A SIR high frequency selective filter with double tight coupling of amplitude and phase

Abstract

The present invention provides an amplitude-phase dual tight coupling SIR high-frequency selective filter. The filter comprises: two resonator units with the same structure, the two resonator units are distributed in mirror symmetry on a dielectric substrate; wherein the resonator unit comprises a first quarter-wavelength SIR resonator, a high-impedance feeder and a 50-ohm standard feeder; the first quarter-wavelength SIR resonator comprises a first low-impedance line and a first high-impedance line, the first high-impedance line is divided into a first part and a second part, the first part and the second part are perpendicular to each other so that the first high-impedance line is L-shaped as a whole, one end of the first part away from the L-shaped right angle is connected to the first low-impedance line, and one end of the second part away from the L-shaped right angle is provided with a metal via; one end of the high-impedance feeder is connected to the first part and parallel to the second part, and the other end is connected to the 50-ohm standard feeder.

Description

Technical Field

[0001] The invention relates to the field of electromagnetic field and microwave technology, and in particular to a high-frequency filter, and in particular to an amplitude-phase double tight coupling SIR high-frequency selective filter. Background Art

[0002] As one of the key components of modern microwave millimeter wave systems, the performance of filters directly affects the quality of the entire system, including channel capacity, signal-to-noise ratio, distortion and other indicators. With the development needs of microwave millimeter wave systems for miniaturization, lightness, high reliability, versatility, high integration and low cost, (quasi) elliptic function filters with low insertion loss, high frequency selectivity and good out-of-band suppression have been widely used. The number and position distribution of finite frequency transmission zeros are the determining factors affecting the performance of (quasi) elliptic function filters.

[0003] The design methods of (quasi) elliptic function filters mainly include introducing cross-coupling between non-adjacent resonators and introducing hybrid electromagnetic coupling between adjacent resonators. Among them, the N-order cross-coupling filter can realize N-2 finite frequency transmission zeros, but its defects are that the coupling topology is relatively complex and the position of the transmission zero cannot be adjusted independently. The N-order hybrid electromagnetic coupling filter can realize N-1 finite frequency transmission zeros, and has the advantages of simple coupling topology and independent adjustable position of transmission zeros. It can be seen that compared with the cross-coupling filter, the hybrid electromagnetic coupling filter of the same order exhibits more superior filtering performance, including more transmission zeros with independent and controllable positions, and compact and simple topology. Therefore, the theory and technology of hybrid electromagnetic coupling has quickly become one of the hot frontiers of high-performance quasi-elliptic function filter research. However, the current related theories and application research of hybrid electromagnetic coupling only use or consider the electromagnetic amplitude coupling between resonators to introduce and control the transmission zeros, and do not consider the influence and improvement of the electromagnetic phase coupling between resonators on the filter performance. The inventors found that the electromagnetic phase coupling between resonators actually has a key influence on the improvement of filter performance. Summary of the invention

[0004] Aiming at the problem that the traditional hybrid electromagnetic coupling filter does not consider the influence and improvement of the electromagnetic phase coupling between resonators on the filter performance, the present invention provides a SIR high frequency selectivity filter with double amplitude and phase tight coupling.

[0005] The present invention provides an amplitude-phase dual tight coupling SIR high-frequency selective filter, comprising: two resonator units with the same structure, the two resonator units are distributed in a mirror-symmetrical manner on a dielectric substrate; wherein the resonator unit comprises a first quarter-wavelength SIR resonator, a high-impedance feeder and a 50-ohm standard feeder; the first quarter-wavelength SIR resonator comprises a first low-impedance line and a first high-impedance line; the first high-impedance line is divided into a first part and a second part, the first part and the second part are perpendicular to each other so that the first high-impedance line is L-shaped as a whole, one end of the first part away from the L-shaped right angle is connected to the first low-impedance line, and one end of the second part away from the L-shaped right angle is provided with a metal via; one end of the high-impedance feeder is connected to the first part and parallel to the second part, and the other end is connected to the 50-ohm standard feeder.

[0006] Furthermore, the center frequency is adjusted by adjusting the overall length of the first low-impedance line and the second portion.

[0007] Furthermore, the length of the high-impedance feed line is greater than the length of the second portion.

[0008] Further, the distance between the 50-ohm standard feed lines of the two resonator units is greater than the distance between the metal vias of the two resonator units, and the distance between the metal vias of the two resonator units is greater than the distance between the first parts of the two resonator units.

[0009] Furthermore, the position of the transmission zero point is adjusted by adjusting the distance between the two first parts.

[0010] Furthermore, the position of the transmission zero point and the return loss are adjusted by adjusting the position of the connection portion between the first portion and the first low-impedance line in the width direction of the first low-impedance line.

[0011] Furthermore, a transmission zero point is generated by adjusting the distance between the second portion and the high impedance feed line, and the return loss and the position of the transmission zero point are adjusted.

[0012] Further, a second quarter-wavelength SIR resonator is respectively arranged on the outer side of the two resonator units; the second quarter-wavelength SIR resonator includes two parts, a second low-impedance line and a second high-impedance line, the second high-impedance line is divided into a third part and a fourth part, the third part and the fourth part are perpendicular to each other so that the second high-impedance line is L-shaped as a whole, and the end of the third part away from the right angle of the L-shape is connected to the second low-impedance line; the two second and the second quarter-wavelength SIR resonators are connected through their respective fourth parts;

[0013] The two first low-impedance lines are adjacent and located between the two second low-impedance lines, the two first high-impedance lines are located on the same side of the two first low-impedance lines, recorded as the first side, and the two second high-impedance lines are located on the same side of the two second low-impedance lines, recorded as the second side; the first side and the second side are opposite ends of each other.

[0014] Furthermore, the length of the first low-impedance line is consistent with the length of the second low-impedance line.

[0015] Furthermore, the resonant frequency is adjusted by adjusting the length of the third portion so as to match the resonant frequency of a filter composed of two resonator units having the same structure.

[0016] Beneficial effects of the present invention:

[0017] After introducing the path length of electric and magnetic coupling into the hybrid coupling filter unit, the present invention designs a quasi-elliptic function microwave filter of hybrid electromagnetic coupling technology under amplitude-phase dual coupling by adjusting the ratio of the path length, that is, by comprehensively considering the amplitude coupling and phase coupling of the hybrid electromagnetic coupling. The filter achieves a high selection technical goal of having N transmission zeros of N order (for example, a second-order filter has a transmission zero of finite frequency in the upper and lower stop bands respectively; a third-order filter has two transmission zeros of finite frequency in the upper stop band and one transmission zero of finite frequency in the lower stop band), and provides a new method for designing quasi-elliptic function microwave filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 One of the structural schematic diagrams of an amplitude-phase dual tight coupling SIR high frequency selective filter provided by an embodiment of the present invention;

[0019] Figure 2 A second structural schematic diagram of an amplitude-phase dual tight coupling SIR high frequency selective filter provided by an embodiment of the present invention;

[0020] Figure 3 The embodiment of the present invention provides Figure 2 S-parameter plot of the second-order filter response of the filter shown;

[0021] Figure 4 A third structural schematic diagram of an amplitude-phase dual tight coupling SIR high frequency selective filter provided by an embodiment of the present invention;

[0022] Figure 5 A fourth structural schematic diagram of an amplitude-phase dual tight coupling SIR high frequency selective filter provided by an embodiment of the present invention;

[0023] Figure 6 The embodiment of the present invention provides Figure 5 S-parameter plot of the third-order filter response of the filter shown;

[0024] Figure numerals: 1 is the first low impedance line, 2 is the first part of the first high impedance line, 3 is the second part of the first high impedance line, 4 is the high impedance feed line, 5 is the 50 ohm standard feed line, 6 is the metal via, 7 is the second low impedance line, 8 is the third part of the second high impedance line, and 9 is the fourth part of the second high impedance line. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the present invention, dual amplitude-phase coupling means: coupling is performed by utilizing both the amplitude and the phase between the resonators at the same time; and tight coupling means: the structure between the two coupled resonators is compact.

[0027] Example 1

[0028] like Figure 1 As shown, an embodiment of the present invention provides an amplitude-phase dual tight coupling SIR high frequency selective filter, comprising: two resonator units with the same structure, the two resonator units are distributed in a mirror-symmetrical manner on a dielectric substrate; wherein the resonator unit comprises a first quarter-wavelength SIR resonator, a high-impedance feeder 4 and a 50-ohm standard feeder 5; the first quarter-wavelength SIR resonator comprises a first low-impedance line 1 and a first high-impedance line, the first high-impedance line is divided into a first part 2 and a second part 3, the first part 2 and the second part 3 are perpendicular to each other so that the first high-impedance line is L-shaped as a whole, the first part 2 is connected to the first low-impedance line 1 at one end away from the L-shaped right angle, and the second part 3 is provided with a metal via 6 at one end away from the L-shaped right angle; one end of the high-impedance feeder 4 is connected to the first part 2 and is parallel to the second part 3, and the other end is connected to the 50-ohm standard feeder 5.

[0029] Specifically, the microstrip line of the filter is made on a dielectric substrate, and the back of the dielectric substrate is a metal copper sheet. The metal via 6 is provided at one end of the high-impedance line to short-circuit the first quarter-wavelength SIR resonator and the back metal of the dielectric substrate, so that the resonant frequency of the first quarter-wavelength SIR resonator is the same as the half wavelength. The amplitude coupling adjustment in this embodiment is mainly achieved through two parts: there is electromagnetic hybrid coupling between the first low-impedance line 1 and the first part 2, and the amplitude coupling adjustment is achieved by adjusting the spacing between the two; there is also electromagnetic hybrid coupling between the second part 3 and the high-impedance feeder, and the amplitude coupling adjustment can also be achieved by adjusting the spacing between the two.

[0030] By setting the first high-impedance line to be in an overall L-shape, on the one hand, the size of the filter can be effectively reduced, and on the other hand, a coupling path can be added, so that energy is transmitted from the 50-ohm standard feeder line 5 through the high-impedance feeder line 4 to the first quarter-wavelength SIR resonator, and can be transmitted to both the first part 2 and the second part 3. In other words, energy can be transmitted through different propagation paths. Since the electrical lengths of different propagation paths are different, there must be a phase difference between the signals on different propagation paths, thereby realizing phase coupling adjustment.

[0031] The two resonator units are designed with mirror symmetry, so that the two first quarter-wavelength SIR resonators have both electrical coupling and magnetic coupling.

[0032] In the embodiment of the present invention, better impedance matching can be achieved by connecting the 50 ohm standard feeder and the resonator through a high impedance feeder. For example, in order to meet the international standard 50Ω impedance matching, in this embodiment, the 50 ohm standard feeder W0 is set to 1.57 mm, and if the width of the high impedance line is 0.4 mm, the difference between the two values ​​is too large, and the transition through the high impedance feeder can achieve better impedance matching, so that more energy signals can enter the resonator.

[0033] As an implementable embodiment, the center frequency is adjusted by adjusting the overall length of the first low-impedance line and the second portion.

[0034] As an implementable embodiment, the length of the high-impedance feed line is greater than the length of the second portion to ensure better phase coupling adjustment.

[0035] In the embodiment of the present invention, Figure 1 As shown, the length direction of the 50-ohm standard feeder line 5 is parallel to the length direction of the second part 3, and the width direction is perpendicular to the length direction of the second part 3, so that the whole composed of the high-impedance feeder line 4 and the 50-ohm standard feeder line 5 is tightly phase-coupled with the first high-impedance line.

[0036] As an implementation method, the distance between the 50-ohm standard feed lines 5 of the two resonator units is greater than the distance between the metal vias 6 of the two resonator units, and the distance between the metal vias 6 of the two resonator units is greater than the distance between the first parts 2 of the two resonator units.

[0037] As an implementation method, the distance between the two first low-impedance lines 1 is fixed, and the position of the transmission zero point is adjusted by adjusting the distance between the two first parts 2 .

[0038] As an implementable embodiment, the position of the transmission zero point and the return loss are adjusted by adjusting the position of the connection portion between the first portion 2 and the first low-impedance line 1 in the width direction of the first low-impedance line 1 .

[0039] As an implementable embodiment, a transmission zero point is generated by adjusting the distance between the second portion 3 and the high impedance feed line 4 and the return loss and the position of the transmission zero point are adjusted.

[0040] Example 2

[0041] Based on the above embodiments, the present invention provides a specific amplitude-phase double tight coupling SIR high frequency selective second-order filter, which adopts RogersRT / duroid 5880 dielectric substrate with a thickness of 0.508mm and a dielectric constant of

[0042] ε r =2.2, the substrate is made of copper, and the resonator is made of SIR.

[0043] Figure 2 In the figure, the filtering structure of the second-order filter is L1=L2=8mm, W1=W2=1.7mm, S1=0.43mm, L3=-L4=5.1mm, W3=W4=0.4mm, L5=L6=2mm, W5=W6=0.4mm, L00=3mm, W00=0.4mm, L0=2mm, W0=1.57mm, D0=0.5mm, D1=0.7mm, S2=0.65mm, S3=0.15mm.

[0044] Among them, L1 and L2 represent the length of the first low-impedance line; W1 and W2 represent the width of the first low-impedance line; S1 represents the distance between the two first low-impedance lines; L3 and L4 represent the length of the first part of the first high-impedance line; W3 and W4 represent the width of the first part of the first high-impedance line; L5 and L6 represent the length of the second part of the first high-impedance line; W5 and W6 represent the width of the second part of the first high-impedance line; L00 and W00 represent the length and width of the high-impedance feeder respectively; L0 and W0 represent the length and width of the 50-ohm standard feeder respectively; D0 and D1 represent the inner diameter and outer diameter of the metal via respectively; S2 represents the distance between the first part and one side of the first low-impedance line in the width direction of the first low-impedance line, which is used to limit the positional relationship of the connecting part between the first part and the first low-impedance line in the width direction of the first low-impedance line, and the position of the transmission zero point and the return loss are adjusted by adjusting the value of S2; S3 represents the distance between the high-impedance feeder and the second part.

[0045] The indicators achieved by the second-order filter are: the center frequency of the filter is 2.82GHz, S11 return loss RL<-20dB, 3dB bandwidth = 215MHz, relative bandwidth 7.6%, because the amplitude-phase dual tight coupling technology is used to calculate the electromagnetic coupling ratio, so there is a finite frequency transmission zero point TZ1 = 0.92GHz and TZ2 = 4.5GHz on both sides of the passband. Compared with the traditional electromagnetic hybrid coupling technology, the present invention can effectively introduce more transmission zero points by adopting the amplitude-phase dual tight coupling.

[0046] The filter of the present invention can adjust the center frequency by adjusting the length of the resonator. By adjusting S2, the position of the upper stopband transmission zero point can be adjusted; by adjusting S1, the positions of the two zero points can be adjusted at the same time. Both resonators are quarter-wavelength resonators, which effectively reduces the size of the filter and is more conducive to miniaturization. The design is all copper strip microstrip line design, which is easy to process. Figure 3 From the filter response shown, we can see that the second harmonic is beyond 10GHz, the out-of-band suppression is strong, the filter size and coupling spacing parameters have a large range of variation, and the sensitivity is low. The overall size of the filter is 21.1mmx13.83mm. Among them, port L0 is an international standard 50Ω impedance matching independent feed. In general, the filter has a compact structure and high selectivity.

[0047] Example 3

[0048] The SIR high frequency selective filter in Example 1 is actually a second-order filter. It can be understood that the high-order filter is constructed with the second-order filter as a unit. In order to further construct a high-order filter, based on the above Example 1, as Figure 3As shown, the embodiment of the present invention further provides an amplitude-phase dual tight coupling SIR high frequency selective filter, which is different from the embodiment 1 in that the filter in the embodiment of the present invention is composed of two quarter-wavelength resonators and one half-wavelength resonator, specifically: a second quarter-wavelength SIR resonator is respectively arranged on the outer sides of the two resonator units; the second quarter-wavelength SIR resonator includes a second low-impedance line 7 and a second high-impedance line, the second high-impedance line is divided into a third part 8 and a fourth part 9, the third part 8 and the fourth part 9 are perpendicular to each other so that the second high-impedance line is L-shaped as a whole, and the end of the third part 8 away from the right angle of the L-shape is connected to the second low-impedance line 7; the two second and the second quarter-wavelength SIR resonators are connected through their respective fourth parts 9;

[0049] The two first low-impedance lines 1 are adjacent and located between the two second low-impedance lines 7, the two first high-impedance lines are located on the same side of the two first low-impedance lines 1, recorded as the first side, and the two second high-impedance lines are located on the same side of the two second low-impedance lines 7, recorded as the second side; the first side and the second side are opposite ends of each other.

[0050] In the embodiment of the present invention, the fourth-order filter is constructed without adopting the traditional cascade scheme, but the third-order filter is constructed by combining a quarter wavelength and a half wavelength in an innovative way. This construction method can firstly realize the high selection index of the N-order filter with N finite transmission zeros, and can more effectively utilize the spatial structure to make the filter more miniaturized, thereby meeting the contemporary communication needs. In addition, by designing a half-wavelength resonator to surround two quarter-wavelength resonators, better electromagnetic coupling can be achieved, effectively increasing the bandwidth of the filter.

[0051] As an implementable embodiment, the length of the first low-impedance line 1 is consistent with the length of the second low-impedance line 7 .

[0052] As an implementable embodiment, the resonant frequency is adjusted by adjusting the length of the third portion 8 so as to match the resonant frequency of a filter composed of two resonator units having the same structure (ie, the second-order filter in the above-mentioned embodiments 1 and 2).

[0053] Example 4

[0054] Based on the above embodiment 3, a specific embodiment of the present invention is a SIR high frequency selective third-order filter with double tight coupling of amplitude and phase, which adopts RogersRT / duroid 5880 dielectric substrate with a thickness of 0.508mm and a dielectric constant of ε r =2.2, the substrate is made of copper, and the resonator is made of SIR.

[0055] Figure 5 In the figure, the filtering structure of the third-order filter is L1=L4=8mm, W1=1.7mm, L8=6.49mm, W8=0.4mm, L7=3.1mm, S1=0.33mm, L5=5.1mm, L6=2.4mm, L00=3mm, W00=0.4mm, L0=2mm, W0=1.57mm, D0=0.5mm, D1=0.7mm, S2=0.65mm, S3=0.75mm.

[0056] Among them, L1 and L4 represent the length of the second low impedance line; W1 represents the width of the second low impedance line; L8 represents the sum of the lengths of the fourth parts of the two second high impedance lines; W8 represents the width of the fourth part of the second high impedance line; L7 represents the length of the third part of the second high impedance line; S1 represents the distance between the second low impedance line and the first low impedance line; L5 represents the length of the first part of the first high impedance line; L6 represents the length of the second part of the first high impedance line; L00 and W00 (refer to Figure 2 , not shown in the figure) represent the length and width of the high impedance feed line respectively; L0 and W0 (refer to Figure 2 , not shown in the figure) respectively represent the length and width of a 50-ohm standard feeder line; D0 and D1 respectively represent the inner diameter and outer diameter of the metal via; S2 represents the distance between the first part and one side of the first low-impedance line in the width direction of the first low-impedance line, which is used to define the connection position relationship between the first low-impedance line and the first part; S3 represents the distance between the high-impedance feeder line and the second part.

[0057] Figure 6 The figure shows the S parameter diagram of the third-order filter. It can be seen from the figure that the center frequency of the filter is 2.82GHz, the S11 return loss RL<-20dB, the 3dB bandwidth = 423MHz, and the relative bandwidth is 15%. Because the amplitude-phase dual tight coupling technology is used to calculate the electromagnetic coupling ratio, the lower stop band of the passband has a finite frequency transmission zero point TZ1=0.92GHz, and the upper stop band has two finite frequency transmission zero points TZ2=3.29GHz and TZ3=5.04GHz respectively.

[0058] The third-order filter of the embodiment of the present invention can adjust the center frequency by adjusting the length of the resonator. By adjusting S2, the position of the upper stopband transmission zero TZ2 can be adjusted; by adjusting S1, the positions of the TZ1 and TZ3 zeros can be adjusted simultaneously. The two middle resonators are both quarter-wavelength resonators, and then a half-wavelength resonator plus two quarter-wavelength resonators are used. This design more effectively reduces the size of the filter, making the overall size of the high-order filter and the second-order filter unit similar, which is more conducive to miniaturization. The design is all copper tape microstrip line design, which is easy to process. Figure 6From the filter response shown, we can see that the second harmonic is also outside 10GHz, the out-of-band suppression is strong, the filter size and coupling spacing parameters have a large range of variation, and the sensitivity is low. The overall size of the filter is 21.1mmx13.79mm. Port L0 is an international standard 50Ω impedance matching independent feed. In general, the filter structure is more compact and has higher selectivity.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A SIR high frequency selective filter with double tight coupling of amplitude and phase, characterized in that: include: Two resonator units with the same structure, the two resonator units are distributed in a mirror-symmetrical manner on a dielectric substrate; wherein the resonator unit comprises a first quarter-wavelength SIR resonator, a high-impedance feeder and a 50-ohm standard feeder; The first quarter-wavelength SIR resonator includes a first low-impedance line and a first high-impedance line. The first high-impedance line is divided into a first part and a second part. The first part and the second part are perpendicular to each other so that the first high-impedance line is L-shaped as a whole. The end of the first part away from the L-shaped right angle is connected to the first low-impedance line, and the end of the second part away from the L-shaped right angle is provided with a metal via; one end of the high-impedance feeder is connected to the first part and parallel to the second part, and the other end is connected to the 50-ohm standard feeder; the position of the transmission zero point and the return loss are adjusted by adjusting the position of the connecting part between the first part and the first low-impedance line in the width direction of the first low-impedance line; the transmission zero point is generated by adjusting the distance between the second part and the high-impedance feeder, and the return loss and the position of the transmission zero point are adjusted.

2. The SIR high frequency selective filter with double tight coupling of amplitude and phase according to claim 1, characterized in that: The center frequency is adjusted by adjusting the overall length of the first low impedance line and the second portion.

3. The SIR high frequency selective filter with double amplitude and phase tight coupling according to claim 1, characterized in that: The length of the high impedance feed line is greater than the length of the second portion.

4. The SIR high frequency selective filter with double amplitude and phase tight coupling according to claim 1, characterized in that: The distance between the 50-ohm standard feed lines of the two resonator units is greater than the distance between the metal vias of the two resonator units, and the distance between the metal vias of the two resonator units is greater than the distance between the first parts of the two resonator units.

5. The SIR high frequency selective filter with double amplitude and phase tight coupling according to claim 1, characterized in that: The position of the transmission zero point is adjusted by adjusting the distance between the two first parts.

6. The SIR high frequency selective filter with double amplitude and phase tight coupling according to any one of claims 1 to 5, characterized in that: A second quarter-wavelength SIR resonator is respectively arranged on the outer side of the two resonator units; the second quarter-wavelength SIR resonator includes two parts, a second low-impedance line and a second high-impedance line, the second high-impedance line is divided into a third part and a fourth part, the third part and the fourth part are perpendicular to each other so that the second high-impedance line is L-shaped as a whole, and the end of the third part away from the right angle of the L-shape is connected to the second low-impedance line; the two second and the second quarter-wavelength SIR resonators are connected through their respective fourth parts; The two first low-impedance lines are adjacent and located between the two second low-impedance lines, the two first high-impedance lines are located on the same side of the two first low-impedance lines, recorded as the first side, and the two second high-impedance lines are located on the same side of the two second low-impedance lines, recorded as the second side; the first side and the second side are opposite ends of each other.

7. The SIR high frequency selective filter with double amplitude and phase tight coupling according to claim 6, characterized in that: The length of the first low-impedance line is consistent with the length of the second low-impedance line.

8. The SIR high frequency selective filter with double amplitude and phase tight coupling according to claim 6, characterized in that: The resonant frequency is adjusted by adjusting the length of the third portion so as to match the resonant frequency of a filter composed of two resonator units having the same structure.

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