Double-frequency filter based on SIW and HMSIW

Abstract

The utility model discloses a double-frequency filter based on an SIW and an HMSIW. The double-frequency filter comprises a dielectric substrate, an upper metal layer, a lower metal layer, a metal through hole array penetrating through the upper metal layer and the lower metal layer, a 50-ohm feed port and a conical conversion feed structure. An SIW structure is arranged on the upper surface of the substrate, H-shaped complementary split-ring resonators which are symmetrically arranged are arranged on a metal layer on the upper surface of the substrate, so that the dual-frequency filter with metamaterial characteristics is realized, and an HMSIW-based miniaturized dual-frequency filter is realized by cutting an SIW equivalent magnetic wall. Compared with the existing metal waveguide, LTCC (Low Temperature Co-Fired Ceramic) process and the like, the processing difficulty is reduced, and the requirements of easy processing, miniaturization and high performance of modern wireless communication are met.

Description

Technical Field

[0001] The utility model belongs to the technical field of radio frequency communication, in particular to a dual-frequency filter based on SIW and HMSIW. Background Art

[0002] With the division of communication system standards, spectrum resources are becoming increasingly crowded. Filters working in a single frequency band can no longer meet the requirements of communication services. Therefore, it is of great significance to study multi-frequency filters.

[0003] The substrate integrated waveguide (SIW) structure not only integrates the easy processing and simple structure characteristics of traditional microstrip transmission lines, but also has the characteristics of low insertion loss and high Q value of metal waveguides. Therefore, research based on SIW technology has attracted the attention of many scholars.

[0004] In response to the further miniaturization needs of SIW filters, the main methods include: 1 / n mode cutting technology, SIW loading technology, folding technology, etc. Among them, 1 / n mode cutting technology is common in half-mode SIW, quarter-mode SIW, etc., that is, cutting along the equivalent magnetic wall of full-mode SIW, and the electric field distribution is basically unchanged while the size can be greatly reduced. The principle of miniaturization of SIW loading technology is to disturb the field distribution of SIW cavity by loading a structure with special characteristics, and the resonant frequency is reduced. For example, a complementary open resonant ring, a structure with negative dielectric constant characteristics in a specific frequency band, is used to load it on the surface of SIW to change its electric field distribution and reduce the resonant frequency to achieve the miniaturization of the filter. At the same time, loading structures with negative magnetic permeability characteristics and negative dielectric constant characteristics on the surface of SIW can construct a filter with composite left-handed characteristics. The miniaturization of SIW based on folding technology, as the name suggests, generally achieves a reduction in plane area through multi-layer folding.

[0005] However, the miniaturization of SIW filters based on folding technology has higher processing requirements due to its multi-layer stacking structure, which requires higher processing costs and finer processing precision.

[0006] The defective ground structure is a special structure etched on the ground plane. It improves the performance of microwave circuits by changing the current path in the circuit without changing the circuit size. Due to its slow wave effect, single-pole low-pass characteristics and high impedance characteristics, it is generally used to improve the out-of-band suppression performance of microwave devices and achieve device miniaturization. Utility Model Content

[0007] The technical problem solved by the utility model is to overcome the defects mentioned in the background technology and provide a dual-frequency filter based on SIW and HMSIW.

[0008] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a dual-frequency filter based on SIW, comprising: a dielectric substrate, an upper layer and a lower layer of metal layers arranged on the surface of the dielectric substrate, two rows of metal through-hole arrays penetrating the upper and lower metal layers, and 50-ohm feeding ports arranged on both sides of the dielectric substrate; a SIW structure is arranged on the upper surface of the dielectric substrate, and H-type complementary open resonant rings are etched symmetrically on the surface of the SIW, and a symmetrical C-type defective ground structure is etched on the bottom metal layer, and the overall structure is symmetrically distributed.

[0009] Furthermore, the feeding port is a trapezoidal transition feeding microstrip structure.

[0010] Furthermore, the SIW structure is a completely symmetrical structure, and its symmetry axis is parallel to the electrical wall of the SIW.

[0011] Furthermore, each branch of the H-type complementary open resonant ring is a rectangular slot structure.

[0012] Furthermore, the dielectric substrate is provided with two rows of periodic metal through holes with regular gaps.

[0013] Furthermore, the relative dielectric constant of the dielectric substrate is 2.2, and the loss tangent value is 0.0009.

[0014] A dual-frequency filter based on HMSIW comprises: a dielectric substrate, an upper metal layer and a lower metal layer arranged on the surface of the dielectric substrate, two rows of metal through-hole arrays penetrating the upper and lower metal layers, and 50-ohm feeding ports arranged on both sides of the dielectric substrate; a SIW structure is arranged on the upper surface of the dielectric substrate, and symmetrically arranged H-shaped complementary open resonant rings are etched on the surface of the SIW, and a semi-symmetrical C-shaped defective ground structure is etched on the bottom metal layer.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] The utility model provides two technical solutions. The first solution is a SIW dual-frequency filter. By etching a single H-type complementary open resonant ring on the surface of SIW, the complementary open resonant ring with a negative dielectric constant combined with an H-type gap with a negative magnetic permeability constitutes a second-order single-frequency filter with a composite left-right hand characteristic, achieving miniaturized performance. Compared with the traditional square complementary open resonant ring without an H-type gap, the SIW combined with the H-type complementary open resonant ring adds one more transmission zero point at the low frequency of the first passband, thereby improving the selectivity of the filter. The second passband is controlled by etching two symmetrically arranged H-type complementary open resonant rings on the surface of SIW, and adjusting the coupling spacing between them and the metal through-holes, and etching a symmetrical C-type defect ground structure on the ground to improve the out-of-band suppression performance. The above-mentioned entire structure is completely symmetrical, and its symmetry axis is parallel to the electric wall of SIW. The second solution is to apply the principle of half-mode substrate integrated waveguide to cut the equivalent magnetic wall along SIW, further realizing the miniaturization of the filter, and greatly reducing the size of the filter while not changing the performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a plan schematic diagram based on the SIW filter provided by the utility model;

[0018] Figure 2 It is a schematic diagram of S parameters based on SIW filter simulation and testing provided by the utility model;

[0019] Figure 3 It is a plan schematic diagram of the HMSIW filter provided by the utility model;

[0020] Figure 4 It is a schematic diagram of S parameters for simulation and testing of the HMSIW filter provided by the utility model.

[0021] Numbers in the figure:

[0022] 1. Metal through hole; 2. H-type complementary open resonant ring; 3. Defective ground structure; 4. Feeding port; 5. Dielectric substrate. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] Example 1: Please refer to Figure 1-2The utility model provides a technical solution: a dual-frequency filter based on SIW, comprising: a dielectric substrate 5, an upper layer and a lower layer metal layer arranged on the surface of the dielectric substrate 5, two rows of metal through-hole 1 arrays penetrating the upper and lower metal layers, and 50-ohm feeding ports 4 arranged on both sides of the dielectric substrate 5; a SIW structure is arranged on the upper surface of the dielectric substrate 5, and H-type complementary open resonant rings 2 are etched symmetrically on the surface of the SIW, which increases the transmission zero point at the low frequency of the first passband compared to the traditional square complementary open resonant ring without H-type gaps, and a symmetrical C-shaped defect ground structure 3 is etched on the bottom metal layer, and the overall structure is symmetrically distributed, which changes the current path and improves the out-of-band suppression capability.

[0025] A single H-type complementary open resonant ring 2 is set on the SIW surface to realize the second-order single-frequency filtering characteristics of the first passband. This method is a filter with composite left-handed characteristics based on SIW loading technology. The second passband is flexibly adjusted by optimizing the coupling parameters between the symmetrical H-type complementary open resonant ring and the metal through hole 1.

[0026] The feeding port 4 is a trapezoidal transition feeding microstrip structure, which uses the trapezoidal structure to transition the SIW and the 50 ohm microstrip line.

[0027] The SIW structure is a completely symmetrical structure, and its symmetry axis is parallel to the electrical wall of the SIW.

[0028] Each branch of the H-type open resonant ring 2 is a rectangular slot structure.

[0029] The dielectric substrate 5 is provided with two rows of periodic metal through holes 1 with regular intervals, and the insertion loss in the passband is adjusted by setting a suitable interval.

[0030] The relative dielectric constant of the dielectric substrate 5 is 2.2, and the loss tangent is 0.0009.

[0031] like Figure 2 As shown, a dual-band pass filter with center frequencies of 3.5 GHz and 4.9 GHz and relative bandwidths of 4.6% and 2.5% respectively can be obtained, operating in the n78 and n79 frequency bands.

[0032] The size of the filter is only 0.28λg*0.18λg, where λg is the waveguide wavelength, which ensures miniaturization while ensuring functionality.

[0033] Embodiment 2: Figure 3 and Figure 4As shown: a dual-frequency filter based on HMSIW, comprising: a dielectric substrate 5, an upper layer and a lower layer of metal layers arranged on the surface of the dielectric substrate 5, two rows of metal through-hole 1 arrays penetrating the upper and lower metal layers, and 50-ohm feeding ports 4 arranged on both sides of the dielectric substrate 5; a SIW structure is arranged on the upper surface of the dielectric substrate 5, and a symmetrically arranged H-type complementary open resonant ring 2 is etched on the SIW surface, and a semi-symmetrical C-type defective ground structure 3 is etched on the bottom metal layer. The overall structure is symmetrically distributed, and is cut and constructed by the SIW dual-frequency filtering structure, without changing its electric field distribution, and achieving a size reduction of 50% on the basis of maintaining its original dual-frequency filtering performance.

[0034] By optimizing appropriate structural parameters, such as Figure 4 As shown, a dual-frequency bandpass filter with a center frequency of 3.5 GHz / 4.9 GHz is finally obtained; it can be seen that the filtering bandwidth and frequency band have basically not changed, and it still works in the n78 and n79 frequency bands.

[0035] The size of the filter is only 0.30λg*0.08λg, where λg is the waveguide wavelength. This achieves further miniaturization while ensuring functionality.

[0036] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual-frequency filter based on SIW, characterized in that: include: A dielectric substrate (5), an upper metal layer and a lower metal layer arranged on the surface of the dielectric substrate (5), an array of two rows of metal through holes (1) penetrating the upper and lower metal layers, and 50-ohm feeding ports (4) arranged on both sides of the dielectric substrate (5); a SIW structure is arranged on the upper surface of the dielectric substrate (5), and symmetrically arranged H-shaped complementary open resonant rings (2) are etched on the SIW surface, and a symmetrical C-shaped defective ground structure (3) is etched on the bottom metal layer.

2. The SIW-based dual-frequency filter according to claim 1, characterized in that: The feeding port (4) is a trapezoidal conversion feeding microstrip structure.

3. The dual-frequency filter based on SIW according to claim 1, characterized in that: The SIW structure is a completely symmetrical structure, and its symmetry axis is parallel to the electrical wall of the SIW.

4. The dual-frequency filter based on SIW according to claim 1, characterized in that: Each branch of the H-type complementary open resonant ring (2) is a rectangular slot structure.

5. The SIW-based dual-frequency filter according to claim 1, characterized in that: The dielectric substrate (5) is provided with two rows of periodic metal through holes (1) with regular gaps.

6. The SIW-based dual-frequency filter according to claim 1, characterized in that: The relative dielectric constant of the dielectric substrate (5) is 2.2, and the loss tangent value is 0.0009.

7. A dual-frequency filter based on HMSIW, characterized in that: include: A dielectric substrate (5), an upper metal layer and a lower metal layer arranged on the surface of the dielectric substrate (5), an array of two rows of metal through holes (1) penetrating the upper and lower metal layers, and 50-ohm feeding ports (4) arranged on both sides of the dielectric substrate (5); a SIW structure is arranged on the upper surface of the dielectric substrate (5), and symmetrically arranged H-shaped complementary open resonant rings (2) are etched on the SIW surface, and a semi-symmetrical C-shaped defective ground structure (3) is etched on the bottom metal layer.

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