A multi - transmission zero - pole broadband power divider with high isolation performance

Abstract

The present invention discloses a multi - transmission zero - pole broadband power divider with high isolation performance, comprising: a first port; two second ports; two transmission branches, which are symmetrically arranged; one end of the two transmission branches is simultaneously connected to the first port, and the other ends are respectively connected to the two second ports; the two transmission branches are respectively composed of multiple segments of transmission lines connected in series; two three - section short - circuit stub lines, which are arranged corresponding to the two transmission branches; the three - section short - circuit stub lines are connected to the transmission branches, and the connection positions are close to the first port; two two - section open - circuit stub lines, which are arranged corresponding to the two transmission branches; the two - section open - circuit stub lines are connected to the transmission branches, and the connection positions are close to the first port; two groups of short - circuit stub lines, which are arranged corresponding to the two transmission branches; each group of short - circuit stub lines includes multiple segments of short - circuit stub lines, and the multiple segments of short - circuit stub lines are arranged corresponding to the multiple segments of transmission lines, and the short - circuit stub lines are connected to one end of the transmission line close to the second port.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave radio frequency communication, and particularly relates to a multi-transmission zero-pole broadband power divider with high isolation performance. Background Art

[0002] As an important part of a radio frequency circuit, a power divider can distribute the power input from one port to multiple branches, and is an important microwave passive device.

[0003] In recent years, many broadband filtering power dividers have been proposed, which can achieve the performance of power splitting while realizing filtering to reduce the size of the circuit. Microstrip line and slot line structures, ring resonators, coupled lines and transmission lines with short-circuited stubs and open-circuited stubs can be used to implement broadband power dividers. Currently, the mainstream method for realizing ultra-wideband filtering characteristics is to achieve equal ripple in the passband through Chebyshev polynomials. This method cannot generate out-of-band zeros, and the frequency selectivity and roll-off characteristics of the device are poor. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-transmission zero-pole broadband power divider with high isolation performance, which can achieve equal ripple characteristics in the passband, introduce out-of-band zeros on the premise of ensuring in-band filtering characteristics, and improve the frequency selectivity and roll-off characteristics of the device.

[0005] The technical solution provided by the present invention is as follows:

[0006] A multi-transmission zero-pole broadband power divider with high isolation performance, comprising:

[0007] A first port;

[0008] Two second ports;

[0009] Two transmission branches, which are symmetrically arranged; one ends of the two transmission branches are simultaneously connected to the first port, and the other ends are respectively connected to the two second ports in one-to-one correspondence;

[0010] Wherein, the two transmission branches are respectively composed of multiple segments of transmission lines connected in series;

[0011] Two three-section short-circuited stubs, which are arranged in one-to-one correspondence with the two transmission branches; the three-section short-circuited stubs are connected to the transmission branches, and the connection positions are close to the first port;

[0012] Two two-section open-circuited stubs, which are arranged in one-to-one correspondence with the two transmission branches; the two-section open-circuited stubs are connected to the transmission branches, and the connection positions are close to the first port;

[0013] Two groups of short - circuit stub lines, which are arranged in one - to - one correspondence with the two transmission branches; each group of the short - circuit stub lines includes multiple segments of short - circuit stub lines, and the multiple segments of short - circuit stub lines are arranged in one - to - one correspondence with the multiple segments of transmission lines. The short - circuit stub line is connected to one end of its corresponding transmission line close to the second port;

[0014] Multiple isolation resistors, which are connected across the two transmission branches. The isolation resistors are arranged in one - to - one correspondence with the multiple segments of transmission lines, and the connection positions of the isolation resistors are in one - to - one correspondence with the positions of the short - circuit stub lines.

[0015] Preferably, one end of the three - segment short - circuit stub line is connected to the transmission branch, and the other end is grounded.

[0016] Preferably, one end of the two - segment open - circuit stub line is connected to the transmission branch, and the other end is open - circuited.

[0017] Preferably, the two transmission branches are respectively composed of three segments of transmission lines connected in series.

[0018] Preferably, the electrical length of each segment of the transmission line and each segment of the short - circuit stub line is a quarter - wavelength.

[0019] Preferably, the three - segment short - circuit stub line is composed of two segments of transmission lines and one segment of short - circuit stub line connected in series;

[0020] Among them, the electrical length of each segment of the transmission line and the short - circuit stub line in the three - segment short - circuit stub line is a quarter - wavelength.

[0021] Preferably, the two - segment open - circuit stub line is composed of one segment of transmission line and one segment of open - circuit stub line connected in series;

[0022] Among them, the electrical length of each segment of the transmission line and the open - circuit stub line in the two - segment open - circuit stub line is a quarter - wavelength.

[0023] The beneficial effects of the present invention are as follows:

[0024] The high - isolation multi - transmission zero - pole broadband power divider provided by the present invention can achieve an equi - ripple characteristic in the passband through the cascade of the transmission line and the short - circuit line; by adding three - segment short - circuit stub lines and two - segment open - circuit stub lines, while ensuring the in - band filtering characteristic, out - of - band zeros can be introduced simultaneously, improving the frequency selectivity and roll - off characteristic of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the circuit schematic diagram of the high - isolation multi - transmission zero - pole broadband power divider in the embodiment of the present invention.

[0026] Figure 2This is the circuit schematic diagram of the even-mode analysis of the multi-transmission zero-pole broadband power divider with high isolation performance in the embodiments of the present invention.

[0027] Figure 3 This is the circuit schematic diagram of the odd-mode analysis of the multi-transmission zero-pole broadband power divider with high isolation performance in the embodiments of the present invention.

[0028] Figure 4 This is the structural schematic diagram of the multi-transmission zero-pole broadband power divider with high isolation performance in the embodiments of the present invention.

[0029] Figure 5 This is the S-parameter experimental result diagram of the multi-transmission zero-pole broadband power divider with high isolation performance in the embodiments of the present invention. Detailed implementation manners

[0030] The following further describes the present invention in detail with reference to the accompanying drawings, so that those skilled in the art can implement it according to the description in the specification.

[0031] The present invention provides a multi-transmission zero-pole broadband power divider with high isolation performance. The power divider includes a microstrip circuit of the upper-layer multi-transmission zero-pole broadband power divider, a dielectric substrate in the middle layer, and a full-plane metal grounding layer in the lower layer.

[0032] As Figure 1 shown, the microstrip circuit of the upper-layer multi-transmission zero-pole broadband power divider has an up-and-down symmetric structure, including a first port P1, two up-and-down transmission branches, two up-and-down second ports P2 and P3, two up-and-down three-section short-circuit stub lines USS3 and DSS3, two up-and-down two-section open-circuit stub lines UOS2 and DOS2, two up-and-down groups of short-circuit stub lines, and multiple isolation resistors. Among them, the first port P1 is located at the leftmost end of the circuit, and the two up-and-down second ports P2 and P3 are located at the right end of the circuit and are up-and-down symmetric; the two up-and-down transmission branches are symmetrically arranged. The left ends of the two up-and-down transmission branches are simultaneously connected to the first port P1. The right end of the upper transmission branch is connected to the upper second port P2, and the right end of the lower transmission branch is connected to the lower second port P3; the two up-and-down transmission branches are respectively composed of multiple sections of transmission lines connected in series.

[0033] The two up-and-down three-section short-circuit stub lines USS3 and DSS3 are arranged in one-to-one correspondence with the two up-and-down transmission branches; the upper three-section short-circuit stub line USS3 is connected to the upper transmission branch, and the connection position is close to the first port P1. The lower three-section short-circuit stub line DSS3 is connected to the lower transmission branch, and the connection position is close to the second port P1.

[0034] Two upper and lower two-section open stub lines are provided in one-to-one correspondence with the upper and lower two transmission branches; the two upper-section open stub lines are connected to the upper transmission branch, and the connection position is close to the first port P1; the two lower-section open stub lines are connected to the lower transmission branch, and the connection position is close to the first port P1.

[0035] Two upper and lower groups of short-circuit stub lines are provided in one-to-one correspondence with the upper and lower two transmission branches; each group of short-circuit stub lines includes multiple short-circuit stub lines, and the multiple short-circuit stub lines are provided in one-to-one correspondence with the multiple transmission lines. The short-circuit stub lines are respectively connected to one end of its corresponding transmission line close to the second port.

[0036] Multiple isolation resistors are connected across the two transmission branches. The isolation resistors are provided in one-to-one correspondence with the multiple transmission lines, and the connection positions of the isolation resistors are in one-to-one correspondence with the positions of the short-circuit stub lines.

[0037] In this embodiment, the upper and lower two transmission branches are respectively composed of three transmission lines connected in series. The upper transmission branch is composed of a first upper transmission line UTL1, a second upper transmission line UTL2, and a third upper transmission line UTL3; the lower transmission branch is composed of a first lower transmission line DTL1, a second lower transmission line DTL2, and a third lower transmission line DTL3. Correspondingly, each group of short-circuit stub lines includes three short-circuit stub lines; the upper group of short-circuit stub lines includes: a first upper short-circuit stub line USS1_1, a second upper short-circuit stub line USS1_2, and a third upper short-circuit stub line USS1_3; the lower group of short-circuit stub lines includes: a first lower short-circuit stub line DSS1_1, a second lower short-circuit stub line DSS1_2, and a third lower short-circuit stub line DSS1_3. Correspondingly, the number of isolation resistors is three, which are respectively: a first isolation resistor R1, a second isolation resistor R2, and a third isolation resistor R3.

[0038] The first upper transmission line UTL1, the first lower transmission line DTL1, the second upper transmission line UTL2, the second lower transmission line DTL2, the third upper transmission line UTL3, and the third lower transmission line DTL3 are connected symmetrically up and down in sequence. Among them, the left ends of the first upper transmission line UTL1 and the first lower transmission line DTL1 are simultaneously connected to the first port P1, and the right ends of the third upper transmission line UTL3 and the third lower transmission line DTL3 are respectively connected to the upper second port P2 and the lower third port P3.

[0039] One end of the three upper-section short-circuit stub line USS3 on the upper side is connected to the left end of the first upper transmission line UTL1, and the other end is grounded; one end of the three lower-section short-circuit stub line DSS3 on the lower side is connected to the left end of the first lower transmission line DTL1, and the other end is grounded.

[0040] One end of the two-section open stub line UOS2 on the upper side is connected to the left end of the first upper transmission line UTL1, and the other end is open; one end of the two-section open stub line DOS2 on the lower side is connected to the left end of the first lower transmission line DTL1, and the other end is open.

[0041] One end of the first upper short stub line USS1_1 is connected to the right end of the first upper transmission line UTL1, and the other end is grounded; one end of the first lower short stub line DSS1_1 is connected to the right end of the first lower transmission line DTL1, and the other end is grounded.

[0042] One end of the second upper short stub line USS1_2 is connected to the right end of the second upper transmission line UTL2, and the other end is grounded; one end of the second lower short stub line DSS1_2 is connected to the right end of the second lower transmission line DTL2, and the other end is grounded.

[0043] One end of the third upper short stub line USS1_3 is connected to the right end of the third upper transmission line UTL3, and the other end is grounded; one end of the third lower short stub line DSS1_3 is connected to the right end of the third lower transmission line DTL3, and the other end is grounded.

[0044] The three-section short stub line USS3 on the upper side includes two series-connected transmission lines USS3_1, USS3_2 and a short stub line USS3_3; the three-section short stub line DSS3 on the lower side includes two series-connected transmission lines DSS3_1, DSS3_2 and a short stub line DSS3_3. Among them, one end of USS3_1 is connected to the left end of the first upper transmission line UTL1, and one end of USS3_3 is grounded; one end of DSS3_1 is connected to the left end of the first lower transmission line DTL1, and one end of DSS3_3 is grounded.

[0045] The two-section open stub line UOS2 on the upper side includes a series-connected transmission line UOS2_1 and an open stub line UOS2_2; the two-section open stub line DOS2 on the lower side includes a series-connected transmission line DOS2_1 and an open stub line DOS2_2. Among them, one end of UOS2_1 is connected to the left end of the first upper transmission line UTL1, and one end of UOS2_2 is grounded; one end of DOS2_1 is connected to the left end of the first lower transmission line DTL1, and one end of DOS2_2 is grounded.

[0046] The first isolation resistor R1, the second isolation resistor R2 and the third isolation resistor R3 are connected across the upper and lower two transmission branches of the circuit. Among them, the two ends of the first isolation resistor R1 are respectively connected to the right ends of the first upper transmission line UTL1 and the first lower transmission line DTL1, the two ends of the second isolation resistor R2 are respectively connected to the right ends of the second upper transmission line UTL2 and the second lower transmission line DTL2, and the two ends of the third isolation resistor R3 are respectively connected to the right ends of the third upper transmission line UTL3 and the third lower transmission line DTL3.

[0047] The electrical lengths of the first upper transmission line UTL1, the first lower transmission line DTL1, the first upper short-circuit stub USS1_1, the first lower short-circuit stub DSS1_1, the second upper transmission line UTL2, the second lower transmission line DSS2, the second upper short-circuit stub USS1_2, the second lower short-circuit stub DSS1_2, the third upper transmission line UTL3, the third lower transmission line DTL3, the third upper short-circuit stub USS1_3, and the third lower short-circuit stub DSS1_3 are all one-quarter wavelength.

[0048] The electrical lengths of the transmission lines USS3_1, USS3_2 and the short-circuit stub USS3_3 included in the three-section short-circuit stub USS3 on the upper side, and the transmission lines DSS3_1, DSS3_2 and the short-circuit stub DSS3_3 included in the three-section short-circuit stub DSS3 on the lower side are all one-quarter wavelength.

[0049] The electrical lengths of the transmission line UOS2_1 and the open-circuit stub UOS2_2 included in the two-section open-circuit stub UOS2 on the upper side, and the transmission line DOS2_1 and the open-circuit stub DOS2_2 included in the two-section open-circuit stub DOS2 on the lower side are both one-quarter wavelength.

[0050] The even- and odd-mode equivalent circuits of the power divider in this embodiment are as Figures 2 - 3 shown, and the electrical lengths of all the transmission lines and stub lines are 90°.

[0051] According to Figure 2 the even-mode analysis circuit schematic diagram of the multi-transmission zero-pole broadband power divider with high isolation performance shown, the input impedances Z ine1 , Z ine2 , Z ine3 , Z ine4 , Z ine5 , Z ine6 :

[0052] Z ine1 = jZ S11 (-Z S12 / tanθ + Z S11 tanθ) / (Z S12 + Z S11 )

[0053]

[0054] Z ine3 = 2||Z ine1 ||Z ine2

[0055] Z ine4 = Z1(Z ine3+jZ1tanθ) / (Z1+jZ ine3 tanθ)||jZ S3 tanθ

[0056] Z ine5 =Z2(Z ine4 +jZ2tanθ) / (Z2+jZ ine4 tanθ)||jZ S4 tanθ

[0057] Z ine6 =Z3(Z ine5 +jZ3tanθ) / (Z3+jZ ine5 tanθ)||jZ S5 tanθ

[0058] Thus, the even-mode reflection coefficient Γ e and S 11 :

[0059] S 11 =Γ e

[0060] Γ e =(Z ine6 -1) / (Z ine6 +1)

[0061] where Z ine1 is the input impedance of two-section open stub lines (UOS2 / DOS2); Z ine2 is the input impedance of three-section short stub lines (USS3 / DSS3); Z ine3 is the input impedance of the first-port load in parallel with two-section open stub lines (UOS2 / DOS2) and three-section short stub lines (USS3 / DSS3); Z ine4 is the input impedance of the first-port load in parallel with two-section open stub lines (UOS2 / DOS2), three-section short stub lines (USS3 / DSS3), series-connected with the first transmission line (UTL1 / DTL1), and in parallel with the first short stub line (USS1_1 / DSS1_1); Z ine5 is the input impedance of the first-port load in parallel with two-section open stub lines (UOS2 / DOS2), three-section short stub lines (USS3 / DSS3), series-connected with the first transmission line (UTL1 / DTL1), in parallel with the first short stub line (USS1_1 / DSS1_1), series-connected with the second transmission line (UTL2 / DSS2), and in parallel with the second short stub line (USS1_2 / DSS1_2); Z ine6The input impedance is obtained by connecting two open - stub lines (UOS2 / DOS2) in parallel to the first - port load, three short - stub lines (USS3 / DSS3) in parallel, a first transmission line (UTL1 / DTL1) in series, a first short - stub line (USS1_1 / DSS1_1) in parallel, a second transmission line (UTL2 / DSS2) in series, a second short - stub line (USS1_2 / DSS1_2) in parallel, a third transmission line (UTL3 / DSS3) in series, and a third short - stub line (USS1_3 / DSS1_3) in parallel.

[0062] According to Figure 3 the odd - mode analysis circuit schematic diagram of the multi - transmission zero - pole broadband power divider with high isolation performance shown, the input impedance Z ino1 , Z ino2 , Z ino3 :

[0063] Z ino1 = jZ1tanθ || jZ S3 tanθ || R1 / 2

[0064] Z ino2 = Z2(Z ino1 + jZ2tanθ) / (Z2 + jZ ino1 tanθ) || jZ S4 tanθ || R2 / 2

[0065] Z ino3 = Z3(Z ino2 + jZ3tanθ) / (Z3 + jZ ino2 tanθ) || jZ S5 tanθ || R3 / 2

[0066] Thus, the even - mode reflection coefficient Γ o and S 22 , S 33 , S 32 :

[0067] Γ o =(Z ino3 - 1) / (Z ino3 + 1)

[0068] S 22 = S 33 =(Γ e + Γ o ) / 2

[0069] S 32 =(Γ e - Γ o ) / 2

[0070] Among them, Z ino1 is the input impedance of the load at the first port, which is in series with the first transmission line (UTL1 / DTL1), in parallel with the first short-circuit stub line (USS1_1 / DSS1_1), and in parallel with half of the first isolation resistor (R1); Z ino2 is the input impedance of the load at the first port, which is in series with the first transmission line (UTL1 / DTL1), in parallel with the first short-circuit stub line (USS1_1 / DSS1_1), in parallel with half of the first isolation resistor (R1), in series with the second transmission line (UTL2 / DSS2), in parallel with the second short-circuit stub line (USS1_2 / DSS1_2), and in parallel with half of the second isolation resistor (R2); Z ino3 is the input impedance of the load at the first port, which is in series with the first transmission line (UTL1 / DTL1), in parallel with the first short-circuit stub line (USS1_1 / DSS1_1), in parallel with half of the first isolation resistor (R1), in series with the second transmission line (UTL2 / DSS2), in parallel with the second short-circuit stub line (USS1_2 / DSS1_2), in parallel with half of the second isolation resistor (R2), in series with the third transmission line (UTL3 / DSS3), in parallel with the third short-circuit stub line (USS1_3 / DSS1_3), and in parallel with half of the third isolation resistor (R3).

[0071] Z S11 and Z S12 are the characteristic impedances of UOS2_1 (DOS2_1) and UOS2_2 (DOS2_2) in the two open-circuit stub lines respectively, and Z S21 、Z S22 and Z S23 are the characteristic impedances of the three short-circuit stub lines USS3_1 (DSS3_1), USS3_2 (DSS3_2) and USS3_3 (DSS3_3) respectively, which can provide additional transmission zeros to enhance the out-of-band rejection performance of the stopband. R1, R2, and R3 are isolation resistors used for isolation in the passband. All electrical lengths θ are 90° at the center frequency.

[0072] To further illustrate the present invention, the equal-ripple level in the passband is controlled to -20 dB as a constraint condition and substituted into the reflection coefficient relationship to obtain the circuit parameters, thus obtaining the embodiments of the present invention. As Figure 4As shown, in this embodiment, the characteristic impedance values of the first port, the upper second port, and the lower second port are all normalized to 1Ω. The width of the first upper (lower) transmission line is 0.43mm, the width of the second upper (lower) transmission line is 0.93mm, the width of the third upper (lower) transmission line is 1.28mm, the width of the first upper (lower) short-circuit stub line is 3.81mm, the width of the second upper (lower) short-circuit stub line is 4.76mm, and the width of the third upper (lower) short-circuit stub line is 3.15mm. The width of the series transmission line in the two open-circuit stub lines on the upper (lower) side is 0.29mm, and the width of the series open-circuit stub line is 3.73mm. The width of the first series transmission line (USS3_1, DSS3_1) in the three short-circuit stub lines on the upper (lower) side is 0.13mm, the width of the second series transmission line (USS3_2, DSS3_2) is 4.9mm, and the width of the third series short-circuit stub line (USS3_3, DSS3_3) is 0.67mm. Among them, there is a through hole with a diameter of 0.5mm grounded at the end of the third series short-circuit stub line (USS3_3, DSS3_3).

[0073] Figure 5 This is the S-parameter test result diagram of the multi-transmission zero-pole broadband power divider with high isolation performance in this embodiment. It can be seen that within the passband of the power divider, the performances of S11, S22, and S32 are excellent, respectively below -15.1dB, -11.1dB, and -10.1dB. The working bandwidth of the power divider is wide, and 4 transmission zeros are generated outside the band, improving the roll-off characteristic and frequency selectivity of the power divider.

[0074] The present invention provides a multi-transmission zero-pole broadband power divider with high isolation performance. Through the cascade of transmission lines and short-circuit lines, the equal-ripple characteristic within the passband can be achieved. The addition of three short-circuit stub lines and two open-circuit stub lines can introduce out-of-band zeros while ensuring the in-band filtering characteristic, improving the frequency selectivity and roll-off characteristic of the device.

[0075] Although the embodiments of the present invention have been disclosed as above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated examples here.

Claims

1. A multi - transmission zero - pole broadband power divider with high isolation performance, characterized in that, Comprising: A first port; Two second ports; Two transmission branches, symmetrically arranged; One end of the two transmission branches is simultaneously connected to the first port, and the other ends are respectively connected to the two second ports; Wherein, the two transmission branches are respectively composed of multiple segments of transmission lines connected in series; Two three-section short-circuit stub lines, arranged corresponding to the two transmission branches; The three-section short-circuit stub lines are connected to the transmission branches, and the connection positions are close to the first port; Wherein, one end of the three-section short-circuit stub line is connected to the transmission branch, and the other end is grounded; Two two-section open-circuit stub lines, arranged corresponding to the two transmission branches; The two-section open-circuit stub lines are connected to the transmission branches, and the connection positions are close to the first port; Wherein, one end of the two-section open-circuit stub line is connected to the transmission branch, and the other end is open-circuited; Two groups of short-circuit stub lines, arranged corresponding to the two transmission branches; Each group of the short-circuit stub lines includes multiple segments of short-circuit stub lines, and the multiple segments of short-circuit stub lines are arranged corresponding to the multiple segments of transmission lines, and the short-circuit stub lines are connected to one end of the corresponding transmission line close to the second port; Multiple isolation resistors, bridging between the two transmission branches, the isolation resistors are arranged corresponding to the multiple segments of transmission lines, and the connection positions of the isolation resistors are corresponding to the positions of the short-circuit stub lines.

2. The multi-transmission zero-pole broadband power divider with high isolation performance according to claim 1, characterized in that, The two transmission branches are respectively composed of three segments of transmission lines connected in series.

3. The multi-transmission zero-pole broadband power divider with high isolation performance according to claim 2, characterized in that, The electrical length of each segment of the transmission line and each segment of the short-circuit stub line is one-quarter wavelength.

4. The multi-transmission zero-pole broadband power divider with high isolation performance according to claim 2 or 3, characterized in that, The three-section short-circuit stub line is composed of two segments of transmission lines and one segment of short-circuit stub line connected in series; Wherein, the electrical length of each segment of transmission line and short-circuit stub line in the three-section short-circuit stub line is one-quarter wavelength.

5. The multi-transmission zero-pole broadband power divider with high isolation performance according to claim 4, wherein The two-section open-circuit stub line is composed of one segment of transmission line and one segment of open-circuit stub line connected in series; Wherein, the electrical length of each segment of transmission line and open-circuit stub line in the two-section open-circuit stub line is one-quarter wavelength.

Images