Miniaturized wide-stopband cavity bandpass filter for satellite communication and manufacturing method thereof

Abstract

The application discloses a miniaturized wide-stop-band cavity band-pass filter for satellite communication and a manufacturing method thereof, and particularly relates to the technical field of communication. The application creatively proposes a miniaturized cavity band-pass filter with wide-stop-band characteristics in view of the problems of large size and serious harmonic dispersion of a traditional metal waveguide filter; the technical scheme is as follows: a rectangular groove is etched on the center area of the upper surface of the metal ridge of a ridge waveguide resonator, and a tuning column is embedded in the groove; this design not only realizes effective downshift of the fundamental mode resonance frequency, but also widens the range of high-frequency non-dispersive frequency, so that the overall filter has smaller cross-sectional size and wider upper stop band; a half-wavelength metal resonant groove is constructed between two ridge waveguide resonators, and together with the original resonator, a three-order filter is formed, which effectively reduces the longitudinal size, introduces cross coupling, and produces a significant transmission zero point effect in the upper stop band area.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a miniaturized wide-stopband cavity bandpass filter for satellite communication and a manufacturing method thereof. Background Art

[0002] With the continuous advancement of satellite communication technology, the performance requirements for satellite communication systems are becoming increasingly stringent. This trend has greatly promoted extensive research in the field of bandpass filters (BPFs). Research focuses on achieving filter miniaturization, reducing insertion loss (IL), and widening the upper stopband rejection range. Metal waveguide (WG) resonators have been the subject of extensive research due to their high power handling and low loss. However, their large size makes it difficult to meet the miniaturization requirements of modern communication systems. To reduce size, dielectric resonators (DRs) and dielectric waveguides are widely used in filter design. However, filters using these technologies face severe harmonic spurious issues, resulting in insufficient upper stopband rejection width, which in turn limits their application in multi-standard wireless communication systems. Compared to WG resonators of the same size, ridge waveguide resonators have lower fundamental mode resonant frequency and wider single-mode operating bandwidth, which are crucial for achieving filter miniaturization and widening the upper stopband rejection range. Despite this, the current bandpass filters based on ridge waveguide resonators still have considerable potential and space for improvement in terms of further miniaturization and widening of the upper stopband. Summary of the Invention

[0003] The present invention solves the problem in the prior art of severe harmonic spurs, which leads to insufficient upper stopband suppression. The present invention provides a miniaturized wide-stopband cavity bandpass filter for satellite communications and a manufacturing method. A rectangular groove is deeply etched in the central area of ​​the upper surface of the metal ridge of the ridge waveguide resonator, and a tuning column is embedded in the groove. This design shifts the fundamental mode resonant frequency of the ridge waveguide resonator from 3.2 GHz to 2.1 GHz, achieving an effective downward shift of the fundamental mode resonant frequency and widening the range of high-frequency spurious-free frequencies from 3.8 times the center frequency to 4.8 times the center frequency. This means that the constructed filter has a smaller cross-sectional size and a wider upper stopband. An ultra-thin half-wavelength metal resonant slot is constructed between two ridge waveguide resonators, and a resonant unit is constructed using the half-wavelength metal resonant slot, which successfully reduces the distance between the ridge waveguide resonators. While reducing the longitudinal length of the constructed filter, cross-coupling is introduced, thereby producing a significant zero-point effect in the upper stopband region, greatly improving the suppression level of the upper stopband and achieving a stopband suppression of >40dB in the 2.72-10.38GHz frequency band.

[0004] The present invention provides a miniaturized wide-stopband cavity bandpass filter for satellite communications, comprising a rectangular cavity, a probe, a ridge waveguide resonator, a tuning column, and a half-wavelength resonant slot; the SMA probe is connected to the metal ridge for signal input and output;

[0005] Furthermore, the ridge waveguide resonator has a rectangular groove extending downward from the center area of ​​the upper surface, and the lower bottom surface of the rectangular groove does not reach the bottom of the ridge waveguide resonator; the tuning post extends downward from the upper surface of the filter cavity, and the lower bottom surface of the tuning post does not reach the lower bottom surface of the rectangular groove in the ridge waveguide resonator. The ridge waveguide resonator and the tuning post together constitute the first basic resonant unit of the filter;

[0006] Furthermore, a half-wavelength metal resonant slot is placed between two ridge waveguides embedded in tuning columns, and its slot length is half of the operating wavelength of the filter, constituting the second basic resonant unit of the filter.

[0007] Furthermore, the entire filter is made of metal aluminum.

[0008] The present invention also provides a method for manufacturing the miniaturized wide-stopband cavity bandpass filter for satellite communication, comprising the following steps:

[0009] S1: Determine the size of the ridge waveguide resonator, tuning column and half-wavelength resonant slot, and determine the size of the ridge waveguide resonator, tuning column and half-wavelength resonant slot according to the center frequency of the target operating frequency band, so that the ridge waveguide resonator can work at TE within the target frequency band. 10 model;

[0010] S2: A third-order filter passband with a ripple factor of 0.03dB, a center frequency of 2.2GHz, and a relative bandwidth of 19% is set. Fitting is performed using a Chebyshev low-pass prototype filter circuit, and the theoretically required coupling coefficient and quality factor are calculated using relevant formulas. The quality factor and the coupling coefficient between adjacent resonant cavities are extracted using electromagnetic simulation software.

[0011] S3: Optimize parameters to achieve the design and fabrication of a miniaturized wide-stopband cavity bandpass filter with good performance.

[0012] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0013] 1. The present invention provides a miniaturized wide-stopband cavity bandpass filter for satellite communications, which utilizes a half-wavelength metal resonant slot and a ridge waveguide resonator with a tuning column to achieve the design of a miniaturized wide-stopband cavity bandpass filter. Compared with bandpass filters using metal waveguides and traditional ridge waveguides, the present design introduces tuning columns and half-wavelength metal resonant slots, resulting in a smaller size and a wider upper stopband. Due to the poor spurious characteristics brought by the dielectric, the present design has a wider upper stopband compared to bandpass filters designed using dielectric waveguides and dielectric resonators.

[0014] 2. The present invention provides a miniaturized wide-stopband cavity bandpass filter for satellite communications. The ridge waveguide bandpass filter of the present invention has an insertion loss of less than 0.45dB in the operating frequency band, a bandwidth of 19%, a return loss of less than -17dB, and achieves a 2.72-10.38GHz stopband suppression of >40dB and spurious-free suppression of 4.8 times the center frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0016] Figure 1 The overall structure of the present invention is shown in FIG. Figure 1 ;

[0017] Figure 2 Schematic diagram of the internal structure of the present invention Figure 1 ;

[0018] Figure 3 Schematic diagram of the internal structure of the present invention Figure 2 ;

[0019] Figure 4 A top view of the present invention;

[0020] Figure 5 For the present invention Figure 1 A sectional view of the part;

[0021] Figure 6 For the present invention Figure 1 Cross-sectional view at point B;

[0022] Figure 7 The present invention Figure 1 Cross-sectional view at point C;

[0023] Figure 8 It is the simulation result diagram of the present invention;

[0024] Figure 9 The parameters of the fixed ridge waveguide resonator of the present invention are a=25.2mm, b=12.6mm, a r =10mm,b r =11.8mm, the fundamental mode resonant frequency f0 and the tuning column extension length h c relationship diagram;

[0025] Figure 10 The parameters of the fixed ridge waveguide resonator of the present invention are a=25.2mm, b=12.6mm, a r =10mm,b r =11.8mm, the ratio n of the first high-order mode resonant frequency to the fundamental mode resonant frequency and the tuning column insertion length h c relationship diagram;

[0026] Figure 11 The external quality factor Q is extracted when the probe is inserted at different lengths l1. e With SMA probe position b p relationship diagram;

[0027] Figure 12 When the length l1 of the fixed probe of the present invention is 2.5 mm, the distance l4 between the ridge waveguide resonator and the half-wavelength resonant slot and the coupling coefficient K between the first resonator and the second resonator are 12 and the coupling coefficient K between the first resonator and the third resonator 13 relationship diagram;

[0028] Description of reference numerals:

[0029] 1. Rectangular cavity; 2. Ridge waveguide resonator; 201. Rectangular groove; 3. Tuning column; 4. Metal baffle; 5. Probe. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] Example 1:

[0032] This embodiment incorporates a ridge waveguide resonator 2, a tuning post 3, and a half-wavelength resonant slot on a metal baffle 4 within a rectangular cavity 1 measuring 32.8 mm long, 25.2 mm wide, and 12.6 mm high. A rectangular groove 201 extends downward from the top surface of the ridge waveguide resonator 2, with its lower bottom surface not reaching the bottom of the ridge waveguide resonator 2. Rectangular groove 201 is 6 mm long, 3 mm wide, and 8.3 mm high. The tuning post 3 extends downward from the top surface of the filter cavity, with its lower bottom surface not reaching the bottom of the rectangular groove 201. The tuning post 3 is 5 mm long, 2 mm wide, and 7.5 mm high. Together, the ridge waveguide resonator 2 and the tuning post 3 constitute one of the basic resonant units of the filter. A half-wavelength metal resonant slot, with a slot length of half the filter's operating wavelength, is placed between the two ridge waveguide resonators 2 embedded within the tuning post 3, forming another basic resonant unit of the filter. This embodiment sets a third-order filter passband with a ripple coefficient of 0.03dB, a center frequency of 2.2GHz, and a relative bandwidth of 19%. It can be fitted by the Chebyshev low-pass prototype filter circuit, and the theoretically required coupling coefficient and quality factor are calculated with the help of relevant formulas. The quality factor and the coupling coefficient between adjacent resonant cavities are extracted through electromagnetic simulation software, and the Q value in the simulation results is calculated. e The relationship between the probe length and height, and the relationship between the coupling coefficient and the distance between the ridge and the half-wavelength resonant slot, the distance between the probe 5 and the lower surface of the rectangular cavity 1 is set to 7 mm, the distance between the ridge waveguide resonator 2 and the side wall of the rectangular cavity 1 is set to 2.5 mm, and the distance between the ridge waveguide resonator 2 and the half-wavelength resonant slot is set to 7.1 mm.

[0033] like Figure 3 As shown, this design has two ports, namely probes 5 at both ends. Signals are input from port 1 and output from port 2. The operating frequency band of this embodiment is 2.04GHz-2.48GHz. The ridge waveguide works as a resonator in the fundamental mode TE 101 In the first harmonic TE mode, the electric field is mainly concentrated in the central area above the ridge. 102 mode, the electric field is mainly concentrated in the longitudinal region above the ridge. Therefore, the tuning column 3 can be embedded in the central region of the ridge to achieve TE 101 The resonant frequency of the mode decreases while the TE 102 It is worth noting that when the depth of the tuning column 3 reaches a threshold, the coaxial mode of the tuning column 3 will replace the TE mode. 102 mode becomes the first harmonic, but due to the fundamental mode TE 101The resonant frequency of the mode still decreases as the depth of the tuning column 3 increases. Therefore, in this case, while lowering the resonant frequency of the fundamental mode of the resonator, the upper stopband range can still be widened. After determining the dimensions of the ridge waveguide resonator 2 and the embedded tuning column 3 based on the center frequency, we constructed a half-wavelength metal resonant slot between the two ridge waveguide resonators 2. Its length is determined by the center frequency, and a resonant unit is constructed using the half-wavelength metal resonant slot. Due to the introduction of the half-wavelength metal resonant slot, a three-pole bandpass filter can be constructed with only two ridge waveguide resonators 2. This compact structure means that cross-coupling between the ridge waveguide resonators 2 is allowed, thereby generating a transmission zero in the upper stopband.

[0034] The simulation results of the miniaturized wide stopband cavity bandpass filter design studied in this case study are shown in Figure 8 , the center frequency is f0 = 2.2GHz, the frequency range is 2.04GHz-2.48GHz, where |S 11 |Less than -17dB, insertion loss less than 0.45dB.

[0035] Example 2:

[0036] This embodiment provides a method for manufacturing the miniaturized wide-stopband cavity bandpass filter for satellite communication, comprising the following steps:

[0037] Step 1: The first step is to determine the size of the ridge waveguide resonator 2, tuning column 3, and half-wavelength metal resonant tank. The size of the ridge waveguide resonator 2, tuning column 3, and half-wavelength metal resonant tank is determined by the center frequency of the target operating frequency band. For one parameter, a = 25.2 mm, b = 12.6 mm, a r =10mm,b r =11.8mm ridge waveguide resonator, please refer to Figure 9 The fundamental mode resonant frequency f0 of the ridge waveguide resonator and the extension length h of the tuning column are given. c The relationship between f0 and h c The size of the tuning column 3 is determined by the increase of h, and the ratio n of the first high-order mode resonant frequency to the fundamental mode resonant frequency increases with h. c After determining the size of the tuning column 3, you can refer to Figure 10 The ratio n of the first higher-order mode resonant frequency to the fundamental mode resonant frequency is obtained. The size of the half-wavelength metal resonant tank can be calculated based on the center frequency of the required passband.

[0038] Step 2: The present invention sets a third-order filter passband with a ripple coefficient of 0.03dB, a center frequency of 2.2GHz, and a relative bandwidth of 19%. It can be fitted by the Chebyshev low-pass prototype filter circuit, and the theoretically required coupling coefficient and quality factor are calculated with the help of relevant formulas. The quality factor and the coupling coefficient between adjacent resonant cavities are extracted by electromagnetic simulation software, such as Figure 11 , Figure 12 Give Q respectively e and the relationship between the length and height of the probe 5, and the relationship between the coupling coefficient and the distance between the ridge and the half-wave metal long resonant slot; Figure 11 Know Q e Follow b p Increases or l1 decreases and increases. Figure 12 It can be seen that as l4 decreases, K 12 and K 13 Increase.

[0039] Step 3. The third step is to optimize the relevant parameters to achieve the design of a miniaturized wide-stopband cavity bandpass filter with good performance. The specific parameters are shown in Table 1 below.

[0040] Table 1: Filter parameter table

[0041]

[0042] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A miniaturized wide-stopband cavity bandpass filter for satellite communications, characterized by: The invention comprises a shell, wherein a rectangular cavity (1) is arranged in the shell, ridge waveguide resonators (2) are arranged in the two side areas inside the rectangular cavity (1), a metal baffle (4) is arranged in the middle area, and a half-wavelength resonant groove is opened on the metal baffle (4); probes (5) are arranged at both ends of the rectangular cavity (1), and the probes (5) are connected to the ridge waveguide resonators (2).

2. The miniaturized wide-stopband cavity bandpass filter for satellite communications according to claim 1, characterized in that: A rectangular groove (201) is provided on the upper surface of the ridge waveguide resonator (2).

3. The miniaturized wide-stopband cavity bandpass filter for satellite communications according to claim 2, characterized in that: The lower bottom surface of the rectangular groove (201) does not reach the bottom of the ridge waveguide resonator (2).

4. The miniaturized wide-stopband cavity bandpass filter for satellite communications according to claim 3, characterized in that: A tuning column (3) is provided in the rectangular groove (201), and the tuning column (3) extends downward from the upper side wall of the rectangular cavity (1) into the rectangular groove (201).

5. The miniaturized wide-stopband cavity bandpass filter for satellite communications according to claim 4, characterized in that: The lower bottom surface of the tuning column (3) does not reach the lower bottom surface of the rectangular groove (201).

6. The miniaturized wide-stopband cavity bandpass filter for satellite communications according to claim 5, characterized in that: The ridge waveguide resonator (2) and the tuning column (3) constitute a first basic resonance unit.

7. The miniaturized wide-stopband cavity bandpass filter for satellite communications according to claim 6, characterized in that: The slot length of the half-wavelength resonance slot on the metal baffle (4) is half of the operating wavelength of the filter, forming a second basic resonance unit.

8. The miniaturized wide-stopband cavity bandpass filter for satellite communications according to claim 7, characterized in that: The filter is made entirely of aluminum.

9. The method for manufacturing a miniaturized wide-stopband cavity bandpass filter for satellite communications according to any one of claims 1 to 8, characterized in that: The steps include: S1: Determine the size of the ridge waveguide resonator (2), the tuning column (3) and the half-wavelength resonant slot, and determine the size of the ridge waveguide resonator (2), the tuning column (3) and the half-wavelength resonant slot according to the center frequency of the target operating frequency band, so that the ridge waveguide resonator (2) works at TE within the target frequency band. 10 model; S2: A third-order filter passband with a ripple factor of 0.03dB, a center frequency of 2.2GHz, and a relative bandwidth of 19% is set. Fitting is performed using a Chebyshev low-pass prototype filter circuit, and the theoretically required coupling coefficient and quality factor are calculated using formulas. The quality factor and the coupling coefficient between adjacent resonant cavities are extracted using electromagnetic simulation software. S3: Optimize parameters to achieve the design and fabrication of a miniaturized wide-stopband cavity bandpass filter with good performance.

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