Waveguide directional coupler based on quartz substrate coupling circuit

Abstract

The invention provides a waveguide directional coupler based on a quartz substrate coupling circuit. Signal coupling is achieved between two waveguides through the quartz substrate coupling circuit. The waveguide directional coupler based on the quartz substrate coupling circuit comprises a waveguide upper cavity, the quartz substrate coupling circuit and a waveguide lower cavity, and the quartz substrate coupling circuit comprises a waveguide coupling probe circuit, a comb-shaped cross coupling suppression circuit and a quartz substrate and is processed by adopting a planar film circuit preparation process. According to the invention, waveguide coupling probe circuits with different parameters are optimally designed, so that waveguide directional couplers with different coupling coefficients can be realized.

Description

Technical Field

[0001] The invention belongs to the field of waveguide directional couplers, and in particular relates to a waveguide directional coupler based on a quartz substrate coupling circuit. Background Art

[0002] Waveguide directional coupler is one of the important components in submillimeter wave circuits. It is used to transfer electromagnetic wave energy from one waveguide to another. Its main functions include: power distribution: coupling part of the power in the input waveguide to the output waveguide to achieve energy distribution among different channels; signal isolation: directional coupler has good directionality and can guide the signal from one path to another without affecting the reverse propagation of the signal or other irrelevant channels; monitoring and detection: by coupling out part of the signal, it can be used to monitor the signal strength and performance in the system in real time.

[0003] The structure commonly used in waveguide directional couplers is a parallel waveguide coupler, which consists of two parallel waveguides. The branch waveguide structure between the two waveguides realizes the coupling of electromagnetic wave energy from one waveguide to another waveguide. The number and size of the branch waveguides determine the coupling coefficient of the waveguide directional coupler. With the increase of the application frequency, the size of the waveguide and the size of the branch waveguide will be further reduced, which greatly increases the difficulty of processing, especially for waveguide directional couplers with weak coupler coefficients. The size of the branch waveguide is generally only tens of microns, and the deviation of processing accuracy can easily lead to changes in the coupling coefficient. In systems or components that use multiple waveguide directional couplers, due to the slight differences in waveguide processing accuracy and alignment accuracy, it is impossible to ensure that the coupling coefficient of each waveguide directional coupler is consistent with the design value, which affects the actual electromagnetic wave energy transmission, and may cause inconsistency in the output energy of each coupling port, affecting the performance of the system or component. Summary of the invention

[0004] The present invention aims at the deficiencies in the prior art and provides a waveguide directional coupler based on a quartz substrate coupling circuit.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a waveguide directional coupler based on a quartz substrate coupling circuit, comprising: a waveguide upper cavity, a quartz substrate coupling circuit and a waveguide lower cavity, wherein the waveguide upper cavity and the waveguide lower cavity are respectively installed above and below the quartz substrate coupling circuit, and the two together form a chamber for accommodating the quartz substrate coupling circuit, wherein the quartz substrate coupling circuit comprises a waveguide coupling probe circuit, a comb-shaped cross-coupling suppression circuit and a quartz substrate, and a plurality of waveguide coupling probe circuits and comb-shaped cross-coupling suppression circuits are alternately arranged on the quartz substrate.

[0007] Optionally, the quartz substrate coupling circuit is manufactured using a planar thin film circuit manufacturing process.

[0008] Optionally, the waveguide coupling probe circuit is composed of a suspended microstrip line and fan-shaped waveguide signal probes at both ends thereof, the fan-shaped waveguide signal probe at one end couples the electromagnetic field signal in the input waveguide into the suspended microstrip line, the suspended microstrip line transmits the electromagnetic field signal to the fan-shaped waveguide signal probe at the other end, and the fan-shaped waveguide signal probe at the other end then radiates the electromagnetic field signal into the output waveguide.

[0009] Optionally, the comb-shaped cross-coupling suppression circuit is arranged between two adjacent waveguide coupling probe circuits to suppress the diffusion and propagation of electromagnetic field signals in the quartz substrate, and the design length of the comb-shaped cross-coupling suppression circuit is consistent with the design length of the suspended microstrip line.

[0010] Optionally, the waveguide upper cavity includes a first through slot, a second through slot, a first groove and a second groove; the first through slot and the second through slot are parallel to the axis of the quartz substrate, and are respectively used to simultaneously accommodate fan-shaped waveguide signal probes at both ends of the suspended microstrip line; the first groove and the second groove are arranged between the first through slot and the second through slot, and a plurality of first grooves and second grooves are alternately and continuously arranged along the axis direction of the quartz substrate, and are respectively used to accommodate each suspended microstrip line and each comb-shaped cross-coupling suppression circuit.

[0011] Optionally, the depth of the first groove is greater than that of the second groove.

[0012] Optionally, the waveguide lower cavity includes a third through slot, a fourth through slot and a third groove; the third through slot and the fourth through slot are parallel to the axis of the quartz substrate, the third through slot cooperates with the first through slot to accommodate a fan-shaped waveguide signal probe at one end of the suspended microstrip line, and the fourth through slot cooperates with the second through slot to accommodate a fan-shaped waveguide signal probe at the other end of the suspended microstrip line; the third groove cooperates with the first groove to accommodate the suspended microstrip line.

[0013] Optionally, the depth of the third groove is smaller than that of the first groove.

[0014] The beneficial effects of the present invention are as follows: the present invention realizes a submillimeter waveband waveguide directional coupler by adopting a quartz substrate coupling circuit. Compared with the branch line waveguide directional coupler that is usually machined, the mechanical structure size cannot be changed after the processing, and the performance parameters such as the coupler coefficient of the coupler cannot be adjusted. If a waveguide directional coupler with different coupling parameters is required, it is necessary to process a waveguide structure with different mechanical sizes. The improvement of the present invention is that after the waveguide structure based on the quartz substrate coupling circuit is processed, the quartz substrate coupling circuit designed with different coupling parameters can be replaced to conveniently adjust the coupler performance. The processing cost and difficulty of the quartz substrate coupling circuit are much lower than that of the waveguide structure. The present invention can reduce the development cost of the system and expand the performance of the system under different coupling coefficients. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of a waveguide directional coupler based on a quartz substrate coupling circuit.

[0016] Figure 2 This is a simulation diagram of a waveguide directional coupler based on a quartz substrate coupling circuit.

[0017] Figure 3 A top view of a waveguide directional coupler based on a quartz substrate coupling circuit.

[0018] Figure 4 This is a design diagram of the quartz substrate coupling circuit.

[0019] Figure 5 This is a cross-sectional view of a waveguide directional coupler based on a quartz substrate coupling circuit.

[0020] Figure 6a and Figure 6b This is a photo of a waveguide directional coupler based on a quartz substrate coupling circuit.

[0021] Figure 7 This is a test diagram of a waveguide directional coupler based on a quartz substrate coupling circuit.

[0022] The figure numbers are as follows: 1-waveguide upper cavity; 1.1-first through slot; 1.2-second through slot; 1.3-first groove; 1.4-second groove; 2-quartz substrate coupling circuit; 2.1-waveguide coupling probe circuit; 2.1.1-suspended microstrip line; 2.1.2-fan-shaped waveguide signal probe; 2.2-comb-shaped cross-coupling suppression circuit; 2.3-quartz substrate; 3-waveguide lower cavity; 3.1-third through slot; 3.2-fourth through slot; 3.3-third groove. DETAILED DESCRIPTION

[0023] The present invention will now be described in further detail with reference to the accompanying drawings.

[0024] The present invention proposes a waveguide directional coupler based on a quartz substrate coupling circuit, such as Figure 1 and Figure 2 As shown, it includes a specially designed complete quartz substrate coupling circuit 2 and a waveguide cavity (waveguide upper cavity 1 and waveguide lower cavity 3). The waveguide upper cavity 1 and the waveguide lower cavity 3 are mechanically positioned to form two parallel waveguides. There is a specially designed chip mounting groove for mounting the quartz substrate coupling circuit 2 in the middle of the two waveguides. The chip mounting groove is machined to be integrally formed with the waveguide upper cavity 1 and the waveguide lower cavity 3. There are grooves of different heights in the chip mounting groove, and the positions of these grooves are symmetrical with the center of the position of the waveguide coupling probe circuit on the quartz substrate coupling circuit. The quartz substrate coupling circuit 2 includes a waveguide coupling probe circuit 2.1, a comb-shaped cross-coupling suppression circuit 2.2 and a quartz substrate 2.3. The quartz substrate coupling circuit 2 is processed by a planar thin film circuit preparation process. By optimizing and designing the waveguide coupling probe circuit 2.1 with different parameters, a waveguide directional coupler with different coupling coefficients can be realized. The waveguide is an E-surface split waveguide, and there is a specially designed groove for mounting the quartz substrate coupling circuit 2 at the split surface.

[0025] In this embodiment, the thickness of the quartz substrate 2.3 is 30 μm. In order to achieve the expected designed working bandwidth, three identical waveguide coupling probe circuits 2.1 are used on the quartz substrate 2.3. Figure 3 As shown, the waveguide coupling probe circuit 2.1 is composed of a suspended microstrip line 2.1.1 and fan-shaped waveguide signal probes 2.1.2 at both ends thereof. The fan-shaped waveguide signal probe 2.1.2 at one end couples the electromagnetic field signal in the input waveguide (i.e., the combination of the first through slot 1.1 and the third through slot 3.1) into the suspended microstrip line 2.1.1, and the suspended microstrip line 2.1.1 transmits the electromagnetic field signal to the fan-shaped waveguide signal probe 2.1.2 at the other end, and the fan-shaped waveguide signal probe 2.1.2 at the other end radiates the electromagnetic field signal into the output waveguide (i.e., the combination of the second through slot 1.2 and the fourth through slot 3.2). Due to the existence of the quartz substrate 2.3, the electromagnetic field signal transmitted on the suspended microstrip line 2.1.1 will diffuse and propagate in the quartz substrate 2.3, and the two adjacent waveguide coupling probe circuits 2.1 will affect each other, so that the expected design goal cannot be achieved. In order to avoid mutual interference between two adjacent waveguide coupling probe circuits 2.1, a comb-shaped cross-coupling suppression circuit 2.2 is used between adjacent waveguide coupling probe circuits 2.1. The comb-shaped cross-coupling suppression circuit 2.2 can effectively suppress the diffusion and propagation of electromagnetic field signals in the quartz substrate 2.3 and reduce mutual interference between adjacent circuits. At the same time, the design length of the comb-shaped cross-coupling suppression circuit 2.2 is consistent with the spacing between the two coupling waveguides.

[0026] like Figure 1 , Figure 5As shown, the waveguide upper cavity 1 includes a first through slot 1.1, a second through slot 1.2, a first groove 1.3 and a second groove 1.4; the first through slot 1.1 and the second through slot 1.2 are parallel to the axis of the quartz substrate 2.3, and are respectively used to simultaneously accommodate the fan-shaped waveguide signal probes 2.1.2 at both ends of the suspended microstrip line 2.1.1; the first groove 1.3 and the second groove 1.4 are arranged between the first through slot 1.1 and the second through slot 1.2, and a plurality of first grooves 1.3 and second grooves 1.4 are alternately and continuously arranged along the axis direction of the quartz substrate 2.3, and are respectively used to accommodate each suspended microstrip line 2.1.1 and each comb-shaped cross-coupling suppression circuit 2.2. The waveguide lower cavity 3 includes a third through slot 3.1, a fourth through slot 3.2 and a third groove 3.3; the third through slot 3.1 and the fourth through slot 3.2 are parallel to the axis of the quartz substrate 2.3, the third through slot 3.1 cooperates with the first through slot 1.1 to accommodate the fan-shaped waveguide signal probe 2.1.2 at one end of the suspended microstrip line 2.1.1, the fourth through slot 3.2 cooperates with the second through slot 1.2 to accommodate the fan-shaped waveguide signal probe 2.1.2 at the other end of the suspended microstrip line 2.1.1; the third groove 3.3 cooperates with the first groove 1.3 to accommodate the suspended microstrip line 2.1.1. Among them, the depth of the first groove 1.3 is greater than that of the second groove 1.4, and the depth of the third groove 3.3 is less than that of the first groove 1.3.

[0027] This embodiment designs slots of different shapes and depths for three different structures, namely, the fan-shaped waveguide signal probe 2.1.2, the suspended microstrip line 2.1.1, and the comb-shaped cross-coupling suppression circuit 2.2. This is because: (1) The fan-shaped waveguide signal probe extends to the input waveguide and the output waveguide respectively. According to the reciprocity principle in the electromagnetic field theory, the fan-shaped waveguide signal probe can couple the input electromagnetic field signal and radiate the output electromagnetic field signal. Therefore, a through slot is designed that can accommodate all the fan-shaped waveguide signal probes on one side at the same time. (2) Each suspended microstrip line has an independent slot. This is the basic theoretical structure of the suspended microstrip line to ensure that the electromagnetic field signal can be transmitted normally on the suspended microstrip line. Through optimization simulation, the width of the suspended microstrip line slot and the depth of the upper and lower side slots can be determined. (3) The comb-shaped cross-coupling suppression circuit is based on the microstrip line structure design, so no slot is opened on its lower side. The main function of the comb-shaped cross-coupling suppression circuit is to reduce the electromagnetic field signal transmitted between two adjacent fan-shaped waveguide signal probes through the quartz substrate, while the coupling of the electromagnetic field signal in the slot space on the upper side of the suspended microstrip line is reduced by reducing the height of the slot on the upper side of the comb-shaped cross-coupling suppression circuit to reduce the coupling in the space.

[0028] The design dimensions of the quartz substrate coupling circuit operating in the 200-290GHz frequency band are as follows: Figure 4 As shown in the figure, Ang_pl and Ang_p2 represent the angles of the fan-shaped waveguide signal probe, R_p1 and R_p2 represent the radius of the fan-shaped waveguide signal probe, Figure 5The relevant dimensions in the chip mounting slots of the upper waveguide cavity 1 and the lower waveguide cavity 3 are marked. In the specific implementation, two quartz substrate coupling circuits with different coupling coefficients are designed, which are -17dB and -20dB respectively.

[0029] Table 1 Quartz substrate coupling circuit and waveguide structure dimensions

[0030]

[0031]

[0032] Figure 6a and Figure 6b This is a photo of the final waveguide structure and the quartz substrate coupling circuit installed. The left picture shows a -20dB coupler, and the right picture shows a -17dB coupler. The quartz substrate coupling circuit is placed in a specially designed circuit mounting slot and fixed at both ends with hot melt wax to prevent the quartz substrate coupling circuit from shifting during use.

[0033] Figure 7 These are the test results of the waveguide directional coupler based on the quartz substrate coupling circuit. From the test, the coupling coefficients of the two couplers are basically consistent with the simulation results, which proves the correctness of the coupler design.

[0034] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A waveguide directional coupler based on a quartz substrate coupling circuit, characterized in that: include: A waveguide upper cavity (1), a quartz substrate coupling circuit (2) and a waveguide lower cavity (3), wherein the waveguide upper cavity (1) and the waveguide lower cavity (3) are respectively installed above and below the quartz substrate coupling circuit (2), and the two together form a cavity for accommodating the quartz substrate coupling circuit (2), wherein the quartz substrate coupling circuit (2) comprises a waveguide coupling probe circuit (2.1), a comb-shaped cross-coupling suppression circuit (2.2) and a quartz substrate (2.3), and a plurality of waveguide coupling probe circuits (2.1) and comb-shaped cross-coupling suppression circuits (2.2) are alternately arranged on the quartz substrate (2.3).

2. A waveguide directional coupler based on a quartz substrate coupling circuit as claimed in claim 1, characterized in that: The quartz substrate coupling circuit (2) is manufactured using a planar thin film circuit manufacturing process.

3. A waveguide directional coupler based on a quartz substrate coupling circuit as claimed in claim 1, characterized in that: The quartz substrate (2.3) is a complete rectangle, and no etched through-hole structure exists on the quartz substrate (2.3).

4. A waveguide directional coupler based on a quartz substrate coupling circuit as claimed in claim 1, characterized in that: The waveguide coupling probe circuit (2.1) is composed of a suspended microstrip line (2.1.1) and fan-shaped waveguide signal probes (2.1.2) at both ends thereof. The fan-shaped waveguide signal probe (2.1.2) at one end couples the electromagnetic field signal in the input waveguide into the suspended microstrip line (2.1.1), the suspended microstrip line (2.1.1) transmits the electromagnetic field signal to the fan-shaped waveguide signal probe (2.1.2) at the other end, and the fan-shaped waveguide signal probe (2.1.2) at the other end radiates the electromagnetic field signal into the output waveguide.

5. A waveguide directional coupler based on a quartz substrate coupling circuit as claimed in claim 4, characterized in that: The comb-shaped cross-coupling suppression circuit (2.2) is arranged between two adjacent waveguide coupling probe circuits (2.1) and is used to suppress the diffusion and propagation of electromagnetic field signals in the quartz substrate (2.3); the design length of the comb-shaped cross-coupling suppression circuit (2.2) is consistent with the design length of the suspended microstrip line (2.1.1).

6. A waveguide directional coupler based on a quartz substrate coupling circuit as claimed in claim 5, characterized in that: The waveguide upper cavity (1) comprises a first through slot (1.1), a second through slot (1.2), a first groove (1.3) and a second groove (1.4); the first through slot (1.1) and the second through slot (1.2) are parallel to the axis of the quartz substrate (2.3), and are respectively used to simultaneously accommodate fan-shaped waveguide signal probes (2.1.2) at both ends of a suspended microstrip line (2.1.1); the first groove (1.3) and the second groove (1.4) are arranged between the first through slot (1.1) and the second through slot (1.2), and a plurality of first grooves (1.3) and second grooves (1.4) are alternately and continuously arranged along the axis direction of the quartz substrate (2.3), and are respectively used to accommodate each suspended microstrip line (2.1.1) and each comb-shaped cross-coupling suppression circuit (2.2).

7. A waveguide directional coupler based on a quartz substrate coupling circuit as claimed in claim 6, characterized in that: The first groove (1.3) has a depth greater than that of the second groove (1.4).

8. A waveguide directional coupler based on a quartz substrate coupling circuit as claimed in claim 6, characterized in that: The waveguide lower cavity (3) comprises a third through slot (3.1), a fourth through slot (3.2) and a third groove (3.3); the third through slot (3.1) and the fourth through slot (3.2) are parallel to the axis of the quartz substrate (2.3); the third through slot (3.1) cooperates with the first through slot (1.1) to accommodate a fan-shaped waveguide signal probe (2.1.2) at one end of a suspended microstrip line (2.1.1); the fourth through slot (3.2) cooperates with the second through slot (1.2) to accommodate a fan-shaped waveguide signal probe (2.1.2) at the other end of the suspended microstrip line (2.1.1); the third groove (3.3) cooperates with the first groove (1.3) to accommodate the suspended microstrip line (2.1.1).

9. A waveguide directional coupler based on a quartz substrate coupling circuit as claimed in claim 8, characterized in that: The depth of the third groove (3.3) is smaller than that of the first groove (1.3).

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