Millimeter wave branch waveguide directional coupler based on artificial surface plasmon

Abstract

The invention discloses a millimeter wave branch waveguide directional coupler based on artificial surface plasmon, which belongs to the technical field of millimeter wave devices and specifically comprises an input port, a straight-through port, a coupling port, an isolation port, a multi-branch waveguide and a matched load structure. The matched load structure extends into the slots in the centers of the E surfaces on the two sides of the isolation port; the input port is connected to the straight-through port through a main waveguide with a 90-degree outer side fillet, and the isolation port is connected to the coupling port through an auxiliary waveguide with a 90-degree outer side fillet; the multi-branch waveguide is arranged between the main waveguide and the auxiliary waveguide; the matched load structure comprises a load substrate, and an artificial surface plasmon and a multi-stage gradient sawtooth groove structure which are located on the surface of the load substrate. According to the invention, the matching load structures are arranged at the central slots of the E surfaces at the two sides of the isolation port, the isolation degree of the output port is improved, and the matching load structures are not influenced by the lossy wave-absorbing material and the relatively low working temperature of the thin-film resistor by using the excellent heat-conducting property of aluminum nitride and the high temperature resistance of metallic nickel.

Description

Technical Field

[0001] The present invention belongs to the technical field of millimeter wave devices, and in particular relates to a millimeter wave branch waveguide directional coupler based on artificial surface plasmons. Background Art

[0002] In recent years, with the gradual maturity of semiconductor transistor and microfabrication technologies, millimeter-wave solid-state devices have rapidly developed and been applied in fields such as wireless communications, nondestructive testing, medical imaging, electronic countermeasures, and precision guidance. High-power solid-state millimeter-wave devices are core components for information sensing, transmission, and detection in millimeter-wave systems. However, the output power provided by a single power amplifier is insufficient to meet the high-power output requirements of millimeter-wave systems. The current solution is to use power combining technology to increase system output power.

[0003] Rectangular waveguides, with their low loss and high power handling, are a standard transmission and interconnection method for millimeter-wave modules and systems. Currently, rectangular waveguide-based millimeter-wave power combining structures primarily include T-junctions, magic-T junctions, and directional couplers. Typically, to improve output port isolation or achieve electromagnetic energy absorption at the isolated port, additional components, such as resistive films or wedge-shaped / conical absorbers, are added to the isolated port. However, these additional components are difficult to precisely assemble within the isolated port and incur additional manufacturing costs and insertion losses.

[0004] Therefore, a new isolation port design method is urgently needed to avoid the problem of difficulty in accurately assembling additional components in the isolation port. Summary of the Invention

[0005] To address the technical problem of the difficulty in accurately assembling components such as resistive films or wedge-shaped / conical absorbing materials in isolated ports, the present invention provides a millimeter-wave branch waveguide directional coupler based on artificial surface plasmons. By integrating a matching load structure based on artificial surface plasmons into the isolated port, a highly integrated, high-power-capacity, and low-cost millimeter-wave branch waveguide directional coupler design is achieved.

[0006] The technical solutions adopted in the present invention are as follows:

[0007] A millimeter-wave branch waveguide directional coupler based on artificial surface plasmons includes an input port, a through port, a coupled port, an isolation port, a multi-branch waveguide, and a matching load structure; the matching load structure extends into the center slots of the E-surface on both sides of the isolation port;

[0008] The input port is connected to the through port through a main waveguide with a 90° outer rounded corner, and the isolation port is connected to the coupling port through a sub-waveguide with a 90° outer rounded corner; the multi-branch waveguide is arranged between the main waveguide and the sub-waveguide.

[0009] Furthermore, the matching load structure includes a load substrate, and artificial surface plasmons and a multi-level gradient sawtooth groove structure located on the surface of the load substrate.

[0010] Furthermore, the artificial surface plasmon and the multi-level gradient sawtooth groove structure are made of metal nickel.

[0011] Furthermore, the material of the load substrate is aluminum nitride.

[0012] Furthermore, the artificial surface plasmon includes 6 sawtooth grooves, and the multi-level gradient sawtooth groove structure includes a total of 9 levels of sawtooth grooves with decreasing groove depths.

[0013] Furthermore, the multi-branch waveguide includes a total of 5 branches.

[0014] Furthermore, the interval between adjacent branches and the length of each branch in the multi-branch waveguide are both one-quarter wavelength.

[0015] Furthermore, a section of the waveguide in the main waveguide close to the straight-through port and a section of the waveguide in the auxiliary waveguide close to the coupling port are both gradually decreasing waveguides for expanding bandwidth.

[0016] Furthermore, the through port and the coupled port are both connected to the planar circuit via a grounded coplanar waveguide transition structure.

[0017] Furthermore, the input port, through port, coupled port and isolated port are all standard waveguides.

[0018] The beneficial effects of the present invention are:

[0019] The present invention proposes a millimeter-wave branch waveguide directional coupler based on artificial surface plasmons. The isolation of the output port is improved by providing matching load structures at the center slots of the E-surface on both sides of the isolation port. When the artificial surface plasmons and the multi-level gradient sawtooth groove structure of the matching load structure are preferably made of metallic nickel, and the material of the load substrate is preferably made of aluminum nitride, the matching load structure is no longer affected by lossy absorbing materials and the low operating temperature of thin-film resistors by utilizing the excellent thermal conductivity of aluminum nitride and the high temperature resistance of metallic nickel. Furthermore, the matching load structure of the present invention can be manufactured using traditional thin-film processes or PCB (printed circuit board) processes and can be assembled using mature micro-assembly processes. Compared with resistive thin-film components, there is no need to separately attach resistors, and compared with wedge-shaped / conical absorbing materials, there is no need to manually cut and shape them, thereby facilitating assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of the millimeter-wave branch waveguide directional coupler based on artificial surface plasmons proposed in Example 1 of the present invention;

[0021] Figure 2 Schematic diagram of the matching load structure in Example 1 of the present invention;

[0022] Figure 3 Schematic diagram of the installation of the matching load structure at the isolation port in Example 1 of the present invention;

[0023] Figure 4 This is a schematic diagram of back-to-back power combining of a millimeter-wave branch waveguide directional coupler based on artificial surface plasmons proposed in Example 1 of the present invention;

[0024] Figure 5 This is the simulation result of the millimeter-wave branch waveguide directional coupler based on artificial surface plasmon proposed in Example 1 of the present invention;

[0025] Figure 6 This is the back-to-back power combination simulation result of the millimeter-wave branch waveguide directional coupler based on artificial surface plasmon proposed in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Although limited embodiments are described below, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0027] Example 1

[0028] This embodiment provides a millimeter wave branch waveguide directional coupler based on artificial surface plasmon, the structure of which is as follows: Figure 1 As shown, it includes an input port (Port1), a through port (Port3), a coupled port (Port2), an isolation port, a multi-branch waveguide and a matching load structure.

[0029] like Figure 2 As shown, the matching load structure includes a load substrate, and artificial surface plasmons and a multi-level gradient sawtooth groove structure located on the surface of the load substrate; wherein, the material of the load substrate is aluminum nitride; the material of the artificial surface plasmons and the multi-level gradient sawtooth groove structure is metallic nickel; the artificial surface plasmons include 6 sawtooth grooves, and the multi-level gradient sawtooth groove structure includes a total of 9 levels of sawtooth grooves with decreasing groove depth.

[0030] like Figure 3 As shown, the matching load structure extends into the center slots of the E-surface on both sides of the isolation port.

[0031] The input port, through port, coupled port and isolated port are all WR10 standard waveguides.

[0032] The input port is connected to the through port through a main waveguide with a 90° outer rounded corner, and the isolation port is connected to the coupling port through a secondary waveguide with a 90° outer rounded corner.

[0033] The multi-branch waveguide is arranged between the main waveguide and the auxiliary waveguide, and includes 5 branches in total. The interval between adjacent branches and the length of each branch are both one-quarter wavelength.

[0034] A section of the waveguide in the main waveguide close to the straight-through port and a section of the waveguide in the auxiliary waveguide close to the coupling port are both gradually decreasing waveguides, which are used to expand the bandwidth.

[0035] The through port and the coupled port are both connected to the planar circuit via a grounded coplanar waveguide transition structure.

[0036] The millimeter wave branch waveguide directional coupler based on artificial surface plasmon proposed in this embodiment is simulated and tested, and the results are as follows: Figure 5 As shown in the figure, in the frequency range of 86 GHz to 98 GHz, the insertion loss from Port 1 to Port 2 and from Port 1 to Port 3 is approximately 3 dB, and the in-band amplitude non-flatness is less than 0.3 dB. In the frequency range of 80 GHz to 100 GHz, the return loss of each port and the isolation between Port 2 and Port 3 are both better than 18 dB.

[0037] Figure 4 This is a schematic diagram of back-to-back power synthesis of the millimeter-wave branch waveguide directional couplers based on artificial surface plasmons proposed in this embodiment. The through port (or coupling port) in the first millimeter-wave branch waveguide directional coupler based on artificial surface plasmons couples the signal to the planar grounded coplanar waveguide transmission line through an E-plane probe, and then the signal is synthesized and output through the second back-to-back millimeter-wave branch waveguide directional coupler based on artificial surface plasmons.

[0038] right Figure 4 The back-to-back power combination of the millimeter-wave branch waveguide directional coupler based on artificial surface plasmon is simulated and tested. The results are shown in Figure 6 As shown, it can be seen that in the frequency range of 81GHz to 100GHz, the insertion loss of the back-to-back power combining network is less than 1.3dB, and the in-band return loss is better than 15dB.

[0039] In summary, this embodiment achieves high isolation of the output port by providing a matching load structure at the center slots of the E-surface on both sides of the isolation port. It also has the characteristics of high temperature resistance and easy assembly, which is beneficial to the integration of high-power solid-state millimeter-wave devices.

[0040] The above embodiments only illustrate the principles and advantages of the present invention, and are not intended to limit the present invention. They are only for helping to understand the principles of the present invention. The scope of protection of the present invention is not limited to the above configurations and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the disclosed technology without departing from the essence of the present invention, but they are still within the scope of protection of the present invention.

Claims

1. A millimeter-wave branch waveguide directional coupler based on artificial surface plasmon, characterized in that: It includes an input port, a through port, a coupled port, an isolated port, a multi-branch waveguide and a matching load structure; the matching load structure extends into the center slots of the E-surface on both sides of the isolated port; The input port is connected to the through port through a main waveguide with a 90° outer rounded corner, and the isolation port is connected to the coupling port through a sub-waveguide with a 90° outer rounded corner; the multi-branch waveguide is arranged between the main waveguide and the sub-waveguide.

2. The millimeter-wave branch waveguide directional coupler based on artificial surface plasmon according to claim 1, characterized in that: The matching load structure includes a load substrate, and artificial surface plasmons and a multi-level gradient sawtooth groove structure located on the surface of the load substrate.

3. The millimeter-wave branch waveguide directional coupler based on artificial surface plasmon according to claim 2, characterized in that: The material of the artificial surface plasmon and the multi-level gradient sawtooth groove structure is metal nickel.

4. The millimeter-wave branch waveguide directional coupler based on artificial surface plasmon according to claim 2, characterized in that: The material of the load substrate is aluminum nitride.

5. The millimeter-wave branch waveguide directional coupler based on artificial surface plasmon according to claim 2, characterized in that: The artificial surface plasmon includes 6 sawtooth grooves, and the multi-level gradient sawtooth groove structure includes a total of 9 levels of sawtooth grooves with decreasing groove depths.

6. The millimeter-wave branch waveguide directional coupler based on artificial surface plasmon according to claim 2, characterized in that: The multi-branch waveguide includes 5 branches in total.

7. The millimeter-wave branch waveguide directional coupler based on artificial surface plasmon according to claim 2, characterized in that: The interval between adjacent branches and the length of each branch in the multi-branch waveguide are both a quarter of a wavelength.

8. The millimeter-wave branch waveguide directional coupler based on artificial surface plasmon according to claim 2, characterized in that: A section of the waveguide in the main waveguide close to the straight-through port and a section of the waveguide in the auxiliary waveguide close to the coupling port are both gradually decreasing waveguides.

9. The millimeter-wave branch waveguide directional coupler based on artificial surface plasmon according to claim 2, characterized in that: The through port and the coupled port are both connected to the planar circuit via a grounded coplanar waveguide transition structure.

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