CN115911796A - A Millimeter Wave Filter Power Splitter Based on Substrate Integrated Waveguide - Google Patents

Abstract

The invention belongs to the technical field of radio frequency communication, and specifically relates to a millimeter-wave filter power splitter based on a substrate integrated waveguide, comprising: a metal layer on an upper substrate, a medium layer on a substrate, and a metal layer below a substrate; the metal layer on the lower substrate serves as a ground plane, and The lower surface of the entire dielectric layer of the substrate is covered, and the upper metal layer of the substrate is arranged on the upper surface of the dielectric layer of the substrate; the dielectric layer of the substrate is provided with a number of regularly arranged metal through holes, and the metal through holes run through the entire dielectric layer of the substrate, connecting the upper metal layer of the substrate with the Substrate metal layer. The filter power splitter proposed by the present invention is a filter power splitter structure coupled with three SIW cavities. In the two SIW rectangular cavities at the output end, the coupling window and the microstrip SIW transition structure are orthogonal and vertical to each other. The structure A transmission zero point can be introduced in the S-parameter diagram to enhance the out-of-band rejection of the filter power splitter, thereby improving the filtering performance of the filter power splitter.

Description

A Millimeter Wave Filter Power Splitter Based on Substrate Integrated Waveguide

technical field

The invention belongs to the technical field of radio frequency communication, and in particular relates to a millimeter wave filter power splitter based on a substrate integrated waveguide.

Background technique

In the electromagnetic wave frequency band, the electromagnetic wave in the range of 30GHz to 300GHz is defined as the millimeter wave band. The electromagnetic wave in this frequency band has the characteristics of wide frequency band, narrow beam, and small window frequency atmospheric absorption attenuation. It has strong anti-attenuation ability when it is used in communication systems. , strong anti-interference ability, large information capacity, and high confidentiality. Therefore, millimeter wave technology has great application value in the field of communication, and has been widely researched and applied in military and civilian fields.

In microwave and millimeter wave radio frequency circuits, filters and power dividers are usually cascaded to suppress harmonics on the basis of power distribution and eliminate noise and interference caused by nonlinear devices. However, the cascaded circuit of the filter and the power divider is large, which is not conducive to the realization of a miniaturized radio frequency circuit system. At the same time, the circuit loss of this structure is large, and the design cost is high. Therefore, some researchers have proposed a filter power splitter that integrates the design of the power splitter and the filter to realize a power splitter with frequency selective performance, and avoid additional cascading at the input of the power splitter or the microstrip to the SIW transition structure. Filter, thereby reducing the size and loss of the entire radio frequency system, so it has become an important means of realizing the miniaturized radio frequency front end.

As the frequency of radio frequency system applications continues to increase, the millimeter wave frequency band can be used on a large scale, but higher requirements are placed on the processing accuracy of the circuit, which also increases the processing cost accordingly, limiting the promotion of millimeter wave applications. Substrate Integrated Waveguide (SIW) is a new type of microwave and millimeter wave transmission line structure, which can be obtained through Printed Circuit Board (PCB) processing technology, and its processing technology is mature and low in price. SIW realizes a nearly closed waveguide structure on the dielectric substrate, which not only has the advantages of low loss and high Q value, but also can be easily integrated with planar circuits. This transmission structure has broad application prospects in the microwave and millimeter wave high-frequency bands.

At present, with the increasingly scarce communication spectrum, the microwave and millimeter wave bands have been widely used due to their rich spectrum resources. However, the increase in frequency has brought difficulties in manufacturing and processing. At present, the manufacturing processes of high-frequency devices such as metal waveguides and LTCC processes are widely used. These processes are difficult to process, and there are many factors that need to be considered in the design, resulting in Its design and production costs are relatively high.

Existing filter power splitters, such as bandpass filter power splitters based on SIW coupled cavities, have a structure as shown in Figure 1, using the dual-mode response (TE ₁₀₁ mode and TE ₁₀₂ mode) of the SIW triangular cavity to design Dual-band band-pass filter power divider, but the input return loss effect of the first passband is not good (only better than 10dB), and no structure such as cross-coupling is introduced into the filter power divider, so that the entire S-parameter The transmission zero point is not introduced in the result figure, resulting in limited passband out-of-band suppression effect and poor frequency selection effect. In the prior art, the half-mode SIW triangular cavity is used to construct the power distribution output cavity, but the quality factor (Q value) of the half-mode SIW cavity is lower than that of the full-mode SIW cavity, especially in the high-frequency millimeter wave frequency band.

Contents of the invention

In order to solve the above technical problems, the present invention proposes a millimeter-wave filter power divider based on a substrate integrated waveguide, including: a metal layer on the upper substrate, a dielectric layer on the substrate, and a metal layer on the lower substrate;

The lower metal layer of the substrate is used as the ground plane, covering the lower surface of the entire substrate dielectric layer, and the upper substrate metal layer is arranged on the upper surface of the substrate dielectric layer; the substrate dielectric layer is provided with several regularly arranged metal through holes, and the metal through holes run through the entire substrate The dielectric layer is connected to the upper metal layer of the substrate and the lower metal layer of the substrate.

Preferably, the regularly arranged metal vias form three rectangular arrays, forming a SIW rectangular resonant cavity including a first cavity, a second cavity and a third cavity.

Further, a microstrip SIW transition structure is provided at the midpoint of each cavity of the SIW rectangular resonator, corresponding to the first microstrip SIW transition structure, the second microstrip SIW transition structure, and the third microstrip Take to the SIW transitional structure.

Further, three metal through holes are set in the third cavity of the SIW rectangular resonator, two metal through holes are respectively set in the first cavity and the second cavity, and the metal through holes set in the first cavity and the second cavity Longitudinal symmetrical distribution.

Further, the SIW rectangular resonant cavity forms the first coupling opening and the second coupling opening through the gaps in the metal through hole array.

Further, the two coupling windows are longitudinally and symmetrically distributed.

Further, the SIW transition structure of the first microstrip is vertically orthogonal to the first coupling window, the SIW transition structure of the second microstrip is perpendicular to the second coupling window, and the SIW transition structure of the third microstrip is set On the longitudinal symmetry line of the first microstrip to the SIW transition structure and the second microstrip to the SIW transition structure, the first microstrip to the SIW transition structure, the second microstrip to the SIW transition structure, and the third microstrip to the SIW transition structure form a symmetrical structure distribution.

Further, the microstrip to SIW transition structure is composed of a microstrip line and a coplanar waveguide structure.

Beneficial effects of the present invention:

1. The filter power splitter proposed by the present invention is a filter power splitter structure coupled with three SIW cavities. In the two SIW rectangular cavities at the output end, the coupling window and the microstrip SIW transition structure are orthogonal to each other. This structure can introduce a transmission zero in the S-parameter diagram to enhance the out-of-band rejection of the filter power splitter, thereby improving the filtering performance of the filter power splitter.

2. The three-cavity coupling filter power division structure proposed in the present invention has the characteristics of simple structure, easy processing and low cost. It introduces a transmission zero point, its structure is simple, and it can be manufactured and processed by PCB technology. It is less difficult to process and low in cost. It is suitable for It is used in microwave and millimeter wave high frequency front-end system applications.

Description of drawings

FIG. 1 is a schematic structural diagram of an existing bandpass filter power divider based on an SIW coupling cavity;

Fig. 2 is a top view of the substrate medium and the metal layer stacked on the upper surface of the substrate of the millimeter wave filter power splitter based on the substrate integrated waveguide of the present invention;

3 is a three-dimensional view of the dielectric substrate, the metal layer on the upper surface of the substrate, and the metal layer on the lower surface of the substrate of the millimeter wave filter power splitter based on the substrate integrated waveguide of the present invention;

Fig. 4 is the substrate dielectric layer layout with scale mark of the millimeter-wave filter power divider based on the substrate integrated waveguide of the present invention;

Fig. 5 is the layout of the metal layer on the upper surface of the substrate with scale marks of the millimeter wave filter power splitter based on the substrate integrated waveguide of the present invention;

Fig. 6 is a simulation result diagram of the millimeter wave filter power divider based on the substrate integrated waveguide of the present invention;

In the figure: 1: first cavity; 2: microstrip to SIW transition structure; 3: coupling window; 4, 6: metal via; 5: second cavity; 7: third cavity; 8: substrate The upper metal layer; 9: the lower metal layer of the substrate; 10: the dielectric layer of the substrate;

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

A millimeter-wave filter power splitter based on a substrate integrated waveguide, as shown in Figure 2 and Figure 3, includes: a substrate upper metal layer (8), a substrate dielectric layer (10) and a substrate lower metal layer (9), wherein The lower metal layer (9) of the substrate is used as a ground plane and covers the entire lower surface of the dielectric layer (10) of the substrate.

As shown in Figures 4 and 5, the substrate dielectric layer (10) is provided with several metal through holes, and the metal through holes run through the entire substrate dielectric layer (10), connecting the substrate upper metal layer (8) and the substrate lower metal layer (9). ); regularly arranged metal vias form a rectangular array, forming the first cavity (1), the second cavity (5), and the third cavity (7) of the SIW rectangular resonator; the first cavity (1 ) and the second cavity (5) and the third cavity (7) through the coupling window (3) formed by the gap of the metal through hole array, so that the electromagnetic wave energy of the third cavity (7) is coupled to the two In the first cavity (1) and the second cavity (5) of cascaded cavities, and then form the coupling filter power division between the cavities; the width of the coupling window (3) can control the cavity (1) and ( 7) The amount of coupling between them realizes the adjustment of the resonant frequency point positions of the two cavities; there are two coupling windows (3) and they are longitudinally symmetrical.

Three metal through holes (4) are set in the SIW rectangular resonant cavity (7) to interfere with the TE ₁₀₁ mode electromagnetic wave in the third cavity (7), and the three metal through holes (4) suppress the resonance of the fundamental mode So as to achieve the purpose of eliminating the first passband.

The coupling window (3) of the first cavity (1) of the SIW rectangular resonator is vertically and orthogonally arranged with the microstrip SIW transition structure (2), so that the third cavity (7) can be connected with the first cavity (1) Coupling excites the TE ₁₀₂ mode, and sets the microstrip SIW transition structure at the midpoint of the side of the first cavity (1), where the TE ₁₀₂ mode cancels positive and negative, thereby obtaining a stable transmission Zero point; in order to adjust the resonant frequency of the SIW cavity so that the resonant frequency of the third cavity (7) and the first cavity (1) are close to form a filter passband, two metal through holes ( 6); the setting method of the second cavity (5) is the same as that of the first cavity (1), and the two are arranged symmetrically along the longitudinal direction.

The microstrip to SIW transition structure (2) is used to convert the TEM mode to the TE mode. The quasi-TEM mode electromagnetic wave is transmitted on the microstrip line, and the TE mode electromagnetic wave is transmitted by the SIW. The electromagnetic wave on the microstrip line is transmitted to the SIW. A transition structure is required.

The input and output of the filtering power dividing circuit is realized by three microstrip SIW transition structures (2), which are composed of microstrip lines and coplanar waveguide structures; one input transition structure is arranged in the third cavity (7), two Two output transition structures are respectively arranged in the first cavity (1) and the second cavity (5).

The configuration of the overall circuit is distributed symmetrically along the longitudinal direction, so that the configuration can reduce the influence of the phase difference in the filtering effect.

The working principle of the present invention: the SIW rectangular cavity is connected to two output SIW resonant cavities by setting two coupling windows, the windows of equal width realize 3dB power distribution, and the coupling window and output transition structure of the output SIW resonant cavity Orthogonal setting, the electromagnetic and magnetic field distribution at the midline position on the side of the output cavity is very weak. Setting the output transition structure at this position can make the TE102 mode excited in the output cavity cancel positive and negative at this position, and the TEM cannot be excited. mode, which in turn creates transmission zeros in the stopband.

Embodiment 1, the present invention is simulated, the selected dielectric substrate material is Rogers RT5880, the relative permittivity ε _r =2.2, the loss tangent tanθ=0.0009, and the thickness is 0.508mm.

The S-parameter results obtained by simulation are shown in Figure 6, where S ₁₁ represents the return loss of the input port, and S ₂₁ and S ₃₁ represent the transmission coefficient. It can be seen from the S-parameter diagram that the center frequency of this example is 35.39GHz, and the 3dB bandwidth is 1.16 GHz. From the S ₁₁ curve, it can be seen that the return loss is basically better than 20dB, and the matching is good; from the S ₂₁ and S ₃₁ curves, it can be seen that the two curves almost overlap, and there is a Transmission zero point, the transmission coefficient on the right side of the transmission zero point is better than 29dB, and the out-of-band suppression effect is good.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (8)

1. A millimeter-wave filter power splitter based on a substrate integrated waveguide, characterized in that it comprises: an upper metal layer on a substrate, a dielectric layer on a substrate, and a lower metal layer on a substrate; The lower metal layer of the substrate is used as the ground plane, covering the lower surface of the entire substrate dielectric layer, and the upper substrate metal layer is arranged on the upper surface of the substrate dielectric layer; the substrate dielectric layer is provided with several regularly arranged metal through holes, and the metal through holes run through the entire substrate The dielectric layer is connected to the upper metal layer of the substrate and the lower metal layer of the substrate. 2. A millimeter-wave filter power splitter based on a substrate integrated waveguide according to claim 1, wherein the regularly arranged metal through-holes form three rectangular arrays, forming a first cavity, a second Cavities, SIW rectangular resonators of the third cavity. 3. A millimeter-wave filter power splitter based on a substrate integrated waveguide according to claim 2, wherein a microstrip SIW is provided at the midpoint of each cavity of the SIW rectangular resonator The transition structure corresponds to the first microstrip SIW transition structure, the second microstrip SIW transition structure, and the third microstrip SIW transition structure. 4. A millimeter-wave filter power splitter based on a substrate integrated waveguide according to claim 2, wherein three metal through holes are arranged in the third cavity of the SIW rectangular resonator, the first cavity, the second cavity The two cavities are respectively provided with two metal through holes, and the metal through holes arranged in the first cavity and the second cavity are longitudinally symmetrically distributed. 5. A millimeter-wave filter power divider based on a substrate integrated waveguide according to claim 2, wherein the SIW rectangular resonator constitutes the first coupling window and the second coupling window through the metal through-hole array gap . 6. A millimeter-wave filter power splitter based on a substrate-integrated waveguide according to claim 4, wherein the two coupling windows are longitudinally symmetrically distributed. 7. A millimeter-wave filter power divider based on a substrate integrated waveguide according to claim 3 or 5, wherein the first microstrip to SIW transition structure is vertically orthogonal to the first coupling window, and the first The second microstrip SIW transition structure and the second coupling window are arranged vertically and orthogonally, and the third microstrip SIW transition structure is arranged on the longitudinal symmetry line of the first microstrip SIW transition structure and the second microstrip SIW transition structure , the first microstrip to the SIW transition structure, the second microstrip to the SIW transition structure, and the third microstrip to the SIW transition structure form a symmetrical structure distribution. 8. A millimeter wave filter power splitter based on a substrate integrated waveguide according to claim 3, wherein the microstrip to SIW transition structure is composed of a microstrip line and a coplanar waveguide structure.

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