A substrate-integrated waveguide coupler with filtering and high directivity

Abstract

This invention discloses a substrate integrated waveguide coupler with filtering and high directionality. It constructs a pair of three half-mode substrate integrated waveguide coupling lines formed by E-type metal to form a resonant point. By utilizing the adjustment effect of its internal slots and grooves on coupling and isolation characteristics, combined with the control effect of the external feeding structure on matching and isolation, a high degree of control freedom is obtained. It can realize a substrate integrated waveguide coupler with filtering function and high directionality, while taking into account phase difference fluctuation, overall size and weak coupling capability.

Description

Technical Field

[0001] This invention relates to a microwave communication device, and more particularly to a substrate integrated waveguide coupler. Background Technology

[0002] Substrate integrated waveguides (DIWBs) possess characteristics such as low loss and high quality factor. DIWB-based couplers are suitable for high-frequency operation and can couple input signals to the coupling port at a certain ratio. Highly directional DIWB couplers allow the signal output at the isolation end to be significantly lower than that at the coupling end. When applied to power monitoring and signal analysis in communication systems, this can reduce measurement errors and improve the dynamic range of measurements. When DIWB couplers have filtering capabilities, they can reduce measurement errors caused by out-of-band signals and reduce the number of filters in the main and coupling channels, thereby lowering system loss, size, and cost. Therefore, integrating directional coupling and filtering functions into DIWB couplers to form highly directional DIWB couplers with filtering capabilities is beneficial for improving system performance, reducing the number of system components, reducing size, and lowering cost, and has significant engineering value and importance.

[0003] Existing substrate integrated waveguide couplers primarily achieve directional coupling but lack filtering capabilities. Their implementation methods can be broadly categorized into four types. The first method achieves high directional coupling by opening a coupling window in a shared via region of parallel substrate integrated waveguides. However, this results in significant phase difference fluctuations between the through port and the coupled port, and the large size is due to the use of full-mode substrate integrated waveguides. The second method incorporates via disturbance field distribution in the central region of a cross-shaped substrate integrated waveguide cavity to achieve directional coupling. However, this method suffers from large size, inability to weaken the interference field, and still excessive phase difference fluctuations between the through port and the coupled port. The third method achieves high directional coupling by opening a coupling window in a shared via region of two back-to-back half-mode substrate integrated waveguides, and the circuit size is reduced to some extent. However, the phase difference fluctuations between the through port and the coupled port remain significant. The fourth method uses a common-mode slot coupling or a stacked slot coupling method between a pair of face-to-face half-mode substrate integrated waveguides to form directional coupling, but the phase difference fluctuations between the through port and the coupled port remain significant. Therefore, on the one hand, it is necessary to propose a substrate-integrated waveguide coupler with filtering and high directivity, and on the other hand, it is necessary to take into account the phase difference fluctuation between the through port and the coupled port, the overall size, and the ability to achieve weak coupling. Summary of the Invention

[0004] Purpose of the invention: To address the aforementioned existing technologies, a substrate-integrated waveguide coupler is proposed that simultaneously possesses filtering functionality and high directionality, while also taking into account phase difference fluctuations, overall size, and weak coupling capability.

[0005] Technical solution: A substrate-integrated waveguide coupler with filtering and high directivity includes a top metal layer structure, a bottom metal layer structure, metallized vias, and a dielectric substrate; the top metal layer structure and the bottom metal layer structure are located on the top and bottom surfaces of the dielectric substrate, respectively;

[0006] The top metal layer structure is symmetrical both horizontally and vertically, including four metal strips, four stepped metals, four short branches, four trapezoidal metals and a pair of E-type metals; among them, the pair of E-type metals are symmetrically arranged face to face about the horizontal center line, and each E-type metal is formed by opening a pair of vertical long slots on one long side of a rectangular metal, and a pair of narrow slits on both sides and a wide slit in the middle are formed between the face-to-face E-type metals.

[0007] Each E-type metal has a power supply structure connected to its left and right sides, forming a total of four ports. Each power supply structure includes a short stub, a stepped metal, and a trapezoidal metal connected in sequence. A short stub is loaded on the inner side of the stepped metal. A vertical short slot one is opened at the connection between the stepped metal and the trapezoidal metal. A vertical short slot two is opened at the connection between the E-type metal and the trapezoidal metal.

[0008] The metallized via consists of two rows of metal vias located on the top and bottom sides of the E-type metal facing each other. The metallized vias pass through the dielectric substrate and connect the top metal layer structure and the bottom metal layer structure.

[0009] Furthermore, the length of the vertical groove is 0.32λ. g ~0.35λ g The length of the narrow slit is between 0.20λ. g ~0.23λ g The length of the wide slit is between 0.20λ. g ~0.23λ g between.

[0010] Furthermore, the vertical length of the short branch is 0.02λ. g ~0.03λ g Between these points, the length of the first vertical short groove is 0.07λ. g ~0.08λ g Between 0.20λ, the length of the second vertical short groove is... g ~0.23λ g between.

[0011] Furthermore, the pair of E-type metals, the bottom metal layer structure, the metallized via, and the dielectric substrate constitute three half-mode substrate integrated waveguide coupling lines, namely, half-mode substrate integrated waveguide coupling lines located on both sides and a half-mode substrate integrated waveguide coupling line located in the middle; by adjusting the width of the narrow slit and the wide slit, the coupling degree and coupling flatness of the substrate integrated waveguide coupler can be controlled, the isolation frequency and level and the isolation bandwidth and level can be controlled, and the phase difference fluctuation between the through port and the coupling port can be controlled.

[0012] Furthermore, the isolation frequency and level, as well as the working frequency and isolation level, are controlled by adjusting the lengths of the narrow slit and the wide slit, respectively.

[0013] Furthermore, the isolation level of the substrate-integrated waveguide coupler can be individually controlled by adjusting the length of the short stub in the vertical direction.

[0014] Furthermore, the matching level of the overall circuit is controlled by adjusting the length of the vertical short slot.

[0015] Beneficial Effects: Existing substrate integrated waveguide couplers only achieve directionality and lack filtering capabilities. They also suffer from large phase difference fluctuations between the through port and the coupled port, large overall size, or inability to achieve weak coupling. This invention constructs a pair of three-segment half-mode substrate integrated waveguide coupling lines formed by E-type metal to create a resonant point. Utilizing the adjustment of coupling and isolation characteristics through internal slots and grooves, combined with the control of matching and isolation by the external feeding structure, a high degree of control freedom is achieved. This enables the realization of a substrate integrated waveguide coupler with filtering capabilities and high directionality, while also addressing phase difference fluctuations, overall size, and the ability to achieve weak coupling.

[0016] Specifically, the three-segment half-mode substrate integrated waveguide coupling line consists of an E-type metal, a rectangular metal ground, a metallized via, and a dielectric substrate. It contains two vertical short slots, a vertical long slot, a pair of narrow slots, and a wide slot, providing a resonant point for the overall circuit. The slots and slots have a modulating effect on the frequency and bandwidth, coupling performance, isolation performance, and phase difference fluctuation of each channel, and have a high degree of control freedom, enabling simultaneous filtering and directional coupling functions.

[0017] The microstrip feeding structure consists of metal strips, stepped metal, short stubs, trapezoidal metal, and vertical short slots. The lengths of the short stubs and slots can be used to adjust the isolation level and matching level, respectively, which further improves the control freedom of the overall circuit and is conducive to the realization of multiple functions of the overall circuit. Attached Figure Description

[0018] Figure 1 This is a diagram of the top metal structure of the substrate-integrated waveguide coupler of the present invention;

[0019] Figure 2This is a diagram of the bottom metal structure of the substrate-integrated waveguide coupler of the present invention;

[0020] Figure 3 Simulation of the substrate-integrated waveguide coupler of this invention S Parametric curves;

[0021] Figure 4 The simulated phase difference curve between the through port and the coupled port of the substrate integrated waveguide coupler of this invention is shown. Detailed Implementation

[0022] The invention will now be further explained with reference to the accompanying drawings.

[0023] A substrate-integrated waveguide coupler with filtering and high directivity is composed of a top metal layer structure, a bottom metal layer structure, metallized vias, and a dielectric substrate.

[0024] like Figure 1 As shown, the top metal layer structure is symmetrical both horizontally and vertically, comprising four metal strips 101, four stepped metals 102, four short branches 103, four trapezoidal metals 104, and a pair of E-shaped metals 105. The pair of E-shaped metals 105 are symmetrically arranged face-to-face about a horizontal centerline. Each E-shaped metal 105 is formed by opening a pair of vertical slots 108 along one long side of a rectangular metal section. Between the face-to-face E-shaped metals 105, a pair of narrow slits 109 on either side and a wide slit 110 in the middle are formed. The length of the vertical slots 108 is 0.32λ. g ~0.35λ g Between them, the length of the narrow slits 109 on both sides is 0.20λ g ~0.23λ g Between them, the length of the wide slit 110 in the middle is 0.20λ. g ~0.23λ g Between, λ g The wavelength of the guided wave corresponding to the center frequency.

[0025] Each E-type metal 105 has a power supply structure connected to its left and right sides, forming four ports in total. Each power supply structure includes a short stub 103, a stepped metal 102, and a trapezoidal metal 104 cascaded together. A short stub 103 is loaded on the inner side of the stepped metal 102. A vertical short slot 106 is formed at the connection between the stepped metal 102 and the trapezoidal metal 104; a vertical short slot 107 is formed at the connection between the E-type metal 105 and the trapezoidal metal 104. The vertical length of the short stub 103 is 0.02λ. g ~0.03λ g Between these, the length of the vertical short groove 106 is 0.07λ. g ~0.08λg Between, the length of the vertical short groove 2107 is 0.20λ. g ~0.23λ g between.

[0026] like Figure 2 As shown, the bottom metal layer structure is a rectangular metal ground 201. Between the top and bottom metal layer structures is a dielectric substrate, which is a complete rectangular dielectric 401. The metallized vias consist of two rows of metal vias 301 located on the upper and lower sides of the E-type metal 105 facing each other. The metal vias 301 pass through the dielectric substrate and connect the top and bottom metal layer structures.

[0027] In the above structure, the E-type metal 105, the rectangular metal ground 201, the metal via 301, and the dielectric substrate form three half-mode substrate integrated waveguide coupling lines, namely, half-mode substrate integrated waveguide coupling lines located on both sides and one half-mode substrate integrated waveguide coupling line located in the middle. The metal strip 101, the stepped metal 102, the short stub 103, the trapezoidal metal 104, and the vertical short slot 106 form a microstrip feeding structure.

[0028] This invention features a fully reciprocal structure. Signals are fed into any port, pass through the corresponding microstrip feeding structure, and are transmitted to three half-mode substrate integrated waveguide coupling lines. Then, they are output from the microstrip feeding structures of the through port, coupling port, and isolation port, respectively. Under the action of the overall circuit, a substrate integrated waveguide coupler with filtering and high directivity is realized.

[0029] In this process, the half-mode substrate integrated waveguide coupling lines on both sides and in the middle provide resonant points for the overall circuit. The resonant frequency and bandwidth can be adjusted by controlling the overall width of the coupling lines along the vertical direction, as well as the length and width of the inner vertical long slot 108 and the outer vertical short slot 107. The slot widths of the narrow slot 109 and wide slot 110 of the three half-mode substrate integrated waveguide coupling lines can simultaneously adjust the coupling degree and coupling flatness, and can respectively affect the isolation frequency and level, as well as the isolation bandwidth and level. Simultaneously, the narrow slot 109 and wide slot 110 can regulate the phase difference fluctuation between the through port and the coupled port. Furthermore, the lengths of the narrow slot 109 and wide slot 110 can control the isolation frequency and level, as well as the operating frequency and isolation level, respectively. Therefore, by adjusting the combination of the narrow slot 109 and wide slot 110, a high degree of control freedom can be obtained in terms of coupling, isolation, and phase difference, ensuring that the performance in all three aspects is optimized simultaneously. The length of the short stub 103 of the microstrip feeding structure can be used to independently adjust the isolation level. The length of the vertical short slot 106 inside the microstrip feed structure mainly controls the matching level of the overall circuit. The specific shape and size of the stepped metal 102 and trapezoidal metal 104 can be obtained through existing simulation optimization techniques according to the impedance matching requirements.

[0030] In summary, this invention has a high degree of adjustment freedom, can simultaneously achieve high directionality and filtering functions, and can take into account phase difference fluctuations, overall size and weak coupling capabilities.

[0031] This embodiment uses an F4B substrate with a circuit size of 1.64λ. g × 0.65λ g . Figure 3 , Figure 4 This embodiment is given. S The parameter response curves, as shown in the figure, indicate a 3-dB operating bandwidth frequency range of 5.88 GHz - 7.75 GHz, representing a relative bandwidth of 24.4%. The minimum insertion loss is only 0.93 dB, achieving two transmission poles at 6.64 GHz and 6.91 GHz, thus realizing a second-order filter response. The coupling is 10.77 dB, and the 3-dB operating bandwidth frequency range of the coupled channel is 5.66 GHz - 7.99 GHz, representing a relative bandwidth of 34.1%. The directional frequency range where coupling minus isolation is greater than 10 dB is 6.35 GHz - 7.32 GHz, representing a relative bandwidth of 14.2%. This corresponds to a coupling port ripple of ±0.94 dB, with a maximum directional bandwidth of 40 dB. The phase difference between the output signals at the through and coupled ends is 94.3° ± 1.5°, indicating good phase difference stability.

[0032] 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. A substrate-integrated waveguide coupler with filtering and high directivity, characterized in that, It includes a top metal layer structure, a bottom metal layer structure, metallized vias, and a dielectric substrate; the top metal layer structure and the bottom metal layer structure are located on the top and bottom surfaces of the dielectric substrate, respectively; The top metal layer structure is symmetrical both horizontally and vertically, including four metal strips (101), four stepped metals (102), four short branches (103), four trapezoidal metals (104), and a pair of E-shaped metals (105); among them, the pair of E-shaped metals (105) are symmetrically arranged face to face about the horizontal center line, and each E-shaped metal (105) is formed by opening a pair of vertical long slots (108) on one long side of a rectangular metal. A pair of narrow slits (109) on both sides and a wide slit (110) in the middle are formed between the face-to-face E-shaped metals (105). Each E-type metal (105) has a power supply structure connected to its left and right sides, forming a total of four ports. Each power supply structure includes a short stub (103), a stepped metal (102), and a trapezoidal metal (104) connected in sequence. A short stub (103) is loaded on the inner side of the stepped metal (102). A vertical short slot one (106) is opened at the connection between the stepped metal (102) and the trapezoidal metal (104). A vertical short slot two (107) is opened at the connection between the E-type metal (105) and the trapezoidal metal (104). The metallized via consists of two rows of metal vias located on the upper and lower sides of the face-to-face E-type metal (105). The metallized vias pass through the dielectric substrate and connect the top metal layer structure and the bottom metal layer structure.

2. The substrate-integrated waveguide coupler according to claim 1, characterized in that, The length of the vertical slot (108) is 0.32λ. g ~0.35λ g Between these points, the length of the narrow slit (109) is 0.20λ. g ~0.23λ g Between these points, the length of the wide slit (110) is 0.20λ. g ~0.23λ g Between, λ g The wavelength of the guided wave corresponding to the center frequency.

3. The substrate-integrated waveguide coupler according to claim 2, characterized in that, The short branch (103) has a vertical length of 0.02λ. g ~0.03λ g Between these points, the length of the vertical short groove one (106) is 0.07λ. g ~0.08λ g Between, the length of the vertical short groove two (107) is 0.20λ g ~0.23λ g between.

4. The substrate integrated waveguide coupler according to any one of claims 1-3, characterized in that, The pair of E-type metals (105), the bottom metal layer structure, the metallized via, and the dielectric substrate form three half-mode substrate integrated waveguide coupling lines, namely, half-mode substrate integrated waveguide coupling lines located on both sides and a half-mode substrate integrated waveguide coupling line located in the middle; by adjusting the width of the narrow slit (109) and the wide slit (110), the coupling degree and coupling flatness of the substrate integrated waveguide coupler are controlled, the isolation frequency and level and the isolation bandwidth and level are controlled, and the phase difference fluctuation between the through port and the coupling port is controlled.

5. The substrate-integrated waveguide coupler according to claim 4, characterized in that, The isolation frequency and level, as well as the working frequency and isolation level, are controlled by adjusting the lengths of the narrow slit (109) and the wide slit (110), respectively.

6. The substrate-integrated waveguide coupler according to claim 4, characterized in that, The isolation level of the substrate integrated waveguide coupler can be individually controlled by adjusting the length of the short stub (103) in the vertical direction.

7. The substrate-integrated waveguide coupler according to claim 4, characterized in that, The matching level of the overall circuit is controlled by adjusting the length of the vertical short slot 1 (106).

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