Folding type broadband five-frequency-band band-pass filter

Abstract

The invention discloses a folding type broadband five-frequency-band band-pass filter which comprises two input and output microstrip feeder lines, two three-step impedance resonators, two step impedance resonators and two uniform impedance branch lines. One stepped impedance resonator is horizontally placed, and the other stepped impedance resonator is vertically placed and located below the center of the horizontally placed stepped impedance resonator; the two ends of the horizontally placed stepped impedance resonator are respectively connected with an input / output microstrip feeder line, and the two sides of the vertically placed stepped impedance resonator are respectively loaded with a uniform impedance stub line; the two three-step impedance resonators are respectively positioned below the input and output microstrip feeder lines; and the three-step impedance resonator adopts a folded structure. According to the invention, the stepped impedance resonators are adopted to load the uniform impedance branch lines, and the folded three-stepped impedance resonators are adopted, so that the structure of the band-pass filter is simplified, the size of the band-pass filter is reduced, and meanwhile, the wider passband bandwidth is realized.

Description

Technical Field

[0001] The present application relates to the field of microwave communication technology, and in particular to a folded broadband five-band bandpass filter. Background Art

[0002] With the rapid development of wireless communication technologies such as 5G, standard communication systems such as LTE, WLAN, and WiMAX are also developing rapidly. The increasing shortage of spectrum resources has made the research of multi-band bandpass filters a hot topic. As one of the indispensable key components of multi-frequency transceiver systems, multi-band bandpass filters can effectively filter out useless noise signals and reduce interference between communication frequency bands, thereby achieving high-quality communication. At present, wireless communication equipment is gradually developing in the direction of miniaturization, multi-function and low cost. Therefore, the research on miniaturized multi-band bandpass filters has important practical significance and broad application prospects.

[0003] In the prior art, Chinese patent CN113097671A discloses a miniaturized broadband five-band bandpass filter, including an upper microstrip structure, an intermediate dielectric substrate and a lower grounded metal plate, wherein the upper microstrip structure is attached to the upper surface of the intermediate dielectric substrate, and the lower grounded metal plate is attached to the lower surface of the intermediate dielectric substrate. The upper microstrip structure is a five-band bandpass filter, and the five-band bandpass filter includes an input feeder and an output feeder at both ends, a square structure is arranged between the input feeder and the output feeder, a regular octagonal structure is arranged inside the square structure, and two groups of gradient stepped impedance resonators are symmetrically arranged inside the regular octagonal structure along the diagonal of the square structure as the center line.

[0004] The filter structure of the above-mentioned prior art is relatively complex, so the size is still relatively large; in addition, the passband bandwidth of the above-mentioned prior art is relatively narrow. Summary of the invention

[0005] The present application provides a folded broadband five-band bandpass filter to solve the problems of complex filter structure, large size and narrow passband bandwidth in the prior art.

[0006] On the one hand, the present application provides a folded broadband five-band bandpass filter, including: two input and output microstrip feed lines, two three-step impedance resonators, two step impedance resonators and two uniform impedance branch lines.

[0007] One of the stepped impedance resonators is placed horizontally, and the other stepped impedance resonator is placed vertically and is located below the center of the horizontally placed stepped impedance resonator.

[0008] Two ends of the horizontally placed stepped impedance resonator are respectively connected to one of the input and output microstrip feed lines, and two sides of the vertically placed stepped impedance resonator are respectively loaded with one of the uniform impedance branch lines.

[0009] The two three-step impedance resonators are respectively located below one of the input and output microstrip feed lines and connected to the input and output microstrip feed lines.

[0010] The three-step impedance resonator adopts a folded structure.

[0011] In a possible implementation, the two input and output microstrip feed lines, the two three-step impedance resonators, the two step impedance resonators and the two uniform impedance branch lines are all printed on the surface of a dielectric substrate.

[0012] The two input and output microstrip feed lines, the two three-step impedance resonators and the two uniform impedance branch lines are all symmetrical about the vertically placed step impedance resonator.

[0013] In a possible implementation manner, the input and output microstrip feed lines are placed horizontally, and a side of the input and output microstrip feed lines away from the stepped impedance resonator is connected to an SMA connector.

[0014] In a possible implementation, the three-step impedance resonator is composed of three uniform impedances with different widths.

[0015] In a possible implementation manner, the two uniform impedance branch lines are both parallel to the vertically placed stepped impedance resonator.

[0016] In a possible implementation manner, the two uniform impedance branch lines are respectively located between a horizontally placed stepped impedance resonator and one of the input and output microstrip feed lines.

[0017] In a possible implementation manner, the impedance of the two input and output microstrip feed lines is 50Ω.

[0018] A folded broadband five-band bandpass filter in the present application has the following advantages:

[0019] By using a stepped impedance resonator to load a uniform impedance branch line and a folded three-step impedance resonator, the bandpass filter structure is simplified and the size is reduced, thereby reducing the manufacturing cost; at the same time, the overall structure of a folded broadband five-band bandpass filter in the present application also achieves a wider passband bandwidth, and the relative percentage bandwidths corresponding to the five passbands are all greater than 13%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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 or the description of the prior art 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.

[0021] Figure 1 A schematic diagram of the structure of a folded broadband five-band bandpass filter provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of the structure of a filter provided in an embodiment of the present application that is not loaded with a uniform impedance branch line;

[0023] Figure 3 A frequency response curve corresponding to a filter provided in an embodiment of the present application that is not loaded with a uniform impedance branch line;

[0024] Figure 4 A frequency response curve corresponding to a folded broadband five-band bandpass filter provided in an embodiment of the present application;

[0025] Figure 5 A schematic diagram of the physical dimensions of a folded broadband five-band bandpass filter provided in an embodiment of the present application.

[0026] Description of reference numerals:

[0027] 100-input and output microstrip feed lines, 200-three-step impedance resonator, 300-step impedance resonator, 400-uniform impedance branch line. 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] like Figure 1 As shown, an embodiment of the present application provides a folded broadband five-band bandpass filter, including: two input and output microstrip feed lines 100, two three-step impedance resonators 200, two step impedance resonators 300 and two uniform impedance branch lines 400.

[0030] One of the stepped impedance resonators 300 is placed horizontally, and the other stepped impedance resonator 300 is placed vertically and is located below the center of the horizontally placed stepped impedance resonator 300 .

[0031] Two ends of the horizontally placed stepped impedance resonator 300 are respectively connected to one of the input and output microstrip feed lines 100 , and two sides of the vertically placed stepped impedance resonator 300 are respectively loaded with one of the uniform impedance branch lines 400 .

[0032] The two three-step impedance resonators 200 are respectively located under one of the input / output microstrip feed lines 100 and connected to the input / output microstrip feed line 100 .

[0033] The three-step impedance resonator 200 adopts a folded structure.

[0034] Exemplarily, the two input and output microstrip feed lines 100 , the two three-step impedance resonators 200 , the two step impedance resonators 300 , and the two uniform impedance branch lines 400 are all printed on the surface of a dielectric substrate.

[0035] The two input and output microstrip feed lines 100 , the two three-step impedance resonators 200 , and the two uniform impedance branch lines 400 are all symmetrical about the vertically placed step impedance resonator 300 .

[0036] Specifically, in this embodiment, the dielectric substrate adopts Rogers RT / duroid5880 model, with a thickness of 0.79 mm, a relative dielectric constant of 2.2, and a loss tangent value of 0.0018.

[0037] Exemplarily, the input / output microstrip feed line 100 is placed horizontally, and a side of the input / output microstrip feed line 100 away from the stepped impedance resonator 300 is connected with an SMA connector.

[0038] Exemplarily, the three-step impedance resonator 200 is composed of three uniform impedances of different widths.

[0039] Exemplarily, the two uniform impedance branch lines 400 are parallel to the vertically placed stepped impedance resonator 300 .

[0040] Exemplarily, the two uniform impedance branch lines 400 are respectively located between a horizontally placed stepped impedance resonator 300 and one of the input and output microstrip feed lines 100 .

[0041] Exemplarily, the impedance of the two input and output microstrip feed lines 100 is 50Ω.

[0042] like Figure 2 FIG. 4 is a schematic diagram of the structure of a filter without a uniform impedance branch line 400. Figure 1 compared to, Figure 2The filter structure in FIG. 1 removes the uniform impedance branch lines 400 on both sides of the vertically placed stepped impedance resonator 300, and the other structures and physical dimensions are the same as those in FIG. Figure 1 same.

[0043] like Figure 3 FIG. 4 is a frequency response curve corresponding to a filter without loading the uniform impedance branch line 400. Figure 3 and Figure 2 Corresponding. Figure 3 It can be seen that when the uniform impedance branch line 400 is not loaded, the performance at the fifth passband is poor and the attenuation is small. Therefore, the uniform impedance branch line 400 has a greater impact on the fifth passband of the five-band bandpass filter, and it is necessary to load the uniform impedance branch line 400.

[0044] like Figure 4 The figure shows the frequency response curve of a folded broadband five-band bandpass filter. Figure 4 and Figure 1 correspond. Figure 4 In, S 11 The curve represents the return loss, S 21 The curve represents the insertion loss, given by Figure 4 S 11 From the curve, we can see that the ranges of the five passbands are 0.21-0.62GHz, 1.08-2.05GHz, 2.64-3.56GHz, 4.19-4.98GHz, 5.74-6.58GHz, and the corresponding center frequencies are 0.38GHz, 1.73GHz, 3.39GHz, 4.61GHz, and 6.34GHz, respectively; the relative percentage bandwidths of the five passbands are 107.9%, 56%, 27.1%, 17.1%, and 13.2%, respectively, showing a wide bandwidth, especially the first passband bandwidth is as high as 107.9%. Figure 4 It can also be seen that the frequency response curve corresponding to a folded broadband five-band bandpass filter produces a total of 9 transmission poles, ( Figure 4 TP1 to TP9 are transmission poles) are 0.38GHz, 0.54GHz, 1.22GHz, 1.73GHz, 2.71GHz, 2.96GHz, 3.39GHz, 4.61GHz, and 6.34GHz, which effectively improves the performance of the bandpass filter and makes the filtering performance between each passband even better.

[0045] like Figure 5 The figure shows the physical dimensions of a folded broadband five-band bandpass filter. Figure 5 and Figure 1 correspond. Figure 5The physical dimensions are as follows: L1 = 21.87, L2 = 21.33, L3 = 21.56, L4 = 20.39, L5 = 20.55, L6 = 3.7, L7 = 16, L8 = 16, L9 = 15.34, W1 = 1.68, W2 = 0.5, W3 = 1.26, W4 = 0.84, W5 = 1.34, W6 = 1, W7 = 1.8, W8 = 1.8, W9 = 2.32, W 10 =2.38, and the unit of each physical dimension is millimeter. Figure 5 The radius of the middle via is 0.25mm. The final design size of the filter is 0.15λ g ×0.09λ g , where λ g is the waveguide wavelength corresponding to the center frequency of the first passband. Figure 5 It can be seen that the folded broadband five-band bandpass filter of the present application exhibits an extremely small circuit design size.

[0046] The embodiment of the present application uses a stepped impedance resonator 300 to load a uniform impedance branch line 400, and uses a folded three-step impedance resonator 200 to simplify the bandpass filter structure and reduce the size, thereby reducing the manufacturing cost; at the same time, a wider passband bandwidth is also achieved through the overall structure of a folded broadband five-band bandpass filter in the present application, and the relative percentage bandwidths corresponding to the five passbands are all greater than 13%.

[0047] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0048] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A folded broadband five-band bandpass filter, characterized in that: include: Two input and output microstrip feed lines, two three-step impedance resonators, two step impedance resonators and two uniform impedance branch lines; One of the stepped impedance resonators is placed horizontally, and the other stepped impedance resonator is placed vertically and is located below the center of the horizontally placed stepped impedance resonator; Two ends of the horizontally placed stepped impedance resonator are respectively connected to one of the input and output microstrip feed lines, and two sides of the vertically placed stepped impedance resonator are respectively loaded with one of the uniform impedance branch lines; The two three-step impedance resonators are respectively located below one of the input and output microstrip feed lines and connected to the input and output microstrip feed lines; The three-step impedance resonator adopts a folded structure.

2. A folded broadband five-band bandpass filter according to claim 1, characterized in that: The two input and output microstrip feed lines, the two three-step impedance resonators, the two step impedance resonators and the two uniform impedance branch lines are all printed on the surface of the dielectric substrate; The two input and output microstrip feed lines, the two three-step impedance resonators and the two uniform impedance branch lines are all symmetrical about the vertically placed step impedance resonator.

3. A folded broadband five-band bandpass filter according to claim 1, characterized in that: The input and output microstrip feed lines are placed horizontally, and a side of the input and output microstrip feed lines away from the stepped impedance resonator is connected with an SMA connector.

4. A folded broadband five-band bandpass filter according to claim 1, characterized in that: The three-step impedance resonator is composed of three uniform impedances of different widths.

5. A folded broadband five-band bandpass filter according to claim 1, characterized in that: The two uniform impedance branch lines are both parallel to the vertically placed stepped impedance resonator.

6. A folded broadband five-band bandpass filter according to claim 1, characterized in that: The two uniform impedance branch lines are respectively located between a horizontally placed stepped impedance resonator and one of the input and output microstrip feed lines.

7. A folded broadband five-band bandpass filter according to claim 1, characterized in that: The impedance of the two input and output microstrip feed lines is 50Ω.

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