Reconfigurable low-coupling dual-mode transmission line

Abstract

According to the reconfigurable low-coupling dual-mode transmission line provided by the invention, the transmission line can support the transmission of orthogonal dual-mode electromagnetic waves, and the transmission line has a reconfigurable function by integrating the diodes into the transmission line structure. The transmission line is provided with three metal layers, media are filled among the metal layers, the metal layers are connected through conductive through holes, diodes are welded on the metal layers, and transmission modes of the transmission line can be switched among a dual-mode state, an odd-mode state, an even-mode state and a cut-off state by controlling bias voltage of the diodes, so that electromagnetic wave transmission characteristics can be freely regulated and controlled. Due to the fact that the transmitted dual-mode electromagnetic waves are mutually orthogonal, the transmission line can have lower crosstalk when transmitting multiple paths of signals, the coupling degree of the transmission line can be reduced along with increase of the transmission distance, and the transmission line has the advantages of multi-mode transmission, reconfiguration, low coupling and high integration level. And a signal transmission scheme can be provided for a high-integration-level and multifunctional system.

Description

Technical Field

[0001] The invention relates to a low-coupling microwave transmission line technology, which is used for realizing a low-coupling, lossless microwave transmission line for transmitting multi-path signals in an integrated system, and belongs to the field of microwave devices and new artificial electromagnetic materials. Background Art

[0002] With the rapid development of information technology today, the system has higher and higher requirements for transmitting large-capacity information, which requires integrating more signal transmission channels in a smaller system space. The microstrip line structure commonly used in transmitting signals in current microwave systems has weak field binding ability. When the system develops towards high integration and the space becomes smaller and smaller, adjacent microstrip lines are prone to crosstalk, resulting in signal distortion. Therefore, the traditional microstrip line structure is not conducive to use in the design of high-integration microwave systems.

[0003] To solve the above problems, scholars have proposed artificial surface plasmon structures that can simulate the characteristics of surface plasmon structures. Surface plasmons are surface electromagnetic wave modes that exist at the junction of metals and dielectrics in the optical frequency band. The propagation of surface plasmon modes in the direction perpendicular to the interface decays exponentially, so the mode has strong field binding. In the microwave or terahertz frequency band, surface plasmons are difficult to propagate on the metal surface because metals have the characteristics of ideal conductors. To address this problem, scholars have proposed using a variety of metamaterial structures to simulate surface plasmon modes in the microwave terahertz band. Among the many artificial surface plasmon metamaterial structures, the ultra-thin comb-shaped metal strip structure has become a hot topic in this direction because it is compatible with modern integrated circuit processes. Compared with traditional microstrip lines, artificial surface plasmon transmission lines have the advantages of low crosstalk and easy conformality, so they can be used in highly integrated microwave terahertz circuit systems. However, although the general artificial surface plasmon structure can greatly reduce the crosstalk between lines compared to microstrip lines, its transmission electromagnetic wave mode is single-mode transmission like the microstrip line, and the space occupancy still needs to be reduced. In addition, both artificial surface plasmon transmission lines and microstrip lines have the problem of increased inter-line coupling as the length of the transmission line increases. Therefore, how to further reduce the crosstalk of multi-channel signal transmission in integrated circuits and further reduce the space occupancy of transmission lines is still a valuable research issue. Summary of the invention

[0004] Technical problem: To solve the existing problems, the present invention provides a reconfigurable low-coupling dual-mode transmission line, which can transmit dual-mode electromagnetic waves with a lower coupling degree and has the characteristics of reconfigurability. Compared with traditional microstrip lines and artificial surface plasmon transmission lines, it has the advantages of low coupling, high integration, and flexible controllability, and has a high application prospect in practice.

[0005] Technical solution: The present invention proposes a reconfigurable low-coupling dual-mode transmission line, the main body of which is composed of a plurality of reconfigurable low-coupling dual-mode transmission line units connected in series, each of which is arranged in a straight line and is located in the middle of the overall structure of the transmission line, wherein each transmission line unit includes a five-layer structure, namely, three metal layers and two dielectric layers, and the order of the layers is top metal layer unit, first dielectric layer, middle metal layer unit, second dielectric layer, and bottom metal layer unit; the top metal layer unit and the bottom metal layer unit are connected to the middle metal layer unit through metal through holes, respectively; the overall layered structure of the transmission line is composed of three metal layers and two dielectric layers, like the transmission line unit, wherein the top metal layer includes a plurality of top metal layers The units are connected in series, and an upper feeding structure and an upper bias circuit structure are provided at both ends; the middle metal layer includes the plurality of middle metal layer units connected in series, and a circular hole structure is provided at both ends; the bottom metal layer includes the plurality of bottom metal layer units connected in series, and a lower feeding structure and a lower bias circuit structure are provided at both ends; in order to excite electromagnetic waves of two modes, two independent input ports and two independent output ports are provided, wherein the first input port and the first output port are connected to the upper feeding structure on the top metal layer unit through a 50Ω microstrip line, for exciting even-mode electromagnetic waves; the second input port and the second output port are placed on the bottom metal layer and connected to the lower feeding structure, and the transmission of odd-mode electromagnetic waves is excited through the transition of the slotted structure in the middle metal layer unit.

[0006] The top metal layer unit in the transmission line unit includes a microstrip line structure, a first top metal patch, a second top metal patch, a third top metal patch, and a fourth top metal patch symmetrically connected in parallel on both sides of the microstrip line structure, a first varactor diode connected between the first top metal patch and the second top metal patch, and a second varactor diode connected between the third top metal patch and the fourth top metal patch.

[0007] The middle metal layer unit in the transmission line unit is a metal ground, and a slot structure is provided in the middle of the middle metal layer unit along the signal transmission direction.

[0008] The bottom metal layer unit in the transmission line unit is provided with a first bottom metal patch, a second bottom metal patch, and a third bottom metal patch. The three bottom metal patches are arranged in a "U shape", and a first PIN diode is connected between the first bottom metal patch and the second bottom metal patch, and a second PIN diode is connected between the second bottom metal patch and the third bottom metal patch.

[0009] The first top metal patch of the top metal layer unit and the first bottom metal patch of the bottom metal layer unit are connected to the middle metal layer unit through metal through holes; the fourth top metal patch of the top metal layer unit and the third bottom metal patch of the bottom metal layer unit are connected to the middle metal layer unit through metal through holes.

[0010] In the transmission line, microstrip line structures in a plurality of series-connected reconfigurable low-coupling dual-mode transmission line units are connected in series.

[0011] The second top metal patch and the third top metal patch are in a zigzag shape and are respectively connected to the microstrip line structure.

[0012] By controlling the bias of the first and second varactor diodes in the top metal layer unit and the on and off of the first and second PIN diodes in the bottom metal layer unit, the transmission mode of the transmission line is switched among dual mode, odd mode, even mode and cut-off state.

[0013] When the transmission line works in the dual-mode transmission mode, two independent signals are transmitted, and the more transmission line units there are, that is, the longer the transmission line is, the higher the isolation between the two signals is.

[0014] .The reconfigurable low-coupling dual-mode transmission line according to claim 1 is characterized in that the material of the first dielectric layer and the second dielectric layer is Rogers RO4003 substrate.

[0015] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0016] 1. The present invention can realize dual-mode transmission of electromagnetic waves, effectively improving the information transmission capacity.

[0017] 2. The present invention can flexibly control the transmitted electromagnetic waves through diodes and has a reconfigurable function.

[0018] 3. The present invention can occupy less space when transmitting multi-channel signals compared with traditional single-mode transmission lines.

[0019] 4. The dual-mode signal transmitted by the present invention has a lower coupling degree, and the coupling degree can be further reduced as the length of the transmission line increases. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a structural diagram of a reconfigurable low-coupling dual-mode transmission line unit; a is a mechanical structure diagram, and b is a three-layer plan view. In the figure, V1 is the voltage loaded on the microstrip line, V2 is the voltage loaded on the metal ground and the metal patch connected to the metal through hole, V3 is the voltage loaded on the metal patch on the bottom metal layer that is not connected to the metal through hole, a1, a3, a4 are the widths of different metal patches, a2 is the width of the microstrip line, b1, b2, b3, b4 are the lengths of different metal patches, c1, c3, c4 are the distances between different metal patches, c2 is the width of the slot on the metal ground, z x is the length of the meander structure in the metal patch, z yis the width of the meander structure in the metal patch, r1 is the radius of the metal through hole, and p is the total length of the unit.

[0021] Figure 2 is the dispersion curve of the reconfigurable low-coupling dual-mode transmission line unit when it works in the dual-mode transmission state;

[0022] Figure 3 The figure is a schematic diagram of the overall structure of the reconfigurable low-coupling transmission line; the upper part is a schematic diagram of the top metal layer structure, the middle part is a schematic diagram of the middle metal layer structure, and the lower part is a schematic diagram of the bottom metal layer structure. In the figure, w1, w2, w3, w4, and w5 are the widths of different microstrip lines, l1, l2, l3, and l4 are the lengths of different microstrip lines, r2 and r5 are the radii of different circular patch structures, r4 is the radius of the circular hole in the metal ground, and r3 and r6 are the radii of the fan-shaped structure in the bias circuit.

[0023] Figure 4 It is the S parameter of the simulated and measured reconfigurable low-coupling dual-mode transmission line transmitting even-mode electromagnetic waves.

[0024] Figure 5 It is the simulated and measured S-parameter of the odd-mode electromagnetic wave transmitted by the reconfigurable low-coupling dual-mode transmission line.

[0025] The figure includes: a top metal layer unit 1, an upper feeding structure 11, an upper bias circuit structure 12, a microstrip line structure 1.1, a first top metal patch 1.2, a second top metal patch 1.3, a third top metal patch 1.4, a fourth top metal patch 1.5, a first varactor diode 1.6, a second varactor diode 1.7, a first input port 1.8, and a first output port 1.9;

[0026] Intermediate metal layer unit 2, circular hole structure 21, slotted structure 2.1;

[0027] Bottom metal layer unit 3, bottom feeding structure 31, bottom bias circuit structure 32, first bottom metal patch 3.1, second bottom metal patch 3.2, third bottom metal patch 3.3, first PIN diode 3.4, second PIN diode 3.5, second input port 3.6, second output port 3.7;

[0028] A first dielectric layer 4 , a second dielectric layer 5 , and a metal through hole 6 . DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific examples;

[0030] The main body of the reconfigurable low-coupling dual-mode transmission line of the present invention is composed of a plurality of reconfigurable low-coupling dual-mode transmission line units connected in series, wherein the transmission line units are arranged in a straight line and are located in the middle of the overall structure of the transmission line, wherein each transmission line unit includes a five-layer structure, namely, three metal layers and two dielectric layers, and the order of the interlayer arrangement is a top metal layer unit 1, a first dielectric layer 4, an intermediate metal layer unit 2, a second dielectric layer 5, and a bottom metal layer unit 3; the top metal layer unit 1 and the bottom metal layer unit 3 are respectively connected to the intermediate metal layer unit 2 through a metal through hole 6; the overall layered structure of the transmission line is composed of three metal layers and two dielectric layers like the transmission line unit, wherein the top metal layer includes a plurality of top metal layer units 1 connected in series, and an upper feed structure 11 and an upper bias structure 12 are provided at both ends. A circuit structure 12 is provided; the middle metal layer includes the plurality of middle metal layer units 2 connected in series, and circular hole structures 21 are provided at both ends; the bottom metal layer includes the plurality of bottom metal layer units 3 connected in series, and a lower feeding structure 31 and a lower bias circuit structure 32 are provided at both ends; in order to excite electromagnetic waves of two modes, two independent input ports and two independent output ports are provided, wherein the first input port 1.8 and the first output port 1.9 are connected to the upper feeding structure 11 on the top metal layer unit 1 through a 50Ω microstrip line, for exciting even-mode electromagnetic waves; the second input port 3.6 and the second output port 3.7 are placed on the bottom metal layer 3 and connected to the lower feeding structure 31, and the transmission of odd-mode electromagnetic waves is excited through the transition of the slotted structure 2.1 in the middle metal layer unit 2.

[0031] In the three-layer metal layer structure, the top metal layer unit 1 and the middle metal layer unit 2 are the main structures supporting dual-mode electromagnetic wave transmission, and the bottom metal layer unit 3 is mainly used to load the bias voltage to control the diode. The top metal layer unit 1 and the bottom metal layer unit 3 are connected by a metal through hole through the middle metal layer unit 2.

[0032] The top metal layer 1 in the transmission line unit includes a microstrip line structure 1.1, a first top metal patch 1.2, a second top metal patch 1.3, a third top metal patch 1.4, and a fourth top metal patch 1.5 which are symmetrically connected in parallel on both sides of the microstrip line structure 1.1, a first varactor diode 1.6 is connected between the first top metal patch 1.2 and the second top metal patch 1.3, and a second varactor diode 1.7 is connected between the third top metal patch 1.4 and the fourth top metal patch 1.5.

[0033] The middle metal layer 2 in the transmission line unit is a metal ground, and a slot structure 2.1 is provided in the middle of the middle metal layer 2 along the signal transmission direction.

[0034] The bottom metal layer 3 in the transmission line unit is provided with a first bottom metal patch 3.1, a second bottom metal patch 3.2, and a third bottom metal patch 3.3. The three bottom metal patches are arranged in a "U shape", and a first PIN diode 3.4 is connected between the first bottom metal patch 3.1 and the second bottom metal patch 3.2, and a second PIN diode 3.5 is connected between the second bottom metal patch 3.2 and the third bottom metal patch 3.3.

[0035] The first top metal patch 1.2 of the top metal layer 1 and the first bottom metal patch 3.1 of the bottom metal layer 3 are connected to the middle metal layer 2 through a metal through hole 6; the fourth top metal patch 1.5 of the top metal layer 1 and the third bottom metal patch 3.3 of the bottom metal layer 3 are connected to the middle metal layer 2 through a metal through hole 6. In the transmission line, the microstrip line structures 1.1 in the multiple series-connected reconfigurable low-coupling dual-mode transmission line units are connected in series. The second top metal patch 1.3 and the third top metal patch 1.4 are in a zigzag shape and are connected to the microstrip line structure 1.1 respectively. By controlling the bias of the first varactor diode 1.6 and the second varactor diode 1.7 in the top metal layer 1 and the on-off of the first PIN diode 3.4 and the second PIN diode 3.5 in the bottom metal layer unit 3, the transmission mode of the transmission line is switched between dual mode, odd mode, even mode and cut-off state.

[0036] The more the number of the plurality of series-connected reconfigurable low-coupling dual-mode transmission line units is, the stronger the field binding capability is.

[0037] The reconfigurable low-coupling dual-mode transmission line unit has a microstrip line in the top metal layer unit 1 loaded with a voltage V1, a patch in the top metal layer unit 1 and the bottom metal layer unit 3 connected by a metal through hole loaded with a voltage V2, and an independent patch in the bottom metal layer unit 3 loaded with a voltage V3. The capacitance of the varactor diode can be controlled by a bias voltage (V1-V2), and the on-off of the PIN diode can be controlled by a bias voltage (V2-V3). By flexibly changing the bias voltage, the transmission line can operate in single odd-mode transmission, single even-mode transmission, dual-mode transmission and cut-off states.

[0038] The dielectric layer material is Rogers RO4003 substrate, and its thicknesses are t1 and t2 respectively. The more the number of the multiple series-connected reconfigurable low-coupling dual-mode transmission line units is, the stronger the field binding capability is.

[0039] The specific structure of the reconfigurable low-coupling dual-mode transmission line unit is as follows: Figure 1As shown, the unit period p = 8mm, the patch width a1 = 0.4mm in the top metal layer unit 1, the patch length b1 = 0.6mm, b2 = 0.8mm, the patch gap c1 = 0.2mm, the microstrip line width a2 = 0.16mm, and the meandering structure length z between the patch and the microstrip line x =0.6mm, width z y =0.14mm, metal through hole radius r1 =0.15mm. In the bottom metal layer unit 3, the patch width a3 =0.66mm, a4 =1.8mm, the patch length b3 =0.9mm, b4 =1mm, and the patch gap c3 =0.48, c4 =0.2mm.

[0040] The operating frequency of the transmission line is set to 4GHz. When the diode is in different states, the reconfigurable low-coupling dual-mode transmission line can transmit electromagnetic waves of different modes. When the voltage of the varactor diode is 0.2pF and the PIN diode is disconnected, the transmission line can operate in a dual-mode transmission state; when the voltage of the varactor diode is 0.6pF and the PIN diode is disconnected, the transmission line unit can only support odd-mode electromagnetic wave transmission; when the capacitance of the varactor diode is 0.2pF and the PIN diode is turned on, the transmission line unit can only support even-mode electromagnetic wave transmission; when the capacitance of the varactor diode is 0.6pF and the PIN diode is turned on, the transmission line unit is in a cut-off state and cannot transmit electromagnetic waves. In the dual-mode working state, the dispersion curve of the reconfigurable low-coupling dual-mode transmission line unit is as follows: Figure 2 shown.

[0041] Feeding method and bias circuit for reconfigurable low-coupling dual-mode transmission line Figure 3As shown, in order to excite two modes of electromagnetic waves, two independent input and two independent output ports are required. The first input port 1.8 and the first output port 1.9 are connected to the transmission line on the top metal layer unit 1 through a 50Ω microstrip line to excite even-mode electromagnetic waves; the second input port 3.6 and the second output port 3.7 are placed on the bottom metal layer unit 3 to excite the transmission of odd-mode electromagnetic waves through the transition of the slot structure in the middle metal layer unit 2. The width of the 50Ω microstrip line w1 = 1.8mm, due to the circular hole in the middle metal layer unit 2, a circular structure is added to the 50Ω feed line for impedance matching, the radius of the circular structure r2 = 1.5mm, the radius of the circular hole r4 = 1.5mm, the width of the feed line connected to the port in the bottom metal layer unit 3 w3 = 0.45mm, the distance between the end of the feed line and the metal patch l3 = 6mm, and the radius of the circular structure at the end of the feed line r5 = 1.5mm. The length of the bias circuit line in the top metal layer unit 1 is l2 = 13mm, the width is w2 = 0.2mm, and the radius of the fan-shaped patch is r3 = 8mm. The length of the bias circuit line in the bottom metal layer unit 3 is l4 = 13mm, the width is w4 = 0.2mm, the radius of the fan-shaped patch is r6 = 8mm, and the line width connecting each patch is w5 = 0.16mm.

[0042] The simulation and measured results of the transmission line structure formed by 40 units in series are shown in Figure 4 and Figure 5 As shown, at the operating frequency of 4 GHz, the insertion loss of the overall structure for even and odd modes is higher than -1.37 dB, and the isolation is less than -35 dB, indicating that the transmission line can maintain a high isolation when transmitting two signals.

Claims

1. A reconfigurable low-coupling dual-mode transmission line, characterized in that: The transmission line body is composed of a plurality of reconfigurable low-coupling dual-mode transmission line units connected in series. The transmission line units are arranged in a straight line and are located in the middle of the overall structure of the transmission line. Each transmission line unit includes a five-layer structure, namely, three metal layers and two dielectric layers. The order of the layers is top metal layer unit (1), first dielectric layer (4), middle metal layer unit (2), second dielectric layer (5), and bottom metal layer unit (3). The top metal layer unit (1) and the bottom metal layer unit (3) are connected to the middle metal layer unit (2) through metal through holes (6), respectively. The overall layered structure of the transmission line is composed of three metal layers and two dielectric layers, just like the transmission line unit. The top metal layer includes a plurality of top metal layer units (1) connected in series, and an upper feeding structure (11) and an upper bias circuit structure (12) are provided at both ends. The intermediate metal layer comprises the plurality of intermediate metal layer units (2) connected in series, with circular hole structures (21) provided at both ends; the bottom metal layer comprises the plurality of bottom metal layer units (3) connected in series, with a lower feeding structure (31) and a lower bias circuit structure (32) provided at both ends; in order to excite electromagnetic waves of two modes, two independent input ports and two independent output ports are provided, wherein the first input port (1.8) and the first output port (1.9) are connected to the upper feeding structure (11) on the top metal layer unit (1) through a 50Ω microstrip line, for exciting even-mode electromagnetic waves; the second input port (3.6) and the second output port (3.7) are placed on the bottom metal layer (3) and connected to the lower feeding structure (31), and the transmission of odd-mode electromagnetic waves is excited through the transition of the slotted structure (2.1) in the intermediate metal layer unit (2).

2. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that The top metal layer unit (1) in the transmission line unit comprises a microstrip line structure (1.1), a first top metal patch (1.2), a second top metal patch (1.3), a third top metal patch (1.4), and a fourth top metal patch (1.5) symmetrically connected in parallel on both sides of the microstrip line structure (1.1); a first variable capacitance diode (1.6) is connected between the first top metal patch (1.2) and the second top metal patch (1.3); and a second variable capacitance diode (1.7) is connected between the third top metal patch (1.4) and the fourth top metal patch (1.5).

3. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that The middle metal layer unit (2) in the transmission line unit is a metal ground, and a slot structure (2.1) is provided in the middle of the middle metal layer unit (2) along the signal transmission direction.

4. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that The bottom metal layer unit (3) in the transmission line unit is provided with a first bottom metal patch (3.1), a second bottom metal patch (3.2), and a third bottom metal patch (3.3); the three bottom metal patches are arranged in a "U" shape, and a first PIN diode (3.4) is connected between the first bottom metal patch (3.1) and the second bottom metal patch (3.2), and a second PIN diode (3.5) is connected between the second bottom metal patch (3.2) and the third bottom metal patch (3.3).

5. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that The first top metal patch (1.2) of the top metal layer unit (1) and the first bottom metal patch (3.1) of the bottom metal layer unit (3) are connected to the middle metal layer unit (2) via a metal through hole (6); the fourth top metal patch (1.5) of the top metal layer unit (1) and the third bottom metal patch (3.3) of the bottom metal layer unit (3) are connected to the middle metal layer unit (2) via a metal through hole (6).

6. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that In the transmission line, microstrip line structures (1.1) in a plurality of series-connected reconfigurable low-coupling dual-mode transmission line units are connected in series.

7. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that The second top metal patch (1.3) and the third top metal patch (1.4) are in a zigzag shape and are respectively connected to the microstrip line structure (1.1).

8. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that By controlling the bias voltage of a first varactor diode (1.6) and a second varactor diode (1.7) in a top metal layer unit (1) and the on / off of a first PIN diode (3.4) and a second PIN diode (3.5) in a bottom metal layer unit (3), the transmission mode of the transmission line is switched among a dual mode, an odd mode, an even mode and a cut-off state.

9. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that When the transmission line works in the dual-mode transmission mode, two independent signals are transmitted, and the more transmission line units there are, that is, the longer the transmission line is, the higher the isolation between the two signals is.

10. The reconfigurable low-coupling dual-mode transmission line according to claim 1, characterized in that The materials of the first dielectric layer (4) and the second dielectric layer (5) are Rogers RO4003 substrates.

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