Non-equal division type multi-path broadband filtering power divider and design method

Abstract

The invention discloses a non-equal division type multi-path broadband filtering power divider and a design method, and belongs to the technical field of wireless communication. The non-equal division type multi-path broadband filtering power divider comprises three-wire coupling lines, open-circuit stub lines, a distribution network and an isolation network; the three-wire coupling line, the open-circuit stub line, the distribution network and the isolation network are connected in sequence; the three-wire coupling line comprises a first coupling line, a second coupling line and a third coupling line; the open-circuit stub line comprises a first stub line and a second stub line; the distribution network comprises n transmission lines, and first terminals of the n transmission lines are connected and then connected with a first terminal of the distribution network; the isolation network comprises x isolation modules, the second terminals of any two transmission lines are connected through one isolation module, and the value of x is n (n-1) / 2. The non-equal division type multipath broadband filtering power divider provided by the invention has the functions of enhancing the power distribution ratio and broadband isolation.

Description

Technical Field

[0001] The invention relates to the field of wireless communication systems, and in particular to a non-equal division type multi-path broadband filtering power distributor and a design method thereof. Background Art

[0002] In wireless communication systems, unequal power dividers play a more critical role than equal power dividers, such as the feed network and power amplifier of antenna arrays. With the increasing demand for high integration and low cost, filter power dividers (FPDs) have received great attention because they can not only distribute power to two or more paths according to a specified power ratio, but also filter out unwanted signals. So far, people have made great efforts to enhance the bandwidth of equal power filter power dividers and improve their out-of-band suppression capabilities.

[0003] For unequal power dividers, due to the limitation of manufacturing process, the maximum power ratio of the traditional Wilkinson power divider is almost limited to 4. In order to improve the power ratio, many related research reports have been published. Generally speaking, these methods can be divided into three categories.

[0004] The first category is to replace the extremely narrow microstrip line with a new equivalent high impedance transmission line, such as defective ground structure, introduction of lumped elements in the transmission line, and impedance transformers formed by short-circuited coupled lines or open / short-circuited stubs. However, the bandwidth of this method is limited.

[0005] The second method is to achieve a large power division ratio (PDR) through the appropriate phase of the transmission line, and to achieve an arbitrary power division ratio by adjusting the electrical length of the uniform 50-ohm transmission line. However, this method is only effective at the center frequency, and the phase imbalance is large, and phase compensation is required for the in-phase or out-of-phase output.

[0006] The third category is to use resonators or new materials and structures, and develop a 10:1 filter power divider using slot lines and path resonators. The design of this power divider is based on the filter principle, so the comprehensive design process is relatively complicated.

[0007] For multi-way power dividers, they can be easily implemented by cascading basic two-way units, but this only works for 2 nIn order to develop n-way power dividers, Gysel or Bagley topology and multilayer substrate integrated waveguide technology are applied. Reconfigurable power dividers based on reconfigurable impedance matching networks can also be introduced to construct n-way topology. In order to improve frequency selectivity, multimode resonators and broadband bandpass impedance transformers are introduced. In this regard, isolation between non-adjacent paths is another difficult problem. This problem can be solved by introducing new isolation networks, but such radial isolation networks will lead to larger structure sizes. However, these reported works only focus on equal power dividers. When the power ratio is unequal and the number of distribution paths increases, the maximum achievable power ratio will decrease, and the maximum power ratio is also limited to less than 5. Therefore, designing a universal n-way topology with enhanced power distribution ratio and broadband isolation function remains a challenging task. Summary of the invention

[0008] The present invention aims to provide a non-equal division type multi-path broadband filtering power distributor with enhanced power distribution ratio and broadband isolation function and a design method thereof.

[0009] To achieve the above object, the technical solution of the present invention is:

[0010] A non-equally divided multi-channel broadband filtering power distributor comprises a three-wire coupling line, an open-circuit short stub, a distribution network and an isolation network; the three-wire coupling line, the open-circuit short stub, the distribution network and the isolation network are connected in sequence;

[0011] The three-wire coupling line includes a first coupling line, a second coupling line and a third coupling line, wherein the first terminal of the first coupling line is connected to the first terminal of the third coupling line and then connected to the input terminal of the non-equally divided multi-channel broadband filter power divider, and the second terminal of the second coupling line is connected to the first terminal of the open-circuit stub and the first terminal of the distribution network;

[0012] The open stub includes a first stub and a second stub, the first terminal of the first stub is the first terminal of the open stub, and the second terminal of the first stub is connected to the first terminal of the second stub;

[0013] The distribution network comprises n transmission lines, and first terminals of the n transmission lines are connected to form first terminals of the distribution network;

[0014] The isolation network includes x isolation modules, and the second terminals of any two transmission lines are connected through one isolation module, wherein the value of x is n(n-1) / 2.

[0015] Optionally, the isolation module includes a first isolation transmission line, a second isolation transmission line, a third isolation transmission line, a first resistor and a second resistor, the first terminal of the first isolation transmission line is connected to the second terminal of any one of the two transmission lines, the second terminal of the first isolation transmission line is connected to the first terminal of the first resistor, and the second terminal of the first resistor is grounded; the first terminal of the second isolation transmission line is connected to the second terminal of the other of the two transmission lines, the second terminal of the second isolation transmission line is connected to the first terminal of the second resistor, and the second terminal of the second resistor is grounded; the first terminal of the third isolation transmission line is connected to the midpoint of the series connection of the first isolation transmission line and the first resistor, and the second terminal of the third isolation transmission line is connected to the midpoint of the series connection of the second isolation transmission line and the second resistor.

[0016] Optionally, the second terminal of any one of the transmission lines is an output terminal of the unequally divided multi-channel broadband filter power distributor; the unequally divided multi-channel broadband filter power distributor includes n output terminals.

[0017] Optionally, the first isolation transmission line and the second isolation transmission line include quarter-wavelength transmission lines; and the third isolation transmission line includes a half-wavelength transmission line.

[0018] Optionally, the first short stub and the second short stub include half-wavelength short stubs.

[0019] Optionally, the open-circuit stub includes a stepped impedance open-circuit stub.

[0020] A design method for a non-equally divided multi-channel broadband filter power distributor is applied to any of the non-equally divided multi-channel broadband filter power distributors described above, comprising:

[0021] Step S1: Setting the power ratio k1 of the unequally divided multi-channel broadband filter power divider 2 :k2 2 :…:k n 2 ; where k n is the output power of the nth output terminal;

[0022] Step S2: setting the strip width and gap width of the three-wire coupled line, and calculating the even-mode impedance and odd-mode impedance of the three-wire coupled line, the expression is as follows:

[0023] Z e =Z0[1+Z0J+(Z0J) 2 ]; Z o =Z0[1-Z0J+(Z0J) 2 ]

[0024] Among them, Z e is the even-mode impedance, Z o is the odd-mode impedance, J is the susceptance of the three-wire coupled line;

[0025] Step S3: Calculate the characteristic impedance of all transmission lines according to the power ratio set in step S1 and the even-mode impedance and the odd-mode impedance calculated in step S2. The expression is as follows:

[0026]

[0027] Among them, Z n is the characteristic impedance of the nth transmission line, R T1 is the impedance of the first input terminal, R Tn is the impedance of the nth output terminal, Z e is the even-mode impedance, Z o is the odd-mode impedance, k n is the output power of the nth output terminal, k i is the output power of the i-th output terminal;

[0028] Calculate the value of the isolated transmission line, the expression is as follows:

[0029]

[0030] Among them, R Tm is the impedance of the mth output terminal, Z mn is the characteristic impedance of the first isolated transmission line, Z nm is the characteristic impedance of the second isolated transmission line, R mn The first isolated transmission line is connected to a first resistor, R nm A second resistor connected to the second isolated transmission line; the value of m is 2, 3, ..., n+1 and m≠n;

[0031] The characteristic impedance of the first isolated transmission line, the relationship between the characteristic impedance of the first isolated transmission line and the resistance are obtained, and the expression is as follows:

[0032]

[0033] Among them, k m is the output power of the mth output terminal.

[0034] Optionally, the design method of the unequally divided multi-channel broadband filter power distributor further includes: performing electromagnetic simulation and optimization on the unequally divided multi-channel broadband filter power distributor.

[0035] The non-equal-division multi-channel broadband filter power divider and design method proposed in the present application, by adding a three-wire coupled line and an open-circuit short-circuit line, calculating the parameters of the three-wire coupled line, the open-circuit short-circuit line and the isolation network, can relax the large impedance requirement of the branch with lower power capacity, and significantly improve the achievable power division ratio of the non-equal-division multi-channel broadband filter power divider. The isolation between any two output terminals can be designed independently, and the return loss and power division ratio of the input terminals in the present application can be adjusted independently. Compared with other non-equal power dividers, no additional impedance transformation part is required at the output terminal.

[0036] In order to make the above features and advantages of the invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of a non-equally divided multi-channel broadband filtering power divider.

[0038] Figure 2 It is a structural schematic diagram of a non-equally divided two-way broadband filtering power divider.

[0039] Figure 3 It is a structural schematic diagram of the isolation module 41 of the unequally divided two-way broadband filtering power distributor proposed in the present application.

[0040] Figure 4 Figure (a) is a schematic diagram of the bandwidth of the power divider under different Z23 values ​​(ZF=60Ω).

[0041] Figure 4 Figure (b) is a schematic diagram showing the variation of 20dB bandwidth with ZF (Z23=80Ω).

[0042] Figure 5 Schematic diagram of odd-mode and even-mode reflection coefficient and isolation of the power divider under different R23 values.

[0043] Figure 6 Schematic diagram of the impedance of the low-power branch changing with the power distribution ratio.

[0044] Figure 7 Schematic diagram of the theoretical amplitudes of |S11|, |S21| and |S31| of the proposed unequal power divider under the conditions of k2=5, 8 and 12.

[0045] Figure 8 Schematic diagram of total voltage and current of unequally divided three-way broadband filtering power divider.

[0046] Fig. 9Figure (a) is a schematic diagram of the S parameter amplitude of the unequally divided multi-channel broadband filtering power divider and other power dividers when the power division ratio is 13:2:1.

[0047] Fig. 9 Figure (b) is a schematic diagram of the change of S11 bandwidth with ZF.

[0048] Fig. 9 Figure (c) is a schematic diagram of the bandwidth of S11 under different Zmn values.

[0049] Fig. 9 Figure (d) is a schematic diagram showing how isolation varies with R23.

[0050] Fig. 9 Figure (e) is a schematic diagram showing how the isolation varies with R34.

[0051] Fig. 9 Figure (f) is a schematic diagram showing how isolation varies with R24.

[0052] Fig.10 The structure and physical diagram of a unequally divided three-way broadband filter power divider with a power distribution ratio of 5:3:2.

[0053] Fig.11 Schematic diagram of simulation and measured results of a unequally divided three-way broadband filter power divider with a power distribution ratio of 5:3:2.

[0054] Fig.12 The structure and physical diagram of a unequally divided three-way broadband filtering power divider with a power distribution ratio of 8:1:1.

[0055] Fig.13 Schematic diagram of simulation and measured results of a unequally divided three-way broadband filtering power divider with a power distribution ratio of 8:1:1.

[0056] Fig.14 Schematic diagram of the isolation module provided for this application. DETAILED DESCRIPTION

[0057] In order to make the purpose and technical solution of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment 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.

[0058] In one embodiment of the present application, please refer to Figure 1 , Figure 1This is a structural schematic diagram of a non-equally divided multi-channel broadband filter power divider provided in the present application. The non-equally divided multi-channel broadband filter power divider includes a three-wire coupled line 1, an open-circuit short line 2, a distribution network 3 and an isolation network 4. The three-wire coupled line 1, the open-circuit short line 2, the distribution network 3 and the isolation network 4 are connected in sequence.

[0059] The three-wire coupling line 1 includes a first coupling line 11, a second coupling line 12 and a third coupling line 13. The first terminal of the first coupling line 11 is connected to the first terminal of the third coupling line 13 and then connected to the input terminal Port1 of the unequally divided multi-way broadband filtering power divider. The second terminal of the second coupling line 12 is connected to the first terminal of the open short line 2 and the first terminal of the distribution network 3.

[0060] The open stub 2 is a step impedance open stub, specifically comprising a first stub Z s1 and the second stub Z s2 , the first short stub Z s1 The first terminal of the open short stub 2 is the first terminal of the open short stub 2. s1 The second terminal is connected to the second stub Z s2 The first terminal;

[0061] The distribution network 3 includes n transmission lines Z1-Z n , the n transmission lines Z1~Z n After being connected, the first terminal of becomes the first terminal of the distribution network 3.

[0062] The isolation network 4 includes x isolation modules 41 - 4x. The second terminals of any two transmission lines are connected through one isolation module, wherein the value of x is n(n-1) / 2.

[0063] As an example, see Fig.14 , Fig.14 Schematic diagram of the isolation module provided in this application, each isolation module includes an isolation transmission line Z nm , isolated transmission line Z mn , isolated transmission line Z F , resistor R nm And the resistor R mn , isolated transmission line Z nm The first terminal of the transmission line Z is connected to the second terminal of any one of the two transmission lines, and the isolation transmission line Z mn The first terminal of the transmission line Z is connected to the second terminal of the other transmission line of the two transmission lines, and the isolation transmission line Z nm The second terminal is connected to the resistor R nm The first terminal, resistor R nmThe second terminal of the grounded, isolated transmission line Z mn The second terminal is connected to the resistor R mn The first terminal, resistor R mn The second terminal of the isolated transmission line Z is grounded; F The first terminal is connected to the isolated transmission line Z nm And the resistor R nm The midpoint of the series connection, isolated transmission line Z F The second terminal is connected to the isolated transmission line Z mn And the resistor R mn The midpoint of the series connection. Wherein, m=2, 3, ..., n+1 (m≠n).

[0064] As an example, the second terminal of any transmission line is an output terminal of the unequally divided multi-channel broadband filter power divider; the unequally divided multi-channel broadband filter power divider includes n output terminals, namely port2 to port(n+1).

[0065] As an example, the isolated transmission line Z nm With isolated transmission line Z mn comprising a quarter-wavelength transmission line; the isolation transmission line Z F Includes half-wavelength transmission lines.

[0066] As an example, the stub Z s1 With short stub Z s2 Includes half-wavelength stubs.

[0067] The non-equal-division multi-channel broadband filter power divider proposed in this application, by adding a three-wire coupled line and an open-circuit short-circuit line, calculating the parameters of the three-wire coupled line, the open-circuit short-circuit line and the isolation network, can relax the large impedance requirement of the branch with lower power capacity, and significantly improve the achievable power division ratio of the non-equal-division multi-channel broadband filter power divider. The isolation between any two output terminals can be designed independently, and the return loss and power division ratio of the input terminal Port1 in this application can be adjusted independently. Compared with other non-equal power dividers, no additional impedance transformation part is required at the output terminal.

[0068] Furthermore, according to the transfer matrix of the relationship between voltage and current, Figure 1 The relationship between voltage and current can be expressed as

[0069]

[0070] Where θ represents the electrical length (i.e., physical length / operating wavelength), Z n-1represents the characteristic impedance of the n-1th transmission line, j represents an imaginary number, U0 is the voltage at the input terminal Port1, U1 is the voltage output by the open short-circuit stub 2, I0 is the current at the input terminal Port1, I1 is the current output by the open short-circuit stub 2, U n is the voltage of the output terminal Portn, I na is the current input to the n-1th transmission line, I nb is the current output of the n-1th transmission line, I nc is the current flowing into the isolation network 4 from the output terminal Portn, I (n+1)c is the current input into the isolation network 4 from the output terminal Port(n+1), U n+1 is the voltage of the output terminal Port(n+1), [M1] is the ABCD matrix of the three-wire coupled line 1 and the open short stub 2, and [M2] is the ABCD matrix of the isolation network 4.

[0071] As an example, the power ratio of the unequal multi-channel broadband filter power divider is specified as k1 2 :k2 2 :…:k n 2 , the reflection coefficients of the input terminal Port1 and the output terminals Port2 to Port(n+1) should be 0; in order to obtain good isolation parameters, the isolation parameters between the output terminals Port2 to Port(n+1) should be 0. Then the transmission line Z n The characteristic impedance expression is as follows:

[0072]

[0073] Among them, R T1 is the impedance of input terminal Port1, R Tn is the impedance of the output terminal Port(n), Z e is the even-mode impedance, Z o is the odd-mode impedance, k n is the output power of the nth output terminal, k i is the output power of the ith output terminal.

[0074] Furthermore, the constraint condition of the ABCD matrix [M2] of the isolated network 4 is established. For the isolated network 4, the corresponding ABCD matrix [M2] can be obtained by multiplying the ABCD matrices of the cascaded part. The specific expression is as follows:

[0075]

[0076] Among them, Z mn Represents the isolated transmission line Z mn The characteristic impedance, Znm Represents the isolated transmission line Z nm characteristic impedance.

[0077] For ease of analysis, the impedance of all terminals is normalized to 1Ω. In order to achieve ideal isolation between terminals, the constraints of the ABCD matrix [M2] of the isolation network 4 are expressed as:

[0078]

[0079] Where k = k m / k n (m, n=2, 3,..., n+1, m≠n), k m is the output power of the mth output terminal.

[0080] Furthermore, in order to make formula (3) equal to formula (4), the relationship between the parameters of the isolation module can be obtained as follows:

[0081]

[0082] Furthermore, the isolated transmission line Z in the isolation network 4 mn , isolated transmission line Z nm , resistor R nm And the resistor R mn The value expression is as follows:

[0083]

[0084] Among them, R Tm is the impedance of the output terminal Port(m).

[0085] In another embodiment of the present application, please refer to Figure 2 , Figure 2 This is a structural schematic diagram of the unequally divided two-way broadband filter power distributor proposed in this application. The unequally divided two-way broadband filter power distributor includes a three-wire coupling line 1, an open-circuit short-circuit line 2, a distribution network 3 and an isolation network 4. Its connection method is consistent with that of the unequally divided multi-way broadband filter power distributor, which will not be repeated here; wherein, the distribution network 3 includes two transmission lines Z1 and Z2, and the isolation network 4 includes an isolation module 41. Figure 2 The non-equally divided two-way broadband filter power divider in the embodiment includes two output terminals, namely output terminal Port2 and output terminal Port3. Figure 2 The working principle of the present application is introduced. Due to the asymmetric structure of the non-equally divided two-way broadband filter power divider proposed in the present application, the odd-even mode analysis method cannot be directly applied. Therefore, a general analysis method is adopted. Through the transmission matrix, the relationship between the voltage and current of each part of the non-equally divided two-way broadband filter power divider is expressed as:

[0086]

[0087] Wherein, θ represents the electrical length (i.e., physical length / operating wavelength), Z1 represents the characteristic impedance of the first transmission line, Z2 represents the characteristic impedance of the second transmission line, j represents an imaginary number, U0 is the voltage at the input terminal Port1, U1 is the voltage output by the open short stub 2, U2 is the voltage at the output terminal Port2, U3 is the voltage at the output terminal Port3, I0 is the current at the input terminal Port1, I1 is the current output by the open short stub 2, I 2a is the current of the input transmission line Z1, I 2b is the current of the output transmission line Z1, I 3a is the current of the input transmission line Z2, I 3b is the current of the output transmission line Z2, I 2c The input isolation transmission line Z 23 The current, I 3c The input isolation transmission line Z 32 , [M1] is the ABCD matrix of the three-wire coupled line 1 and the open short-circuit line 2, and [M2] is the ABCD matrix of the isolation network 4.

[0088] Furthermore, according to Kirchhoff's current law, the relationship between the above voltage and current is obtained as follows:

[0089]

[0090] Among them, I2 is the current of the input / output terminal Port2, and I3 is the current of the input / output terminal Port3.

[0091] As an example, the output power of output terminal Port2 is set to P2, and the output power of output terminal Port3 is set to P3. At this time, the power distribution ratio is P2 / P3=k 2 :1, I2 is k times of I3. When θ=90°, all S parameters of the proposed non-uniform two-way broadband filter power divider are shown in formula (9):

[0092]

[0093] S 23 =S 32 =2Z1Z2(B-Z1Z2)(9d)

[0094] S 12 =S 21 =j2Z1Z2(Z1+AZ2+BZ2)(9e)

[0095] S 13 =S 31=j2Z1Z2(Z2+BZ1+DZ1)(9f)

[0096] Among them, S 11 is the return loss of input terminal Port1, S 22 is the return loss of output terminal Port2, S 33 is the return loss of output terminal Port3, S 12 is the transmission coefficient from output terminal Port2 to input terminal Port1, S 21 is the transmission coefficient from input terminal Port1 to output terminal Port2, S 13 is the transmission coefficient from output terminal Port3 to input terminal Port1, S 31 is the transmission coefficient from input terminal Port1 to output terminal Port3, S 23 With S 32 is the isolation parameter between the output terminal Port3 and the output terminal Port2, and A, B, C and D are the elements of the ABCD matrix of the isolation network.

[0097] Furthermore, in order to obtain the set power ratio k 2 :1, the ratio of the square of the absolute value of the transmission coefficient from input terminal Port1 to output terminal Port2 to the square of the absolute value of the transmission coefficient from input terminal Port1 to output terminal Port3 should be k 2 , and the reflection coefficient of each input terminal and output terminal is 0; in order to obtain good isolation parameters, the isolation parameters should all be 0. It can be expressed as the following formula:

[0098] S 11 =S 22 =S 33 =0;|S 21 | 2 / |S 31 | 2 =k 2 (10a)

[0099] S 32 =S 23 =0 (10b)

[0100] As an example, when the transmission coefficient is given priority, the characteristic impedance of the transmission line Z1 and the transmission line Z2 in the distribution network 3 is expressed as follows:

[0101]

[0102] Among them, Z e is the even-mode impedance of the three-wire coupled line 1, Z o The odd-mode impedance of three-wire coupled line 1, RT1 is the terminal impedance of input terminal Port1, R T2 is the terminal impedance of output terminal Port2, R T3 is the terminal impedance of the output terminal Port3. In formulas (11a) and (11b), the terminal impedance can be any real number, so there is no need to set an additional impedance transformation part at the output terminal.

[0103] Specifically, the present application sets a three-wire coupling line 1, which is equivalent to a J inverter topology structure, which uses the susceptance J to represent the influence of the strip width and gap width of the coupling line on the coupling degree. Therefore, the even-mode impedance Z of the three-wire coupling line 1 is e and odd-mode impedance Z o The formula is expressed as:

[0104] Z e =Z0[1+Z0J+(Z0J) 2 ]; Z o =Z0[1-Z0J+(Z0J) 2 ] (12)

[0105] Where J is the susceptance of the three-wire coupled line 1, which can be calculated using filter theory once the bandwidth is determined.

[0106] As an example, see Figure 3 , Figure 3 This is a structural diagram of the isolation module 41 of the non-equally divided two-way broadband filter power distributor proposed in this application. Figure 2 The isolated transmission line Z in F , 2θ is equivalent to two series resistors Z F , θContinue to combine Figure 3 The isolation degree of the isolation module 41 is analyzed. Figure 3 The voltage and current of the isolation module 41 are expressed by the formula:

[0107]

[0108]

[0109] Among them, U2 is the voltage of output terminal Port2, U3 is the voltage of output terminal Port3, U R2 is the input resistance R 23 Voltage, U F The input transmission line Z F2 Voltage, U R3 is the input resistance R 32 The voltage, I 23 The input isolation transmission line Z 23 Current, I' 23The output isolation transmission line Z 23 The current, I F2 The input isolation transmission line Z F1 Current, I' F The input isolation transmission line Z F2 The current, I F3 The output isolation transmission line Z F2 The current, I 32 The input isolation transmission line Z 32 Current, I' 32 The output isolation transmission line Z 32 of current.

[0110] As an example, when power is applied to the output terminal Port2, in order to satisfy the isolation parameters in formula (10b) that are both 0, U3 and I 32 should be zero at the same time. Therefore, the constraint condition of the ABCD matrix [M2] of the isolation network 4 is established, and the expression is as follows:

[0111]

[0112] Furthermore, the ABCD matrix [M2] of the isolation network 4 can be obtained by multiplying the ABCD matrices of the cascaded parts, as shown below:

[0113]

[0114] Among them, Z 23 Represents the isolated transmission line Z 23 The characteristic impedance, Z 32 Represents the isolated transmission line Z 32 characteristic impedance.

[0115] Furthermore, in order to make formulas (13a), (13b), (13c), (13d) and formula (14) equal at the center frequency f0 of the operating frequency band, the relationship between the parameters in the additional isolation network Iso. can be obtained as follows:

[0116] Z 23 =kZ 32 (16a)

[0117]

[0118] Among them, R T2 is the terminal impedance of output terminal Port2, R T3 is the terminal impedance of the output terminal Port3.

[0119] Specifically, there are many parameters that affect the performance of the non-equally divided two-way broadband filter power divider proposed in this application. For the frequency bandwidth of the non-equally divided two-way broadband filter power divider proposed in this application, based on the ABCD matrix [M2] of the isolation network 4 obtained by formula (15), the parameters of the isolation network 4 can be obtained by the isolation transmission line Z 23 and isolated transmission line Z F To determine, where the isolated transmission line Z F are canceled out during calculations. Figure 4 In Figure (a), Figure 4 Figure (a) shows different isolated transmission lines Z 23 The bandwidth diagram of the non-equally divided two-way broadband filter power divider is shown in Figure 1, where the normalized frequency represents the ratio of the current collected frequency to the center frequency f0. F By comparing these curves, it can be found that the bandwidth will increase with the isolation transmission line Z 23 increases with the increase of . Figure 4 Figure (b) shows different isolated transmission lines Z F The bandwidth diagram of the non-equally divided two-way broadband filter power divider. 23 By comparing these curves, it can be found that the bandwidth will increase with the isolation transmission line Z F increases with the increase of .

[0120] Furthermore, for the isolation S between the output terminal Port2 and the output terminal Port3 of the non-equally divided two-way broadband filter power divider proposed in this application, 32 , see Figure 5 , set the resistor R according to formula (16b) 23 The value of Figure 5 For different R 23 The odd-mode reflection coefficient, even-mode reflection coefficient and isolation of the unequally divided two-way broadband filter power divider under the value. e is the even mode reflection coefficient, Γ o is the odd mode reflection coefficient, S 32 is the isolation degree. Figure 5 It can be seen that setting R 23 The values ​​are 80Ω and 115Ω, the isolation between the output terminal Port2 and the output terminal Port3 reaches the maximum value at the center frequency f0, and the bandwidth is limited because Γ e =Γ o This condition only occurs at the center frequency f0. 23 The value of Γ o has a significant impact, and with the R 23The decrease in value will produce |S 32 |two transmission zeros, which in turn expands the isolation bandwidth.

[0121] Furthermore, according to basic microwave theory, when a larger power division ratio is specified, the lower power branch always requires a high impedance, which restricts the maximum achievable power division ratio due to manufacturing process limitations. Assuming the power division ratio is k 2 :1, the working bandwidth is 50%, then according to formula (12), the even-mode impedance Z is calculated e and odd-mode impedance Z o Select 139Ω and 32.62Ω respectively. Figure 6 , Figure 6 The impedance of the low power branch varies with the power split ratio. Figure 6 It can be seen that the achievable range of the power ratio of the non-equally divided two-way broadband filter power divider proposed in this application is 1≤k 2 ≤15, while the maximum k that can be achieved by Wilkinson power divider or gradient power divider 2 The value is only 8. The power division ratio of the Wilkinson power divider is limited to less than 4 due to the extremely narrow width of the microstrip line of its lower power branch, and an additional impedance transformation part is usually required at the output terminal.

[0122] As an example, Table 1 further lists the parameter values ​​of each transmission line of the unequal two-way broadband filter power divider when the proposed unequal two-way broadband filter power divider is used and the power division ratios are 5, 8 and 12. It can be seen from the table that the parameter values ​​of all transmission lines are within 120Ω.

[0123] Table 1 Figure 2 The value of each transmission line under different power distribution ratios (R T1 =R T2 =R T3 =50Ω)

[0124]

[0125]

[0126] Among them, W t1 is the outer width of the microstrip transmission line in the three-line coupled line 1, W t2 is the inner width of the three coupling lines in the three-line coupling line 1, S t is the gap width between the three coupling lines in the three-line coupling line 1.

[0127] For further information, see Figure 7 , Figure 7 For k 2=5, 8 and 12, the theoretical amplitude diagram of |S11|, |S21| and |S31| of the unequal two-way broadband filter power divider. It can be seen that the unequal two-way broadband filter power divider proposed in the present application significantly relaxes the high impedance requirement for the lower power branch by introducing the three-wire coupling line 1, and the bandwidth and power division ratio are improved.

[0128] Furthermore, the non-equally divided two-way broadband filter power divider proposed in the present application will have improved out-of-band suppression performance by introducing the three-wire coupling line 1, and a pair of transmission zeros will be generated due to the presence of the open-circuit short stub 2. Please continue to read Figure 7 , the out-of-band suppression performance is better than 18dB, and a pair of transmission zeros f can be observed z1 With f z2 Therefore, good filtering performance can be obtained. Transmission zero point f z1 With f z2 The position can be expressed as:

[0129]

[0130] In another embodiment of the present application, please refer to Figure 8 , Figure 8 This is a structural schematic diagram of the unequally divided three-way broadband filter power divider proposed in this application. The unequally divided three-way broadband filter power divider includes a three-wire coupling line 1, an open-circuit short-circuit line 2, a distribution network 3 and an isolation network 4. Its connection method is consistent with that of the unequally divided multi-way broadband filter power divider, which will not be repeated here; wherein, the distribution network 3 includes three transmission lines Z1, Z2 and Z3, and the isolation network 4 includes isolation modules 41, isolation modules 42 and isolation modules 43. Figure 8 The non-equally divided three-way broadband filter power divider in the embodiment includes three output terminals, namely output terminal Port2, output terminal Port3 and output terminal Port4. Specifically, according to the concept of transmission matrix of the relationship between voltage and current. Figure 8 The relationship between voltage and current in the unequally divided three-way broadband filter power divider is expressed as:

[0131]

[0132] Where θ represents the electrical length (i.e., physical length / operating wavelength), Z n-1 represents the characteristic impedance of the n-1th transmission line, j represents an imaginary number, U0 is the voltage at the input terminal Port1, U1 is the voltage output by the open short-circuit stub 2, I0 is the current at the input terminal Port1, I1 is the current output by the open short-circuit stub 2, U n is the voltage of the output terminal Portn, I na is the current input to the n-1th transmission line, I nbis the current output of the n-1th transmission line, I nc is the current flowing into the isolation network 4 from the output terminal Portn, I (n+1)c is the current input into the isolation network 4 from the output terminal Port(n+1), U n+1 is the voltage of the output terminal Port(n+1), [M1] is the ABCD matrix of the three-wire coupled line 1 and the open short stub 2, and [M2] is the ABCD matrix of the isolation network 4.

[0133] As an example, the power ratio of the unequal three-way broadband filter power divider is specified as k1 2 :k2 2 :k3 2 , the reflection coefficients of the input terminal Port1 and the output terminals Port2 to Port4 should be 0; in order to obtain good isolation parameters, the isolation parameters between the output terminals Port2 to Port4 should be 0. Then the transmission line Z n The characteristic impedance expression is as follows:

[0134]

[0135] Where R T1 is the impedance of input terminal Port1, R Tn is the impedance of the output terminal Port(n), Z e is the even-mode impedance, Z o is the odd-mode impedance, k n is the output power of the nth output terminal.

[0136] Furthermore, the constraint condition of the ABCD matrix [M2] of the isolated network 4 is established. For the isolated network 4, the corresponding ABCD matrix [M2] can be obtained by multiplying the ABCD matrices of the cascaded part. The specific expression is as follows:

[0137]

[0138] Among them, Z mn Represents the isolated transmission line Z mn The characteristic impedance, Z nm Represents the isolated transmission line Z nm characteristic impedance.

[0139] For ease of analysis, the impedance of all terminals is normalized to 1Ω. In order to achieve ideal isolation between terminals, the constraints of the ABCD matrix [M2] of the isolation network 4 are expressed as:

[0140]

[0141] Where k = k m / kn (m, n=2, 3, 4, m≠n).

[0142] In order to make formula (20) equal to formula (21), the relationship between the parameters of the isolation network 4 can be obtained as follows:

[0143]

[0144] Furthermore, the isolated transmission line Z in the isolation network 4 mn , isolated transmission line Z nm , resistor R nm And the resistor R mn The value expression is as follows:

[0145]

[0146] As an example, the power ratio of the non-equally divided three-way broadband filter power divider proposed in this application is set to 13:2:1. Fig. 9 , Fig. 9 Figure (a) shows the magnitude of the proposed unequal three-way broadband filter power divider with a power splitting ratio of 13:2:1 compared with Gysel PDs. It should be noted that Gysel PDs cannot achieve such a high power splitting ratio. Fig. 9 Figure (b) shows the proposed unequally divided three-way broadband filter power divider on different isolation transmission lines Z mn The bandwidth under the value. It can be seen from the figure that as the isolated transmission line Z mn As the value increases, the return loss S 11 The bandwidth will increase. Fig. 9 Figure (c) shows the proposed unequally divided three-way broadband filter power divider on different isolated transmission lines Z F The bandwidth under the value. As can be seen from the figure, when Z F When is smaller, the proposed unequally divided three-way broadband filter power divider can achieve a wider frequency bandwidth.

[0147] Furthermore, for the isolation S between the output terminal Port2 and the output terminal Port3 of the unequally divided three-way broadband filter power divider proposed in this application, 32 , Isolation S between output terminal Port4 and output terminal Port3 34 And the isolation S between output terminal Port2 and output terminal Port4 42 Based on formulas (17a) and (17b), the parameters of the isolated transmission line with an additional isolation network Iso. between any two output terminals are only related to the power ratio of the two output terminals. Fig. 9 , Fig. 9Figures (d)-(f) show the relationship between the resistance R 23 , resistor R 34 and resistor R 24 Isolation S when changing 32 , Isolation S 43 And the isolation S 42 The amplitude of . Fig. 9 As can be seen from Figure (d), the isolation degree S 32 The bandwidth increases with the resistance R 23 The decrease of isolation S 43 and isolation S 42 There is almost no change. And the isolation degree S 43 and isolation S 42 The bandwidth is mainly determined by the resistor R 34 and resistor R 24 Decision. Fig. 9 As shown in Figure (e), the isolation S 43 The bandwidth increases with the resistance R 34 The decrease of isolation S 32 and isolation S 42 There is almost no change. Fig. 9 As shown in Figure (f), the isolation S 42 The bandwidth increases with the resistance R 24 The decrease of isolation S 32 and isolation S 43 There is almost no variation. Therefore, the isolation between any two output terminals can be designed independently.

[0148] As another example, the present application has produced and measured two unequally divided three-way broadband filter power dividers with power distribution ratios of 5:3:2 and 8:1:1. The structure of the unequally divided three-way broadband filter power divider designed by the present application includes two dielectric layers, and the dielectric layers include: a top metal layer and a bottom layer; the top metal layer is a distribution network 3 and an isolation network 4, and the bottom layer is a three-wire coupling line 1 and an open-circuit stub 2. Between the two dielectric layers, there is a metal layer as a common ground layer.

[0149] As an example, see Fig.10 , Fig.10 (a) is a structural diagram of a non-equally divided three-way broadband filter power divider with a power distribution ratio of 5:3:2 designed in this application, please refer to Fig.10 In Figure (b), Fig.10Figure (b) is a physical picture of the non-equally divided three-way broadband filter power divider with a power distribution ratio of 5:3:2 designed in this application. The substrate of the non-equally divided three-way broadband filter power divider designed in this application adopts Rogers 4003C material, which has a thickness of 0.508 mm and a dielectric constant of 3.55. The specific dimensions of the design are determined as follows: W0=1.1, W1=1, W2=0.56, W3=0.49, W23=0.23, W32=0.52W34=0.43, W43=0.15, W24=0.24, W42=0.65, Wt1=0.16, Wt2=0.26, Ws=1.1, WF=1.1, L0=8, L1=24, L2=24.88, L3=25.02, L23 =25.01, L32=24.24, L34=23.87, L43=24.84, L24=25, L42=23.84, Lt=24.28, Ls=41.6, LF=48.34 and St=0.16 (all units are mm), and R23=185, R32=100, R34=100, R43=150, R24=140 and R42=125 (all units are ohms).

[0150] For further information, see Fig.11 , Fig.11 Figures (a)-(c) in the figure show the simulation results and measured results of the non-equally divided three-way broadband filter power divider, which are in good agreement with each other. As for the measured results, the in-band insertion loss of each output terminal is 3±0.4dB, 5.23±0.6dB and 7±0.7dB respectively. Its operating bandwidth can reach 51.57% and the return loss is 15dB. Fig.11 (b) shows the return loss amplitude of the three output terminals, and the in-band return loss is better than 14.5dB. Fig.11 (c) shows the simulated and measured isolation between any two output terminals of the unequally divided three-way broadband filter power divider. Under the definition standard of 20 dB, the measured isolation bandwidths are 80%, 117%, and 118.54%, respectively.

[0151] As another example, for a non-equal three-way broadband filter power divider with a power splitting ratio of 8:1:1, a single open-circuit stub is replaced by three parallel stubs for ease of practical fabrication and optimized performance. Fig.12 , Fig.12 Figure (a) is a structural diagram of a non-equally divided three-way broadband filter power divider with a power distribution ratio of 8:1:1 designed in this application. Fig.12Figure (b) is a physical picture of a non-equally divided three-way broadband filter power divider designed in the present application with a power distribution ratio of 8:1:1. The schematic diagram is etched on a Rogers 4003C substrate with a relative dielectric constant of 3.55 and a thickness of 0.508 mm. Fig.12 The final actual dimensions shown in Figure (a) are as follows: W0 = 1.1, W1 = 1.27, W2 = 0.1, W 23 =0.13,W 32 =0.1.08,W 34 =0.25,W 43 =0.25,W 24 =0.13,W 42 =1.08,W t1 =0.28,W t2 =0.13,W s1 =0.16,W s2 =0.26,L0=8,L1=24,L2=26.34,L 23 =24.87,L 32 =22.73,L 34 =24.88,L 43 =24.88,L 24 =24.87,L 42 =22.73,L t =25.46,L s1 =41.6 and S t =0.14 (all units are in millimeters). The selected chip resistors are R 23 =150,R 32 =75,R 34 =140,R 43 =140,R 24 =150 and R 42 =75 (all units are in ohms).

[0152] For further information, see Fig.13 , Fig.13 Figures (a)-(c) show the simulated and measured S parameters of the fabricated unequally divided three-way broadband filtering power divider. Fig.13 Figure (a) shows the amplitude responses of |S11|, |S21|, |S31| and |S41| respectively. The measured bandwidth can reach 48.45%, and the return loss is greater than 15dB. At the same time, the in-band insertion loss is 0.97+0.6dB and 10+0.5dB respectively, and the out-of-band suppression is better than 20dB. Fig.13 Figure (b) shows the simulated and measured return losses of the output terminals, which are better than 12dB. Fig.13 Figure (c) shows the simulated and measured amplitudes of |S32|, |S42| and |S43|. In terms of isolation, with 20dB as the reference, the measured bandwidth reaches 102%.

[0153] In summary, Table 2 shows in a list the advantages of the non-equal three-way broadband filter power divider with a power distribution ratio of 8:1:1 and the non-equal three-way broadband filter power divider with a power distribution ratio of 5:3:2 proposed in this application and other unequal power dividers. In other related achievements of unequal power dividers, by directly replacing λ / 4 transmission lines, open / short stubs and coupling lines with different electrical lengths, the achievable power distribution ratio of the power divider can be improved, but its operating bandwidth and isolation bandwidth are limited. In addition, in these achievements, the isolation is achieved only by setting a resistor between the two output terminals, which is not applicable to power dividers with multiple distribution branches, and the power capacity is also low.

[0154] Table 2 Comparison with other unequal power distributors

[0155]

[0156] Among them, Proposed I is a unequal three-way broadband filter power divider with a power division ratio of 5:3:2 proposed in this application, Proposed II is a unequal three-way broadband filter power divider with a power division ratio of 8:1:1 proposed in this application, IL is the insertion loss; Iso. is the isolation; PDR is the power division ratio; NA is none; λg is the waveguide wavelength at the center frequency f0; FIWPR is the return loss bandwidth and is independent of the power division ratio; * is the value estimated from the reference.

[0157] In another embodiment of the present application, a design method of a non-equally divided multi-channel broadband filter power divider is proposed, including steps S1 to S4.

[0158] Step S1: Setting the power ratio k1 of the unequally divided multi-channel broadband filter power divider 2 :k2 2 :…:k n 2 ; where k n is the output power of the nth output terminal;

[0159] Step S2: setting the strip width and gap width of the three-wire coupled line 1, and calculating the even-mode impedance and odd-mode impedance of the three-wire coupled line 1; the formulas of the even-mode impedance and odd-mode impedance are expressed as:

[0160] Z e=Z0[1+Z0J+(Z0J) 2 ]; Z o =Z0[1-Z0J+(Z0J) 2 ]

[0161] Among them, Z e is the even-mode impedance, Z o is the odd-mode impedance, J is the susceptance of the three-wire coupled line 1;

[0162] Step S3: Calculate the characteristic impedance of all transmission lines according to the power ratio set in step S1 and the even-mode impedance and the odd-mode impedance calculated in step S2. The expression is as follows:

[0163]

[0164] Among them, Z n is the characteristic impedance of the nth transmission line, R T1 is the impedance of input terminal Port1, R Tn is the impedance of the output terminal Portn, Z e is the even-mode impedance, Z o is the odd-mode impedance, k n is the output power of the nth output terminal, k i is the output power of the i-th output terminal;

[0165] Calculate the value of the isolated transmission line using the following expression:

[0166]

[0167] Among them, Z mn For the isolated transmission line Z mn The characteristic impedance, Z nm For the isolated transmission line Z nm The characteristic impedance, R mn For the isolated transmission line Z mn Connect the resistor R mn , R nm For the isolated transmission line Z nm Connect the resistor R nm , R Tm is the impedance of the output terminal Portm, k m is the output power of the mth output terminal; the value of m is 2, 3, ..., n+1 and m≠n;

[0168] Resistor R mn , resistor R nm The relationship is as follows:

[0169]

[0170] Among them, km is the output power of the mth output terminal.

[0171] As an example, the present application provides a design method for a non-equally divided multi-channel broadband filter power divider, further comprising: Step S4: selecting an isolation transmission line Z according to iterative optimization F The characteristic impedance and resistance R mn value to obtain a wider bandwidth.

[0172] As an example, the bandwidth includes a frequency bandwidth and an isolation bandwidth.

[0173] As an example, the present application provides a design method for a non-equally divided multi-channel broadband filter power divider, further comprising: step S5, performing electromagnetic simulation and optimization on the non-equally divided multi-channel broadband filter power divider.

[0174] The non-equal-division multi-channel broadband filter power divider and design method proposed in the present application, by adding a three-wire coupled line and an open-circuit short-circuit line, calculating the parameters of the three-wire coupled line, the open-circuit short-circuit line and the isolation network, can relax the large impedance requirement of the branch with lower power capacity, and significantly improve the achievable power division ratio of the non-equal-division multi-channel broadband filter power divider. The isolation between any two output terminals can be independently designed to enhance the broadband isolation function, and the return loss and power division ratio of the input terminals in the present application can be independently adjusted. Compared with other non-equal power dividers, no additional impedance transformation part is required at the output terminal.

[0175] Although the present application has been disclosed as above with the embodiments, it is not intended to limit the present application. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be determined by the scope of the attached patent application.

Claims

1. A non-equally divided multi-channel broadband filter power divider, characterized in that: It includes a three-wire coupling line, an open-circuit short stub, a distribution network and an isolation network; the three-wire coupling line, the open-circuit short stub, the distribution network and the isolation network are connected in sequence; The three-wire coupling line includes a first coupling line, a second coupling line and a third coupling line, wherein the first terminal of the first coupling line is connected to the first terminal of the third coupling line and then connected to the input terminal of the non-equally divided multi-channel broadband filter power divider, and the second terminal of the second coupling line is connected to the first terminal of the open-circuit stub and the first terminal of the distribution network; The open stub includes a first stub and a second stub, the first terminal of the first stub is the first terminal of the open stub, and the second terminal of the first stub is connected to the first terminal of the second stub; The distribution network comprises n transmission lines, and first terminals of the n transmission lines are connected to form first terminals of the distribution network; The isolation network includes x isolation modules, and the second terminals of any two transmission lines are connected through one isolation module, wherein the value of x is n(n-1) / 2.

2. The unequally divided multi-channel broadband filtering power divider according to claim 1, characterized in that: The isolation module includes a first isolation transmission line, a second isolation transmission line, a third isolation transmission line, a first resistor and a second resistor, wherein the first terminal of the first isolation transmission line is connected to the second terminal of any one of the two transmission lines, the second terminal of the first isolation transmission line is connected to the first terminal of the first resistor, and the second terminal of the first resistor is grounded; the first terminal of the second isolation transmission line is connected to the second terminal of the other of the two transmission lines, the second terminal of the second isolation transmission line is connected to the first terminal of the second resistor, and the second terminal of the second resistor is grounded; the first terminal of the third isolation transmission line is connected to the series midpoint of the first isolation transmission line and the first resistor, and the second terminal of the third isolation transmission line is connected to the series midpoint of the second isolation transmission line and the second resistor.

3. The unequally divided multi-channel broadband filtering power divider according to claim 2, characterized in that: The second terminal of any one of the transmission lines is an output terminal of the unequally divided multi-channel broadband filter power distributor; the unequally divided multi-channel broadband filter power distributor includes n output terminals.

4. The unequally divided multi-channel broadband filtering power divider according to claim 2, characterized in that: The first isolation transmission line and the second isolation transmission line include quarter-wavelength transmission lines; and the third isolation transmission line includes a half-wavelength transmission line.

5. The unequally divided multi-channel broadband filtering power divider according to claim 1, characterized in that: The first stub and the second stub include half-wavelength stubs.

6. The unequally divided multi-channel broadband filtering power divider according to claim 1, characterized in that: The open stub includes a stepped impedance open stub.

7. A design method for a non-equally divided multi-channel broadband filter power distributor, applied to a non-equally divided multi-channel broadband filter power distributor as claimed in any one of claims 1 to 6, characterized in that: include, Step S1: Setting the power ratio k1 of the unequally divided multi-channel broadband filter power divider 2 :k2 2 :…:k n 2 ; where k n is the output power of the nth output terminal; Step S2: setting the strip width and gap width of the three-wire coupled line, and calculating the even-mode impedance and odd-mode impedance of the three-wire coupled line, the expression is as follows: WITH e =Z0[1+Z0J+(Z0J) 2 ];WITH o =Z0[1-Z0J+(Z0J) 2 ] Among them, Z e is the even-mode impedance, Z o is the odd-mode impedance, J is the susceptance of the three-wire coupled line; Step S3: Calculate the characteristic impedance of all transmission lines according to the power ratio set in step S1 and the even-mode impedance and the odd-mode impedance calculated in step S2. The expression is as follows: Among them, Z n is the characteristic impedance of the nth transmission line, R T1 is the impedance of the first input terminal, R Tn is the impedance of the nth output terminal, Z e is the even-mode impedance, Z o is the odd-mode impedance, k n is the output power of the nth output terminal, k i is the output power of the i-th output terminal; Calculate the value of the isolated transmission line, the expression is as follows: Among them, R Tm is the impedance of the mth output terminal, Z mn is the characteristic impedance of the first isolated transmission line, Z nm is the characteristic impedance of the second isolated transmission line, R mn The first isolated transmission line is connected to a first resistor, R nm A second resistor connected to the second isolated transmission line; the value of m is 2, 3, ..., n+1 and m≠n; The characteristic impedance of the first isolated transmission line, the relationship between the characteristic impedance of the first isolated transmission line and the resistance are obtained, and the expression is as follows: Among them, k m is the output power of the mth output terminal.

8. The design method of the unequally divided multi-channel broadband filtering power divider according to claim 7, characterized in that: Also includes: Electromagnetic simulation and optimization are performed on the unequally divided multi-channel broadband filtering power divider.

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