Broadband terahertz waveguide band-pass filter with high out-of-band rejection

Abstract

The utility model discloses a broadband terahertz waveguide band-pass filter with high out-of-band rejection. The broadband terahertz waveguide band-pass filter comprises an input waveguide, an output waveguide and a plurality of first band elimination elements, the input waveguide serves as the input end of the broadband terahertz waveguide band-pass filter, the output waveguide serves as the output end of the broadband terahertz waveguide band-pass filter, the width of any one of the first band-stop elements is smaller than the width of the input waveguide and the width of the output waveguide, and the width of any one of the first band-stop elements is smaller than that of the output waveguide. The plurality of first band-stop elements are sequentially arranged between the input end and the output end to form a high-frequency stop band of the broadband terahertz waveguide band-pass filter; therefore, a brand-new band-stop element branch structure is adopted to form a high-frequency stop band of the filter, so that the filter has a transmission zero point outside the high-frequency band, and meanwhile, the filter has the advantages of high out-of-band rejection and high bandwidth; therefore, the terahertz radio frequency transmission device is very suitable for large-scale application and popularization in the terahertz radio frequency transmission field.

Description

Technical Field

[0001] The utility model belongs to the technical field of terahertz radio frequency transmission, and in particular relates to a broadband terahertz waveguide bandpass filter with high out-of-band suppression. Background Art

[0002] Terahertz technology has become a research frontier due to its scientific value. Among them, terahertz systems are widely used in radar, detection, imaging, communication and other fields due to a series of advantages such as high bandwidth. As a key component of the RF front end of these systems, bandpass filters with high selectivity and low insertion loss are undoubtedly required. At present, there are many filter structures to choose from in lower frequency bands such as microwaves. However, in the terahertz band, since waveguide filters are metal enclosed structures that can avoid electromagnetic radiation and dielectric loss, they have become the mainstream choice in the terahertz band. In actual applications, waveguide Chebyshev filters are the most commonly used and most common structure. Chebyshev filters are based on waveguide resonant cavities. Compared with other types of filters, they have the characteristics of high Q value, low loss and large power capacity. Therefore, when Chebyshev filters work in the terahertz band, they still have obvious advantages in terms of volume, weight, processing, cost and performance.

[0003] However, ordinary waveguide Chebyshev bandpass filters have problems such as no out-of-band transmission zero, narrow bandwidth, and poor high-frequency out-of-band suppression. In order to obtain broadband characteristics and high out-of-band suppression, the order of the filter needs to be increased. However, the increase in the order of the filter will bring greater losses and increase the size of the filter, which is not conducive to the integration of the system. Therefore, how to provide a terahertz waveguide filter with high out-of-band suppression and large working bandwidth has become a problem that needs to be solved urgently. Utility Model Content

[0004] The utility model aims to provide a broadband terahertz waveguide bandpass filter with high out-of-band suppression, so as to solve the problems of no out-of-band transmission zero point, narrow bandwidth and poor high-frequency out-of-band suppression existing in the prior art.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] In a first aspect, a broadband terahertz waveguide bandpass filter with high out-of-band suppression is provided, comprising:

[0007] An input waveguide, an output waveguide and a plurality of first band-stop elements;

[0008] The input waveguide serves as the input end of the broadband terahertz waveguide bandpass filter, and the output waveguide serves as the output end of the broadband terahertz waveguide bandpass filter, wherein the width of any first bandstop element among a plurality of first bandstop elements is smaller than the widths of the input waveguide and the output waveguide, and the plurality of first bandstop elements are sequentially arranged between the input end and the output end to form a high-frequency stopband of the broadband terahertz waveguide bandpass filter.

[0009] Based on the above disclosed content, the structure of the bandpass filter provided by the utility model is different from that of the traditional resonant cavity-based filter, wherein the bandpass filter of the utility model is input and output via a standard waveguide, and utilizes a plurality of first band-stop elements to form the high-frequency stopband of the filter, and at the same time, the width side of the intermediate waveguide (i.e., the plurality of first band-stop elements) is smaller than that of the input and output waveguides, so that the cutoff frequency of the intermediate waveguide can be increased; based on this, the two provide low-frequency and high-frequency sidebands respectively, thereby complementing each other to form a bandpass filter.

[0010] Through the above design, the utility model adopts a brand-new branch structure of the band-stop element to form the high-frequency stop band of the filter, so that the filter can have a transmission zero point outside the high-frequency band. At the same time, the filter formed by the branch of the band-stop element has a higher bandwidth and out-of-band suppression than the traditional waveguide Chebyshev filter, and the bandwidth of the filter can be flexibly adjusted by adjusting the wide side size of the branch of the band-stop element, and the out-of-band suppression can be improved by increasing the number of band-stop elements; in addition, the size of the band-stop element is much smaller than that of the traditional resonator, so even if the number of band-stop elements is increased, the volume of the filter will not be excessively increased; based on this, the filter provided by the utility model has the advantages of out-of-band transmission zero point, high out-of-band suppression and high bandwidth, and is small in size, so it is very suitable for large-scale application and promotion in the field of terahertz radio frequency transmission.

[0011] In one possible design, a height of a first target band-stop element among the plurality of first band-stop elements is smaller than a height of a second target band-stop element, wherein the first target band-stop element is the first band-stop element among the plurality of first band-stop elements that is close to the input end and the output end, and the second target band-stop element is the first band-stop element among the plurality of first band-stop elements excluding the first target band-stop element.

[0012] In a possible design, the first band-stop elements close to the input end and the output end among the plurality of first band-stop elements have the same height.

[0013] In one possible design, the input waveguide and the output waveguide are of the same size.

[0014] In a possible design, both the input waveguide and the output waveguide have a rectangular parallelepiped structure.

[0015] In a possible design, both the input waveguide and the output waveguide employ a second band-stop element for impedance matching.

[0016] In a possible design, a cross section or a longitudinal section of any first band-stop element is a rectangular section.

[0017] In a possible design, at least three first band-stop elements are arranged between the input end and the output end.

[0018] In a possible design, five first band-stop elements are arranged between the input end and the output end.

[0019] In one possible design, the broadband terahertz waveguide bandpass filter has at least two out-of-band transmission zero points.

[0020] Beneficial effects:

[0021] (1) The utility model adopts a brand-new branch structure of the band-stop element to form the high-frequency stopband of the filter, so that the filter can have a transmission zero outside the high-frequency band. At the same time, the filter formed by the branch of the band-stop element has a higher bandwidth and out-of-band suppression than the traditional waveguide Chebyshev filter, and the bandwidth of the filter can be flexibly adjusted by adjusting the wide side size of the branch of the band-stop element, and the out-of-band suppression can be improved by increasing the number of band-stop elements. In addition, the size of the band-stop element is much smaller than that of the traditional resonator. Therefore, even if the number of band-stop elements is increased, the volume of the filter will not be excessively increased. Based on this, the filter provided by the utility model has the advantages of out-of-band transmission zero, high out-of-band suppression and high bandwidth, and is small in size, so it is very suitable for large-scale application and promotion in the field of terahertz radio frequency transmission.

[0022] (2) The filter provided by the utility model has better performance than ordinary waveguide bandpass filters, and the processing method is the same, that is, it can be processed by computer digital controlled precision machinery, and still has the advantages of high Q value, low loss and large power capacity. Therefore, the utility model still has advantages in size, weight, processing, cost and performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A three-dimensional diagram of a broadband terahertz waveguide bandpass filter with high out-of-band suppression provided by an embodiment of the utility model;

[0024] Figure 2 A top view of a broadband terahertz waveguide bandpass filter with high out-of-band suppression provided by an embodiment of the utility model;

[0025] Figure 3 A structural diagram of a traditional filter provided by the utility model;

[0026] Figure 4 This is a simulation result diagram of the filter provided by the utility model;

[0027] Figure 5 This is a simulation result diagram of the traditional filter provided by the utility model.

[0028] Reference numerals:

[0029] 10 - input waveguide; 20 - output waveguide; 30 - first band-stop element; 40 - waveguide resonant cavity. DETAILED DESCRIPTION

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the utility model will be briefly introduced below in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the utility model, but does not constitute a limitation of the utility model.

[0031] It should be understood that although the terms first, second, etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another unit. For example, a first unit can be referred to as a second unit, and similarly, a second unit can be referred to as a first unit without departing from the scope of the exemplary embodiments of the present utility model.

[0032] It should be understood that the term "and / or" that may appear in this article is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" that may appear in this article describes another type of association object relationship, indicating that two relationships may exist. For example, A / and B can represent two situations: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0033] Example:

[0034] See also Figures 1 to 5As shown, the broadband terahertz waveguide bandpass filter with high out-of-band suppression provided in this embodiment may include, but is not limited to: an input waveguide 10, an output waveguide 20, and a plurality of first band-stop elements 30, and in actual application, the input waveguide 10 serves as the input end of the broadband terahertz waveguide bandpass filter, and the output waveguide 20 serves as the output end of the broadband terahertz waveguide bandpass filter, wherein the width of any first band-stop element 30 among the plurality of first band-stop elements 30 is smaller than the width of the input waveguide 10 and the output waveguide 20, and the plurality of first band-stop elements 30 are sequentially arranged between the input end and the output end, thereby forming a high-frequency stopband of the broadband terahertz waveguide bandpass filter.

[0035] Thus, the bandpass filter provided by this embodiment has a different structure from that of a conventional filter based on a resonant cavity, as can be seen in Figure 1 and Figure 3 As shown, in this embodiment, the band-stop element branches (i.e., the first band-stop element 30) on the waveguide are used to form the high-frequency stop band of the filter, thereby providing a high-frequency band for the waveguide bandpass filter. At the same time, the width of each first band-stop element 30 is smaller than the width of the input waveguide and the output waveguide; thus, the cutoff frequency of the intermediate waveguide can be increased (the width comparison diagram can be seen in Figure 2 Based on this, the two provide low-frequency and high-frequency sidebands respectively, thereby complementing each other to form a bandpass filter.

[0036] Through the above-mentioned design, the structural design of the filter with a new band-stop element branch can make the filter have a transmission zero point in the high-frequency band, and have the advantages of high out-of-band suppression and high bandwidth; at the same time, the bandwidth of the filter provided by the utility model can be flexibly adjusted by adjusting the wide side of the intermediate waveguide, and under the same size, compared with the traditional filter, the bandwidth of this structure is higher; in addition, ordinary waveguide filters need to increase the order, that is, increase the number of resonant cavities to improve the out-of-band suppression, and the out-of-band suppression of the filter provided by this embodiment can also be directly improved by adding band-stop elements, and the suppression degree is much greater than that of ordinary waveguide filters. At the same time, the size of the band-stop element is much smaller than the size of the resonator. Therefore, after adding the band-stop element, its volume is also much smaller than that of the traditional filter, which is very conducive to the integration of the system, and is very suitable for large-scale application and promotion in the field of terahertz radio frequency transmission.

[0037] Optionally, the following discloses a more detailed structural design of the aforementioned broadband terahertz waveguide bandpass filter:

[0038] In a possible design, the input waveguide 10 and the output waveguide 20 have the same size, that is, a symmetrical design is adopted, and both can be but not limited to a rectangular parallelepiped structure; at the same time, in a specific implementation, both can be but not limited to a second band-stop element for impedance matching, and the structural schematic diagram can be seen in Figure 1 shown.

[0039] In a specific embodiment, for example, the height of the first target band-stop element among the plurality of first band-stop elements 30 is smaller than the height of the second target band-stop element, wherein the first target band-stop element is the first band-stop element 30 among the plurality of first band-stop elements 30 close to the input end and the output end, and the second target band-stop element is the first band-stop element 30 among the plurality of first band-stop elements 30 excluding the first target band-stop element; in this way, setting the height of the band-stop element branches at both ends of the intermediate waveguide smaller than the height of the band-stop element branches at both ends can better cooperate with the input waveguide and the output waveguide for impedance matching.

[0040] Optionally, the intermediate waveguide may also be designed with a symmetrical structure, that is, the heights of the first band-stop elements 30 close to the input end and the output end are the same; see Figure 1 As shown, a plurality of first band-stop elements 30 are symmetrically distributed along the first band-stop element in the middle. Thus, the performance of the filter can be improved by adopting a symmetrical structural design.

[0041] Furthermore, for example, the cross section or longitudinal section of any of the first band resistance elements 30 is a rectangular cross section; that is, each band resistance element 30 of this embodiment is also a rectangular parallelepiped structure; at the same time, in order to facilitate processing, the end corners of the first band resistance element 30 are rounded in this embodiment, but in actual design, its structure is still a cubic structure. Figure 1 The schematic diagrams of the first band-stop elements 30 are only for processing purposes.

[0042] In a specific design, for example, at least three first band-stop elements 30 are arranged between the input end and the output end; at the same time, in this embodiment, five first band-stop elements 30 can be arranged between the input end and the output end but are not limited to; in this way, by adopting this structural design, the broadband terahertz waveguide bandpass filter can have at least two out-of-band transmission zero points; of course, the number and width of the aforementioned first band-stop elements 30 can be specifically set according to actual use, and are not limited to the aforementioned examples.

[0043] In addition, this embodiment also provides a simulation schematic diagram of the bandpass filter of this embodiment and a simulation schematic diagram of a traditional filter; see Figure 4 and Figure 5 As shown, Figure 4and Figure 5 A comparison of the S parameters (scattering parameters) of the simulation results of the filter provided in this embodiment and the traditional waveguide Chebyshev bandpass filter is given (the sizes are roughly equal), and the center frequency is 190GHz; the simulation results show that, when the sizes are the same, the bandwidth of the filter structure of this embodiment is greater than that of the traditional waveguide Chebyshev bandpass filter, and the out-of-band suppression of the filter structure of this embodiment is much greater than that of the traditional waveguide Chebyshev bandpass filter. At 230GHz, S21 reaches -90dB (S21 is the insertion loss, S11 is the return loss), while the traditional waveguide Chebyshev bandpass filter is only -15dB, which is a huge gap.

[0044] At the same time, from Figure 4 It can be seen from the simulation results that, since the present embodiment adopts band-stop element branches to construct a new filter structure, the filter of the present embodiment has two transmission zeros out of the band, which are respectively around 215 GHz and 230 GHz. This is also the reason why the out-of-band suppression is much greater than that of the traditional waveguide Chebyshev bandpass filter. Based on this, it can be proved by the above-mentioned simulation data that the bandpass filter of the present embodiment has the advantages of out-of-band transmission zero, high out-of-band suppression and high broadband.

[0045] In summary, the utility model has the following advantages:

[0046] (1) In order to solve the problem of narrow bandwidth of ordinary waveguide bandpass filters, the bandwidth of the filter provided by the present invention can be flexibly adjusted by adjusting the wide side of the middle rectangular waveguide, and the bandwidth of this structure is wider under the same size.

[0047] (2) In order to solve the problem that ordinary waveguide bandpass filters have no transmission zero point and low out-of-band suppression, the filter structure provided by the utility model has a transmission zero point in the high frequency band and high out-of-band suppression. Moreover, under the same size, the out-of-band suppression of this structure is higher.

[0048] (3) Ordinary waveguide filters need to increase the order, that is, the number of resonant cavities, to improve out-of-band suppression. The out-of-band suppression of the filter provided by the present invention can also be directly improved by adding band-stop elements, and the suppression degree is much greater than that of ordinary waveguide filters. At the same time, the size of the band-stop element is much smaller than that of the resonator; therefore, the overall volume is also much smaller than that of traditional filters.

[0049] (4) The filter structure provided by the present invention has better performance than ordinary waveguide bandpass filters, and the processing method is also the same, and both can be processed by computer digital controlled precision machinery (CNC). In this way, it still has the advantages of high Q value, low loss and large power capacity. Based on this, it still has advantages in terms of volume, weight, processing, cost and performance.

[0050] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A broadband terahertz waveguide bandpass filter with high out-of-band suppression, characterized in that: include: An input waveguide (10), an output waveguide (20) and a plurality of first band-stop elements (30); The input waveguide (10) serves as an input end of the broadband terahertz waveguide bandpass filter, and the output waveguide (20) serves as an output end of the broadband terahertz waveguide bandpass filter, wherein the width of any first bandstop element (30) among a plurality of first bandstop elements (30) is smaller than the widths of the input waveguide (10) and the output waveguide (20), and the plurality of first bandstop elements (30) are sequentially arranged between the input end and the output end to form a high-frequency stopband of the broadband terahertz waveguide bandpass filter.

2. A broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 1, characterized in that: The height of a first target band-stop element among the plurality of first band-stop elements (30) is smaller than the height of a second target band-stop element, wherein the first target band-stop element is a first band-stop element (30) among the plurality of first band-stop elements (30) close to the input end and the output end, and the second target band-stop element is a first band-stop element (30) among the plurality of first band-stop elements (30) excluding the first target band-stop element.

3. A broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 2, characterized in that: The first band-resistance elements (30) close to the input end and the output end among the plurality of first band-resistance elements (30) have the same height.

4. A broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 1, characterized in that: The input waveguide (10) and the output waveguide (20) have the same size.

5. The broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 1, characterized in that: The input waveguide (10) and the output waveguide (20) both have a rectangular parallelepiped structure.

6. A broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 4, characterized in that: The input waveguide (10) and the output waveguide (20) both use a second band-stop element for impedance matching.

7. A broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 1, characterized in that: The cross section or longitudinal section of any first band-stop element (30) is a rectangular section.

8. The broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 1, characterized in that: At least three first band-stop elements (30) are arranged between the input end and the output end.

9. The broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 7, characterized in that: Five first band-stop elements (30) are arranged between the input end and the output end.

10. The broadband terahertz waveguide bandpass filter with high out-of-band suppression according to claim 1, characterized in that: The broadband terahertz waveguide bandpass filter has at least two out-of-band transmission zero points.

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