Substrate integrated waveguide coupler with filtering and high directionality

Abstract

The invention discloses a substrate integrated waveguide coupler with filtering and high directionality, a pair of three-section half-mode substrate integrated waveguide coupling lines formed by E-type metal is constructed, resonance points are formed, the coupling and isolation characteristics are adjusted by using internal seams and grooves of the coupling and isolation coupling lines, and the matching and isolation are regulated and controlled by combining an external feed structure. The substrate integrated waveguide coupler with a filtering function and high directionality can be realized, and phase difference fluctuation, overall size and weak coupling realization capability can be considered.

Description

Technical Field

[0001] The invention relates to a microwave communication device, in particular to a substrate integrated waveguide coupler. Background Art

[0002] Substrate integrated waveguides have the characteristics of low loss and high quality factor. Couplers based on substrate integrated waveguides are suitable for high-frequency operation and can couple the input signal to the coupling port at a certain ratio. Highly directional substrate integrated waveguide couplers can make the signal output at the isolation end much lower than the signal output at the coupling end. When used in power monitoring and signal analysis of communication systems, they can reduce measurement errors and improve the measurement dynamic range. When the substrate integrated waveguide coupler has a filtering function, it can reduce the measurement error caused by out-of-band signals, and can reduce the filters of the main channel and the coupling channel, reducing system loss, volume and cost. Therefore, integrating directional coupling and filtering functions into the substrate integrated waveguide coupler to form a substrate integrated waveguide coupler with filtering and high directivity can be beneficial to improving system performance, reducing the number of system components, reducing size and reducing costs, and has important engineering value and significance.

[0003] The existing substrate integrated waveguide coupler basically only achieves directivity and does not have filtering function. There are four main implementation methods. The first method is to achieve high directivity coupling by opening a coupling window in the common through-hole area of ​​parallel substrate integrated waveguides, but the phase difference between the through port and the coupled port fluctuates greatly, and the full-mode substrate integrated waveguide leads to a large size. The second method is to include the through-hole perturbation field distribution in the central area of ​​the cross-shaped substrate integrated waveguide cavity to achieve directional coupling, but there are large sizes, inability to achieve weakening, and the phase difference fluctuation between the through port and the coupled port is still too large. The third method is to achieve high directivity coupling by opening a coupling window in the common through-hole area of ​​two back-to-back half-mode substrate integrated waveguides, and the circuit size is reduced to a certain extent, but the phase difference fluctuation between the through port and the coupled port is still large. The fourth method uses a pair of face-to-face half-mode substrate integrated waveguides to form directional coupling by common-mode slot coupling or stacked slot coupling, but the phase difference fluctuation between the through port and the coupled port is still large. 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 weak coupling realization capability. Summary of the invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a substrate integrated waveguide coupler is proposed which has both filtering function and high directivity, and can take into account phase difference fluctuation, overall size and weak coupling realization capability.

[0005] Technical solution: A substrate integrated waveguide coupler with filtering and high directivity, comprising a top metal layer structure, a bottom metal layer structure, a metallized through hole and a dielectric substrate; the top metal layer structure and the bottom metal layer structure are respectively located on the top surface and the bottom surface of the dielectric substrate; The top metal layer structure is a symmetrical structure both left and right and top and bottom, including four metal strips, four step metals, four short branches, four trapezoidal metals and a pair of E-shaped metals; wherein the pair of E-shaped metals are symmetrically arranged face to face about a horizontal midline, each E-shaped metal is formed by opening a pair of vertical long grooves on a 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 facing E-shaped metals; The left and right sides of each E-shaped metal are respectively connected with a feeding structure, forming a total of four ports. Each feeding structure includes a short branch, a step metal, and a trapezoidal metal cascaded in sequence, and a short branch is loaded on the inner side of the step metal; a vertical short slot 1 is opened on the step metal at the connection with the trapezoidal metal; a vertical short slot 2 is opened on the E-shaped metal at the connection with the trapezoidal metal; The metallized through hole is composed of two rows of metal through holes located on the upper and lower sides of the E-shaped metal facing each other. The metallized through hole passes through the dielectric substrate and connects the top metal layer structure and the bottom metal layer structure.

[0006] Furthermore, the length of the vertical slot 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.

[0007] Furthermore, the length of the short branch in the vertical direction is 0.02λ g ~0.03λ g The length of the vertical short slot is between 0.07λ g ~0.08λ g The length of the vertical short slot 2 is between 0.20λ g ~0.23λ g between.

[0008] Furthermore, the pair of E-type metals, the bottom metal layer structure, the metallized through-holes, and the dielectric substrate constitute three sections of 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 slit widths of the narrow slit and the wide slit, the coupling degree and coupling flatness of the substrate integrated waveguide coupler are regulated, the isolation frequency and level, the isolation bandwidth and level, and the phase difference fluctuation between the through port and the coupling port are regulated.

[0009] Furthermore, the isolation frequency and level as well as the operating frequency and isolation level are controlled respectively by adjusting the lengths of the narrow slit and the wide slit.

[0010] Furthermore, the isolation level of the substrate integrated waveguide coupler is individually regulated by adjusting the length of the short branch in the vertical direction.

[0011] Furthermore, the matching level of the overall circuit is controlled by adjusting the length of the vertical short slot.

[0012] Beneficial effects: The existing substrate integrated waveguide coupler only realizes directivity, does not have filtering function, and has the problem of large phase difference fluctuation between the through port and the coupled port, large overall size or inability to realize weak coupling. The present invention constructs a three-section half-mode substrate integrated waveguide coupling line formed by a pair of E-shaped metals to form a resonance point, and utilizes the adjustment effect of its internal slits and grooves on coupling and isolation characteristics, combined with the regulation effect of the external feeding structure on matching and isolation, to obtain a higher degree of control freedom, which can realize a substrate integrated waveguide coupler with filtering function and high directivity, and can take into account phase difference fluctuation, overall size and weak coupling realization capability.

[0013] Specifically, the three-section half-mode substrate integrated waveguide coupling line is composed of E-shaped metal, rectangular metal ground, metallized through-hole, and dielectric substrate. It contains two vertical short slots, a vertical long slot, a pair of narrow slots and one wide slot, which provide resonance points for the overall circuit. The slots and slots have a regulating effect on the frequency and bandwidth, coupling performance, isolation performance and phase difference fluctuation of each channel. It has a high degree of control freedom and can simultaneously realize filtering and directional coupling functions.

[0014] The microstrip feeding structure consists of metal strips, stepped metal, short branches, trapezoidal metal and vertical short slots. The lengths of the short branches and the slots can respectively adjust the isolation level and the matching level, further improving the control freedom of the overall circuit and facilitating the multi-functional realization of the overall circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a top metal structure diagram of the substrate integrated waveguide coupler of the present invention; Figure 2 This is a bottom metal structure diagram of the substrate integrated waveguide coupler of the present invention; Figure 3 Simulation of the substrate integrated waveguide coupler of the present invention S Parameter curves; Figure 4 It is a phase difference simulation curve between the through port and the coupled port of the substrate integrated waveguide coupler of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further explained below in conjunction with the accompanying drawings.

[0017] A substrate integrated waveguide coupler with filtering and high directivity consists of a top metal layer structure 1, a bottom metal layer structure 2, a metallized through hole 3 and a dielectric substrate 4.

[0018] like Figure 1 As shown, the top metal layer structure 1 is a left-right symmetrical and top-bottom symmetrical structure, including four metal strips 101, four step 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 the horizontal midline. Each E-shaped metal 105 is formed by opening a pair of vertical long grooves 108 on a 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 facing E-shaped metals 105. The length of the vertical long groove 108 is 0.32λ. g ~0.35λ g The length of the narrow slits 109 on both sides is 0.20λ g ~0.23λ g The length of the wide gap 110 in the middle is 0.20λ g ~0.23λ g Between g is the guided wavelength corresponding to the center frequency.

[0019] The left and right sides of each E-type metal 105 are connected to a feeding structure, forming a total of four ports. Each feeding structure includes a short branch 103, a step metal 102, and a trapezoidal metal 104, which are cascaded in sequence. A short branch 103 is loaded on the inner side of the step metal 102. A vertical short slot 106 is opened at the connection between the step metal 102 and the trapezoidal metal 104; a vertical short slot 2 107 is opened at the connection between the E-type metal 105 and the trapezoidal metal 104. The length of the short branch 103 in the vertical direction is 0.02λ. g ~0.03λ g The length of the vertical short slot 106 is between 0.07λ g ~0.08λ g The length of the vertical short slot 107 is between 0.20λ g ~0.23λg between.

[0020] like Figure 2 As shown, the bottom metal layer structure 2 is a rectangular metal ground 201. Between the top metal layer structure 1 and the bottom metal layer structure 2 is a dielectric substrate 4, which is a complete rectangular dielectric 401. The metallized through hole 3 is composed of two rows of metal through holes 301 located on the upper and lower sides of the face-to-face E-shaped metal 105. The metal through hole 301 passes through the dielectric substrate 4 and connects the top metal layer structure 1 and the bottom metal layer structure 2.

[0021] In the above structure, the E-shaped metal 105, the rectangular metal ground 201, the metallized through hole 301, and the dielectric substrate 4 form three sections of 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. The metal strip 101, the step metal 102, the short branch 103, the trapezoidal metal 104, and the vertical short slot 106 form a microstrip feeding structure.

[0022] The present invention is a full-port reciprocal structure. The signal is fed from any port, passes through the corresponding microstrip feeding structure, and is transmitted to the three-section half-mode substrate integrated waveguide coupling line, and then output from the microstrip feeding structures of the through port, the coupling port and the isolation port respectively. Under the action of the overall circuit, a substrate integrated waveguide coupler with filtering and high directivity is realized.

[0023] In this process, the half-mode substrate integrated waveguide coupling lines on both sides and in the middle provide resonance points for the overall circuit, and the resonance frequency and bandwidth can be adjusted by controlling the overall width of the coupling lines along the vertical direction and the length and width of the internal vertical long slot 108 and the outer vertical short slot 107. The widths of the narrow slits 109 and wide slits 110 of the three-section 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 and the isolation bandwidth and level. At the same time, the narrow slits 109 and wide slits 110 can adjust the phase difference fluctuation between the through port and the coupling port; in addition, the lengths of the narrow slits 109 and wide slits 110 can respectively control the isolation frequency and level and the operating frequency and isolation level. Therefore, by adjusting the combination of the narrow slits 109 and wide slits 110, a higher degree of control freedom can be obtained in the three aspects of coupling, isolation and phase difference, ensuring that the three aspects of performance are optimized at the same time. The length of the short branch 103 of the microstrip feeding structure can independently adjust the isolation level. The length of the vertical short slot 106 inside the microstrip feeding structure mainly controls the matching level of the overall circuit. The specific shape and size of the step metal 102 and the trapezoidal metal 104 can be obtained by existing simulation optimization technology according to the impedance matching requirements.

[0024] In summary, the present invention has a high degree of adjustment freedom, can simultaneously achieve high directivity and filtering functions, and can take into account phase difference fluctuations, overall size and weak coupling realization capabilities.

[0025] This embodiment uses an F4B substrate and the circuit size is 1.64λ g × 0.65λ g . Figure 3 , Figure 4 Given this embodiment S Parameter response curve, as can be seen from the figure, the 3-dB working bandwidth frequency range is 5.88 GHz - 7.75 GHz, that is, the relative bandwidth can reach 24.4%, the minimum insertion loss is only 0.93 dB, and the two transmission poles are located at 6.64 GHz and 6.91 GHz, that is, the second-order filtering response is achieved. The coupling degree is 10.77 dB, and the 3-dB working bandwidth frequency range of the coupling channel is 5.66 GHz - 7.99 GHz, that is, the relative bandwidth can reach 34.1%. The coupling degree minus the directivity frequency range of isolation greater than 10 dB is 6.35 GHz - 7.32 GHz, that is, the relative bandwidth can reach 14.2%, the corresponding coupling port fluctuation is between ±0.94 dB, and the maximum directivity can reach 40 dB. The phase difference between the output signal of the through end and the coupling end is 94.3°±1.5°, indicating that the phase difference stability is good.

[0026] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A substrate integrated waveguide coupler with filtering and high directivity, characterized in that: It comprises a top metal layer structure (1), a bottom metal layer structure (2), a metallized through hole (3) and a dielectric substrate (4); the top metal layer structure (1) and the bottom metal layer structure (2) are respectively located on the top surface and the bottom surface of the dielectric substrate (4); The top metal layer structure (1) is a structure that is symmetrical in both left and right directions and in both top and bottom directions, and includes four metal strips (101), four step metals (102), four short branches (103), four trapezoidal metals (104), and a pair of E-shaped metals (105); wherein the pair of E-shaped metals (105) are arranged face to face and symmetrically about a horizontal midline, and each E-shaped metal (105) is formed by opening a pair of vertical long grooves (108) on one long side of a rectangular metal, and a pair of narrow slits (109) on both sides and a wide slit (110) in the middle are formed between the facing E-shaped metals (105); The left and right sides of each E-shaped metal (105) are respectively connected to a feeding structure, forming a total of four ports, each feeding structure comprising a short branch node (103), a step metal (102), and a trapezoidal metal (104) which are sequentially cascaded, and a short branch node (103) is loaded on the inner side of the step metal (102); a vertical short slot 1 (106) is opened on the step metal (102) at the connection with the trapezoidal metal (104); and a vertical short slot 2 (107) is opened on the E-shaped metal (105) at the connection with the trapezoidal metal (104); The metallized through hole (3) is composed of two rows of metal through holes located on the upper and lower sides of the E-shaped metal (105) facing each other. The metallized through hole (3) passes through the dielectric substrate (4) and connects the top metal layer structure (1) and the bottom metal layer structure (2).

2. The substrate integrated waveguide coupler according to claim 1, characterized in that: The length of the vertical long groove (108) is 0.32λ g ~0.35λ g The length of the narrow slit (109) is between 0.20λ g ~0.23λ g The length of the wide slit (110) is between 0.20λ g ~0.23λ g between.

3. The substrate integrated waveguide coupler according to claim 2, characterized in that: The length of the short branch (103) in the vertical direction is 0.02λ g ~0.03λ g The length of the vertical short slot 1 (106) is between 0.07λ g ~0.08λ g The length of the second vertical short slot (107) is between 0.20λ g ~0.23λ g between.

4. The substrate integrated waveguide coupler according to any one of claims 1 to 3, characterized in that: The pair of E-type metals (105), the bottom metal layer structure (2), the metallized through hole (3), and the dielectric substrate (4) form three sections of 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 regulated, the isolation frequency and level, the isolation bandwidth and level, and the phase difference fluctuation between the through port and the coupling port are regulated.

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

6. The substrate integrated waveguide coupler according to claim 4, characterized in that: The isolation level of the substrate integrated waveguide coupler is individually regulated by adjusting the length of the short branch (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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