input segment formed by printing, one end of the input segment is connected to one end of a first bending portion (16), the other end of the first bending portion (16) is connected to one end of a second bending portion (17), the other end of the second bending portion (17) is connected to one end of a metal output segment formed by printing, the input segment and the first bending portion (16) are at an angle of 90°, the first bending portion (16) and the second bending portion (17) are parallel to each other, and the input segment and the output segment are on a straight line; a metallization disk (13) is formed around the 90° phase shifter metallization pattern; The 45° phase shifter comprises a 45° phase shifter ridge layer, the 45° phase shifter ridge layer comprises a first dielectric layer, a 45° phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 45° phase shifter metallization pattern comprises a metal input segment formed by printing, the metal input segment is connected to one end of a third bending portion (18), the other end of the third bending portion (18) is connected to one end of a metal output segment formed by printing, the metal input segment is arranged in parallel with the metal output segment, and the third bending portion (18) is perpendicular to the metal input segment; a metallization disk (13) is formed around the 45° phase shifter metallization pattern; A second metal layer is formed on the back side of the ridge layer (32), and the second metal layer is connected to the metallized disc (13) through a metallized via hole; The output port of the millimeter-wave Butler matrix is ​​connected to an antenna array layer (34); the top layer (33) covers the ridge layer (32) and the antenna array layer (34); the antenna array layer (34) includes a plurality of antenna units; the antenna unit includes a dielectric layer; a front antenna unit is formed on the upper surface of the dielectric layer; the front antenna unit includes a first longitudinal rectangular radiation plate (19); the outer side of the first longitudinal rectangular radiation plate (19) is connected to a second longitudinal rectangular radiation plate (20); the length of the second longitudinal rectangular radiation plate (20) is less than the length of the first longitudinal rectangular radiation plate (19); the outer side of the second longitudinal rectangular radiation plate (20) is connected to a first transverse rectangular radiation plate (21) perpendicular to the second longitudinal rectangular radiation plate (20); the first transverse rectangular radiation plate (21) is perpendicular to the first longitudinal rectangular radiation plate (20); The outer end of the sheet (21) is connected to a second transverse rectangular radiation sheet (22); a third longitudinal rectangular radiation sheet (23) is connected to one side between the first transverse rectangular radiation sheet (21) and the second transverse rectangular radiation sheet (22); a fourth longitudinal rectangular radiation sheet (24) is formed at the end of the second transverse rectangular radiation sheet (22); a fifth longitudinal rectangular radiation sheet (25) is formed on the outer side of the fourth longitudinal rectangular radiation sheet (24); the second transverse rectangular radiation sheet (22) and the fifth longitudinal rectangular radiation sheet (25) are arranged opposite to each other in the center; a sixth longitudinal rectangular radiation sheet (26) is formed on the outer side of the fifth longitudinal rectangular radiation sheet (25); and the length of the sixth longitudinal rectangular radiation sheet (26) is less than that of the fifth longitudinal radiation sheet (25); A back antenna unit is formed on the lower surface of the dielectric layer, and the back antenna unit comprises a seventh longitudinal rectangular radiating plate (27), the outer side of the seventh longitudinal rectangular radiating plate (27) is connected to a third transverse rectangular radiating plate (28), the outer side of the third transverse rectangular radiating plate (28) is connected to a fourth transverse rectangular radiating plate (29), an eighth longitudinal rectangular radiating plate (30) connected to the third transverse rectangular radiating plate (28) and the fourth transverse rectangular radiating plate (29) is formed at the connection between the third transverse rectangular radiating plate (28) and the fourth transverse rectangular radiating plate (29), and the end of the fourth transverse rectangular radiating plate (29) is connected to a ninth longitudinal rectangular radiating plate (31).

2. The millimeter wave Butler matrix beamforming network as claimed in claim 1, characterized in that: The top layer (33) is located on the upper side of the ridge layer (32), and the top layer (33) comprises a second dielectric layer, and a first metal layer is formed on the upper surface of the second dielectric layer.

3. The millimeter wave Butler matrix beamforming network as claimed in claim 1, characterized in that: The two input ports and the two output ports of the broadband directional coupler are provided with a quarter-wavelength balun.

4. The millimeter wave Butler matrix beamforming network according to claim 1, characterized in that: In the broadband directional coupler, one input end intersects with one output end, and the other input end intersects with the other output end, so that the two coupled outputs intersect at two points; the broadband directional coupler comprises a coupler ridge layer, the coupler ridge layer comprises a first dielectric layer, a coupler metallization pattern is formed on the first dielectric layer, the coupler metallization pattern comprises two printed metal input segments and two printed metal output segments, the two input segments and the two input segments are connected together by a printed circular metal connection plate (11), the outer diameters of the two input segments and the two output segments are smaller than the inner diameters, two fan-shaped grooves (12) are formed at the center of the connection plate, the dielectric layer in the fan-shaped groove (12) is exposed, and the two fan-shaped grooves (12) are connected by a connecting portion; the diameter of the connection plate between the input segment and the output segment is larger than the diameter of the connection plate between the input segment and the input segment and larger than the diameter of the connection plate between the output segment and the output segment, and a metallization circular plate (13) is formed around the coupler metallization pattern.

5. The millimeter wave Butler matrix beamforming network as claimed in claim 1, characterized in that: The frequency divider comprises a frequency divider ridge layer, the frequency divider ridge layer comprises a first dielectric layer, a frequency divider metallization pattern is formed on the upper surface of the first dielectric layer, the frequency divider metallization pattern comprises two printed metal input sections and two printed metal output sections, the input sections and the output sections are connected together via rectangular metal connection plates (14), and the input sections and the output sections are respectively located at the four corners of the rectangular metal connection plates (14), three rectangular grooves (15) are formed on the rectangular metal connection plates (14), the rectangular grooves (15) are not connected to each other, and the dielectric layer in the rectangular grooves (15) is exposed; a metallization disk (13) is formed around the frequency divider metallization pattern.

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