Microwave and millimeter wave filter with turnover HMSIW-DGS structure

Abstract

The invention discloses a microwave and millimeter wave filter with an overturned HMSIW-DGS structure, which comprises two metal layers and one dielectric layer, the dielectric layer is arranged between the two metal layers, the lower metal layer is a grounding layer of the filter, the upper metal layer is a structural layer of the filter, and the upper metal layer comprises an HMSIW resonator, a trapezoidal gradual transition, an ohm port, a DGS structure and a metalized through hole; the two sides of the upper metal layer are provided with ohmic ports, the trapezoid gradually-changing transition is adjacent to the ohmic ports, the HMSIW resonator is adjacent to the trapezoid gradually-changing transition, an L-shaped DGS structure is arranged in the HMSIW resonator, and a transmission zero point is introduced through symmetrical etching of the L-shaped DGS structure; the number of the HMSIW resonators is two, and the two HMSIW resonators are in 180-degree overturning and central symmetry cascade connection, so that the phase of a transmission function is overturned, and a transmission zero point is introduced; the two rows of metalized through holes are parallel and are in oblique symmetry to construct a new full-mode SIW resonator, multi-path coupling is formed, and a transmission zero point is introduced.

Description

Technical Field

[0001] The present invention relates to the field of filters, and particularly to a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure. Background Art

[0002] A filter is one of the core components of modern radio frequency systems. Its main function is to filter out unwanted clutter and harmonics in the system, greatly improving the system performance. In the microwave and millimeter-wave fields, the main design technologies for filters are microstrip, substrate integrated waveguide (SIW), waveguide, etc. Others such as SAW, MEMS, electronic thin films, LC inductors and capacitors can only be used for the design of filters below the microwave band and are difficult to increase the frequency band. It is almost impossible for millimeter waves.

[0003] The waveguide is a three-dimensional structure and is naturally not suitable for system miniaturization and integration. The microstrip has a large transmission loss in the millimeter-wave band. In the case of tight power resources in the high-frequency band, there are great limitations. In the high-frequency band, the structural size of the microstrip filter will be very small, breaking through the limitations of PCB processing technology and resulting in inability to process. Therefore, it is mainly used in semiconductor processes.

[0004] In summary, the SIW technology derived from microstrip and waveguide technologies perfectly compensates for the above drawbacks, with characteristics such as small transmission loss in the microwave and millimeter-wave bands and low processing difficulty of printed circuit boards (PCBs). Therefore, it is the preferred technology for designing microwave and millimeter-wave filters.

[0005] Chinese Patent No. CN117810659A discloses a flexible microwave filter based on substrate integrated waveguide. In terms of structure, it includes a first metal layer, a dielectric substrate, a second metal layer, and a metallized via array stacked in sequence from top to bottom. The first metal layer is provided with a first microstrip line feeder and a second microstrip line feeder. The metallized via array penetrates the dielectric substrate and jointly encloses an HMSIW resonator with the first metal layer and the second metal layer. The first metal layer is also provided with a first DGS coupling window, a second DGS coupling window, and a third DGS coupling window. The second metal layer is provided with a first annular coupling window, a second annular coupling window, and a third annular coupling window. The DGS etching of the two metal layers jointly forms an overall DGS structure. This DGS structure is relatively complex, occupying two metal layers, far less simple than the DGS structure composed of only the first metal layer. At the same time, this DGS structure does not introduce transmission zeros to enhance the suppression of the sideband and stopband.

[0006] The Chinese invention patent with the publication number CN103700910A discloses a dual-band filter of complementary split-ring resonator and defected ground structure half-mode substrate integrated waveguide. Two resonators are used to achieve non-interference between the passbands of the dual-band filter. Through the structural design of the dual-band filter, two transmission zeros are introduced to improve the selectivity of the two passbands of the filter and to improve the out-of-band rejection of the filter. The two resonance points are independently controlled by the sizes of two complementary split-ring resonators, realizing an independently controllable dual-band filter. However, the problem is that there are only the transmission zeros introduced by the DGS structure, and there are no transmission zeros formed by the transmission coupling of the resonators. The transmission zeros introduced by the DGS structure are far from the passbands of the filter, and can only improve the suppression degree at the far end of the stopband of the filter, and cannot improve the suppression degree of the sideband at the proximal end of the passband of the filter. Summary of the Invention

[0007] The object of the present invention is to propose a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure to solve the problem in the above prior art that it is impossible to introduce both the DGS transmission zeros and other types of transmission zeros into the filter at the same time.

[0008] A microwave and millimeter-wave filter with a flipped HMSIW-DGS structure includes two metal layers and one dielectric layer. The dielectric layer is in the middle of the two metal layers. The lower metal layer is the grounding layer of the filter, and the upper metal layer is the structural layer of the filter. It is characterized in that the upper metal layer includes an HMSIW resonator, a trapezoidal gradual transition, an ohmic port, a DGS structure, and a metallized via hole; Among them, the metallized via hole penetrates through the two metal layers and the one dielectric layer. Ohmic ports are arranged on both sides of the upper metal layer. The trapezoidal gradual transition is adjacent to the ohmic port, and the HMSIW resonator is adjacent to the trapezoidal gradual transition. An L-shaped DGS structure is arranged inside the HMSIW resonator, and transmission zeros are introduced by symmetric etching of the L-shaped DGS structure; The number of the HMSIW resonators is 2, and the two HMSIW resonators are cascaded in a centrosymmetric manner with a 180-degree flip, so that the phase of the transfer function is flipped and transmission zeros are introduced; The two rows of metallized via holes are parallel to form multipath coupling and introduce transmission zeros.

[0009] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the two HMSIW resonators are cascaded in a centrosymmetric manner with a 180-degree flip to construct three resonators.

[0010] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the resonator includes two half-mode resonators and one full-mode resonator; The full-mode resonator is in the middle of two half-mode resonators, and cross-coupling between the full-mode resonator and the half-mode resonators is achieved.

[0011] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the cross-coupling generates a 180-degree phase difference due to different numbers of resonators involved in the coupling path between the full-mode resonator and the half-mode resonators, introducing one transmission zero in the transfer function of the filter. The two HMSIW resonators are cascaded in a 180-degree flipped center-symmetrical manner, introducing one transmission zero in the transfer function of the filter.

[0012] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the DGS structure introduces transmission zeros, increasing the stopband suppression of the filter. The HMSIW resonator and the metallized vias are skew-symmetrically configured to form a parallelogram full-mode resonator, forming multi-path coupling and introducing transmission zeros.

[0013] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the transmission zeros formed by the transmission coupling of the HMSIW resonator and the transmission zeros introduced by the DGS structure coexist in the filter.

[0014] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the number of ohmic ports is 2, which are 50-ohm ports and are respectively the input port and the output port of the filter.

[0015] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the number of DGS structures is 2, adopting a face-to-face L-shaped pair structure. The DGS structure is a pair of L-shaped grooves dug in the upper metal layer.

[0016] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the bottom plate of the upper metal layer uses a substrate with a thickness of 0.254 mm and dimensions of 15 mm × 9.2 mm.

[0017] Furthermore, for a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, the lower metal layer is entirely covered with copper and is provided with metallized vias at the corresponding positions of the upper metal layer.

[0018] The beneficial effects of the present invention are as follows: By flipping the microwave and millimeter-wave filter with the HMSIW-DGS structure, small transmission losses are achieved through the natural waveguide-like characteristics of SIW. The HMSIW structure is adopted to naturally halve the size of the original SIW filter. The HMSIW resonators are cascaded in a centrosymmetric manner with a 180-degree flip, and two rows of metallized vias are parallel. An oblique symmetric structure constructs a new full-mode SIW resonator, which can increase the filter order and realize multi-resonator cross-coupling without increasing the size, thereby reducing the filter size and introducing transmission zeros at the proximal end of the filter passband to increase the sideband suppression of the filter. The DGS structure introduces transmission zeros at the distal end of the filter passband to increase the stopband suppression of the filter. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure.

[0020] Figure 2 It is a schematic diagram of the evolution from waveguide to SIW.

[0021] Figure 3 It is a structural diagram of the upper metal layer of the K-band filter.

[0022] Figure 4 It is a structural diagram of the lower metal layer of the K-band filter.

[0023] Figure 5 It is a structural diagram of the resonator of the K-band filter.

[0024] Figure 6 It is the coupling topology diagram of the resonator.

[0025] Figure 7 It is the S-parameter diagram of the K-band filter case.

[0026] In the figure: 1 - HMSIW resonator, 2 - trapezoidal gradual transition, 3 - ohmic port, 4 - DGS structure, 5 - metallized via, 6 - half-mode resonator, 7 - full-mode resonator. Detailed Embodiments

[0027] For a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed embodiments of the present invention will now be described with reference to the accompanying drawings.

[0028] A microwave and millimeter-wave filter with a flipped HMSIW-DGS structure operates in the microwave and millimeter-wave frequency bands and can be fabricated using processes such as PCB, semiconductor, and Low-Temperature Co-fired (LTCC) ceramics. It consists of two metal layers and one dielectric layer, with the dielectric layer in the middle of the two metal layers. The lower metal layer serves as the ground layer of the filter, and the upper metal layer is the structural layer of the filter, on which the main structure of the filter is depicted.

[0029] As shown in the Figures 1 - 2 attachment, the upper metal layer includes HMSIW resonators 1. Using SIW technology, small transmission losses are achieved. With the HMSIW structure, the size of the original SIW filter is naturally halved. The 180-degree flipped center-symmetric cascading of two HMSIW resonators 1 enables the construction of three resonators on a single SIW. There are two half-mode resonators 6 and one full-mode resonator 7, and the full-mode resonator 7 is in the middle of the two half-mode resonators 6, realizing cross-coupling between the resonators.

[0030] As shown in the Figure 6 attachment, the coupling paths between a half-mode resonator 6 - another half-mode resonator 6 and a half-mode resonator 6 - full-mode resonator 7 - another half-mode resonator 6 form cross-coupling. Cross-coupling means that there are multiple coupling paths between the resonators of a filter. Different numbers of resonators involved in the coupling paths result in a 180-degree phase difference, generating transmission zeros.

[0031] The cross-coupling between the resonators and the 180-degree flipping of the two HMSIW resonators 1 introduce two transmission zeros in the transfer function of the filter.

[0032] An L-shaped DGS structure 4 is provided inside the HMSIW resonator 1. By symmetrically etching the L-shaped DGS structure 4, transmission zeros are introduced. The transmission zeros of the DGS structure 4 are generally not very close to the passband, so the rectangular coefficient of the DGS structure 4 is not high enough, but the stopband suppression of the DGS structure 4 is good enough. At the same time, the DGS structure 4 can adjust the center frequency of the filter to achieve the purpose of reducing the size of the filter.

[0033] As shown in the Figures 1 - 2 attachment, operating in the K band, a microwave and millimeter-wave filter with a flipped HMSIW-DGS structure exhibits a center-symmetric structure. There is an ohmic port 3 on each side, which is the input and output port of the filter and is used to connect to other circuits.

[0034] Adjacent to the ohmic port is a trapezoidal tapered transition 2 for impedance transformation.

[0035] Adjacent to the trapezoidal gradient transition is the HMSIW resonator 1. Each HMSIW resonator 1 contains a DGS structure 4, and the DGS structure can introduce transmission zeros in the filter transfer function.

[0036] The flip combination of two HMSIW resonators can create an additional full-mode SIW resonator. As Figure 5 shown, without increasing the size, the order of the filter is increased, that is, the bandwidth of the filter is increased. At the same time, multi-path cross-coupling is introduced, increasing the transmission zeros.

[0037] Due to the 180-degree flip of the two HMSIW resonators 1, transmission zeros are also added to the filter transfer function.

[0038] The number of DGS structures 4 is 2, and the opposite L-shaped pair structure is adopted; the DGS structure 4 is a pair of L-shaped grooves dug in the upper metal layer. The bottom plate of the upper metal layer uses a substrate with a thickness of 0.254 mm, and the size is 15 mm × 9.2 mm. Compared with the three-stage cascaded original SIW filter, it is 0.45, which can reduce the size of the original SIW filter by 65%.

[0039] As shown in the appendix Figure 3 shown, the lower metal layer is entirely covered with copper, and there are metallized vias 5 at the corresponding positions of the upper metal layer.

[0040] As shown in the appendix Figure 5 shown, it is the resonator identification diagram of the filter. The two half-mode resonators 6 are rectangular dotted frames; one full-mode resonator 7 is a parallelogram dotted frame. The full-mode resonator 7 is not an additional physical structure, but is composed of half of each of the two HMSIW resonators 1. It is a parallelogram physical structure and can be understood as a parallel full-mode resonator that does not occupy additional physical dimensions.

[0041] As shown in the appendix Figure 7 shown, it is the S-parameter curve of the filter. The in-band return loss is better than 20 dB, and the transmission loss is 1 - 1.4 dB. According to the simulation process, if further optimized, the loss will be reduced. There are two transmission zeros at the near end of the out-of-band, greatly improving the sideband suppression and optimizing the rectangularity coefficient. There are also two transmission zeros at the far end of the out-of-band, increasing the stopband rejection.

[0042] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A microwave and millimeter-wave filter with a flipped HMSIW-DGS structure, comprising two metal layers and one dielectric layer. The dielectric layer is in the middle of the two metal layers. The lower metal layer is the grounding layer of the filter, and the upper metal layer is the structural layer of the filter. It is characterized in that The upper metal layer includes an HMSIW resonator (1), a trapezoidal tapered transition (2), an ohmic port (3), a DGS structure (4), and a metallized via hole (5); Ohmic ports (3) are provided on both sides of the upper metal layer. The trapezoidal tapered transition (2) is adjacent to the ohmic port (3), the HMSIW resonator (1) is adjacent to the trapezoidal tapered transition (2), and an L-shaped DGS structure (4) is provided in the HMSIW resonator (1). Transmission zeros are introduced by symmetric etching through the L-shaped DGS structure (4); The number of the HMSIW resonators (1) is 2. The two HMSIW resonators (1) are cascaded in a centrosymmetric manner with a 180-degree flip, so that the phase of the transfer function is flipped, introducing transmission zeros; The two rows of metallized via holes (5) are parallel, forming multipath coupling and introducing transmission zeros.

2. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 1, characterized in that, The two HMSIW resonators (1) are cascaded in a centrosymmetric manner with a 180-degree flip to construct three resonators.

3. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 2, characterized in that The resonator includes two half-mode resonators (6) and one full-mode resonator (7); The full-mode resonator (7) is in the middle of the two half-mode resonators (6) to complete the cross-coupling between the full-mode resonator (7) and the half-mode resonator (6).

4. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 3, wherein The cross-coupling generates a 180-degree phase difference due to the different numbers of resonators involved in the coupling path between the full-mode resonator (7) and the half-mode resonator (6), introducing one transmission zero in the transfer function of the filter; The two HMSIW resonators (1) are cascaded in a centrosymmetric manner with a 180-degree flip, introducing one transmission zero in the transfer function of the filter.

5. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 1, characterized in that, The DGS structure (4) introduces transmission zeros, increasing the stopband suppression of the filter; The HMSIW resonator (1) and the metallized via hole (5) are skew-symmetric to form a parallelogram full-mode resonator, forming multipath coupling and introducing transmission zeros.

6. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 1, wherein The transmission zeros formed by the transmission coupling of the HMSIW resonator (1) and the transmission zeros introduced by the DGS structure (4) coexist in the filter at the same time.

7. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 1, characterized in that, The number of the ohmic ports (3) is 2, which are 50-ohm ports and are the input port and output port of the filter respectively.

8. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 1, characterized in that, The number of the DGS structures (4) is 2, adopting an opposite L-shaped pair structure; The DGS structure (4) is a pair of L-shaped grooves dug in the upper metal layer.

9. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 1, characterized in that, The bottom plate of the upper metal layer uses a substrate with a thickness of 0.254 mm and a size of 15 mm × 9.2 mm.

10. The microwave and millimeter-wave filter with a flipped HMSIW-DGS structure according to claim 1, characterized in that, The lower metal layer is entirely covered with copper and is provided with metallized via holes (5) at the corresponding positions of the upper metal layer.

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