CN216872258U

CN216872258U - Millimeter wave Butler matrix beam forming network

Info

Publication number: CN216872258U
Application number: CN202220534240.XU
Authority: CN
Inventors: 胡南
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-03-11
Filing date: 2022-03-11
Publication date: 2022-07-01
Anticipated expiration: 2032-03-11

Abstract

The utility model discloses a millimeter wave Butler matrix beam forming network which comprises a top layer and a ridge layer, wherein the ridge layer comprises a millimeter wave Butler matrix comprising 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-degree phase shifter, a first frequency divider, a second 90-degree phase shifter, a third broadband directional coupler, a fourth broadband directional coupler, a first 45-degree phase shifter, a second frequency divider and a second 45-degree phase shifter. The network has the advantages of wide bandwidth, small size and the like.

Description

Millimeter wave Butler matrix beamforming network

Technical Field

The utility model relates to the technical field of array antennas, in particular to a millimeter wave Butler matrix beam forming network.

Background

Spatial multiplexing is of great significance in millimeter wave communication and image 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 power in the area being imaged, thereby reducing errors from surrounding areas (e.g., beamer radar). There are several techniques for spatial multiplexing, such as Ruzelens, Rotman lens, Blass matrix, Nolen matrix, and Butler matrix. Ruze and Rotman lenses are one time delay beamforming technique. It is used for wideband signals, and the direction of the generated beam is independent of the working frequency. However, they have problems such as too large a size required to form the lens, and too high a loss of lens area and dummy load. On the other hand, Blass, Nolen, and Butler matrices are matrix-based beamforming networks that are constructed using a set of couplers, dividers, and phase shifters. They have the advantage of small size and low loss compared to lens-based beamforming, except that the Blass matrix uses dummy load and is therefore lossy. Such beamforming based on the butler matrix type can achieve a wide operating bandwidth, however, the use of fixed phase shifters results in beam tilt that varies with frequency, which limits its application.

The butler matrix is more advantageous than other beamforming networks. It is the matrix with the least number of components compared to other matrix-based beamforming networks, and therefore its size is small. Furthermore, the signal passes through a small area (component area) compared to a lens-based beam forming network where the signal passes through a large area, which reduces dielectric and metal losses. In the millimeter wave band, Butler matrices have been implemented in several technologies. In the microstrip technology, an 8 x 8 Butler matrix has a bandwidth of 4% around 25GHz, a phase change of ± 7.7 °, and an output amplitude change of no more than 1dB around 10 dB. Another 4 x 4 microstrip Butler (Butler) matrix appears, which is 4.9% bandwidth at 60 GHz. A 4 x 4 one-dimensional Butler matrix (Butler matrix) is implemented using Substrate Integrated Waveguide (SIW) technology, with a bandwidth of 6.67% around 60 GHz. Moreover, the phase error is +/-24 degrees, and the insertion loss is as high as 2.5 dB. Another 4 x 4 substrate integrated waveguide butler matrix has a bandwidth of 7.15% around 28 GHz. The two layers of superposed substrate integrated waveguide butler matrixes and the couplers in the vertical direction are 8 multiplied by 8 butler matrixes. The main limitation of these structures is the high insertion and electrical losses in the Substrate Integrated Waveguide (SIW). In addition, the area through which the signal passes is small (element area), which reduces electrical losses compared to lens-based beam forming networks.

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 x 4 microstrip butler matrix appears with a bandwidth of 4.9% around 60 GHz. A 4 x 41-D butler matrix is implemented in Substrate Integrated Waveguide (SIW) technology with a bandwidth of 6. Another 4 x 4 substrate integrated waveguide butler matrix appears with a bandwidth of 7.15% and a frequency of 28 GHz. A two-layer substrate integrated waveguide butler matrix with vertical directional couplers to have an 8 x 8 butler matrix. The main limitation of these structures is high insertion loss due to the electrical losses of the Substrate Integrated Waveguide (SIW) technology.

SUMMERY OF THE UTILITY MODEL

The technical problem to be solved by the utility model is how to provide a millimeter wave Butler matrix beam forming network with broadband performance.

In order to solve the technical problems, the technical scheme adopted by the utility model is as follows: a millimeter wave butler matrix beamforming network, characterized by: the broadband phase shifter comprises a top layer and a ridge layer, wherein the ridge layer comprises a millimeter wave Butler matrix, the millimeter wave Butler matrix comprises a first broadband directional coupler and a second broadband directional coupler, two input ports are respectively arranged on the first broadband directional coupler and the second broadband directional coupler, one output port of the first broadband directional coupler is connected with an input end of a first 90-degree phase shifter, the other output end of the first broadband directional coupler is connected with one input end of a first frequency divider, one output port of the second broadband directional coupler is connected with an input end of a second 90-degree phase shifter, the other output end of the second broadband directional coupler is connected with the other input end of the first frequency divider, the output end of the first 90-degree phase shifter is connected with one input end of a third broadband directional coupler, and one output end of the first frequency divider is connected with the other input end of the third broadband directional coupler, the output of the second 90 phase shifter is connected to one input of a fourth broadband directional coupler, the other output end of the first frequency divider is connected with the other input end of the fourth broadband directional coupler, one output of the third broadband directional coupler is connected to the first output port via a first 45 phase shifter, the other output end of the third broadband directional coupler is connected with one input end of the second frequency divider, one output end of the second frequency divider is connected with the second output port, one output end of the fourth broadband directional coupler is connected with the third output port through the second 45-degree phase shifter, the other output end of the fourth broadband directional coupler is connected with the other input end of the second frequency divider, and the other output end of the second frequency divider is connected with the fourth output port; the top layer is positioned on the upper side of the ridge layer and comprises a second dielectric layer, and a first metal layer is formed on the upper surface of the second dielectric layer; and the two input ports and the two output ports of the broadband directional coupler are provided with a quarter-wavelength balun.

The further technical scheme is as follows: the broadband directional coupler comprises a coupler ridge layer, the coupler ridge layer comprises a first dielectric layer, a coupler metalized pattern is formed on the first dielectric layer, the coupler metalized pattern comprises two printed metal input sections and two printed metal output sections, the two input sections and the two input sections are connected together through a circular metal connecting disc formed by printing, the diameters of the outer sides of the two input sections and the two output sections are smaller than the diameter of the inner side of the two input sections and the two output sections, two fan-shaped grooves are formed in the center of the connecting disc, the dielectric layers in the fan-shaped grooves are exposed and leaked out, and the two fan-shaped grooves are communicated through a communicating part; the diameter of the connecting disc between the input section and the output section is larger than that of the connecting disc between the input section and the output section and larger than that of the connecting disc between the output section and the output section, and a metalized disc is formed around the coupler metalized pattern.

The further technical scheme is as follows: the frequency divider comprises a frequency divider ridge layer, the frequency divider ridge layer comprises a first medium layer, a frequency divider metallization pattern is formed on the upper surface of the first medium layer, the frequency divider metallization pattern comprises two metal input sections formed by printing and two metal output sections formed by printing, the input sections and the output sections are connected together through a rectangular metal connecting disc, the input sections and the output sections are respectively positioned on four corners of the rectangular metal connecting disc, three rectangular grooves are formed in the rectangular metal connecting disc, the rectangular grooves are not communicated with each other, and the medium layer in the rectangular grooves is exposed; and a metalized disc is formed around the metalized pattern of the frequency divider.

The further technical scheme is as follows: the 90-degree phase shifter comprises a 90-degree phase shifter ridge layer, the 90-degree phase shifter ridge layer comprises a first medium layer, a 90-degree phase shifter metallization pattern is formed on the upper surface of the first medium layer, the 90-degree phase shifter metallization pattern comprises a metal input section formed by printing, one end of the input section is connected with one end of a first bending portion, the other end of the first bending portion is connected with one end of a second bending portion, the other end of the second bending portion is connected with one end of a metal output section formed by printing, the position between the input section and the first bending portion is 90 degrees, the first bending portion and the second bending portion are parallel to each other, and the input section and the output section are on the same straight line; and a metalized disk is formed around the metalized pattern of the 90-degree phase shifter.

The further technical scheme is as follows: the 45-degree phase shifter comprises a 45-degree phase shifter ridge layer, the 45-degree phase shifter ridge layer comprises a first dielectric layer, a 45-degree phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 45-degree phase shifter metallization pattern comprises a metal input section formed by printing, the metal input section is connected with one end of a third bent portion, the other end of the third bent portion is connected with one end of a metal output section formed by printing, the metal input section is arranged in parallel with the metal output section, and the third bent portion is perpendicular to the metal input section; and a metalized disk is formed around the 45-degree phase shifter metalized pattern.

The further technical scheme is as follows: an output port of the millimeter wave Butler matrix is connected with an antenna array layer, the ridge layer and the antenna array layer are covered by the top layer, the antenna array layer comprises a plurality of antenna units, each antenna unit comprises a dielectric layer, a front antenna unit is formed on the upper surface of the dielectric layer, each front antenna unit comprises a first longitudinal rectangular radiating sheet, the outer side of each first longitudinal rectangular radiating sheet is connected with a second longitudinal rectangular radiating sheet, and the length of each second longitudinal rectangular radiating sheet is smaller than that of each first longitudinal rectangular radiating sheet; a first transverse rectangular radiation piece perpendicular to the second longitudinal rectangular radiation piece is connected to the outer side of the second longitudinal rectangular radiation piece, a second transverse rectangular radiation piece is connected to the outer end of the first transverse rectangular radiation piece, a third longitudinal rectangular radiation piece is connected to one side between the first transverse rectangular radiation piece and the second transverse rectangular radiation piece, a fourth longitudinal rectangular radiation piece is formed at the end of the second transverse rectangular radiation piece, a fifth longitudinal rectangular radiation piece is formed on the outer side of the fourth longitudinal rectangular radiation piece, the centers of the second transverse rectangular radiation piece and the fifth longitudinal rectangular radiation piece are oppositely arranged, a sixth longitudinal rectangular radiation piece is formed on the outer side of the fifth longitudinal rectangular radiation piece, and the length of the sixth longitudinal rectangular radiation piece is smaller than that of the fifth longitudinal radiation piece;

the antenna comprises a dielectric layer, a back surface antenna unit is formed on the lower surface of the dielectric layer and comprises a seventh longitudinal rectangular radiating sheet, a third transverse rectangular radiating sheet is connected to the outer side of the seventh longitudinal rectangular radiating sheet, a fourth transverse rectangular radiating sheet is connected to the outer side of the third transverse rectangular radiating sheet, an eighth longitudinal rectangular radiating sheet connected with the third transverse rectangular radiating sheet is formed at the joint of the third transverse rectangular radiating sheet and the fourth transverse rectangular radiating sheet, and a ninth longitudinal rectangular radiating sheet is connected to the end portion of the fourth transverse rectangular radiating sheet.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: in the butler matrix of the network, firstly, a broadband directional coupler is designed by using S11 and 7.35GHz bandwidth, S41< -15dB and the output phase difference is 90.9 degrees +/-1.62 degrees. Compared with other couplers in metal RGW and PRGW, it has the advantages of wide band, small phase difference, etc. Second, the return loss and isolation of a wideband frequency divider with a bandwidth from 26.8 to 33.9GHz is better than 14dB, and the insertion loss is better than 0.5 dB. The design is small compared to others and maintains a wide bandwidth. Thirdly, the same technical design is adopted for the broadband phase shifter concept based on the coupled line coupler, the bandwidth is 27 to 33.6GHz, the return loss is better than 15dB, and the output phase difference is 45 +/-2 degrees. All developed components were combined to construct a 4 x 4Butler matrix and simulations in which a bandwidth of 21.25% was achieved with return loss and isolation greater than 10 dB. The butler matrix is combined with a designed semi-log periodic antenna array and a coaxial to PRGW transition. The resulting beams are 13 deg. and 36 deg. at the center frequency.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Fig. 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;

FIG. 1b is a phase difference between the S parameter and the output port of the PRGW 3-dB coupler proposed in the embodiment of the present invention;

FIG. 2a is a schematic diagram of a ridge layer of the frequency divider according to an embodiment of the present invention;

FIG. 2b is a diagram of S parameters of the frequency divider in an embodiment of the present invention;

FIG. 3a is a schematic diagram of a ridge layer of a phase shifter in an embodiment of the present invention;

FIG. 3b is a diagram of S parameters of a phase shifter in an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a ridge layer of the millimeter wave Butler matrix in the embodiment of the present invention;

fig. 5 is a diagram of the S-parameters (fed from port 1) of the millimeter wave butler matrix in the embodiment of the present invention;

FIG. 6 is a diagram of the S-parameters (fed from Port 2) of the millimeter wave Butler matrix in an embodiment of the present invention;

FIG. 7 is a phase difference between output ports of the millimeter wave Butler matrix for each excitation of the input ports in the embodiment of the present invention;

fig. 8a is an exploded view of an antenna array (radiating element), a ridge layer (part) and a top layer (part) in an embodiment of the present invention;

fig. 8b is a schematic front view of an antenna unit according to an embodiment of the present invention;

fig. 8c is a schematic diagram of a back structure of an antenna unit according to an embodiment of the present invention;

fig. 9 is a graph of the S-parameters (fed from 1 port) of an antenna array in an embodiment of the utility model;

figure 10 is a radiation pattern diagram of the antenna array when fed at different frequencies (28GHz, 30GHz, 32GHz) from port 2;

FIG. 11 is a functional block diagram of the Butler rectangle in an embodiment of the present invention;

wherein: 1. a first broadband directional coupler; 2. a second broadband directional coupler; 3. a first 90 ° phase shifter; 4. a first frequency divider; 5. a second 90 ° phase shifter; 6. a third broadband directional coupler; 7. a fourth broadband directional coupler; 8. a first 45 ° phase shifter; 9. a second frequency divider; 10. a second 45 ° phase shifter; 11. a circular metal connection pad; 12. a fan-shaped groove; 13. a metallized disc; 14. a rectangular metal connection pad; 15. a rectangular groove; 16. a first bending portion; 17. a second bending portion; 18. a third bend portion; 19. a first longitudinal rectangular radiating patch; 20. a second longitudinal rectangular radiating patch; 21. a first transverse rectangular radiating patch; 22. a second transverse rectangular radiating patch; 23. a third longitudinal rectangular radiating patch; 24. a fourth longitudinal rectangular radiating patch; 25. a fifth longitudinal rectangular radiating patch; 26. a sixth longitudinal rectangular radiation sheet; 27. a seventh longitudinal rectangular radiating patch; 8. a third transverse rectangular radiating patch; 29. a fourth transverse rectangular radiating patch; 30. an eighth longitudinal rectangular radiating patch; 31. a ninth longitudinal rectangular radiating patch; 32. a ridge layer; 33. a top layer; 34. an antenna array layer.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

The utility model discloses a millimeter wave Butler matrix beam forming network, which comprises a top layer 33 and a ridge layer 32, wherein the ridge layer 32 comprises a millimeter wave Butler matrix, the components of the 4 x 4Butler (Butler) matrix are a 3-dB coupler, a 45-degree phase shifter and a frequency divider, specifically, as shown in figures 11 and 4, the millimeter wave Butler matrix comprises a first broadband directional coupler 1 and a second broadband directional coupler 2, the first broadband directional coupler 1 and the second broadband directional coupler 2 are respectively provided with two input ports, one output port of the first broadband directional coupler 1 is connected with an input end of a first 90-degree phase shifter 3, the other output end of the first broadband directional coupler 1 is connected with one input end of a first frequency divider 4, one output port of the second broadband directional coupler 2 is connected with an input end of a second 90-degree phase shifter 5, the other output end of the second broadband directional coupler 2 is connected with the other input end of a first frequency divider 4, the output end of the first 90 ° phase shifter 3 is connected with one input end of a third broadband directional coupler 6, one output end of the first frequency divider 4 is connected with the other input end of the third broadband directional coupler 6, the output end of the second 90 ° phase shifter 5 is connected with one input end of a fourth broadband directional coupler 7, the other output end of the first frequency divider 4 is connected with the other input end of the fourth broadband directional coupler 7, one output end of the third broadband directional coupler 6 is connected with a first output port through a first 45 ° phase shifter 8, the other output end of the third broadband directional coupler 6 is connected with one input end of a second frequency divider 9, and one output end of the second frequency divider 9 is connected with a second output port, one output end of the fourth broadband directional coupler 7 is connected to the third output port through 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.

To implement a wideband butler (butler) matrix, each component should be wideband and output phase stable. Therefore, the present application proposes to apply ridge gap technology (ridge gap technology) to design wideband components in printed circuit boards. For directional couplers, conventional spur couplers are relatively narrow in bandwidth. In this application, modifications are introduced to have wide bandwidth, low amplitude imbalance and low phase deviation. The goal is to construct a suitable wideband butler matrix to achieve 20% bandwidth. The proposed coupler has higher performance than other RGW and PRGW couplers. With respect to frequency dividers, which have a built-in layer of guiding structure and use a three quarter wavelength band, there are sufficient design variables to result in broadband performance. The proposed frequency divider has a wide bandwidth (≧ 20%) and compact size. However, the proposed device size is much smaller than proposed (5.18 λ)₀×2.14λ₀). Phase shifters are key components in butler matrices and matrix-based beamforming networks. This patent has designed a passive fixed phase shifter for PRGW technique. Passive phase shifters have implemented unrelated technologies in the millimeter wave frequency band. The structure has a stable phase difference and has a bandwidth of 20% around 36 GHz. However, the insertion loss is about 0.7dB due to some radiation loss. The RGW90 ° phase shifter uses a ferrite material and has a bandwidth of 16.67% and a phase change of 10 ° around 30 GHz.

The coupler design depends on adding a quarter on all ports of the normal spur couplerA balun of one wavelength. Uniform and multidimensional analysis of couplers has been used to build a complete circuit model. This can be achieved by having two coupled outputs intersect at two points, rather than only one point as in conventional couplers. The unit of PRGW, the material of which is Roger RT 6002 (epsilon)_r2.94, tan δ 0.0012), bandgap from 22.3GHz to 43.1 GHz. Fig. 1a shows the geometry of the coupler, showing the dimensions of the coupler. Fig. 1b shows the S-parameter and the output phase difference. The output amplitude imbalance of the coupler is 3.38 +/-0.43 dB, the output phase difference is 90.9 +/-1.62 degrees, and the output loss and the isolation are better than 15dB on the working frequency band (26.4-33.8 GHz).

As shown in fig. 1a, the broadband directional coupler includes a coupler ridge layer, the coupler ridge 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 sections and two printed metal output sections, the two input sections and the two input sections are connected together through a circular metal connection pad 11, the diameters of the outer sides of the two input sections and the two output sections are smaller than the diameter of the inner side, two fan-shaped grooves 12 are formed in the center of the connection pad, the dielectric layer in the fan-shaped grooves 12 leaks out, and the two fan-shaped grooves 12 are communicated through a communication part; the diameter of the connecting disc between the input section and the output section is larger than that of the connecting disc between the input section and the output section and larger than that of the connecting disc between the output section and the output section, and a metalized disc 13 is formed around the coupler metalized pattern.

The proposed coupler design relies on adding a quarter wave balun at all ports of a common spur coupler. Even and odd analysis of the proposed coupler has been used to build a complete circuit model. Genetic algorithms are then the best parameters for obtaining the proposed coupler, where the objective function is to have a low amplitude imbalance over a wide frequency band. This is achieved by having two coupled outputs intersect at two points instead of only one point in a conventional coupler. Finally, the proposed coupler was designed in PRGW technology and a computer was used to simulate the unit cell of PRGW, where the material is Roger RT 6002(∈ r ═ 2.94, tan δ ═ 0.0012) and the bandgap is 22.3-43.1 GHz. Fig. 1a) shows the geometry of the coupler and table I shows the dimensions of the coupler. For the S parameter, the simulation result is shown in fig. 1b) with a difference from the output p. The output amplitude imbalance of the proposed coupler is-3.38 + -0.43 dB and the output phase difference is 90.9 deg + -1.62 deg.. Return loss and isolation are better than 15dB in the operating band (26.4 to 33.8 GHz).

Table 1 presents the dimensions of the 3dB coupler

Parameter	W_line	W_match	L_match
				Value(mm)	1.38	1.582	3.14
Parameter	r_center	W_ring1	W_ring1
				Value(mm)	1.753	1.595	3.05

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

As shown in fig. 2b, the frequency divider includes a frequency divider ridge layer, the frequency divider ridge layer includes a first dielectric layer, a frequency divider metallization pattern is formed on an upper surface of the first dielectric layer, the frequency divider metallization pattern includes two printed metal input sections and two printed metal output sections, the input sections and the output sections are connected together through a rectangular metal connection pad 14, the input sections and the output sections are respectively located on four corners of the rectangular metal connection pad 14, three rectangular grooves 15 are formed on the rectangular metal connection pad 14, the rectangular grooves 15 are not communicated with each other, and the dielectric layer in the rectangular grooves 15 is exposed; a metalized disc 13 is formed around the divider metallization pattern.

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

TABLE 2 PRGW divider size

Parameter	W_line	W₁	W₂	W₃
					Value(mm)	1.38	1.56	1.49	0.52
Parameter	W₄	L₁	L₂	L₃
					Value(mm)	1.23	3.65	3.65	3.65

The proposed frequency divider has a planar structure, compact size (1.1 λ 0 × 0.5 λ 0) and wide bandwidth, 13.33% of bandwidth, and 1.5 λ of size₀×1.5λ₀。

As shown in fig. 3a, 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 an upper surface of the first dielectric layer, the 90 ° phase shifter metallization pattern includes a printed metal input section, one end of the input section 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 printed metal output section, the input section is 90 ° away from the first bending portion 16, the first bending portion 16 and the second bending portion 17 are parallel to each other, and the input section and the output section are in a straight line; a metalized disk 13 is formed around the 90 ° phase shifter metallization pattern.

The 45-degree phase shifter comprises a 45-degree phase shifter ridge layer, the 45-degree phase shifter ridge layer comprises a first dielectric layer, a 45-degree phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 45-degree phase shifter metallization pattern comprises a metal input section formed by printing, the metal input section is connected with one end of a third bent portion 18, the other end of the third bent portion 18 is connected with one end of a metal output section formed by printing, the metal input section and the metal output section are arranged in parallel, and the third bent portion 18 is perpendicular to the metal input section; a metalized disk 13 is formed around the 45 ° phase shifter metallization pattern.

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 about a 90 ° phase shifter, a Schiffman phase shifter is given. A standard 4 x 4Butler matrix of 45 phase shifters was designed so analysis using coupled line couplers determined the initial value of the coupling length and the coupling coefficient to produce a broadband 45 phase shift. The structure is shown in FIG. 3a, and the dimensions are listed in Table III. The resulting S-parameter and output phase difference are shown in fig. 3 (b). The proposed phase shifter has a wide bandwidth of 27 to 33.6GHz with an output phase shift of 45 DEG + -2 DEG, a return loss of better than 15dB, S21 > -0.4 dB.

TABLE 3 dimensions of phase shifters

Parameter	W_line	W_line2	W₁	W₂	W₃
						Value(mm)	1.38	1.35	1.49	1.28	0.88
Parameter	W₄	L₁	L₂	S
						Value(mm)	1.4	5.99	10.64	0.15

The geometry of the proposed Butler matrix is shown in fig. 4. The key point is the consistency of the geometric length and the desired phase. Table 4 shows the parameter-directed output ports of the Butler matrix, which are equally spaced.

TABLE 4 size of Butler matrix structure

Parameter	L_cp	L_pn	L_cc	L_cx	L_xt	L_c
							Value(mm)	6.1	12.73	19.78	6.5	10.95	9.88
Parameter	L_o1	L_o2	L_o3	L_oH	W_x	d
							Value(mm)	9.8	16.85	4.24	4.64	3.65	6

Fig. 5 and 6 show the s-parameters of the butler matrix for the excitation from

ports

1 and 2, respectively. The output phase difference between each excited output port of the input port is shown in fig. 7. 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 ± 1.6dB over the entire frequency band. The phase error is about 10 deg. across the band when fed from port 1 and port 4. The phase error when feeding from

ports

2 and 3 is within ± 10 ° in the frequency range of 28 to 33GHz, and the phase error is higher in the frequency range of 27 to 28 GHz.

The top layer 33 is located on the upper side of the ridge layer 32, and 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 surface of the ridge layer 32 (the back surface of the first dielectric layer), and the second metal layer is connected with the metalized disc through a metalized via hole.

As shown in fig. 8a to 8c, an antenna array layer 34 is connected to an output port of the millimeter wave butler matrix, the top layer 33 covers the ridge layer and the antenna array layer, the antenna array layer 34 includes a plurality of antenna units, a front antenna unit is formed on an upper surface of the dielectric layer, the front antenna unit includes a first longitudinal rectangular radiating patch 19, a second longitudinal rectangular radiating patch 20 is connected to an outer side of the first longitudinal rectangular radiating patch 19, and a length of the second longitudinal rectangular radiating patch 20 is smaller than a length of the first longitudinal rectangular radiating patch 19; a first transverse rectangular radiating plate 21 perpendicular to the second longitudinal rectangular radiating plate 20 is connected to the outer side of the second longitudinal rectangular radiating plate, the outer end of the first transverse rectangular radiating fin 21 is connected with a second transverse rectangular radiating fin 22, a third longitudinal rectangular radiating patch 23 is connected to one side between the first transverse rectangular radiating patch 21 and the second transverse rectangular radiating patch 22, the end of the second transverse rectangular radiating plate 22 is formed with a fourth longitudinal rectangular radiating plate 24, a fifth longitudinal rectangular radiation piece 25 is formed at 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 at the outer side of the fifth longitudinal rectangular radiation piece 25, the length of the sixth longitudinal rectangular radiation piece 26 is smaller than that of the fifth longitudinal radiation piece 25;

a back antenna unit is formed on the lower surface of the dielectric layer, the back antenna unit comprises a seventh longitudinal rectangular radiating sheet 27, a third transverse rectangular radiating sheet 28 is connected to the outer side of the seventh longitudinal rectangular radiating sheet 27, a fourth transverse rectangular radiating sheet 29 is connected to the outer side of the third transverse rectangular radiating sheet 28, an eighth longitudinal rectangular radiating sheet 30 connected with the third transverse rectangular radiating sheet 28 is formed at the joint of the third transverse rectangular radiating sheet 28 and the fourth transverse rectangular radiating sheet 29, and a ninth longitudinal rectangular radiating sheet 31 is connected to the end of the fourth transverse rectangular radiating sheet 29.

A modified version of the semilog periodic dipole antenna was implemented using Roger RT 6002 (epsilonr 2.94, tan δ 0.0012) with a thickness of 0.254 mm and a copper cladding of 0.017 mm. The antenna geometry PRGW input is shown in fig. 8. The antenna is designed in an array of four elements fed by a 4 x 4Butler matrix. Two virtual antenna elements are used, with all array elements having a symmetrical radiation pattern. They are connected to open-ended transmission lines and since the coupling between the antennas is small (< 24dB), the effect of reflecting power from them on the radiation pattern is negligible. Furthermore, rectangular cutouts are introduced between the antenna elements to potentially reduce coupling therebetween. The simulated S parameters of the antenna array are shown in fig. 9 for port 1 excitation. The radiation patterns at different frequencies are shown in fig. 10, where the 3-dB beamwidth ranges from 117 ° at 27GHz to 92 ° at 33 GHz.

In the application, firstly, a broadband directional coupler is designed by using bandwidths of S11 and 7.35GHz, S41< -15dB and an output phase difference is 90.9 degrees +/-1.62 degrees. It has a wide band and a small phase difference compared to other couplers in the metals RGW and PRGW. Second, the return loss and isolation of a wideband frequency divider with a bandwidth from 26.8 to 33.9GHz is better than 14dB, and the insertion loss is better than 0.5 dB. The design is small compared to others and maintains a wide bandwidth. Thirdly, the same technical design is adopted for the broadband phase shifter concept based on the coupled line coupler, the bandwidth is 27 to 33.6GHz, the return loss is better than 15dB, and the output phase difference is 45 +/-2 degrees. All developed components were combined to construct a 4 x 4Butler matrix and simulations in which 21.25% bandwidth was achieved with return loss and isolation greater than 10 dB. The butler matrix is combined with a designed semi-log periodic antenna array and a coaxial to PRGW transition. The resulting beams are 13 deg. and 36 deg. at the center frequency.

Claims

1. A millimeter wave butler matrix beamforming network, characterized by: the broadband phase shifter comprises a top layer (33) and a ridge layer (32), wherein the ridge layer (32) comprises a millimeter wave Butler matrix, the millimeter wave Butler matrix comprises a first broadband directional coupler (1) and a second broadband directional coupler (2), two input ports are respectively arranged on the first broadband directional coupler (1) and the second broadband directional coupler (2), one output port of the first broadband directional coupler (1) is connected with an input end of a first 90-degree phase shifter (3), the other output end of the first broadband directional coupler (1) is connected with one input end of a first frequency divider (4), one output port of the second broadband directional coupler (2) is connected with an input end of a second 90-degree phase shifter (5), and the other output end of the second broadband directional coupler (2) is connected with the other input end of the first frequency divider (4), an output of the first 90 DEG phase shifter (3) is connected to one input of a third broadband directional coupler (6), an output of the first frequency divider (4) is connected to the other input of the third broadband directional coupler (6), an output of the second 90 DEG phase shifter (5) is connected to one input of a fourth broadband directional coupler (7), the other output of the first frequency divider (4) is connected to the other input of the fourth broadband directional coupler (7), one output of the third broadband directional coupler (6) is connected to a first output port via a first 45 DEG phase shifter (8), the other output of the third broadband directional coupler (6) is connected to one input of a second frequency divider (9), and one output of the second frequency divider (9) is connected to a second output port, one output end of the fourth broadband directional coupler (7) is connected with a third output port through a second 45-degree phase shifter (10), the other output end of the fourth broadband directional coupler (7) is connected with the other input end of a second frequency divider (9), and the other output end of the second frequency divider (9) is connected with a fourth output port; the top layer (33) is positioned on the upper side of the ridge layer (32), the top layer (33) comprises a second medium layer, and a first metal layer is formed on the upper surface of the second medium layer; and the two input ports and the two output ports of the broadband directional coupler are provided with a quarter-wavelength balun.

2. The millimeter-wave Butler matrix beamforming network of claim 1, wherein: 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.

3. The millimeter-wave Butler matrix beamforming network of claim 1, wherein: 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 metal input sections formed by printing and two metal output sections formed by printing, the two input sections and the two input sections are connected together through a circular metal connecting disc (11) formed by printing, the diameters of the outer sides of the two input sections and the two output sections are smaller than that of the inner sides of the two input sections and the two output sections, two fan-shaped grooves (12) are formed in the center of the connecting disc, the dielectric layer in the fan-shaped grooves (12) leaks in a naked mode, and the two fan-shaped grooves (12) are communicated through a communicating part; the diameter of the connecting disc between the input section and the output section is larger than that of the connecting disc between the input section and the output section and larger than that of the connecting disc between the output section and the output section, and a metalized disc (13) is formed around the coupler metalized pattern.

4. The millimeter-wave Butler matrix beamforming network of claim 1, wherein: 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 metal input sections formed by printing and two metal output sections formed by printing, the input sections and the output sections are connected together through a rectangular metal connecting disc (14), the input sections and the output sections are respectively positioned on four corners of the rectangular metal connecting disc (14), three rectangular grooves (15) are formed in the rectangular metal connecting disc (14), the rectangular grooves (15) are not communicated with the rectangular grooves (15), and the dielectric layer in the rectangular grooves (15) is exposed and leaked; and a metalized disc (13) is formed around the frequency divider metalized pattern.

5. The millimeter-wave Butler matrix beamforming network of claim 1, wherein: the 90-degree phase shifter comprises a 90-degree phase shifter ridge layer, the 90-degree phase shifter ridge layer comprises a first medium layer, a 90-degree phase shifter metallization pattern is formed on the upper surface of the first medium layer, the 90-degree phase shifter metallization pattern comprises a metal input section formed by printing, one end of the input section is connected with one end of a first bending portion (16), the other end of the first bending portion (16) is connected with one end of a second bending portion (17), the other end of the second bending portion (17) is connected with one end of a metal output section formed by printing, the position between the input section and the first bending portion (16) is 90 degrees, the first bending portion (16) and the second bending portion (17) are parallel to each other, and the input section and the output section are on the same straight line; and a metalized disk (13) is formed around the 90-degree phase shifter metalized pattern.

6. The millimeter-wave Butler matrix beamforming network of claim 1, wherein: the 45-degree phase shifter comprises a 45-degree phase shifter ridge layer, the 45-degree phase shifter ridge layer comprises a first dielectric layer, a 45-degree phase shifter metallization pattern is formed on the upper surface of the first dielectric layer, the 45-degree phase shifter metallization pattern comprises a metal input section formed by printing, the metal input section is connected with one end of a third bent portion (18), the other end of the third bent portion (18) is connected with one end of a metal output section formed by printing, the metal input section is arranged in parallel with the metal output section, and the third bent portion (18) is perpendicular to the metal input section; and a metalized disc (13) is formed around the 45-degree phase shifter metalized pattern.

7. The millimeter wave Butler matrix beamforming network of any of claims 3-6, wherein: and a second metal layer is formed on the back surface of the ridge layer (32), and the second metal layer is connected with the metalized disc (13) through a metalized through hole.

8. The millimeter wave butler matrix beamforming network of claim 7, wherein: an output port of the millimeter wave Butler matrix is connected with 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) comprises a plurality of antenna units, each antenna unit comprises a dielectric layer, a front antenna unit is formed on the upper surface of each dielectric layer, each front antenna unit comprises a first longitudinal rectangular radiating sheet (19), a second longitudinal rectangular radiating sheet (20) is connected to the outer side of each first longitudinal rectangular radiating sheet (19), and the length of each second longitudinal rectangular radiating sheet (20) is smaller than that of each first longitudinal rectangular radiating sheet (19); a first transverse rectangular radiation piece (21) perpendicular to the second longitudinal rectangular radiation piece (20) is connected to the outer side of the second longitudinal rectangular radiation piece, a second transverse rectangular radiation piece (22) is connected to the outer end of the first transverse rectangular radiation piece (21), 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), the second transverse rectangular radiation piece (22) and the fifth longitudinal rectangular radiation piece (25) are oppositely arranged in the center, and a sixth longitudinal rectangular radiation piece (26) is formed on the outer side of the fifth longitudinal rectangular radiation piece (25), the length of the sixth longitudinal rectangular radiation piece (26) is smaller than that of the fifth longitudinal rectangular radiation piece (25);

the lower surface of dielectric layer is formed with back antenna element, back antenna element includes seventh vertical rectangle radiation piece (27), the outside of seventh vertical rectangle radiation piece (27) is connected with third horizontal rectangle radiation piece (28), the outside of third horizontal rectangle radiation piece (28) is connected with fourth horizontal rectangle radiation piece (29), the junction of third horizontal rectangle radiation piece (28) and fourth horizontal rectangle radiation piece (29) is formed with eighth vertical rectangle radiation piece (30) rather than being connected, the end connection of fourth horizontal rectangle radiation piece (29) has ninth vertical rectangle radiation piece (31).