Compact low-frequency-band wide-band-pass superconducting filter
By designing a compact low-band broadband pass superconducting filter with multiple narrow and long single helical resonators, the difficulties in broadband microwave filters in the prior art in the design of widepassband and broadband external suppression are solved, and the effects of high band edge steepness and broadband external suppression are achieved.
Patent Information
- Application Number
- CN202411823154.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-03-21
AI Technical Summary
There are difficulties in designing wide-passband and out-of-broadband suppression in existing broadband microwave filters, especially in the case of strong coupling between resonators, the responses of different frequencies in the passband are difficult to adjust consistently, and the out-of-band suppression design is relatively complex.
A compact low-band broadband pass superconducting filter is designed, using multiple low-frequency single-helical resonators with particularly narrow and long, fewer turns and larger internal space. By cascade these resonators, broadband pass and broadband external suppression of the VU band are achieved. The long sides of the resonator are arranged in parallel adjacent to each other, and adjacent resonators are coupled to each other, and a multi-turn single helical coil is arranged outside the hollow white structure to enhance the inner adjacent coupling.
Superconducting microwave filters that achieve broadband pass and broadband ex-band suppression are simple in design, with a compact overall structure, and the band edge steepness and out-of-band suppression indexes reach a high level.
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Figure CN119674481A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of microwave communication technology, and in particular to a compact low-frequency band wideband superconducting filter. Background Art
[0002] With the rapid development of wireless communication technology, more and more communication frequency bands are being developed and utilized, and the electromagnetic environment in space has become very complex. The performance requirements of microwave filters for high-performance microwave receiver front ends are also getting higher and higher. The ideal microwave filter has a rectangular filtering characteristic, which can filter out the signals of the required frequency band and completely filter out the signals of the remaining frequency bands. Due to factors such as the microwave loss of metal materials, the filtering performance of actual microwave filters is far behind that of ideal filters. Compared with conventional metals, the surface resistance of high-temperature superconducting materials in the microwave frequency band is two to three orders of magnitude smaller, which is very small. Resonators and filters made of high-temperature superconducting materials have a series of advantages such as low loss and high frequency selectivity, which can greatly improve the sensitivity of microwave receivers and other performance.
[0003] Wireless communication systems that process broadband signals require microwave filters with wide passband characteristics. The required microwave filters have the characteristics of low loss in the wide passband and high suppression outside the passband. The design of wide passband microwave filters requires strong coupling between resonators and strong coupling between resonators and input and output ends. The purpose of passband widening is achieved through strong electromagnetic coupling between resonators. In the case of strong coupling between resonators, it is difficult to adjust the responses of different frequencies in the passband. In addition, due to the inherent multi-order resonance characteristics of planar microstrip structure resonators, the design of the out-of-band suppression of the formed filter is a difficult problem. In order to solve these problems, broadband microwave filters are currently designed with resonator structures with high multiplication ratios. Commonly used structures include step impedance (SIR) structures, interdigitated capacitor structures, quarter-wavelength structure resonators, etc. From the overall design of the filter, methods such as staggered multiplication and introduction of notch points are proposed to improve the wide suppression capability of the filter.
[0004] In the above-mentioned resonator and filter design methods, the optimization of the resonator structure has a very high suppression on the filter's stopband, but the stopband will be cut off at the parasitic frequency. At the same time, the filter coupling design needs to meet the coupling characteristics of the resonator, and the design of a wide passband is very difficult. Although the method of parasitic passband suppression from the filter as a whole can have a wide stopband, the suppression degree of the stopband is generally not high. In actual filter design, the above two methods are often combined to improve the wide suppression capability of the filter. Therefore, there is an urgent need for a superconducting filter with a simple design, a wide passband and wideband external suppression. Summary of the invention
[0005] The purpose of the present application is to provide a compact low-frequency band wide-band superconducting filter with a simple design, a wide passband and wideband external suppression.
[0006] To achieve the above objectives, this application provides the following solutions:
[0007] The present application provides a compact low-frequency band wide-bandpass superconducting filter, comprising a substrate, a frequency band selective resonator component, a first feed line position and a second feed line position.
[0008] The frequency band selection resonator assembly includes multiple resonators; the length of the resonator is greater than the width; the long sides of the multiple resonators are adjacent and arranged in parallel on a side surface of the substrate, and the adjacent resonators are coupled to each other; a hollow blank structure is arranged inside each resonator, and a multi-turn coil is arranged outside the hollow blank structure, the multi-turn coil is a single helix structure, and the tail end line of the outer coil of the resonator is connected to the ground; the length of the substrate is less than the width.
[0009] The first feeder position and the second feeder position are respectively connected to the outer coils of the resonators arranged at both ends, and the first feeder position and the second feeder position are spaced apart from the connected resonators by a set distance.
[0010] Optionally, the first feed line position and the second feed line position are located in the middle of both ends of one side surface of the substrate.
[0011] Optionally, the first distance and the second distance of the hollow blank structure in each resonator are the same, the first distance is the distance between the long sides of the innermost circle of the coil of the hollow blank structure, and the second distance is the distance between the long sides of the outermost circle of the coil of the hollow blank structure.
[0012] Optionally, the first distance is 0.32 mm, and the second distance is 1.4 mm.
[0013] Optionally, the number of the resonators ranges from 10 to 14.
[0014] Optionally, the long side distance of the resonator coil is 14.
[0015] Optionally, the length and width of the substrate are 18 mm and 28.5 mm respectively.
[0016] Optionally, the third distance of the hollow blank structure of each external resonator is greater than the fourth distance of the hollow blank structure of each internal resonator, and the fifth distance of the hollow blank structure of the external resonator is greater than the sixth distance of the hollow blank structure of the internal resonator; the external resonators are two resonators close to the first feeder line position and the second feeder line position, respectively, and the internal resonator is a resonator other than the external resonators; the third distance and the fourth distance are respectively the distances between the long sides of the innermost circle of coils of the hollow blank structures of the external resonators and the internal resonators; the fifth distance and the sixth distance are respectively the distances between the long sides of the outermost circle of coils of the hollow blank structures of the external resonators and the internal resonators.
[0017] Optionally, the length and width of the substrate are 30 mm and 39.8 mm respectively.
[0018] Optionally, the line width of the coil is 0.08 mm.
[0019] According to the specific embodiments provided in this application, this application discloses the following technical effects:
[0020] The present application provides a compact low-frequency band wide-band superconducting filter, including a substrate, a band-selective resonator assembly, a first feeder position and a second feeder position, wherein the band-selective resonator assembly includes a plurality of resonators; the length of the resonator is greater than the width; the long sides of the plurality of resonators are adjacent and arranged in parallel on a side surface of the substrate, and the adjacent resonators are coupled to each other; a hollow blank structure is arranged inside each resonator, and a plurality of coils are arranged outside the hollow blank structure, and the plurality of coils are single-helix structures to strengthen the internal adjacent coupling, and the tail end line of the outer coil of the resonator is connected to the ground. The first feeder position and the second feeder position are respectively connected to the outer coil of the resonator arranged at both ends, and the first feeder position and the second feeder position are separated from the connected resonator by a set spacing. By cascading a plurality of particularly narrow and long low-frequency single-helix resonators with fewer coils and larger internal spaces, a series of superconducting microwave filters with wide passband and broadband external suppression in the VU band are designed. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0022] Figure 1 A schematic structural diagram of a compact low-frequency band wideband superconducting filter provided in one embodiment of the present application;
[0023] Figure 2 for Figure 1 The schematic diagram of the comparison between the simulation design results and the measured results of the compact low-frequency band wideband superconducting filter shown;
[0024] Figure 3 A schematic structural diagram of a compact low-frequency band wideband superconducting filter provided by another embodiment of the present application;
[0025] Figure 4 for Figure 1 The schematic diagram of the comparison between the simulation design results and the measured results of the compact low-frequency band wideband superconducting filter shown;
[0026] Reference numerals:
[0027] First feed line position—1, second feed line position—2, substrate—3, resonator—4, external resonator—5, internal resonator—6, ground strip—7. DETAILED DESCRIPTION
[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0029] The resonator with a stepped impedance structure can control the frequency multiplication ratio of the designed resonator within a certain range by controlling the length ratio and impedance ratio of the high and low impedance parts, and has a high degree of design freedom.
[0030] The interdigital capacitor structure refers to the introduction of densely arranged adjacent microstrip line structures in the resonator to form a quasi-lumped circuit equivalent to a capacitor. The capacitance value of this structure will increase with the increase of the number and length of interdigital fingers. Since the interdigital capacitor structure has different equivalent capacitance values at the base frequency and the multiplier frequency, the impact on the base frequency is much greater than that on the multiplier frequency, which can effectively improve the multiplier ratio of the resonator.
[0031] The quarter-wavelength structure changes the boundary conditions of the resonator by grounding one end of the resonator, so that the electrical length of the original half-wavelength resonator can be reduced to a quarter of the wavelength. At the same time, due to the existence of the grounded end, the even harmonics of the fundamental frequency of the resonator are suppressed, and the first high-order harmonic frequency of the resonator is three times the fundamental frequency of the resonator, thereby effectively pushing up the parasitic passband frequency of the resonator.
[0032] The interleaved frequency-doubling filter design method is to design the resonator structure so that the base frequency of the cascaded resonators in the circuit is the same, while the double frequency is at a different frequency. The entire filter circuit has a good passband characteristic at the base frequency, but at the double frequency, a passband cannot be formed due to the mutual inhibition of different resonators, thereby improving the broadband suppression range of the filter.
[0033] The filter design method that introduces a notch point aims at the parasitic passband problem of the filter. By introducing a notch point in the circuit, a high suppression characteristic is obtained at the parasitic passband. The structure of introducing a notch point includes adding a specific stopband structure at the feed line and generating a transmission zero point through a coupled line structure between resonators.
[0034] The main difficulties in the simulation design of broadband superconducting filters in the V and U bands are to achieve sufficiently strong external and internal coupling, to adopt a resonator shape that is as compact as possible, and to deal with the impact of both adjacent and non-adjacent couplings on the large deviation of the resonator frequency when they are both very strong. In response to the above problems, the present application provides a compact low-frequency broadband superconducting filter in the V and U bands that does not require tuning.
[0035] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0036] The present application provides a compact low-frequency band wide-bandpass superconducting filter, comprising a substrate 3, a frequency band selective resonator component, a first feeder position 1 and a first feeder position 2.
[0037] The frequency band selection resonator assembly includes multiple resonators 4; the length of the resonator 4 is greater than the width; the long sides of the multiple resonators 4 are adjacent and arranged in parallel on a side surface of the substrate 3, and the adjacent resonators 4 are coupled to each other; a hollow blank structure is arranged inside each resonator 4, and a multi-turn coil is arranged outside the hollow blank structure, and the multi-turn coil is a single spiral structure, and the tail end line of the outer coil of the resonator 4 is connected to the ground.
[0038] The shape of a single resonator 4 adopts a structure of a single helix with moderate line width and line spacing, a small number of winding coils and a particularly narrow and long structure, a relatively large internal space and a relatively large blank space, and a single-end grounded 1 / 4 wavelength. By adopting a single helix structure resonator 4, the adjacent line currents inside the resonator 4 are in the same direction, which can strengthen the internal adjacent coupling; sufficient line width and internal space further ensure the strong enough internal adjacent coupling required for broadband pass.
[0039] All resonators 4 have the same winding direction, staggered grounding directions, and aligned long sides, which takes into account both sufficiently strong internal adjacent coupling and relatively compact overall dimensions. The overall shape of the substrate 3 is relatively short in length and wide in width, that is, the length of the substrate 3 is smaller than the width.
[0040] External coupling of superconducting filter: The first feeder position 1 and the first feeder position 2 are respectively connected to the outer coil of the resonator 4 arranged at both ends, and the first feeder position 1 and the first feeder position 2 are separated from the connected resonator 4 by a set distance. The first feeder position 1 and the first feeder position 2 are located in the middle of both ends of one side of the substrate 3. The first feeder position 1 and the first feeder position 2 are directly connected to the appropriate position of the outer coil of the first section resonator 4 at both ends by using the shortest possible feeder line. The first feeder position 1 and the first feeder position 2 are centered up and down, and maintain a sufficient distance from the first section resonator 4 at both ends, while taking into account sufficiently strong external coupling, a relatively compact overall appearance, and as little impact on the frequency of the first section resonator 4 as possible.
[0041] For the U frequency band, the number of resonators 4 ranges from 10-14.
[0042] In an exemplary embodiment, Figure 1 As shown, a compact low-frequency band wideband superconducting filter with 14 resonators is provided, wherein the first distance and the second distance of the hollow blank structure in each resonator 4 are the same, the first distance being the distance between the long sides of the innermost coil of the hollow blank structure, and the second distance being the distance between the long sides of the outermost coil of the hollow blank structure.
[0043] Figure 1 In the embodiment, the compact low-frequency band wideband superconducting filter further includes a grounding strip 7 , which is disposed at the top and bottom of the substrate 3 , and is connected to the grounding end of the coil in each resonator 4 .
[0044] Figure 1 In the embodiment, the first distance may be 0.32 mm and the second distance may be 1.4 mm. The long side distance of the coil in the resonator 4 is 14. The length and width of the substrate 3 are 18 mm and 28.5 mm respectively. The line width of the coil in the resonator 4 may be 0.08 mm.
[0045] For the V band, the number of resonators can be 20. In the design of the V band with a relatively wider bandwidth and higher band edge steepness requirements, specific methods such as more sections, smaller line width and line spacing, narrower and longer single resonators, relatively wider and more empty outer two resonators, and relatively narrower remaining resonators are adopted to make the overall structure of the superconducting filter more compact and the band edge steeper.
[0046] In an exemplary embodiment, Figure 3As shown, a compact low-frequency band wideband superconducting filter with 20 resonators is provided, the third distance of the hollow blank structure of each external resonator 5 is greater than the fourth distance of the hollow blank structure of each internal resonator 6, and the fifth distance of the hollow blank structure of the external resonator 5 is greater than the sixth distance of the hollow blank structure of the internal resonator 6; the external resonators 5 are two resonators respectively close to the first feeder position 1 and the first feeder position 2, and the internal resonator 6 is a resonator other than the external resonator 5; the third distance and the fourth distance are respectively the distances between the long side lines of the innermost circle of the hollow blank structure of the external resonator 5 and the internal resonator 6; the fifth distance and the sixth distance are respectively the distances between the long side lines of the outermost circle of the hollow blank structure of the external resonator 5 and the internal resonator 6.
[0047] Figure 3 In the embodiment, the length and width of the substrate 3 are 30 mm and 39.8 mm respectively. The line width and spacing of the coils in the external resonator 5 and the internal resonator 6 can be 0.08 mm. The width of the external resonator 5 can be 2.32 mm and the length can be 26.80 mm. The width of the internal resonator 6 can be 1.20 mm and the length can be 26.80 mm.
[0048] Figure 3 In the embodiment, the grounding strip 7 is connected to the grounding ends of the coils in the external resonator 5 and the internal resonator 6.
[0049] Based on the above settings, a series of V and U band wideband non-tuning superconducting filters are prepared using a 2-inch MgO substrate 3. The structures are relatively compact and 10-14 sections wideband filter is realized in a relatively small size. In particular, one of them realizes a 20-section wideband filter in the V band. Figure 1 The compact low-band wideband superconducting filter with 14 resonators shown in FIG. Figure 3 A compact low-band wideband superconducting filter with 20 resonators is shown.
[0050] like Figure 2 As shown, the above method is used to design and manufacture Figure 1 The compact low-frequency wideband superconducting filter with 14 resonators shown in the figure has very good agreement between the measured results and the simulated design, especially the reflection coefficient S11 waveform is almost the same, which verifies that the simulation calculation and manufacturing process of the above method are very accurate. Figure 4 As shown, the measured results are in good agreement with the simulation design, and both achieve very high band edge steepness and out-of-band suppression indicators.
[0051] The narrow and long single low-frequency resonator structure is very conducive to the compact cascading of multi-section resonators, so it is particularly suitable for low-frequency band wide-band superconducting filters such as V and U. Only a simple number of sections is used to greatly improve the band edge steepness and out-of-band suppression at the same time. It does not require complex design calculation methods such as cross-coupling, nor does it need to sacrifice a lot of proximal out-of-band suppression in exchange for the improvement of band edge steepness. Increasing the number of sections is relatively simple, and the band edge steepness and out-of-band suppression can be greatly improved at the same time.
[0052] By adopting several other broadband resonator structures, fewer cascades of 8-12 sections and the introduction of a suitable cross-coupling design method, the design and production of a low-frequency broadband tuning-free superconducting filter can also be achieved. However, the cross-coupling design is complicated and difficult, and it is not easy to match the S11 in the band very well, and the out-of-band suppression near the transmission zero point will deteriorate a lot. The added cross-coupling structure also takes up the necessary size of the substrate 3, and the overall structure cannot be sufficiently compact. Therefore, compared to the use of several other broadband resonator structures, fewer cascades of 8-12 sections and the introduction of a suitable cross-coupling design method, the compact low-frequency broadband superconducting filter structure provided by the present application is more compact, and the band edge steepness and out-of-band suppression are both particularly good.
[0053] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0054] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.
Claims
1. A compact low-frequency wideband superconducting filter, characterized in that: The compact low-frequency band wide-bandpass superconducting filter comprises a substrate, a band-selective resonator assembly, a first feeder position and a second feeder position; The frequency band selection resonator assembly includes a plurality of resonators; the length of the resonator is greater than the width; the long sides of the plurality of resonators are adjacent and arranged in parallel on a side surface of the substrate, and the adjacent resonators are coupled to each other; a hollow blank structure is arranged inside each of the resonators, and a multi-turn coil is arranged outside the hollow blank structure, and the multi-turn coil is a single helix structure, and the tail end of the outer coil of the resonator is connected to the ground; the length of the substrate is less than the width; The first feeder position and the second feeder position are respectively connected to the outer coils of the resonators arranged at both ends, and the first feeder position and the second feeder position are spaced apart from the connected resonators by a set distance.
2. The compact low-frequency wideband superconducting filter according to claim 1, characterized in that: The first feed line position and the second feed line position are located in the middle of both ends of one side surface of the substrate.
3. The compact low-frequency band wideband superconducting filter according to claim 1, characterized in that: The first distance and the second distance of the hollow blank structure in each resonator are the same, the first distance is the distance between the long sides of the innermost circle of the coil of the hollow blank structure, and the second distance is the distance between the long sides of the outermost circle of the coil of the hollow blank structure.
4. The compact low-frequency band wideband superconducting filter according to claim 3, characterized in that: The first distance is 0.32 mm, and the second distance is 1.4 mm.
5. The compact low-frequency band wideband superconducting filter according to claim 3, characterized in that: The number of the resonators ranges from 10 to 14.
6. The compact low-frequency band wideband superconducting filter according to claim 3, characterized in that: The long side distance of the resonator coil is 14.
7. The compact low-frequency band wideband superconducting filter according to claim 3, characterized in that: The length and width of the substrate are 18 mm and 28.5 mm, respectively.
8. The compact low-frequency band wideband superconducting filter according to claim 1, characterized in that: The third distance of the hollow blank structure of each external resonator is greater than the fourth distance of the hollow blank structure of each internal resonator, and the fifth distance of the hollow blank structure of the external resonator is greater than the sixth distance of the hollow blank structure of the internal resonator; the external resonators are two resonators close to the first feeder line position and the second feeder line position respectively, and the internal resonator is a resonator other than the external resonator; the third distance and the fourth distance are respectively the distances between the long sides of the innermost circle of coils of the hollow blank structures of the external resonators and the internal resonators; the fifth distance and the sixth distance are respectively the distances between the long sides of the outermost circle of coils of the hollow blank structures of the external resonators and the internal resonators.
9. The compact low-frequency band wideband superconducting filter according to claim 8, characterized in that: The length and width of the substrate are 30 mm and 39.8 mm, respectively.
10. The compact low-frequency band wideband superconducting filter according to claim 1, characterized in that: The line width of the coil is 0.08 mm.