A multi-mode dual-notch ultra-wideband filter based on interdigital coupling and sis

Abstract

The application discloses a kind of based on interdigital coupling and SIS multi-mode double trap wave ultra-wideband filter, comprising: dielectric plate, first component assembly fixed on the top of the dielectric plate and second structural assembly fixed on the bottom of the dielectric plate;The first component assembly includes first feed line port port, second feed line port port is oppositely arranged with the first feed line port port, is arranged between the multi-mode resonator of first feed line port port and second feed line port port and is arranged below the second trap structure of the multi-mode resonator;The multi-mode resonator includes first transmission line, second transmission line is fixedly connected on one side of first transmission line and third transmission line is fixedly connected on the other side of the first transmission line, and the end of the third transmission line away from first transmission line is away from second feed line port port.According to the application, the filter has excellent passband performance high frequency selectivity, double-frequency trap wave function, compact structure and strong processing feasibility.

Description

Technical Field

[0001] This invention relates to the technical field of filters, and in particular to a multimode dual-notch ultrawideband filter based on interdigital coupling and SIS. Background Technology

[0002] Existing ultra-wideband filters mostly employ multimode resonator structures, fed through interdigitated coupling lines, to achieve an ultra-wideband passband of 3.1 GHz to 10.6 GHz. However, existing technologies have the following drawbacks: 1. Unsatisfactory in-band return loss: The traditional interdigital coupling structure has insufficient impedance matching in the ultra-wideband range, resulting in poor return loss in the passband and affecting signal transmission quality.

[0003] 2. Insufficient frequency selectivity: The transition bands on both sides of the passband in the existing design are not steep enough, which limits the ability to suppress out-of-band interference signals and makes it susceptible to interference from signals in adjacent frequency bands.

[0004] 3. Insufficient notch depth and limited interference suppression capability: Existing ultra-wideband filters often focus only on the accuracy of the notch frequency when introducing notches, neglecting the optimization of the notch depth. In most reported designs, the attenuation at the notch point is typically only 10-15 dB, which is insufficient to effectively suppress strong interference signals. Especially in applications requiring simultaneous suppression of multiple interference frequency bands, insufficient notch depth leads to decreased receiver sensitivity and compressed dynamic range, failing to meet the anti-interference requirements in complex electromagnetic environments.

[0005] 4. Miniaturization and high performance are difficult to achieve simultaneously: Maintaining a compact size while achieving low insertion loss, high frequency selectivity, and multiple notch filtering functions is a problem that has not yet been well solved in existing designs. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a multimode dual-notch ultrawideband filter based on interdigital coupling and SIS. To achieve the above-mentioned objective and other advantages of the present invention, a multimode dual-notch ultrawideband filter based on interdigital coupling and SIS is provided, comprising: A dielectric substrate, a first component assembly fixed to the top of the dielectric substrate, and a second structural assembly fixed to the bottom of the dielectric substrate; The first component includes a first feed port, a second feed port disposed opposite to the first feed port, a multimode resonator disposed between the first feed port and the second feed port, and a second notch structure disposed below the multimode resonator. The multimode resonator includes a first transmission line, a second transmission line fixed to one side of the first transmission line, and a third transmission line fixed to the other side of the first transmission line. The end of the second transmission line away from the first transmission line is far from the first feed port, and the end of the third transmission line away from the first transmission line is far from the second feed port. The first feeder port is fixed with an input capacitor terminal tapered interdigital coupling feeder structure at one end near the first transmission line. The second feeder port is fixed to a tapered interdigitated feeder structure at the end of the first transmission line that is close to the output capacitor.

[0007] Preferably, the input capacitor-end tapered interdigitated coupling feed structure includes a first interdigitated coupling line fixed to the first feed port, a first capacitor-end coupling line integrally fixed to one end of the first interdigitated coupling line, a second interdigitated coupling line fixed to the first feed port, and a second capacitor-end coupling line integrally connected to one end of the second interdigitated coupling line. The first interdigitated coupling line and the second interdigitated coupling line are respectively located on both sides of the second transmission line, wherein the first capacitor-end coupling line and the first interdigitated coupling line are perpendicular to each other, and the second interdigitated coupling line and the second capacitor-end coupling line are perpendicular to each other.

[0008] Preferably, a first bent coupling line is integrally connected to the end of the second capacitor terminal coupling line away from the second interdigital coupling line, and the first bent coupling line is perpendicular to the second capacitor terminal coupling line.

[0009] Preferably, the output capacitor terminal tapered interdigital coupling feed structure includes a third interdigital coupling line fixed to the second feed port, a third capacitor terminal coupling line integrally fixed to one end of the third interdigital coupling line, a fourth interdigital coupling line fixed to the second feed port, and a fourth capacitor terminal coupling line integrally connected to one end of the fourth interdigital coupling line, wherein the third interdigital coupling line and the third capacitor terminal coupling line are perpendicular to each other, and the fourth capacitor terminal coupling line and the fourth interdigital coupling line are perpendicular to each other.

[0010] Preferably, one end of the fourth capacitor terminal coupling line is integrally connected to a second bent coupling line, and the second bent coupling line and the fourth capacitor terminal coupling line are perpendicular to each other.

[0011] Preferably, the second notch structure includes a first resonant ring, a second resonant ring located on the outer periphery of the first resonant ring, a fourth resonant ring disposed adjacent to the second resonant ring, and a third resonant ring disposed within the fourth resonant ring.

[0012] Preferably, the second structural component includes a first groove on the back side of the dielectric substrate corresponding to the interdigital coupling line and a second groove disposed adjacent to the first groove.

[0013] Preferably, a step impedance stub is fixedly connected to the first transmission line. The step impedance stub includes a first step impedance transmission line fixedly connected to the first transmission line and a second step impedance transmission line integrally connected to the first step impedance transmission line. An open-circuit stub is fixedly connected to the end of the first transmission line away from the first step impedance transmission line.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are: 1. Compliant with mainstream international standards: The passband range of this invention fully covers the 3.1-10.6GHz ultra-wideband commercial frequency band specified by the U.S. Federal Communications Commission (FCC), and can be directly applied to all ultra-wideband devices that comply with this standard, with good versatility and compliance.

[0015] 2. Excellent passband performance: The passband range is 3.1GHz-10.6GHz, with an absolute bandwidth of 7.5GHz. The insertion loss is less than 1dB, and the return loss is better than 15dB across the entire passband, meeting engineering application requirements and supporting Gbps-level data transmission rates.

[0016] 3. High frequency selectivity: Through the synergistic effect of SIS and DGS, a transmission zero is introduced on each side of the passband, resulting in a steep transition band and strong frequency selectivity.

[0017] 4. Dual-band notch filtering: Two notches are implemented at 6.53GHz and 7.34GHz, with notch depths better than 30dB for both, a significant improvement over existing similar designs (typically only 10-15dB). This effectively suppresses strong interference such as C-band satellite communication signals and X-band radar pulses, preventing receiver blockage and protecting the low-noise amplifier and demodulation circuitry of ultra-wideband systems. Furthermore, the second notch position is adjustable to adapt to different application scenarios.

[0018] 5. Compact structure: The overall size is only 23.85mm × 15mm, achieving multi-functional integration in a miniaturized design.

[0019] 6. High feasibility of processing: It adopts standard microstrip line technology, and the structural parameters are all within the processable range, making it easy to mass-produce. Attached Figure Description

[0020] Figure 1 A dimensioned diagram of the dual-notch ultrawideband filter based on interdigital coupling and SIS according to the present invention; Figure 2 The top structure diagram of the dual notch filter based on interdigital coupling and SIS multimode dual notch ultrawideband filter according to the present invention is shown. Figure 3This is a bottom structural diagram of the dual notch filter based on interdigital coupling and SIS multimode dual notch ultrawideband filter according to the present invention. Figure 4 The diagram shows the general interdigital coupling and improved interdigital coupling structures of the multimode dual notch ultrawideband filter based on interdigital coupling and SIS according to the present invention. Figure 5 This is a schematic diagram showing the simulation comparison of the improved interdigital coupling S-parameters of the multimode dual notch ultrawideband filter based on interdigital coupling and SIS according to the present invention. Figure 6 A schematic diagram of the stepped impedance stub of the multimode dual notch ultrawideband filter based on interdigital coupling and SIS according to the present invention. Figure 7 This is a simulation diagram of the S-parameters of the multimode dual notch ultrawideband filter based on interdigital coupling and SIS according to the present invention after adding SIS and DGS. Figure 8 This is a schematic diagram of the S-parameter simulation of the dual notch ultrawideband filter based on interdigital coupling and SIS according to the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Reference Figure 1 A multimode dual-notch ultrawideband filter based on interdigital coupling and SIS, comprising: A dielectric substrate, a first component assembly fixed to the top of the dielectric substrate, and a second structural assembly fixed to the bottom of the dielectric substrate, such as... Figure 3 As shown, the second structural component includes a first groove 21 on the back side of the dielectric substrate corresponding to the interdigital coupling line and a second groove 22 disposed adjacent to the first groove 21; as Figure 1 As shown, the filter of the invention uses a Rogers 6010 substrate with a relative permittivity of 10.6, a substrate thickness of 1.27 mm, and a loss tangent of 0.0009. The overall structure of the filter is as follows. Figure 1As shown, the specific dimensional parameters are as follows: W1=7.3mm, L1=1mm; W2=0.1mm, L2=4.1mm; W3=0.11mm, L3=4mm; W4=3.2mm, L4=1.26mm; W5=0.2mm; W6=0.1mm; W7=0.15mm, L7=1mm; W8=0.1mm, L8=0.5mm; W9=0.15mm, L9=2mm; L10=2.5mm; L11=1.2mm; L12=0.7mm; G1=0.1mm, G2=0.1mm, G3=0.5mm, G4=0.5mm.

[0023] like Figure 2 As shown, the first component includes a first feed port, a second feed port opposite to the first feed port, a multimode resonator disposed between the first feed port and the second feed port, and a second notch structure disposed below the multimode resonator. The second notch structure includes a first resonant ring 17, a second resonant ring 18 located on the outer periphery of the first resonant ring 17, a fourth resonant ring 20 disposed adjacent to the second resonant ring 18, and a third resonant ring 19 disposed within the fourth resonant ring 20. The multimode resonator has its first three resonant frequencies uniformly distributed in the ultra-wideband range of 3.1 GHz to 10.6 GHz, which are used to form the passband basis of the filter.

[0024] The multimode resonator includes a first transmission line 1, a second transmission line 2 fixed to one side of the first transmission line 1, and a third transmission line 3 fixed to the other side of the first transmission line 1. The end of the second transmission line 2 away from the first transmission line 1 is far from the first feed port, and the end of the third transmission line 3 away from the first transmission line 1 is far from the second feed port. The first feed port, near the first transmission line 1, is fixedly connected to an input capacitor terminal tapered interdigitated coupling feed structure. This input capacitor terminal tapered interdigitated coupling feed structure includes a first interdigitated coupling line 6 fixedly connected to the first feed port, a first capacitor terminal coupling line 8 integrally fixedly connected to one end of the first interdigitated coupling line 6, a second interdigitated coupling line 7 fixedly connected to the first feed port, and a second capacitor terminal coupling line 9 integrally connected to one end of the second interdigitated coupling line 7. The first interdigitated coupling line 6 and the second interdigitated coupling line 7 are located on opposite sides of the second transmission line 2. The first capacitor terminal coupling line 8 is perpendicular to the first interdigitated coupling line 6, and the second interdigitated coupling line 7 is perpendicular to the second capacitor terminal coupling line 9. A first bent coupling line 10 is integrally connected to the end of the second capacitor terminal coupling line 9 away from the second interdigitated coupling line 7. The first bent coupling line 10 is perpendicular to the second capacitor terminal coupling line 9.

[0025] The second feed port, near the end of the first transmission line 1, is fixedly connected to an output capacitor-end tapered interdigital coupling feed structure. This output capacitor-end tapered interdigital coupling feed structure includes a third interdigital coupling line 11 fixedly connected to the second feed port, a third capacitor-end coupling line 13 integrally fixed to one end of the third interdigital coupling line 11, a fourth interdigital coupling line 12 fixedly connected to the second feed port, and a fourth capacitor-end coupling line 14 integrally connected to one end of the fourth interdigital coupling line 12. The third interdigital coupling line 11 and the third capacitor-end coupling line 13 are perpendicular to each other, and the fourth capacitor-end coupling line 14 and the fourth interdigital coupling line 12 are perpendicular to each other. One end of the fourth capacitor-end coupling line 14 is integrally connected to a second bent coupling line 15, which is perpendicular to the fourth capacitor-end coupling line 14.

[0026] Furthermore, the interdigitated coupling feed structure employs a tapered coupling line design with a capacitor at its end to improve impedance matching over the ultra-wideband range and enhance in-band return loss. The input and output structures are symmetrically arranged on both sides of the multimode resonator. For example... Figure 4 As shown, Figure 4 These are the general interdigital coupling (left) and the improved interdigital coupling (right) structures. The interdigital coupling line is extended by bending it 90° at the end of the feed interdigital coupling line to construct the capacitor-end interdigital coupling line, which can improve the in-band return loss. Improving the interdigital coupling line into a tapered coupling line can shift the high-frequency zero point to the passband, thereby improving the frequency selectivity of the high-frequency transition band.

[0027] Furthermore, such as Figure 5 As shown, the simulation comparison of the S-parameters of the improved interdigital coupling shows that, compared with the ordinary interdigital coupling line structure, the improved design can increase the in-band return loss from 18.8 dB to 22.4 dB, while shifting the high-frequency zeros to the passband and improving the steepness of the transition band. This verifies that the improved interdigital coupling can significantly improve the filter performance.

[0028] Furthermore, a stepped impedance stub is fixedly connected to the first transmission line 1. The stepped impedance stub includes a first stepped impedance transmission line 4 fixedly connected to the first transmission line 1 and a second stepped impedance transmission line 5 integrally connected to the first stepped impedance transmission line 4. An open-circuit stub 16 is fixedly connected to the end of the first transmission line 1 furthest from the first stepped impedance transmission line 4. The open-circuit stub 16 is loaded below the center of the MMR and between the two CSRRs. The electrical length of this open-circuit stub in the operating frequency band is much less than 1 / 4 wavelength, and it is not used as an independent resonant unit. Its function is to enhance the resonant coupling between the two CSRRs through local electromagnetic field perturbation, thereby increasing the equivalent Q value of the notch filter unit and significantly increasing the notch depth at 6.53 GHz and 7.34 GHz. The stepped impedance stub, loaded at the center of the multimode resonator, has an impedance ratio k = 4.75 and is used to introduce a transmission zero on each side of the passband, improving the frequency selectivity of the filter.

[0029] Furthermore, such as Figure 6 The diagram shown is a structural diagram of a stepped impedance stub (SIS). In the overall filter structure, it is loaded above the center of the multimode resonator. In order to achieve a selective response with sharp response at the two cutoff frequencies of the filter passband, an SIS with |S21|=0 at frequencies of 3.1 GHz and 10.6 GHz needs to be designed.

[0030] and It is the transmission zero point, among which This means that at the selected frequency, the signal is short-circuited through the branch. According to transmission line theory, the total input admittance of the SIS is: (1) in For characteristic admittance, For electrical length. When At this time, a transmission zero point will be generated: (2) set up By replacing the values ​​in the equation, we get: (3) The equation represents a three-variable equation. Numerical iterative methods can be used to solve it, regardless of whether the value of the electric length is given. k Or give k Using one electrical length value to deduce another, a suitable value can be obtained to determine the size of the SIS. k When the value is 4.75, the dimensions can be more compact while still being machinable. This can be achieved through calculation using equation (3). Z 1 = 25 Ω and Z2 = 118 Ω, corresponding to wire lengths of 1.26 mm and 4 mm.

[0031] Furthermore, the defective structure is etched onto the lower surface of the dielectric substrate, corresponding to the position of the interdigital coupling feed structure, to enhance the coupling strength and further improve the out-of-band rejection capability. The bent capacitor terminal structure used to generate the first notch filter is integrated into the first capacitor terminal coupling line 8 in the input interdigital coupling feed structure and the second capacitor terminal coupling line 9 in the output interdigital coupling feed structure.

[0032] Furthermore, the first notch structure involves extending and bending one capacitor end of the interdigital coupled feed structure by 90° to introduce a first notch at 6.53 GHz to suppress C-band satellite communication signal interference.

[0033] The second notch structure employs a pair of CSRRs coupled below the multimode resonator to introduce a second notch at 7.34 GHz. The notch position can be changed by adjusting the structural dimensions of the CSRRs. The notch is designed to be located at 7.34 GHz to suppress X-band radar pulse interference.

[0034] Furthermore, such as Figure 7 The figure shows the S-parameter simulation after adding SIS and DGS. A symmetrical DGS structure is also introduced to enhance the coupling strength of the interdigital coupling. As can be seen from the figure, two transmission zeros are added at 3.1 GHz and 10.6 GHz, which improves the out-of-band rejection capability and frequency selectivity of the filter. This verifies that by effectively analyzing the data, loading the SIS structure into the filter can introduce transmission zeros at the cutoff frequency.

[0035] Furthermore, such as Figure 8 The diagram shows the S-parameter simulation after introducing two notches. The first notch, located at 6.53 GHz, is introduced by extending and bending one end of an interdigitated capacitor by 90°. This notch blocks some C-band satellite communication signals from entering the UWB receiver, preventing receiver blockage or sensitivity degradation. A second notch is introduced by coupling a pair of CSRRs. The notch's location can be changed by altering the CSRR's structural dimensions, ultimately designed to be at 7.34 GHz. This notch suppresses radar pulse interference, protecting the UWB system's low-noise amplifier and subsequent demodulation circuitry. A 0.5 mm open-circuit stub is added below the center of the MMR and between the two CSRRs to enhance the resonant coupling of the two CSRRs. The S-parameter simulation results show that the notch depth increases from 10 dB to 30 dB, significantly improving the notch depth and better suppressing interference at the notch frequency.

[0036] Verification has shown that the invented ultra-wideband filter has a passband coverage of 3.1 GHz to 10.6 GHz and an absolute bandwidth of 7.5 GHz. The passband range fully covers the 3.1–10.6 GHz ultra-wideband commercial frequency band specified by the US Federal Communications Commission (FCC), supporting Gbps-level data transmission rates. It is suitable for high-speed wireless communication, radar imaging, and the Internet of Things (IoT) scenarios. Simulation results show that the insertion loss is less than 1 dB, the return loss is better than 15 dB, and dual notch filtering is achieved at 6.53 GHz and 7.34 GHz with a notch depth of up to 30 dB, effectively suppressing interference from C-band satellites and X-band radar. While maintaining a compact size (23.85 mm × 15 mm), it achieves synergistic optimization of dual notch filtering, high selectivity, and low insertion loss, demonstrating significant engineering practical value.

[0037] The number of devices and processing scale described herein are for simplification purposes. Applications, modifications, and variations of this invention will be readily apparent to those skilled in the art. Although embodiments of the invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for this invention, and further modifications can be readily implemented by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, this invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A multimode dual-notch ultrawideband filter based on interdigital coupling and SIS, characterized in that, include: A dielectric substrate, a first component assembly fixed to the top of the dielectric substrate, and a second structural assembly fixed to the bottom of the dielectric substrate; The first component includes a first feed port, a second feed port disposed opposite to the first feed port, a multimode resonator disposed between the first feed port and the second feed port, and a second notch structure disposed below the multimode resonator. The multimode resonator includes a first transmission line (1), a second transmission line (2) fixed to one side of the first transmission line (1), and a third transmission line (3) fixed to the other side of the first transmission line (1). The end of the second transmission line (2) away from the first transmission line (1) is far from the first feed port, and the end of the third transmission line (3) away from the first transmission line (1) is far from the second feed port. The first feed port is fixed to one end of the first transmission line (1) with a tapered interdigitated feed structure for the input capacitor. The second feed port is fixed to one end of the first transmission line (1) with a tapered interdigitated feed structure for the output capacitor.

2. The multimode dual-notch ultrawideband filter based on interdigital coupling and SIS as described in claim 1, characterized in that, The input capacitor terminal tapered interdigitated coupling feed structure includes a first interdigitated coupling line (6) fixed to the first feed port, a first capacitor terminal coupling line (8) integrally fixed to one end of the first interdigitated coupling line (6), a second interdigitated coupling line (7) fixed to the first feed port, and a second capacitor terminal coupling line (9) integrally connected to one end of the second interdigitated coupling line (7). The first interdigitated coupling line (6) and the second interdigitated coupling line (7) are located on both sides of the second transmission line (2), wherein the first capacitor terminal coupling line (8) is perpendicular to the first interdigitated coupling line (6), and the second interdigitated coupling line (7) is perpendicular to the second capacitor terminal coupling line (9).

3. A multimode dual-notch ultrawideband filter based on interdigital coupling and SIS as described in claim 2, characterized in that, The second capacitor end coupling line (9) is integrally connected to the end away from the second interdigital coupling line (7) by a first bent coupling line (10), and the first bent coupling line (10) is perpendicular to the second capacitor end coupling line (9).

4. A multimode dual-notch ultrawideband filter based on interdigital coupling and SIS as described in claim 1, characterized in that, The output capacitor terminal tapered interdigital coupling feed structure includes a third interdigital coupling line (11) fixed to the second feed port, a third capacitor terminal coupling line (13) integrally fixed to one end of the third interdigital coupling line (11), a fourth interdigital coupling line (12) fixed to the second feed port, and a fourth capacitor terminal coupling line (14) integrally connected to one end of the fourth interdigital coupling line (12). The third interdigital coupling line (11) and the third capacitor terminal coupling line (13) are perpendicular to each other, and the fourth capacitor terminal coupling line (14) and the fourth interdigital coupling line (12) are perpendicular to each other.

5. A multimode dual-notch ultrawideband filter based on interdigital coupling and SIS as described in claim 4, characterized in that, One end of the fourth capacitor terminal coupling line (14) is integrally connected to a second bent coupling line (15), and the second bent coupling line (15) and the fourth capacitor terminal coupling line (14) are perpendicular to each other.

6. A multimode dual-notch ultrawideband filter based on interdigital coupling and SIS as described in claim 1, characterized in that, The second notch structure includes a first resonant ring (17), a second resonant ring (18) located on the outer periphery of the first resonant ring (17), a fourth resonant ring (20) disposed adjacent to the second resonant ring (18), and a third resonant ring (19) disposed within the fourth resonant ring (20).

7. A multimode dual-notch ultrawideband filter based on interdigital coupling and SIS as described in claim 1, characterized in that, The second structural component includes a first groove (21) on the back side of the dielectric substrate corresponding to the interdigital coupling line and a second groove (22) disposed adjacent to the first groove (21).

8. A multimode dual-notch ultrawideband filter based on interdigital coupling and SIS as described in claim 1, characterized in that, A step impedance stub is fixedly connected to the first transmission line (1). The step impedance stub includes a first step impedance transmission line (4) fixedly connected to the first transmission line (1) and a second step impedance transmission line (5) integrally connected to the first step impedance transmission line (4). An open circuit stub (16) is fixedly connected to one end of the first transmission line (1) away from the first step impedance transmission line (4).

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