A single-layer microstrip coupler

Abstract

The present application relates to the technical field of coupler, and especially relates to a single-layer microstrip coupler, which comprises: a main microstrip line and a secondary microstrip line which are coupled to each other; one end of the main microstrip line is configured as an input port of the coupler, used for receiving an electromagnetic wave signal, and the other end is configured as a through port, used for outputting a signal; one end of the secondary microstrip line is configured as a coupling port of the coupler, and the other end is configured as an isolation port; under the condition that the coupling degree between the main microstrip line and the secondary microstrip line meets the tight coupling degree condition, the non-coupling side of the main microstrip line and the non-coupling side of the secondary microstrip line are both provided with a triangular hole digging area, so as to guide the electromagnetic wave signal to propagate to the through port and the coupling port through the triangular hole digging area. Through the structural arrangement of the coupler, high directivity and tight coupling degree of the single-layer microstrip coupler are realized at the same time, the directivity of the single-layer microstrip coupler is greatly improved, and the performance of the single-layer microstrip coupler is improved.

Description

Technical Field

[0001] This invention relates to the field of coupler technology, and more particularly to a single-layer microstrip coupler. Background Technology

[0002] Directional couplers, as key components of modern communication systems such as microwave and terahertz systems, play an irreplaceable role in signal monitoring, power distribution, system calibration, and feedback control. With the rapid development of 6G communication, satellite, radar systems, and terahertz imaging technology, the demand for high-performance directional couplers is becoming increasingly urgent, especially in terms of high integration, miniaturization, and high precision.

[0003] Microstrip structures (i.e., microstrip lines), as a planar transmission line technology, exhibit significant advantages over traditional waveguide structures. Microstrip lines consist of a single conductor strip on a dielectric substrate, offering advantages such as small size, light weight, wide operating bandwidth, high reliability, and low manufacturing cost, making them particularly suitable for the planar design and integration of microwave integrated circuits. Although the microwave loss of microstrip lines is slightly higher than that of waveguide structures, their planar structure and high compatibility with semiconductor processes make microstrip lines the preferred transmission line form for modern microwave system design, enabling more complex circuit functions and higher-density integration.

[0004] Existing solutions typically employ multilayer or waveguide structures to achieve strong coupling and good directivity in couplers. However, single-layer microstrip couplers face significant challenges in achieving tight coupling, such as 3 dB or 5 dB. On one hand, tight coupling requires a large coupling coefficient within limited physical dimensions, but the side-coupling mode of single-layer microstrip structures limits coupling efficiency. Tight coupling implies a very small coupling spacing between the two coupling lines, significantly increasing the difficulty of electromagnetic field control in the coupling region of a single-layer microstrip structure. This is especially true at high frequencies, where the dispersion characteristics and field distribution of the microstrip lines have a more complex impact on coupling performance. On the other hand, directivity ensures extremely high signal isolation between the coupling port and the isolation port of the coupler, preventing leakage signals from the isolation port from entering the coupled signal. Insufficient directivity of the coupler leads to decreased system accuracy and increased signal interference, severely impacting system performance. Furthermore, under tight coupling conditions, the extremely small coupling spacing of single-layer microstrip couplers makes achieving high directivity very difficult. Furthermore, when a single-layer microstrip coupler achieves strong coupling, i.e., when the coupling spacing is very small, the coupling degree and directivity deteriorate rapidly with the increase of operating frequency and bandwidth.

[0005] Therefore, single-layer microstrip couplers present the challenge of simultaneously achieving tight coupling and high directivity. Summary of the Invention

[0006] This application provides a single-layer microstrip coupler that solves the technical problem of how to simultaneously achieve tight coupling and high directivity in existing single-layer microstrip couplers. It not only achieves both high directivity and tight coupling in a single-layer microstrip coupler, but also significantly improves the directivity of the single-layer microstrip coupler, achieves high matching performance with the load, and enhances the performance of the single-layer microstrip coupler.

[0007] In a first aspect, embodiments of the present invention provide a single-layer microstrip coupler, comprising: a main microstrip line and a sub-microstrip line coupled to each other;

[0008] One end of the main microstrip line is configured as the input port of a coupler for receiving electromagnetic wave signals, and the other end is configured as a through port for outputting signals.

[0009] One end of the sub-microstrip line is configured as the coupling port of the coupler, and the other end is configured as the isolation port;

[0010] When the coupling between the main microstrip line and the sub-microstrip line satisfies the condition of tight coupling, both the uncoupled side of the main microstrip line and the uncoupled side of the sub-microstrip line are provided with triangular punch-hole regions to guide the electromagnetic wave signal to propagate to the through port and the coupling port through the triangular punch-hole regions.

[0011] Optionally, the tight coupling condition is a condition where the coupling distance between the main microstrip line and the sub-microstrip line is in the range of 1.99 micrometers to 2.01 micrometers.

[0012] Optionally, the triangular perforation region of the main microstrip line and the triangular perforation region of the sub-microstrip line are symmetrically distributed along the coupling region between the main microstrip line and the sub-microstrip line.

[0013] Optionally, each of the triangular perforated areas includes: a plurality of rectangular holes;

[0014] The plurality of rectangular holes are spaced apart and are symmetrically distributed along the center line of the triangular excavation area;

[0015] The rectangular hole with the greatest depth among the plurality of rectangular holes is located on the center line of the triangular hole area; the depth of the rectangular holes decreases sequentially from the center line of the triangular hole area toward the two side ports.

[0016] Optionally, the spacing between any two adjacent rectangular holes is consistent, and the width of each rectangular hole is consistent.

[0017] Optionally, the width of the rectangular hole ranges from 1.99 micrometers to 2.01 micrometers.

[0018] Optionally, it may also include: a matching load connected to the isolation port;

[0019] The matching load is a thin-film resistor with a rectangular ring structure; the upper side of the thin-film resistor is connected to the isolation port, and multiple locations of the thin-film resistor are grounded.

[0020] Optionally, the thin-film resistor has symmetrical conductive strips distributed on both sides, and the conductive strips are provided with symmetrical vias. The thin-film resistor is grounded after being connected to the vias through the conductive strips.

[0021] Optionally, rectangular perforations are provided on the coupling side of the main microstrip line and the coupling side of the sub-microstrip line. The rectangular perforations of the main microstrip line and the sub-microstrip line are symmetrically distributed along the center line of the triangular perforation area, and the rectangular perforations of the main microstrip line and the sub-microstrip line are staggered.

[0022] Optionally, on each microstrip line, the rectangular perforation is not through to the rectangular hole, and the depth of the rectangular perforation is less than the depth of the rectangular hole.

[0023] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0024] In this embodiment of the invention, the coupling degree between the mutually coupled main microstrip line and the sub-microstrip line is made to meet the tight coupling (i.e., strong coupling) condition, meaning the coupling distance between the main microstrip line and the sub-microstrip line is sufficiently small. Under the tight coupling condition, triangular via regions are provided on the uncoupled sides of both the main microstrip line and the sub-microstrip line to guide electromagnetic wave signals to propagate to the through port and the coupled port. This not only achieves tight coupling of the coupler but also achieves directivity of more than 20 dB across the entire 110-160 GHz frequency band, thereby enabling the single-layer microstrip coupler to possess characteristics such as high directivity, tight coupling, high frequency (i.e., high operating frequency), and ultra-wideband, thus improving the performance of the single-layer microstrip coupler. Attached Figure Description

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0026] Figure 1 A schematic block diagram of a single-layer microstrip coupler according to an embodiment of the present invention is shown;

[0027] Figure 2A schematic diagram of the single-layer microstrip coupler in Embodiment 1 of the present invention is shown;

[0028] Figure 3 The simulation results of the single-layer microstrip coupler in Embodiment 1 of the present invention are shown in the figure.

[0029] Figure 4 A schematic diagram of the matching load structure of the single-layer microstrip coupler in Embodiment 2 of the present invention is shown;

[0030] Figure 5 The simulation results of the matched load of the single-layer microstrip coupler in Embodiment 2 of the present invention are shown.

[0031] Figure 6 A schematic diagram of the single-layer microstrip coupler in Embodiment 3 of the present invention is shown;

[0032] Figure 7 The simulation results of the single-layer microstrip coupler in Embodiment 3 of the present invention are shown.

[0033] In the attached diagram, 1 is the main microstrip line; 2 is the secondary microstrip line; 10 is the input port; 20 is the through port; 30 is the coupling port; 40 is the isolation port; 50 is the matching load; 51 is the conductor strip; 52 is the via; 60 is the triangular punched area; 61 is the rectangular hole; and 70 is the rectangular toothed hole. Detailed Implementation

[0034] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0035] Example 1

[0036] The first embodiment of the present invention provides a single-layer microstrip coupler, such as Figure 1 and Figure 2 As shown, it includes a main microstrip line 1 and a secondary microstrip line 2 that are coupled to each other. One end of the main microstrip line 1 is configured as the input port 10 of the coupler for receiving electromagnetic wave signals, and the other end is configured as a through port 20 for outputting signals. One end of the secondary microstrip line 2 is configured as the coupling port 30 of the coupler, and the other end is configured as an isolation port 40. Under the condition that the coupling degree between the main microstrip line 1 and the secondary microstrip line 2 meets the tight coupling condition, a triangular punch-hole region 60 is provided on the uncoupled side of the main microstrip line 1 and the uncoupled side of the secondary microstrip line 2, so as to guide the electromagnetic wave signal to propagate to the through port 20 and the coupling port 30 through the triangular punch-hole region 60.

[0037] It should be noted that the single-layer microstrip coupler in this embodiment employs a single-layer coupled microstrip line structure. The main microstrip line 1 and the negative microstrip line are disposed on the dielectric layer. In this embodiment, the coupler couples the electromagnetic wave energy received from the input port 10 to the coupling port 30 for output according to a preset power distribution ratio, while the remaining electromagnetic wave energy is output from the through port 20. The preset power distribution ratio is set according to actual needs. Most of the electromagnetic wave energy / signal is output from the through port 20 to maintain the transmission of the main signal path. A small portion of the electromagnetic wave energy / signal is coupled to the coupling port 30 for output through an electromagnetic coupling mechanism, commonly used for signal sampling, power detection, or feedback control.

[0038] The directivity D of the coupler is defined as the absolute value of the difference between the coupling degree and the isolation degree, where each parameter is reflected in the S-parameters (i.e., scattering parameters), as shown in Equation (1):

[0039] (1);

[0040] Where S31 represents the coupling degree and S41 represents the isolation degree.

[0041] In this embodiment, the coupling degree between the mutually coupled main microstrip line 1 and sub-microstrip line 2 is made to meet the tight coupling (i.e., strong coupling) condition, meaning the coupling distance between the main microstrip line 1 and sub-microstrip line 2 is sufficiently small. Under the tight coupling condition, triangular perforated regions 60 are provided on the non-coupled sides of both the main microstrip line 1 and sub-microstrip line 2 to guide electromagnetic wave signals to propagate to the through port 20 and the coupling port 30. This not only achieves tight coupling of the coupler but also achieves directivity of more than 20 dB in the entire 110-160 GHz frequency band, thereby enabling the single-layer microstrip coupler to have high directivity, tight coupling, high frequency (i.e., high operating frequency), and ultra-wideband characteristics, thus improving the performance of the single-layer microstrip coupler.

[0042] Below, in conjunction with Figure 1 and Figure 2 The specific structure of the single-layer microstrip coupler in this embodiment is described in detail below:

[0043] In this embodiment, the coupling degree between the main microstrip line 1 and the secondary microstrip line 2 of the coupler satisfies the tight coupling condition. Specifically, the tight coupling condition is that the coupling distance between the main microstrip line 1 and the secondary microstrip line 2 is in the range of 1.99 μm to 2.01 μm. The fact that the coupling distance between the main microstrip line 1 and the secondary microstrip line 2 is in the range of 1.99 μm to 2.01 μm indicates that the coupling degree between the main microstrip line 1 and the secondary microstrip line 2 satisfies the tight coupling condition, thus enabling the single-layer microstrip coupler to have a tight coupling.

[0044] Under tight coupling conditions, i.e., when the coupling distance between the two microstrip lines is approximately 2 micrometers, triangular perforated regions 60 are provided on the uncoupled sides of both the main microstrip line 1 and the sub-microstrip line 2. For each microstrip line, the coupling side is the side where the two microstrip lines are coupled to each other, and the uncoupled side is the side corresponding to the coupling side. For example... Figure 2 As shown, the upper side (i.e., the outer side) of the main microstrip line 1 is the non-coupled side, and the lower side (i.e., the inner side) of the main microstrip line 1 is the coupled side. The lower side (i.e., the outer side) of the sub-microstrip line 2 is the non-coupled side, and the upper side (i.e., the inner side) of the sub-microstrip line 2 is the coupled side. The region between the coupled sides of the two microstrip lines is the coupling region.

[0045] exist Figure 2 In this design, the triangular via regions 60 of the main microstrip line 1 and the sub-microstrip line 2 are symmetrically distributed along the coupling region between the main microstrip line 1 and the sub-microstrip line 2. Specifically, on each microstrip line, vias are drilled from the uncoupled side towards the coupled side, i.e., from the outer side of the microstrip line towards the inner side, forming triangular via regions 60. Furthermore, the triangular via regions formed on the uncoupled sides of the two microstrip lines are symmetrically distributed along the coupling region. This achieves a directivity of over 20 dB across the entire 110-160 GHz frequency band for the coupler. The vertical symmetry of the triangular via regions on the two microstrip lines is primarily to maintain the overall symmetrical structure of the coupler, which is more conducive to the matching of odd and even mode impedances and phases, thereby improving directivity. It also facilitates further structural optimization with subsequent inner vias.

[0046] like Figure 2 As shown, each microstrip line's triangular perforation region includes multiple rectangular holes 61. These rectangular holes 61 are spaced apart and symmetrically distributed along the center line of the triangular perforation region 60. The rectangular hole 61 with the greatest depth is located on the center line of the triangular perforation region 60; the depth of the rectangular holes 61 decreases sequentially from the center line of the triangular perforation region 60 towards the two side ports. Furthermore, the spacing between adjacent rectangular holes 61 and the width of the rectangular holes 61 are consistent. The width of the rectangular holes 61 ranges from 1.99 micrometers to 2.01 micrometers.

[0047] Specifically, to achieve a coupling strength of 5dB, the coupling spacing between the two microstrip lines is only about 2 micrometers. Given this small coupling spacing between the main microstrip line 1 and the secondary microstrip line 2, multiple rectangular holes 61 are directly drilled along the outer edge of each microstrip line towards the inner edge. The rectangular holes 61 are spaced apart and symmetrically distributed along the center line of the triangular hole region 60. Furthermore, the deepest rectangular hole 61 is located on the center line of the triangular hole region 60. The depth of the rectangular holes 61 decreases sequentially from the center line of the triangular hole region 60 towards the input port 10 and from the center line of the triangular hole region 60 towards the through port 20, achieving a gradually varying depth. Thus, the distribution of the multiple rectangular holes 61 presents a triangular structure, and the region containing the multiple rectangular holes 61 is called the triangular hole region 60.

[0048] Along the direction from input port 10 to through port 20, the depth of the rectangular aperture 61 gradually decreases from shallow to deep and then back to shallow, and is symmetrical about the center line of the triangular cutout region 60. This design maximizes the impedance at the center point where the coupling strength is strongest (i.e., the center line of the triangular cutout region 60) and minimizes the impedance on both sides (i.e., near the side ports), guiding energy propagation to through port 20 and coupling port 30, and suppressing energy inflow into isolation port 40, thereby improving directivity. The symmetrical rectangular aperture 61 with a depth varying from shallow to deep to shallow on the uncoupled side of each microstrip line allows for effective adjustment of odd and even mode impedance within a coupling spacing of approximately 2 micrometers, improving directivity without weakening the coupling strength.

[0049] The spacing between any two adjacent rectangular holes 61 is consistent, and the width of each rectangular hole 61 is also consistent. This not only ensures both tight coupling and high directionality of energy propagation in the coupler but also facilitates design and manufacturing. The spacing between any two adjacent rectangular holes 61 and the width of each rectangular hole 61 can be set according to actual requirements. For example, the spacing between any two adjacent rectangular holes 61 can be 0.008 mm. The width of the rectangular holes 61 ranges from 1.99 micrometers to 2.01 micrometers, ensuring the size of the rectangular holes 61 is as small as possible while maintaining extreme precision, reducing losses, and ensuring strong coupling and high directionality of the coupler.

[0050] Thus, by setting the structure of the triangular perforated area 60 of each microstrip line, that is, by setting the specific size and position of multiple rectangular holes 61, the electromagnetic field between microstrip lines can be easily controlled under the condition of tight coupling, thereby improving the directivity of the coupler.

[0051] like Figure 3 As shown, Figure 3 This is a simulation result diagram corresponding to the coupler structure in this embodiment. Figure 3In the diagram, S11 represents return loss, S21 represents insertion loss, S31 represents coupling, and S41 represents isolation. In subsequent figures, the meanings of S11, S21, S31, and S41 are the same and will not be repeated. The coupling S31 is approximately 5 dB, the directivity D is above 20 dB, and the return loss S11 is above 15 dB. It can be seen that the coupler structure of this embodiment achieves 5 dB coupling and over 20 dB directivity across the entire 110-160 GHz frequency band. Therefore, the coupler of this embodiment possesses characteristics such as high directivity, tight coupling, high frequency, and ultra-wideband performance, comprehensively improving the performance of a single-layer microstrip coupler.

[0052] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0053] This embodiment features a symmetrical gradient aperture structure, in which symmetrical rectangular apertures with varying depths are added to the outer side of the coupled microstrip lines. This gradual change in depth effectively compensates for odd and even mode impedances, suppressing edge scattering and surface wave resonance interference at a 2-micrometer coupling gap. This successfully achieves 5 dB coupling and over 20 dB directivity within the 110-160 GHz range. This allows the coupler in this embodiment to achieve high directivity under tight coupling conditions, resulting in a coupler with high directivity, tight coupling, high frequency, and ultra-wideband characteristics, comprehensively improving the performance of a single-layer microstrip coupler.

[0054] Example 2

[0055] like Figure 2 As shown, based on the single-layer microstrip coupler of Embodiment 1, the single-layer microstrip coupler of this embodiment further includes: a matching load 50 connected to the isolation port 40. The matching load 50 is a thin-film resistor with a rectangular ring structure; the upper side of the thin-film resistor is connected to the isolation port 40, and multiple positions of the thin-film resistor are grounded.

[0056] Specifically, isolation port 40 is not used in practical applications, therefore a matching load 50 needs to be connected. For example... Figure 2 and Figure 4 As shown, the matching load 50 is a rectangular ring-shaped thin-film resistor with symmetrical conductive strips 51 distributed on both sides. That is, there is one conductive strip 51 on the left side and the same conductive strip 51 on the right side of the thin-film resistor. The conductive strips 51 are also disposed on the dielectric layer. The conductive strips 51 have symmetrical vias 52, and the thin-film resistor is grounded after connecting to the vias 52 through the conductive strips 51. Specifically, each conductive strip 51 has a via 52, and the vias 52 on the left and right sides of the thin-film resistor are symmetrically distributed with respect to the thin-film resistor. Multiple points where the thin-film resistor contacts the conductive strips 51 are grounded through these vias 52. The specific shape of the vias 52 can be set according to actual needs. For example, in... Figure 2and Figure 4 In the middle, the via 52 is circular.

[0057] The working principle of the matching load 50 in this embodiment is as follows: The rectangular ring-shaped thin-film resistor guides energy to propagate in either a clockwise or counterclockwise direction, canceling out the energy flow in opposite directions and reducing the parasitic parameter effects of the thin-film resistor itself. Secondly, the ring structure helps guide current to flow more evenly through the resistor region, reducing current congestion and improving high-frequency current distribution. Then, the symmetrically distributed vias 52 on both sides effectively reduce the path length of energy from the input to ground, providing a very low-inductance and symmetrical grounding path for energy. The matching load 50 structure designed in this embodiment can more effectively control the impedance characteristics and parasitic effects of the thin-film resistor at high frequencies and ultra-wideband frequencies.

[0058] like Figure 2 and Figure 5 As shown, Figure 5 This is a simulation result diagram of the coupler in this embodiment. From... Figure 2 It can be seen that, through the coupler structure configuration of this embodiment, a coupling of 5 dB and directivity of over 20 dB are achieved across the entire 110-160 GHz frequency band. Figure 5 It can be seen that the return loss S11 of the coupler in this embodiment is above 28 dB across the entire frequency band. The rectangular ring-shaped thin-film resistor structure effectively extends the operating bandwidth of the thin-film resistor, enabling it to maintain good matching performance even under high-frequency, ultra-wideband operating conditions of 110-160 GHz. Therefore, the coupler in this embodiment achieves both high directivity and tightness, as well as high matching performance with a matching load of 50, comprehensively improving the performance of the single-layer microstrip coupler.

[0059] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0060] This embodiment designs a matching load structure, employing a rectangular ring-shaped thin-film resistor with symmetrical via distribution. Compared to traditional rectangular matching loads, this embodiment's matching load can form a natural LC resonance, effectively counteracting the parasitic parameters of the thin-film resistor. This forces the current to propagate in two opposite directions, with the reverse-flowing energy canceling each other out, reducing the parasitic parameters of the thin-film resistor. Simultaneously, the structure of this matching load guides the current to flow more evenly through the resistive region, reducing current congestion and achieving current homogenization. This maximizes the improvement of the high-frequency impedance characteristics and parasitic effects of the thin-film resistor matching load, ultimately achieving a reflection coefficient of over 28 dB in the 110-160 GHz frequency band, demonstrating excellent performance.

[0061] Example 3

[0062] Based on the single-layer microstrip coupler of Embodiment 2, such as Figure 6 As shown, rectangular tooth holes 70 are provided on the coupling side of the main microstrip line 1 and the coupling side of the sub-microstrip line 2. The rectangular tooth holes 70 of the main microstrip line 1 and the sub-microstrip line 2 are symmetrically distributed along the center line of the triangular hole area 60, and the rectangular tooth holes 70 of the main microstrip line 1 and the rectangular tooth holes 70 of the sub-microstrip line 2 are staggered.

[0063] Specifically, on each microstrip line, rectangular perforations 70 are drilled along the coupling side (inner side) towards the non-coupling side (outer side). The rectangular perforations 70 are symmetrically distributed along the centerline of the microstrip line. The centerline of the microstrip line is the centerline of the triangular perforation region 60. A set of rectangular perforations 70 is formed by two adjacent rectangular holes. For example... Figure 6 As shown, four sets of rectangular perforations 70 are drilled on the main microstrip line 1. These rectangular perforations 70 are symmetrically distributed along the center line of the triangular perforation area 60; that is, two sets of rectangular perforations 70 are located on the left side of the triangular perforation area 60, and two sets of rectangular perforations 70 are located on the right side of the triangular perforation area 60. Similarly, four sets of rectangular perforations 70 are drilled on the secondary microstrip line 2, symmetrically distributed along the center line of the triangular perforation area 60. The rectangular perforations 70 of the main microstrip line 1 and the rectangular perforations 70 of the secondary microstrip line 2 are staggered. Furthermore, on each microstrip line, the rectangular perforations 70 and rectangular holes 61 are not interconnected, and the depth of the rectangular perforations 70 is less than the depth of the rectangular holes 61.

[0064] The depth, width, spacing between two holes in a group of rectangular holes 70, spacing between two groups of rectangular holes 70, and the specific number of groups of rectangular holes 70 can all be set according to actual needs. The depth, width, and spacing of each group of rectangular holes 70 are consistent. Based on the current limits of machining precision, the width of a single hole in a group of rectangular holes 70 can be 0.002 mm, with a width range of 0.002 mm to 0.004 mm. To minimize the impact of the inner hole of the microstrip line on the original performance of the coupler, the width of a single hole is kept at 0.002 mm. Regarding the depth, to ensure no connection with the outer hole (i.e., rectangular hole 61), the depth range of the rectangular holes 70 is limited to 0.002-0.004 mm. The specific placement of the rectangular holes 70 is related to the phase of the energy, and is optimized by gradually approaching the center line from both sides of the two coupled microstrip lines.

[0065] By creating staggered rectangular perforations 70 on the inner sides of the main microstrip line 1 and the sub-microstrip line 2, the impedance change caused by the connection of the matching load 50 can be effectively utilized. While maintaining the original coupler performance, the odd-even mode impedance is further optimized, improving directivity.

[0066] Figure 7 This is a simulation result diagram corresponding to the coupler in this embodiment. For example... Figure 7 As shown, the coupling S31 remains around 5 dB, and the return loss S11 remains above 15 dB, with little change in either. However, the directivity D reaches over 30 dB, significantly improving the coupler's directivity. Therefore, based on the coupler structure of Embodiment 2, by drilling a rectangular toothed hole 70 on the inner side of the microstrip line, it successfully matches the designed matching load 50, further optimizing the odd-even mode impedance and achieving a directivity of over 30 dB. This embodiment of the single-layer microstrip coupler achieves high directivity under tight coupling strength, further endowing the coupler with high directivity, tight coupling, high frequency, and ultra-wideband characteristics, comprehensively improving the performance of the single-layer microstrip coupler.

[0067] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0068] To further enhance the directivity of the coupler in this embodiment, a novel collaborative design structure for the coupler and matching load is proposed. After connecting the designed matching load to the coupler, a rectangular toothed hole structure with about-center symmetry is further added to the inner side of the coupled microstrip line, based on the coupler structure of Embodiment 2. This structure can fully accommodate the impedance variation introduced by the matching load, and can further compensate for the odd-even mode impedance difference, achieving a significant improvement in directivity. Ultimately, a bandwidth of 110-160 GHz, a coupling degree of 5 dB, and a directivity of over 30 dB were successfully achieved.

[0069] Those skilled in the art will understand that although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0070] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A single-layer microstrip coupler, characterized in that, include: The main microstrip line and the sub-microstrip line are coupled together; One end of the main microstrip line is configured as the input port of a coupler for receiving electromagnetic wave signals, and the other end is configured as a through port for outputting signals. One end of the sub-microstrip line is configured as the coupling port of the coupler, and the other end is configured as the isolation port; When the coupling degree between the main microstrip line and the sub-microstrip line satisfies the tight coupling condition, both the uncoupled side of the main microstrip line and the uncoupled side of the sub-microstrip line are provided with triangular punch-hole areas to guide the electromagnetic wave signal to propagate to the through port and the coupling port through the triangular punch-hole areas; The tight coupling condition is that the coupling distance between the main microstrip line and the sub-microstrip line is in the range of 1.99 micrometers to 2.01 micrometers; The triangular perforation regions of the main microstrip line and the sub-microstrip line are symmetrically distributed along the coupling region between the main microstrip line and the sub-microstrip line. Each of the triangular perforated areas includes: multiple rectangular holes; The plurality of rectangular holes are spaced apart and are symmetrically distributed along the center line of the triangular excavation area; The rectangular hole with the greatest depth among the plurality of rectangular holes is located on the center line of the triangular hole area; the depth of the rectangular holes decreases sequentially from the center line of the triangular hole area toward the two ends. Rectangular perforations are provided on the coupling side of the main microstrip line and the coupling side of the sub-microstrip line. The rectangular perforations of the main microstrip line and the sub-microstrip line are symmetrically distributed along the center line of the triangular perforation area, and the rectangular perforations of the main microstrip line and the sub-microstrip line are staggered.

2. The single-layer microstrip coupler as described in claim 1, characterized in that, The spacing between any two adjacent rectangular holes is consistent, and the width of each rectangular hole is consistent.

3. The single-layer microstrip coupler as described in claim 1, characterized in that, The width of the rectangular hole ranges from 1.99 micrometers to 2.01 micrometers.

4. The single-layer microstrip coupler as described in any one of claims 1 to 3, characterized in that, It also includes: a matching load connected to the isolation port; The matching load is a thin-film resistor with a rectangular ring structure; the upper side of the thin-film resistor is connected to the isolation port, and multiple locations of the thin-film resistor are grounded.

5. The single-layer microstrip coupler as described in claim 4, characterized in that, The thin-film resistor has symmetrical conductive strips distributed on both sides, and the conductive strips are provided with symmetrical vias. The thin-film resistor is grounded after being connected to the vias through the conductive strips.

6. The single-layer microstrip coupler as described in claim 5, characterized in that, On each microstrip line, the rectangular perforations are not interconnected with the rectangular holes, and the depth of the rectangular perforations is less than the depth of the rectangular holes.

Images