CN111740201A - High-isolation six-port network based on SIW structure - Google Patents
High-isolation six-port network based on SIW structure Download PDFInfo
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- CN111740201A CN111740201A CN202010548701.4A CN202010548701A CN111740201A CN 111740201 A CN111740201 A CN 111740201A CN 202010548701 A CN202010548701 A CN 202010548701A CN 111740201 A CN111740201 A CN 111740201A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
- H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
- H01P5/18—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers
Abstract
The invention discloses a high-isolation six-port network based on a SIW structure, which comprises: two power dividers with output port phase difference of 0 degree and 90 degrees and two 3dB directional couplers. Two output arms of the power divider are respectively connected with an isolation resistor in a bridging manner, the input ends of the two power dividers are respectively used as two input ports of a six-port network, and two output ends of each power divider are respectively connected with a 3dB directional coupler through a microstrip structure; the coupling end and the straight-through end of the two 3dB directional couplers are used as four output ports of the six-port network. According to the invention, the isolation between the two input ports and the four output ports of the six-port network is improved by connecting the isolation resistors in a cross mode on the two output arms of the power divider, and the problem of local oscillator leakage can be effectively improved. The six-port network has the advantages of simple structure, low loss, better performance, smaller overall circuit size, low cost, low complexity and easiness in integration.
Description
Technical Field
The invention belongs to the field of six-port circuits, and particularly relates to a high-isolation six-port network based on a SIW structure.
Background
Six-port technology has been in development for microwave and millimeter wave measurement applications for the past 30 years. In 1994, a scheme was proposed to apply this technique to a direct digital receiver. Compared with the traditional receiver, the six-port receiver reduces the circuit complexity, can effectively overcome the problem of local oscillator leakage in a receiver system, and is easy to work in a broadband and convenient to integrate, and the whole front-end circuit is completely composed of passive devices except the local oscillator. In addition to the wide use of six-port circuits for measuring complex reflection coefficients, amplitude and phase, and receiver systems, radar systems employing six-port technology have also emerged in recent years. In fact, the six-port radar also utilizes the characteristic that a six-port junction can measure complex reflection coefficients, such as a doppler radar, an accurate positioning radar, an automobile anti-collision radar and the like which adopt a six-port technology. However, the existing six-port circuit has small isolation between output ports, which affects the accuracy of measuring output signals of four ports and reduces the performance of a six-port network. In addition, the existing six-port circuit is complex, large in size and area, and high in loss, so that the performance of the six-port network is reduced.
The substrate integrated waveguide is a kind of artificial integrated new waveguide structure, it is formed from two rows of metal through holes or pins which are linearly and tightly arranged and embedded in same substrate, and possesses many advantages of coplanar circuit structure microstrip line, etc., such as small volume, light weight and convenient for integration and package of modern microwave integrated circuit and monolithic microwave integrated circuit. Meanwhile, compared with the traditional waveguide component part, the structure has low cost and simple processing technology, and can realize a component with high Q value on a common medium substrate, thereby being more suitable for being applied to a high-frequency circuit substrate. Based on this characteristic, various elements can be directly analyzed and designed using SIW. Thus, a system is easily integrated, reducing size, weight and cost, and greatly improving manufacturing repeatability and reliability.
In document 1 (slow light, "SIW six-port optimization design and application research," 2008 "), a six-port structure is designed by using an SIW structure, the center frequency is 10GHz, the six-port structure includes the design of a coupler and a power divider, and a phase shifting structure is adopted, wherein the diameter and the distance of partial metal holes are changed in an HMSIW, so that perturbation is generated on guided wave transmission, and output phase change is realized. The isolation between the two input ports can reach-20 dB near 10GHz, but the isolation between every two output ports is close to-10 dB near the central frequency, so the isolation effect of the output ends is poor.
Document 2(Shui Liu and Feng Xu, "Novel Substrate-Integrated waveguide phase Shifter and Its Application to Six-Port Junction," in IEEE transactions on Microwave Theory and technology, vol.67, No.10, pp.4167-4174, October.2019.) describes a Complementary Split Ring Resonator (CSRR) -loaded Substrate Integrated Waveguide (SIW) phase Shifter and Its Application in a Six-Port Junction, discusses the loading effect of CSRR on physical quantities, and proposes a new HMSIW 90 ° phase Shifter based on the slow wave effect, which is applied to the Six-Port Junction to further reduce the size of the circuit by using the slow wave effect. However, the circuit adopts a multilayer structure, so that the process complexity is increased, and the isolation between two input ports and four output ports is not considered.
Disclosure of Invention
The invention aims to provide a six-port network which has the characteristics of simple structure, good isolation performance of two input ports and four output ports, easiness in integration, low cost and the like.
The technical solution for realizing the purpose of the invention is as follows: a high isolation six-port network based on a SIW architecture, the six-port network comprising: two power dividers with output port phase difference of 0 degree and 90 degrees and two 3dB directional couplers; the input ends of the two power dividers are respectively used as two input ports of a six-port network, and two output ends of each power divider are respectively connected with a 3dB directional coupler through a microstrip structure; and the coupling end and the straight-through end of the two 3dB directional couplers are used as four output ports of the six-port network.
Furthermore, an isolation resistor is connected between the two output ends of the power divider in a bridging manner.
Furthermore, the input end of the power divider adopts a SIW transmission structure, and the output end of the power divider adopts a HMSIW transmission structure.
Furthermore, a row of metal through holes distributed along the metal hole wall of the HMSIW transmission structure are also arranged on the HMSIW transmission structure of the power divider with the output port having a phase difference of 90 °.
Furthermore, the 3dB directional coupler adopts an HMSIW structure, and a windowing hole is arranged on the metal hole wall of the 3dB directional coupler.
Furthermore, the input port and the output port are both connected with a 50 ohm microstrip line through a microstrip gradient line, so that impedance matching is realized.
Furthermore, the power divider, the 3dB directional coupler and the microstrip structure are located on the same layer of dielectric plate.
Further, the power dividers and the couplers are alternately distributed along the circumference.
Furthermore, the power divider and the coupler are alternately and uniformly distributed along the circumference to form a cross structure.
Compared with the prior art, the invention has the following remarkable advantages: 1) the power divider and the 3dB directional coupler both adopt an SIW structure, and meanwhile, an isolation resistor is connected between two output arms of the power divider in a crossing mode, so that the isolation degree between four output ports in the six ports is effectively improved by improving the isolation effect of the output ends of the power divider; 2) the 90-degree phase difference of the power divider is realized by adding metal through holes in the HMSIW structure, and the phase difference is applied to the output end of the power divider, so that the size of a six-port network can be further reduced; 3) the six-port network has the advantages of simple structure, good isolation performance of output ports, easy integration, small volume and low cost.
The present invention is described in further detail below with reference to the attached drawing figures.
Drawings
FIG. 1 is a schematic diagram of a high isolation six-port structure based on a SIW structure in one embodiment.
Fig. 2 is a schematic structural diagram of a power divider with a phase difference of 0 ° at output ends in an embodiment.
Fig. 3 is a schematic structural diagram of a power divider with a phase difference of 90 ° at output ends in an embodiment.
Fig. 4 is a diagram of a 3dB directional coupler structure in one embodiment.
FIG. 5 shows S for a six-port circuit in one embodiment11And S22And (5) a simulation result graph.
FIG. 6 shows S for a six-port circuit in one embodiment21，S64And S53And (5) a simulation result graph.
FIG. 7 is a diagram of transmission coefficient simulation results for a six-port circuit in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In one embodiment, a high isolation six-port network based on a SIW architecture is provided, the six-port network comprising: two power dividers with output port phase difference of 0 degree and 90 degrees and two 3dB directional couplers; the input ends of the two power dividers are respectively used as two input ports (i) and (ii) of a six-port network, namely a radio frequency signal input end and a local oscillation signal input end, and the two output ends of each power divider are respectively connected with a 3dB directional coupler through a microstrip structure; the coupling end and the straight-through end of the two 3dB directional couplers are used as four output ports (tri, tetra, fifthly and sixthly) of the six-port network.
Furthermore, an isolation resistor is connected between the two output ends of the power divider in a bridging manner, so that the isolation between the two output ends of the power divider is improved.
Preferably, the isolation resistors are all 0603 package size.
Further, in one embodiment, the input end of the power divider adopts a SIW transmission structure, and the output end of the power divider adopts an HMSIW transmission structure.
Further, in one embodiment, a row of metal through holes distributed along a metal hole wall of the HMSIW structure is further provided on the HMSIW structure of the power divider having the output port with a phase difference of 90 °, and the HMSIW structure is used as a phase shift structure to realize 90 ° phase shift.
Further, in one embodiment, the 3dB directional coupler adopts an HMSIW structure, compared with an SIW structure, the coupler keeps good performance of a substrate integrated waveguide coupler, and circuit area is saved by half. Furthermore, energy coupling is carried out on the metal hole wall of the HMSIW structure through windowing, power is evenly distributed to the straight-through end and the coupling end of the coupler, and the phase difference between the straight-through end and the coupling end is 90 degrees.
Further, in one embodiment, the input port and the output port are both connected with a 50 ohm microstrip line through a microstrip gradient line, so as to realize impedance matching.
Further, in one embodiment, the power divider, the 3dB directional coupler, and the microstrip structure are located on the same dielectric slab.
Further, in one embodiment, the power dividers and the couplers are alternately distributed along the circumference.
Further preferably, the power dividers and the couplers are alternately and uniformly distributed along the circumference to form a cross structure.
As a specific example, in one embodiment, the high-isolation six-port network based on the SIW structure of the present invention is verified and explained: with reference to fig. 1, the six-port network in this embodiment is a cross structure, in the figure, two power splitters are symmetrically distributed left and right, two 3dB directional couplers are symmetrically distributed up and down, and two output ends of each power splitter are respectively connected to one 3dB directional coupler through a microstrip structure. The four devices are numbered #1, #2, #3, #4, respectively, in the clockwise direction from the left device. The input ports of the power dividers # 1 and #3 are respectively used as two input ports (r) and (r) of the whole six-port network, the coupling end and the straight-through end of the 3dB directional coupler are used as four output ports (r), (v) and (c) of the six-port network, and the other five ports in the clockwise direction are respectively (r), (g), (r), (g), and (v) with the input port (r) as a starting point.
For the power dividers # 1 and #3, the input end of the power divider is Port1, and the two output ports are Port2 and Port3 from top to bottom.
For coupler # 2, the Port in the lower left corner is denoted Port1, the remaining ports in the clockwise direction are Port2, Port3 and Potr4, respectively, for coupler # 4, the Port in the upper right corner is denoted Port1, the remaining ports in the clockwise direction are Port2, Port3 and Potr4, respectively, and ports 1 to Port4 are input, pass-through, coupled and isolated ports, respectively.
When inputting signal a1When the input signal is input into Port1 of the power divider # 1, Port2 and Port3 will output two signals a with equal amplitude and in phase14And a15，a14And a15The signals are respectively input to Port1 of directional coupler # 2 and Port4 of directional coupler # 4, and then two orthogonal signals with equal amplitude are output from ports 2 and 3 of the couplers respectively. When inputting signal a2When the input of Port1 of power divider # 3 is inputted, Port2 and Port3 will output two signals a with equal amplitude and in phase26And a23，a26And a23The signals are respectively input to Port4 of directional coupler # 2 and Port1 of directional coupler # 4, and then two orthogonal signals with equal amplitude are output from ports 2 and 3 of the couplers respectively. Therefore, the scattering parameter matrix of the six-port network is:
in this embodiment, the power divider, the 3dB directional coupler, and the microstrip structure are located on the same dielectric slab, the dielectric slab is Rogers5880, the center frequency is 17.3GHz, the dielectric constant of the dielectric is 2.2, and the thickness of the slab is 0.508 mm.
In this embodiment, as shown in fig. 2, the power divider with 0 ° phase difference at the output end optimally designed by using simulation software HFSS has a distance W between two rows of metal through holes at the input end of 9.3mm, an equivalent width We of the output end HMSIW structure of 4.35mm, a diameter d of the metal through hole of 0.8mm, a distance S between two adjacent metal through holes of 1.2mm, and a 50 Ω microstrip line width W01.5mm, and an isolation resistor R connected between the two output arms2Has a resistance value of 68 omega and a resistance R2Is located at a distance LR2 of 10mm from the junction of the input-side SIW structure and the output-side HMSIW structure.
In this embodiment, as shown in fig. 3, the power divider optimally designed by using simulation software HFSS and having an output end with a phase difference of 90 ° has a distance W between two rows of metal through holes at an input end of the power divider being 9.3mm, an equivalent width We of an output end HMSIW structure being 4.35mm, a diameter d of each metal through hole being 0.8mm, and a distance S between two adjacent metal through holes being 1.2 mm. The phase shift part is composed of a row of metal through holes distributed along the wall of the metal hole of the HMSIW structure, the metal through holes in the row have the phase shift capacity, and the diameter D of the metal through holes in the middle partviaIs 0.76mm, and the center of the through hole is separated from the output arm HMSDistance H of IW structure edgevia2.07mm, the center distance S of the adjacent through holesviaThe thickness is 1.32mm, and the influence of the parameter setting on the phase difference is large; two metal through holes with different sizes from the middle metal through hole are respectively arranged on two sides of the metal through hole, and the diameter D of each through holevia10.4mm, distance H between center of through hole and edge of HMSIW structure of output armvia1Is 1.86mm, and the center distance S of the adjacent through holesvia11.2mm, the loop loss and the isolation performance can be improved by adjusting the parameters of the through holes at the two sides, and the influence on the phase difference is smaller. 50 omega microstrip line width W01.5mm, and an isolation resistor R connected between the two output arms1Has a resistance value of 100 omega and a resistance R1Is located at a distance LR1 of 11mm from the junction of the input-side SIW structure and the output-side HMSIW structure.
In this embodiment, the designed 3dB directional coupler is designed as shown in fig. 4, and the coupler is designed by using an HMSIW structure, wherein the equivalent width W of the HMSIW structuree4.97mm, the coupling distance L between two rows of metal through holes is 16.9mm, the diameter d of the metal through hole is 0.5mm, the central distance S between two adjacent through holes is 1mm, and the 50 omega microstrip line width W0Is 1.5 mm.
The simulation results of the simulation test performed on the six-port circuit of this embodiment are shown in fig. 5 to 9, and fig. 5 is a return loss curve graph of the input port1 and the input port2 obtained by the simulation of the six-port circuit. Fig. 6 is a diagram of isolation between two input ports and four output ports obtained by the simulation of the six-port circuit. Fig. 7 is a diagram of transmission coefficients from two input ports to four output ports obtained by the simulation of the six-port circuit. Fig. 8 is a diagram of output signal phases of the input port1 to the four output ports obtained by the simulation of the six-port circuit. Fig. 9 is a diagram of output signal phases of the input port2 to four output ports obtained by the simulation of the six-port circuit. As can be seen from fig. 5, 6 and 7, at the center frequency, the return loss of both input ports is lower than-20 dB, and the input port isolation (S) is21) Output port isolation (S)53， S64) Are all lower than-20 dB, and have transmission coefficient (S)31-S61，S32-S62) Is-7.1 + -0.5 dB. S11Less than-15 dB, S in the range of 16.2-17.7GHz22Less than-15 dB in the 16-19GHz range and S in the 16-19GHz range21，S53Are all better than-20 dB and are within the range of 16-18.3GHz64Lower than-20 dB. S31And S61Same phase, S51And S41Same phase, S32And S42In phase, the four output ports maintain a phase difference of 90 DEG around the working frequency41And S61The phase difference is 88.2 DEG, S51And S31The phase difference is 88.5 DEG, S32And S52The phase difference is 91.52 DEG, S62And S42The phase difference was 93.3 °. The six-port circuit simulation result described in this embodiment matches with the circuit theoretical analysis result.
In summary, according to the high-isolation six-port network based on the SIW structure provided by the invention, the isolation between the two input ports and the four output ports of the six-port network is improved by connecting the isolation resistors across the two output arms of the power divider, and the problem of local oscillator leakage can be effectively improved. The six-port network has the advantages of simple structure, low loss, better performance, smaller overall circuit size, low cost, low complexity and easiness in integration.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. A high isolation six-port network based on a SIW architecture, the six-port network comprising: two power dividers with output port phase difference of 0 degree and 90 degrees and two 3dB directional couplers; the input ends of the two power dividers are respectively used as two input ports (i) and (ii) of a six-port network, and two output ends of each power divider are respectively connected with a 3dB directional coupler through a microstrip structure; the coupling end and the straight-through end of the two 3dB directional couplers are used as four output ports (tri, tetra, fifthly and sixthly) of the six-port network.
2. The SIW-based high-isolation six-port network of claim 1, wherein an isolation resistor is connected across two output terminals of the power divider.
3. The SIW structure-based high-isolation six-port network according to claim 1, wherein the input end of the power divider adopts an SIW transmission structure, and the output end of the power divider adopts an HMSIW transmission structure.
4. The high-isolation six-port network based on the SIW structure, as recited in claim 3, wherein said HMSIW transmission structure of the power divider with 90 ° phase difference of output ports is further provided with a row of metal through holes distributed along the metal hole wall of the HMSIW transmission structure.
5. The SIW structure-based high-isolation six-port network according to claim 1, wherein the 3dB directional coupler is an HMSIW structure, and a metal hole wall of the HMSIW structure is provided with a window.
6. The SIW structure-based high-isolation six-port network according to claim 1, wherein the input port and the output port are both connected with a 50-ohm microstrip line through microstrip graduations to realize impedance matching.
7. The SIW structure-based high-isolation six-port network according to claim 1, wherein the power divider, the 3dB directional coupler and the microstrip structure are located on the same dielectric slab.
8. The SIW-based fabric high isolation six-port network of claim 1, wherein the power splitters and couplers are circumferentially distributed in an alternating manner.
9. The SIW structure-based high-isolation six-port network is characterized in that the power dividers and the couplers are alternately and uniformly distributed along the circumference to form a cross structure.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112909472A (en) * | 2021-01-14 | 2021-06-04 | 电子科技大学 | TE based on rectangular waveguide20Mode power divider |
| CN114865263A (en) * | 2022-06-08 | 2022-08-05 | 重庆邮电大学 | Millimeter wave filtering power divider with hollow substrate integrated waveguide |
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| FR2301109A1 (en) * | 1975-02-11 | 1976-09-10 | Secr Defence Brit | DIRECTIONAL COUPLER ESPECIALLY FOR POWER DIVIDERS |
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| FR2301109A1 (en) * | 1975-02-11 | 1976-09-10 | Secr Defence Brit | DIRECTIONAL COUPLER ESPECIALLY FOR POWER DIVIDERS |
| CN103762408A (en) * | 2014-02-14 | 2014-04-30 | 大连海事大学 | Micro-strip mixing ring with non-crossed ports |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112909472A (en) * | 2021-01-14 | 2021-06-04 | 电子科技大学 | TE based on rectangular waveguide20Mode power divider |
| CN114865263A (en) * | 2022-06-08 | 2022-08-05 | 重庆邮电大学 | Millimeter wave filtering power divider with hollow substrate integrated waveguide |
| CN114865263B (en) * | 2022-06-08 | 2023-07-25 | 重庆邮电大学 | Hollow substrate integrated waveguide millimeter wave filtering power divider |
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