CN110277620A - A window grille Butler matrix and its design method - Google Patents

Abstract

The present invention relates to a kind of tracery type butler matrix and its design method, 3dB directional coupler passes through short-circuit arm between any two and connects；Pass through short-circuit arm connection between each 3dB directional coupler and outer conductor.It is more superior with moire behaviors, Insertion Loss fluctuating natures such as the presentations of interior amplitude-frequency due to using short-circuit arm；In addition it is loaded with tuning screw, can be realized the optimal standing wave of product, amplitude-frequency and phase characteristic.Moire behaviors are waited since butler matrix has, are suitable for the Wide-Band Design.The equivalent order for increasing directional coupler of load of short-circuit arm, can effectively expand bandwidth of operation.Butler matrix low cost of the invention, easy processing, good assembly.All turnings of the structure internal and external conductor are fillet, easy to process using Milling Process technique, low in cost.So that internal and external conductor is integrated, having prevented the opposite sliding between internal and external conductor completely helps to promote the consistency of mass product for the load of short-circuit arm.

Description

A window grille Butler matrix and its design method

technical field

The invention relates to a window grille type Butler matrix and a design method thereof, belonging to the technical field of microwave passives.

Background technique

High-throughput communication satellite (HTS, High Throughput Satellite), also known as high-throughput communication satellite, is relative to traditional satellites using the same frequency resources. The main technical features include multi-spot beams, frequency reuse, and high beam gain. Wait. HTS can provide several times or even dozens of times higher capacity than conventional communication satellites. With the gradual maturity of high-throughput payloads and the continuous acceleration of the research and development process of new communication satellite platforms, the demand for HTS satellites continues to increase.

The passive multi-beam network based on the Butler matrix is the core component of the HTS satellite, which is used to achieve signal splitting and synthesis. Figure 1 shows the schematic diagram of the 4×4 Butler matrix, which is a commonly used topology. As can be seen from the figure, the matrix consists of four 3dB directional couplers, including 4 input ports (X1G~X4G) and 4 output ports (X5G~X8G), when a signal is input at a certain input , the four output terminals can output equal-amplitude signals, and the signals at the output terminals have a constant phase difference.

Due to the high frequency band of the Ku-band Butler matrix, the microstrip structure has the problem of poor joint welding sensitivity and consistency, which leads to less use of the microstrip structure Butler matrix in the Ku-band. At present, the Butler matrix of the square coaxial structure is most commonly used in the Ku frequency band, which overcomes the sensitivity of joint welding and can realize the miniaturization of the product. The inner and outer conductors of the traditional square coaxial Butler matrix are separated, and the medium is required for support and positioning. In the process of assembly and joint welding, it is likely to cause inaccurate positioning and relative sliding of the inner and outer conductors. In addition, although the traditional square The coaxial Butler matrix can expand the bandwidth by increasing the order. Since its in-band is not equiripple, the amplitude-frequency performance will deteriorate with the increase of the bandwidth. From this aspect, it is not suitable for wideband Butler. Le Matrix Products.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, aiming at the amplitude-frequency characteristics in the Butler matrix and the sliding problems of the inner and outer conductors, to provide a window pattern Butler matrix and a design method thereof. The directional couplers are connected in twos, so that the inner and outer conductors of the Butler matrix are integrated, which ensures the consistency of batch products; effectively expands the working bandwidth of the product, and realizes the ripple characteristics such as in-band amplitude and frequency.

The object of the present invention is achieved through the following technical solutions:

A window pattern Butler matrix is provided, which includes a cavity, the cavity includes an inner conductor and an outer conductor, the inner conductor includes a short-circuit arm and four 3dB directional couplers, and the rest are outer conductors; between each 3dB directional coupler and the outer conductor are connected through a short-circuit arm.

Preferably, the 3dB directional coupler includes four branch lines, which are a pair of high-impedance branch lines and a pair of low-impedance branch lines arranged oppositely, and the four corner lead-out transmission lines are connected to the short-circuit arm; the short-circuit arm includes a parallel short-circuit arm and a conventional short-circuit arm; two adjacent directional couplers are connected to the parallel short-circuit arm through a transmission line; the transmission lines drawn from the two outer corners of the directional coupler are respectively connected to the outer conductor through the conventional short-circuit arm.

Preferably, the parallel shorting arms are formed of conventional shorting arms that are rotated 90 degrees clockwise and connected to each other.

Preferably, the initial value of the total length of the branch line of the directional coupler is one-quarter wavelength, the initial value of the length of the conventional short-circuit arm is one-quarter wavelength, and the initial value of the length of the parallel short-circuit arm is one-half wavelength. The impedance of the conventional shorting arm and the parallel shorting arm is optimized to determine the final impedance, which is distributed between 5 ohms and 200 ohms.

Preferably, the cavity is obtained by a milling process, and all corners are rounded.

Preferably, it also includes an upper cover, a lower cover and a connector; the upper cover covers the upper surface of the cavity; the connector is fixed to the outside of the upper cover to provide an external interface, and the inner core is welded to the welding hole of the conductor in the cavity ; The lower cover plate covers the lower surface of the cavity; the cavity and the upper and lower cover plates are positioned by pins and assembled with fastening screws.

Preferably, an upper tuning screw and a lower tuning screw are also included; the length of the upper tuning screw and the lower tuning screw entering the cavity is adjusted, thereby changing the standing wave, amplitude frequency and phase characteristics of the window pattern Butler matrix.

Provide a design method based on the window grille Butler matrix, comprising the following steps:

(1) Four identical 3dB directional couplers are used, wherein the branch line length is a quarter wavelength, and the wavelength is calculated according to the center frequency of the working bandwidth;

(2) Calculate the impedance of each branch line of each 3dB directional coupler according to the power distribution relationship;

(3) Establish the circuit model of the window pattern Butler matrix, set the initial value of the length of the conventional short-circuit arm to 1/4 wavelength, the impedance to 1/2 of the impedance of the high-impedance branch line, and the initial value of the length of the parallel short-circuit arm to 1/2 The wavelength and impedance are twice the impedance of the conventional short-circuit arm; the length and impedance of the conventional short-circuit arm, the parallel short-circuit arm and each branch line are optimized with the electrical performance requirements as the ultimate goal;

(4) Establish a 3D model of the cavity according to the final optimized parameters;

(5) Design the upper cover, lower cover, connector, upper tuning screw and lower tuning screw, upper tuning screw, lower tuning screw, pin and fastening screw on the cavity according to the 3D model matching with the cavity through hole;

(6) Process the cavity, process the upper cover, the lower cover, and the connector according to the 3D model, and select the upper tuning screw, the lower tuning screw, the pin and the fastening screw.

Preferably, the designer software is used to establish and optimize the circuit model of the window grille Butler matrix.

Preferably, HFSS software is used to establish a 3D model of the cavity (1) for accurate simulation of the entire field.

Compared with the prior art, the present invention has the following advantages:

(1) The Butler matrix of the present invention has excellent electrical performance, and due to the use of short-circuit arms, the insertion loss in the band exhibits equi-ripple characteristics. The in-band amplitude-frequency characteristic of the traditional square-coaxial Butler matrix is parabolic, and with the increase of the bandwidth, the fluctuation of the differential loss will intensify and deteriorate; the new structure can realize the in-band amplitude-frequency and other ripple characteristics, and the differential loss fluctuation performance is more superior; in addition Loaded with tuning screws to achieve the best VSWR, amplitude frequency and phase characteristics of the product.

(2) Since the Butler matrix has equi-ripple characteristics, it is suitable for broadband design. The loading of the short-circuit arm is equivalent to increasing the order of the directional coupler, which can effectively expand the working bandwidth.

(3) The Butler matrix of the present invention is low-cost, easy to process, and easy to assemble. All the corners of the inner and outer conductors of the structure are rounded, and the milling process can be used, which is convenient to process and low in cost; the components are assembled with fastening screws, and the cover plate and the cavity can be positioned by pins. Simple.

(4) The loading of the short-circuit arm makes the inner and outer conductors integrated, completely eliminates the relative sliding between the inner and outer conductors, reduces the difficulty of assembly, and contributes to the consistency of batch products.

Description of drawings

Figure 1 is a schematic diagram of the principle of 4×4 Butler matrix;

Fig. 2 is the explosion structure diagram of window grille type Butler matrix of the present invention;

Figure 3 is a structural diagram of a window pattern Butler matrix cavity;

Figure 4 is the amplitude-frequency curve;

Figure 5 is the phase balance curve.

Detailed ways

2, the window pattern Butler matrix of the present invention is composed of a cavity 1, an upper cover 2, a lower cover 3, a connector 4, a tuning screw 5, a tuning screw 6, a pin and a fastening screw.

The upper cover plate 2 covers the upper surface of the cavity 1; the connector 4 is used to provide an external interface, and the inner core is welded to the welding hole of the conductor in the cavity. The lower cover 3 covers the lower surface of the cavity 1 . The cavity 1 and the upper and lower cover plates are positioned by pins and assembled with fastening screws.

Adjust the length of the tuning screw 5 and the tuning screw 6 into the covering cavity 1, and then change the standing wave, amplitude frequency and phase characteristics.

As shown in FIG. 3 , the cavity 1 includes an inner conductor and an outer conductor, and the inner conductor includes a parallel shorting arm 1-1, a conventional shorting arm 1-2 and a directional coupler 1-6. The cavity 1 is provided with threaded holes 1-4 and pin holes 1-5 for assembly.

The directional coupler 1-6 includes four branch lines 1-7 with the same length, specifically a pair of high-impedance branch lines Z1, the thinner parts 1-9 in the figure, and a pair of low-impedance branch lines Z2 The thicker part in the figure 1-8. The four corners lead out the transmission line. The four directional couplers 1-6 are connected through a parallel short-circuit arm 1-1. The short-circuit ends at both ends of the parallel short-circuit arm are respectively connected to the outer conductor, and the two sides of the middle of the parallel short-circuit arm are respectively connected to two 3dB directional coupler transmission lines. The short-circuit end of the conventional short-circuit arm is connected to the outer conductor, and the other end is connected through a transmission line and a 3dB directional coupler, and is welded to the connector through welding holes 1-3.

In one embodiment, when the circuit model is established, the four corners of the directional couplers 1-6 lead out conventional shorting arms through transmission lines, and when the two directional couplers are connected to each other, the conventional shorting arms are rotated 90 degrees clockwise to connect to each other That is, a parallel short-circuit arm is formed.

The window pattern Butler matrix is of axisymmetric and center-symmetric structure, including four 3dB directional couplers, of which the 3dB directional couplers are connected by parallel short-circuit arms. The initial length of the branch line of the directional coupler is one-quarter wavelength, the initial length of the conventional shorting arm is one-quarter wavelength, and the initial length of the parallel shorting arm is twice the initial length of the conventional shorting arm. The impedance can be obtained by optimization and is distributed in Between 5 ohms and 200 ohms.

The traditional Butler matrix is to connect four 3dB directional couplers without short-circuit arms. The inner and outer conductors are processed separately, positioned and clamped through the medium, which will cause relative sliding of the inner and outer conductors during the assembly and connector welding process. Cause product performance to deteriorate and deviate from the design.

In the present invention, the inner and outer conductors of the Butler matrix are connected by the parallel short-circuit arm and the conventional short-circuit arm, so that the two are designed and processed in an integrated manner, which can avoid the sliding problem during the assembly and welding process, and improve the consistency of batch products; in addition, In order to achieve the best standing wave, amplitude frequency and phase characteristics of the product, tuning screws are installed on the upper and lower cover plates to achieve fine-tuning of the product performance.

The simulation calculation of the window grille Butler matrix includes the following steps:

1) According to the operating bandwidth of 10.5GHz～12.85GHz, the center frequency f ₀ =11.675GHz is calculated, and the length of the branch line of the 3dB directional coupler is calculated as: 1/4×c/f ₀ =6.42mm, four 3dB directional coupling are identical in size.

2) According to the power distribution relationship of 1:1, calculate the impedance of each branch line of each 3dB directional coupler, high impedance Z1=50.3 ohms, according to the ratio of high and low impedance The calculated low impedance Z2=35.6 ohms, and the length of each branch line is the same.

3) Based on the parameters calculated in 1) and 2), the circuit model of the window pattern Butler matrix is established in the designer, and the length and impedance of the conventional short-circuit arm and the parallel short-circuit arm are optimized with the electrical performance as the goal, and the The width of each branch line is fine-tuned to achieve the desired performance. During optimization, the initial value of the length of the conventional shorting arm is 1/4 wavelength, and the impedance is 1/2×Z1=25.15 ohms. The initial value of the length of the parallel shorting arm is 1/2 wavelength, and the impedance is 2×25.15=50.3 ohms.

4) According to the final optimization parameters, the 3D model of cavity 1 is established in HFSS, and the simulation optimization obtains good performance. Figure 4 and Figure 5 show the simulated amplitude-frequency and phase balance curves respectively. It can be seen from the figure The center frequency is 11.675GHz, the relative bandwidth is 20.13%, the intra-band insertion loss fluctuation is less than 0.2dB, and the phase balance is less than 0.2°.

5) Design the upper cover plate 2, the lower cover plate 3, the connector 4, the tuning screws 5, 6, the tuning screws 5, 6 on the cavity 1, the pins and the holes corresponding to the fastening screws according to the 3D model. hole;

6) According to the 3D model, process cavity 1, process upper cover 2, lower cover 3, connector 4, select tuning screws 5, 6, pins and fastening screws.

The window pattern Butler matrix is composed of four 3dB directional couplers with shorting arms, and the two are also connected by a parallel shorting arm structure, which realizes the integrated design and processing of the inner conductor and the outer conductor. Window pattern Butler matrix, equipped with tuning screws, can be used to achieve port impedance matching, adjust the power distribution ratio and phase characteristics. The cavity body and the upper and lower cover plates are positioned by pins, and are assembled with fastening screws, and the assembly is simple. The operating frequency of the window pattern Butler matrix can be applied in the range of 200MHz to 30GHz.

The window grille-shaped Butler matrix of the present invention is also based on a square coaxial structure, but the structure is optimized and short-circuit arms are introduced. The introduction of this structure can not only effectively expand the bandwidth, but also ensure the equal ripple characteristics in the band. ; In addition, the introduction of the short-circuit arm integrates the inner and outer conductors, enhances its own mechanical stability, and reduces the difficulty of processing and assembly; at the same time, in order to more finely adjust the standing wave, balance and phase balance characteristics of the product, the tuning is loaded. Screws are used to achieve the best performance of the product.

The above is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited to this. Substitutions should be covered within the protection scope of the present invention.

Contents that are not described in detail in the specification of the present invention belong to the well-known technology of those skilled in the art.

Claims (10)

1. a kind of tracery type butler matrix, it is characterised in that: including cavity (1), cavity (1) includes inner conductor and outer conductor, Inner conductor includes short-circuit arm and four 3dB directional couplers, rest part are outer conductor；The 3dB directional coupler is two-by-two Between pass through short-circuit arm connection；Pass through short-circuit arm connection between each 3dB directional coupler and outer conductor.

2. tracery type butler matrix as described in claim 1, it is characterised in that: the 3dB directional coupler includes four Branch line (1-7), for a pair of of high impedance branch line for being oppositely arranged and a pair of of Low ESR branch line, four angles draw transmission lines with Short-circuit arm connection；The short circuit arm includes parallel connection short circuit arm (1-1) and conventional short-circuit arm (1-2)；Two neighboring directional couple Device is connect through transmission line with parallel connection short circuit arm (1-1)；The transmission line that two lateral angles of directional coupler are drawn passes through routine respectively Short-circuit arm (1-2) is connected to outer conductor.

3. tracery type butler matrix as claimed in claim 2, it is characterised in that: the parallel connection short circuit arm (1-1) is conventional 90 degree of interconnections are constituted short-circuit arm (1-2) clockwise or counterclockwise.

4. tracery type butler matrix as claimed in claim 2 or claim 3, it is characterised in that: the branch line overall length of directional coupler Degree initial value is quarter-wave, and the length initial value of conventional short circuit arm is quarter-wave, and parallel connection short circuit arm lengths initial value is The impedance of half wavelength, branch line, conventional short-circuit arm, parallel connection short circuit arm determines final impedance by optimization, is distributed in 5 Ohm is between 200 ohm.

5. tracery type butler matrix as claimed in claim 2 or claim 3, it is characterised in that: the cavity (1) uses Milling Process Technique obtains, and all turnings are fillet.

6. tracery type butler matrix as claimed in claim 2 or claim 3, it is characterised in that: further include upper cover plate (2), lower cover plate (3) and connector (4)；Upper cover plate (2) covers the upper surface of cavity (1)；Connector (4) is fixed on the outside of upper cover plate, is used for External interface is provided, inner core is soldered to the welding hole of cavity inner conductor；Lower cover plate (3) covers the lower surface of cavity (1)；Cavity (1) it is positioned with upper and lower lids three by pin, is assembled with fastening screw.

7. tracery type butler matrix as claimed in claim 6, it is characterised in that: further include upper tuning screw (5) and downward Humorous screw (6)；Tuning screw (5) and lower tuning screw (6) enter cavity (1) internal length in adjusting, and then change tracery Standing wave, amplitude-frequency and the phase characteristic of type butler matrix.

8. a kind of design method based on tracery type butler matrix described in claim 7, it is characterised in that include the following steps:

(1) use four identical 3dB directional couplers, wherein branch's line length be quarter-wave, wavelength according to The centre frequency of bandwidth of operation, which calculates, to be obtained；

(2) according to power distribution relationship, the impedance of each each branch line of 3dB directional coupler is calculated；

(3) circuit model of tracery type butler matrix is established, the initial value that the length of conventional short-circuit arm is arranged is 1/4 wavelength, resistance Anti- initial value is the 1/2 of high impedance branch line impedence；Parallel connection short circuit arm lengths initial value is 1/2 wavelength, and impedance initial value is conventional short 2 times of road arm impedance；Using requirement on electric performance as final goal, to the length of conventional short-circuit arm, parallel connection short circuit arm and each branch line Degree and impedance optimize；

(4) according to final Optimal Parameters, the 3D model of cavity (1) is established；

(5) according to 3D modelling and cavity (1) matched upper cover plate (2), lower cover plate (3), connector (4), upper tuning screw (5) and on lower tuning screw (6), cavity (1) with upper tuning screw (5), lower tuning screw (6), pin and fastening screw pair The through-hole answered；

(6) according to 3D mould processing cavity (1), processing upper cover plate (2), lower cover plate (3), connector (4), tuning screw in selection (5), lower tuning screw (6), pin and fastening screw.

9. design method according to claim 8, it is characterised in that: establish tracery type Butler square using designer software The circuit model of battle array simultaneously optimizes.

10. design method according to claim 8, it is characterised in that: using HFSS software establish the 3D model of cavity (1) into The accurate simulation of the row whole audience.