An artificial surface plasmon circuit structure supporting odd and even mode transmission

Abstract

The application discloses an artificial surface plasmon circuit structure supporting odd mode and even mode transmission, which comprises a dielectric substrate and metal structures on the upper and lower layers of the dielectric substrate; the circuit structure comprises a feeding structure composed of a directional coupler, a phase shifter and a microstrip line, a transition section designed for mode conversion and an artificial surface plasmon transmission line structure. In the circuit structure, odd mode or even mode transmission can be controlled simply by changing an input port. The artificial surface plasmon circuit structure supporting odd mode and even mode transmission can transmit odd mode or even mode without changing any circuit structure, and has the advantages of simple circuit structure and convenient operation, and has a good application prospect in modern communication systems.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of artificial surface plasmon circuit structure of supporting odd mode and even mode transmission, belong to communication and novel artificial electromagnetic field. BACKGROUND

[0002] As a kind of novel artificial electromagnetic material, artificial surface plasmon is developed from the surface plasmon of optical frequency band, and has similar characteristics with the surface plasmon of optical frequency band: field confinement in subwavelength range, field enhancement and flexible dispersion control.Artificial surface plasmon is widely used in radio frequency circuit device design, antenna design and communication system.

[0003] In microwave communication, the circuit supporting odd and even modes has stronger anti-interference ability than single-ended circuit, and can achieve greater bandwidth and higher data transmission rate.However, current research results are limited to a circuit that can only support odd mode or even mode transmission.

[0004] Therefore, an artificial surface plasmon circuit structure that can support odd and even mode transmission has great potential application value in the field of modern communication and other fields. SUMMARY

[0005] Objective: To overcome the deficiencies in the prior art, the present application provides an artificial surface plasmon circuit structure that supports odd and even mode transmission, which can realize different mode signal transmission by different port inputs through the design of feeding structure, transition section and artificial surface plasmon transmission line, i.e., odd mode transmission when the first port input signal; even mode transmission when the second port input signal. The circuit structure is easy to manufacture and simple to operate.

[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present application is:

[0007] An artificial surface plasmon circuit structure that supports odd and even mode transmission, comprising: a dielectric substrate layer, a metal ground layer is provided on the lower surface of the dielectric substrate layer, and a metal structure layer is provided on the upper surface of the dielectric substrate layer.

[0008] The metal structure layer comprises: a first feeding structure, a second feeding structure, a first transition section, a second transition section and an artificial surface plasmon transmission line. The entire circuit structure is axisymmetric with the artificial surface plasmon transmission line. One end of the artificial surface plasmon transmission line is connected to one end of the first transition section, and the other end of the artificial surface plasmon transmission line is connected to one end of the second transition section. The other end of the first transition section is connected to one end of the first feeding structure, and the other end of the second transition section is connected to one end of the second feeding structure.

[0009] As a preferred solution, the first feeding structure and the second feeding structure each comprise a directional coupler, a phase shifter, and a first microstrip line, a second microstrip line, a third microstrip line, and a fourth microstrip line, one end of the directional coupler is connected to one end of the first microstrip line and the second microstrip line respectively, the other end of the directional coupler is connected to one end of the third microstrip line and the fourth microstrip line respectively, one end of the phase shifter is connected to the other end of the third microstrip line and the fourth microstrip line respectively.

[0010] As a preferred solution, the first microstrip line, the second microstrip line, the third microstrip line, and the fourth microstrip line are arranged in a stepped structure.

[0011] As a preferred solution, the phase shifter comprises an upper branch of a "U" shaped microstrip line structure and a lower branch of a straight microstrip line structure.

[0012] As a preferred solution, the first transition section and the second transition section each comprise a fifth microstrip line and a sixth microstrip line, the fifth microstrip line and the sixth microstrip line are arranged in an up-down manner, the ends of the fifth microstrip line and the sixth microstrip line are provided with an artificial surface plasmon transition section, the artificial surface plasmon transition section comprises a plurality of artificial surface plasmon units arranged in sequence, the tooth depths of the plurality of artificial surface plasmon units are arranged to be different depths.

[0013] As a preferred solution, the depths of the tooth depths of the plurality of artificial surface plasmon units increase sequentially from one end of the fifth microstrip line and the sixth microstrip line to the other side.

[0014] As a preferred solution, the artificial surface plasmon transmission line comprises a plurality of artificial surface plasmon units arranged in sequence.

[0015] As a preferred solution, the artificial surface plasmon unit comprises a "cross" shaped artificial surface plasmon arranged in an up-down interval.

[0016] As a preferred solution, the artificial surface plasmon unit is axially symmetrical about a vertical axis Ф3 and axially symmetrical about a horizontal axis λ2.

[0017] As a preferred solution, the artificial surface plasmon transmission line adopts 16 artificial surface plasmon units, and the artificial surface plasmon transition section adopts 6 artificial surface plasmon units.

[0018] Beneficial effects: the artificial surface plasmon circuit structure provided by the application supports odd mode and even mode transmission, and comprises a feeding structure, a transition section designed for mode conversion and an artificial surface plasmon transmission line; the feeding structure comprises a directional coupler, a phase shifter and a microstrip line; the unit structure of the artificial surface plasmon transmission line is composed of two identical "cross" metal structures; the transition section designed for mode conversion is composed of artificial surface plasmons with different tooth heights. The artificial surface plasmon circuit structure supporting odd mode and even mode transmission can realize the transmission of odd mode and even mode without changing any circuit structure, and the transmission of different modes only needs to change the input port. The advantages are as follows:

[0019] 1. The application has simple design and is convenient to process and assemble. The mature PCB processing technology can be used to process the application.

[0020] 2. The artificial surface plasmon transmission line designed by the application has stronger field binding ability than the traditional transmission line, the transmission lines will not cause cross talk, and the size of the circuit structure can be effectively reduced.

[0021] 3. The feeding structure designed by the application can realize the transmission of different modes (odd mode or even mode) by inputting from different ports (first port or second port) without changing any circuit structure. DETAILED DESCRIPTION

[0022] Figure 1 is the overall structure schematic diagram of the artificial surface plasmon circuit of the application.

[0023] Figure 2 is the structure schematic diagram of the feeding structure.

[0024] Figure 3 is the structure schematic diagram of the transition section.

[0025] Figure 4 is the three-dimensional schematic diagram of the artificial surface plasmon unit.

[0026] Figure 5 is the top view schematic diagram of the artificial surface plasmon unit.

[0027] Figure 6 is the port setting schematic diagram of the artificial surface plasmon circuit.

[0028] Figure 7 is the dispersion curve simulation result schematic diagram of the artificial surface plasmon unit.

[0029] Figure 8 is the S parameter and phase difference of the feeding structure of the application, wherein, Figure 8In Figure (a), the S-parameters of the feeding structure are shown when the first microstrip line is used as the input signal at the first port. Figure 8 In diagram (b), the phase difference between the third and fourth ports is shown when the first microstrip line is used as the first port input signal. Figure 8 In the diagram (c), the S-parameters of the feeding structure are shown when the second microstrip line is used as the input signal at the second port. Figure 8 In the diagram, (d) represents the phase difference between the third and fourth ports when the second microstrip line is used as the second port input signal.

[0030] Figure 9 These are the S-parameters of the overall circuit structure of the present invention at different port inputs at a frequency of 17-18 GHz, wherein... Figure 9 In diagram (a), the S-parameters of the entire circuit structure during odd-mode transmission are shown for the first port input. Figure 9 In Figure (b), the S-parameters of the entire circuit structure during even-mode transmission are shown when the second port is input, including both simulation and test results. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0032] The present invention will be further described below with reference to specific embodiments.

[0033] Example 1:

[0034] This embodiment describes an artificial surface plasmon circuit structure that supports both odd-mode and even-mode transmission, such as... Figure 1 As shown, it includes: a dielectric substrate layer 1, a metal ground layer disposed on the lower surface of the dielectric substrate layer 1, and a metal structural layer 2 disposed on the upper surface of the dielectric substrate layer 1.

[0035] The metal structure layer 2 includes: a first feed structure 2-1, a second feed structure 2-5, a first transition section 2-2 and a second transition section 2-4 designed for mode switching, and an artificial surface plasmon transmission line 2-3. The entire circuit structure is axially symmetrical about the center of the artificial surface plasmon transmission line 2-3. One end of the artificial surface plasmon transmission line 2-3 is connected to one end of the first transition section 2-2, and the other end of the artificial surface plasmon transmission line 2-3 is connected to one end of the second transition section 2-4. The other end of the first transition section 2-2 is connected to one end of the first feed structure 2-1, and the other end of the second transition section 2-4 is connected to one end of the second feed structure 2-5.

[0036] Furthermore, in one embodiment, such as Figure 2 As shown, both the first feed structure 2-1 and the second feed structure 2-5 include: a directional coupler 2-1-1, a phase shifter 2-1-2, and a first microstrip line 2-1-3, a second microstrip line 2-1-4, a third microstrip line 2-1-5, and a fourth microstrip line 2-1-6 connected to it. One end of the directional coupler 2-1-1 is connected to one end of the first microstrip line 2-1-3 and the second microstrip line 2-1-4, respectively. The other end of the directional coupler 2-1-1 is connected to one end of the third microstrip line 2-1-5 and the fourth microstrip line 2-1-6, respectively. One end of the phase shifter 2-1-2 is connected to the other end of the third microstrip line 2-1-5 and the fourth microstrip line 2-1-6, respectively.

[0037] Furthermore, in one embodiment, the directional coupler 2-1-1 is axisymmetric about the vertical axis Ф1 and about the horizontal axis λ1. The phase shifter 2-1-2 is axisymmetric about the vertical axis Ф2.

[0038] Furthermore, in one embodiment, the first microstrip line 2-1-3 and the second microstrip line 2-1-4 are axially symmetric about the horizontal axis λ1, and the third microstrip line 2-1-5 and the fourth microstrip line 2-1-6 are axially symmetric about the horizontal axis λ1.

[0039] In another embodiment, the first microstrip line 2-1-3, the second microstrip line 2-1-4, the third microstrip line 2-1-5, and the fourth microstrip line 2-1-6 are configured as a stepped structure to achieve impedance matching.

[0040] In another embodiment, the phase shifter 2-1-2 includes an upper branch of a "U"-shaped microstrip line structure and a lower branch of a straight microstrip line structure.

[0041] Furthermore, in one embodiment, such as Figure 3 As shown, both the first transition segment 2-2 and the second transition segment 2-4 include: a fifth microstrip line 2-2-1 and a sixth microstrip line 2-2-2. The fifth microstrip line 2-2-1 and the sixth microstrip line 2-2-2 are arranged vertically. Artificial surface plasmon transition segments 2-2-3 are provided at the ends of the fifth microstrip line 2-2-1 and the sixth microstrip line 2-2-2. The artificial surface plasmon transition segments 2-2-3 include a plurality of plasmon units 2-3-1 arranged in sequence. The tooth depth 2-2-3-1 of the plurality of plasmon units 2-3-1 is set to a different depth.

[0042] Furthermore, in one embodiment, the artificial surface plasmon transition section 2-2-3 is provided with 6 plasmon units 2-3-1, and the depth of the tooth 2-2-3-1 of the 6 plasmon units 2-3-1 increases sequentially from one end of the fifth microstrip line 2-2-1 and the sixth microstrip line 2-2-2 to the other side.

[0043] Furthermore, in one embodiment, such as Figure 4 As shown, the artificial surface plasmon transmission line 2-3 includes several plasmon units 2-3-1 arranged in sequence. The plasmon unit 2-3-1 includes cross-shaped artificial surface plasmons 2-3-1-1 arranged at intervals.

[0044] Furthermore, in one embodiment, such as Figure 5 As shown, the plasmon unit 2-3-1 is axially symmetric about the vertical axis Ф3 and about the horizontal axis λ2.

[0045] In another embodiment, the number of plasmon units 2-3-1 is set to 16.

[0046] Furthermore, in one embodiment, such as Figure 6 As shown, the first microstrip line 2-1-3 of the first feed structure 2-1 serves as the first port, the second microstrip line 2-1-4 of the first feed structure 2-1 serves as the second port, the third microstrip line 2-1-5 of the first feed structure 2-1 serves as the third port, and the fourth microstrip line 2-1-6 of the first feed structure 2-1 serves as the fourth port. The third microstrip line 2-1-5 of the second feed structure 2-5 serves as the fifth port, and the fourth microstrip line 2-1-6 of the second feed structure 2-5 serves as the sixth port.

[0047] In another embodiment, the dielectric substrate layer 1 is configured as a cuboid structure.

[0048] Example 2:

[0049] This embodiment describes an example of an artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission. In this embodiment, the dimensions of each component of the directional coupler 2-1-1 are: a = 0.68 mm, b = 1.003 mm, c = 3.1 mm, d = 3.4 mm, l2 = 9.4 mm, where a is the width of the arm structure of the directional coupler, b is the width of the long frame structure of the directional coupler, c is the inner cavity height of the long frame structure of the directional coupler, d is the length of the long frame structure of the directional coupler, and l2 is the length of the directional coupler. The four arm structures of the directional coupler are axially symmetric about axes Ф1 and λ1, respectively.

[0050] The dimensions of each component of phase shifter 2-1-2 are: l4 = 4.5 mm, l5 = 4.4 mm, l6 = 15 mm, w2 = 6 mm, w3 = 1.52 mm, x = 1.5 mm. Wherein, l4 is the length of the horizontal microstrip line at one end of the "U" shaped microstrip line structure, l5 is the length of the upper microstrip line of the "U" shaped microstrip line structure, l6 is the length of the straight microstrip line structure, w2 is the spacing between the "U" shaped microstrip line structure and the straight microstrip line structure, w3 is the width of the horizontal microstrip line at one end of the "U" shaped microstrip line structure, and x is the length of the inner bend of the "U" shaped microstrip line structure.

[0051] To test the impedance matching of the port, such as 50 ohms, the dimensions of the microstrip line in the feed structure are: l1 = 9 mm, w1 = 8.12 mm, l3 = 5 mm, where l1 is the distance between the beginning and end of the first or second microstrip line, w1 is the distance between the beginning of the first or second microstrip line, and l3 is the distance between the beginning and end of the third or fourth microstrip line.

[0052] Artificial surface plasmons transmit in a special TM mode, which cannot be directly transitioned from the TEM mode of a microstrip line. Therefore, a progressive artificial surface plasmon transition section was designed to achieve mode conversion. The tooth depth h varies in increments of 0.09 mm. A microstrip line transition section is used to achieve impedance matching between the transition section and the phase shifter. The dimensions of each component in the transition section are p1 = 2 mm, p2 = 2 mm, and h6 = 0.507 mm, where p1 is the length of the fifth or sixth microstrip line, p2 is the width of the fifth or sixth microstrip line, and h6 is the tooth depth of the sixth plasmon unit.

[0053] Rogers RT5880 has a dielectric substrate layer thickness of 0.508 mm, a relative permittivity of 2.2, and a loss tangent of 0.0009.

[0054] The structure of the artificial surface plasmon unit is a symmetrical "+" shaped metal structure, consisting of two "+" shaped artificial surface plasmons. The dimensions are: l = 2.4 mm, w = 1.52 mm, s = 0.39 mm, p = 0.6 mm, h = 0.51 mm, and b = 0.508 mm. Here, l is the length period of the plasmon unit, w is the width of the "+" shaped artificial surface plasmon, s is the distance between the two "+" shaped artificial surface plasmons, p is the length of the tooth depth of the "+" shaped artificial surface plasmon, h is the depth of the tooth depth of the "+" shaped artificial surface plasmon, and b is the thickness of the dielectric substrate layer.

[0055] Both the artificial surface plasmon units and the metallic strata are made of metallic copper, with a thickness of t = 0.035 mm.

[0056] The intrinsic mode solver of simulation software can be used to simulate the dispersion curve of plasmonic elements under these parameters, such as... Figure 7 As shown, the simulation results prove that: (1) the designed plasmonic unit can support both odd and even modes; (2) the odd mode cutoff frequency is slightly lower than the even mode cutoff frequency, indicating that the odd mode has stronger field confinement; (3) the plasmonic unit is at a high cutoff frequency (above 20GHz), which lays the foundation for the design of the entire circuit structure.

[0057] When an artificial surface plasmon polariton (APT) circuit structure supporting both odd-mode and even-mode transmission is used, the input signal is converted into a differential signal by a directional coupler when input through the first port. This differential signal is then converted into the desired odd-mode signal by a phase shifter. The generated odd-mode signal is then transmitted through the APT transmission line and finally coupled back to the single-port output through a transition section and a feeding structure. Similarly, when the input signal is input through the second port, the directional coupler converts the input signal into a differential signal, which is then converted into the desired even-mode signal by a phase shifter. This even-mode signal is then transmitted through the APT transmission line and finally coupled back to the single-port output through a transition section and a feeding structure. The feeding structure allows for the transmission of different signal modes at different input ports; that is, when input through the first port, the entire circuit structure transmits an odd-mode signal (180° phase difference), and when input through the second port, the entire circuit structure transmits an even-mode signal (0° phase difference).

[0058] like Figure 8 As shown, the simulation results of the feeding structure with the first port as the excitation source are as follows: Figure 8 As shown in (a) and 8(b), the designed feeding structure exhibits good transmission in the 17-18 GHz band and can achieve a phase shift performance of 180°±10° within the 17-18 GHz band, meaning that the first port can achieve odd-mode feeding in the 17-18 GHz band. Similarly, the simulation results of the second port as the excitation source are shown in (a) and (b). Figure 8 As shown in (c) and (d), the feed structure can achieve good transmission in the 17-18 GHz range, and the phase difference between the third and fourth ports remains at 0°±15° within the 17-18 GHz range. This indicates that the second port can achieve even-mode feeding in the 17-18 GHz range. In summary, the designed feed structure can achieve both odd-mode and even-mode feeding in the 17-18 GHz operating frequency band, proving the rationality of the present invention.

[0059] like Figure 9 As shown, Figure 9(a) and Figure 9 (b) The S-parameter plots of the entire circuit structure under first-port and second-port excitation are shown respectively, including simulation results and test results. It can be seen that under first-port or second-port excitation, the reflection coefficient S 11 or S 22 Within the frequency band, the reflection rate is below -10 dB, indicating that less than 10% of the energy is reflected back, proving that the overall circuit structure exhibits low reflection. As shown in the figure, within the 17-18 GHz range, both simulation and test results for the two-port excitation demonstrate good transmission characteristics. Specifically, the transmission process is as follows: first, the directional coupler converts the single-port input signal into a differential signal. This differential signal is then converted into the desired odd-mode or even-mode signal by a phase shifter. The generated odd-mode and even-mode signals are then transmitted through an artificial surface plasmon transmission line. Finally, the signal is coupled back to the single-port output signal through a phase shifter and directional coupler identical to those used in the feeding structure. The simulation data and test data agree well.

[0060] In summary, the artificial surface plasmon circuit structure proposed in this invention, which supports both odd and even mode transmission, enables the transmission of both odd and even modes without altering the circuit structure.

[0061] The circuit structure includes a dielectric substrate and two metal layers above and below it; the circuit structure includes a feed structure composed of directional couplers and phase shifters, a transition section designed to achieve mode switching, and an artificial surface plasmon transmission line structure. In this circuit structure, odd-mode or even-mode transmission can be easily controlled by changing the input port. The artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission proposed in this invention can transmit odd-mode and even-mode without changing any circuit structure, and the circuit structure is simple and easy to operate, showing good application prospects in modern communication systems.

[0062] The circuit design of this invention improves the flexibility and efficiency of the circuit and broadens the application fields of artificial surface plasmon transmission lines.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission, characterized in that: include: A dielectric substrate layer, a metal ground layer is disposed on the lower surface of the dielectric substrate layer, and a metal structural layer is disposed on the upper surface of the dielectric substrate layer; The metal structure layer includes: a first feed structure, a second feed structure, a first transition section, a second transition section, and an artificial surface plasmon transmission line. The entire circuit structure is axially symmetrical about the artificial surface plasmon transmission line. One end of the artificial surface plasmon transmission line is connected to one end of the first transition section, and the other end of the artificial surface plasmon transmission line is connected to one end of the second transition section. The other end of the first transition section is connected to one end of the first feed structure, and the other end of the second transition section is connected to one end of the second feed structure. Both the first and second feeding structures include: a directional coupler, a phase shifter, and a first microstrip line, a second microstrip line, a third microstrip line, and a fourth microstrip line. One end of the directional coupler is connected to one end of the first and second microstrip lines, and the other end of the directional coupler is connected to one end of the third and fourth microstrip lines, respectively. One end of the phase shifter is connected to the other end of the third and fourth microstrip lines, respectively.

2. The artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission according to claim 1, characterized in that: The first microstrip line, the second microstrip line, the third microstrip line and the fourth microstrip line are all configured as a stepped structure.

3. The artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission according to claim 1, characterized in that: The phase shifter includes: an upper branch with a "U" shaped microstrip line structure and a lower branch with a straight microstrip line structure.

4. The artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission according to claim 1, characterized in that: Both the first transition section and the second transition section include: a fifth microstrip line and a sixth microstrip line, which are arranged vertically. Artificial surface plasmon transition sections are provided at the ends of the fifth microstrip line and the sixth microstrip line. Each artificial surface plasmon transition section includes a plurality of artificial surface plasmon units arranged in sequence, and the tooth depth of the plurality of artificial surface plasmon units is set to different depths.

5. The artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission according to claim 4, characterized in that: The tooth depth of several artificial surface plasmon units increases sequentially from one end of the fifth microstrip line and the sixth microstrip line to the other side.

6. The artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission according to claim 1, characterized in that: The artificial surface plasmon transmission line includes a plurality of artificial surface plasmon units arranged in sequence.

7. An artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission according to claim 4 or 6, characterized in that: The artificial surface plasmon unit includes cross-shaped artificial surface plasmons arranged at intervals.

8. The artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission according to claim 7, characterized in that: The artificial surface plasmon unit is axially symmetric about the vertical axis Ф3 and about the horizontal axis λ2.

9. An artificial surface plasmon circuit structure supporting odd-mode and even-mode transmission according to claim 4 or 6, characterized in that: The artificial surface plasmon transmission line uses 16 artificial surface plasmon units, and the artificial surface plasmon transition section uses 6 artificial surface plasmon units.

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