Miniaturized wide-stop-band cavity band-pass filter for satellite communication and manufacturing method thereof

Abstract

The invention discloses a miniaturized wide-stop-band cavity band-pass filter for satellite communication and a manufacturing method, and particularly relates to the technical field of communication. The invention innovatively provides a miniaturized cavity band-pass filter with a wide stop-band characteristic aiming at the problems of huge size and serious harmonic stray of a traditional metal waveguide filter. According to the technical scheme, a rectangular groove is etched in the center area of the upper surface of a metal ridge of the ridge waveguide resonator, and a tuning column is embedded in the groove, so that effective downward movement of the fundamental mode resonant frequency is realized, the range of high-frequency spurious-free frequency is widened, and the resonant efficiency of the antenna is improved. Therefore, the whole filter has a smaller cross section size and a wider upper stop band; a half-wavelength metal resonant tank is constructed between two ridge waveguide resonators, and the half-wavelength metal resonant tank and an original resonator form a third-order filter, so that the longitudinal size is effectively reduced, cross coupling is introduced, and a remarkable transmission zero effect is generated in an 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, people have increasingly stringent requirements on the performance of satellite communication systems. This trend has greatly promoted extensive research in the field of bandpass filters (BPFs). The research focuses on achieving miniaturized design of filters, reducing insertion loss (IL), and widening the suppression range of the upper stopband. Metal waveguide (WG) resonators have been widely studied due to their high power capacity and low loss, but their large size makes it difficult to meet the miniaturization requirements of modern communication systems. In order to reduce the size, technologies such as dielectric resonators (DRs) and dielectric waveguides are widely used in the design of filters. However, filters using the above technologies face serious problems of harmonic spurious, which leads to insufficient suppression width of their upper stopband, thus limiting their application in multi-standard wireless communication systems. Compared with metal waveguide resonators of the same size, ridge waveguide resonators have lower fundamental mode resonance frequency and wider single-mode operating bandwidth, which is crucial for achieving miniaturized design of filters and widening the suppression range of the upper stopband. 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 that harmonic spurious waves are serious and result in insufficient suppression of the upper stopband; the present invention provides a miniaturized wide stopband cavity bandpass filter for satellite communications and a manufacturing method, deeply etches a rectangular groove in the central area of ​​the upper surface of the metal ridge of the ridge waveguide resonator, and embeds a tuning column in the groove. This design enables the fundamental mode resonance frequency of the ridge waveguide resonator to shift down from 3.2 GHz to 2.1 GHz, thereby achieving an effective downward shift of the fundamental mode resonance 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, which 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 communication, 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 a metal ridge for signal input and output;

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

[0006] Furthermore, a half-wavelength metal resonant slot is placed in the middle of two ridge waveguides embedded in tuning posts, and its slot length is half of the working wavelength of the filter, forming a 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 works in the target frequency band at TE 10 model;

[0010] S2: Set a third-order filter passband with a ripple factor of 0.03dB, a center frequency of 2.2GHz, and a relative bandwidth of 19%, fit it through the Chebyshev low-pass prototype filter circuit, and calculate the theoretically required coupling coefficient and quality factor with the help of relevant formulas; extract the quality factor and the coupling coefficient between adjacent resonant cavities through 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 communication, which realizes the design of a miniaturized wide stopband cavity bandpass filter by utilizing a half-wavelength metal resonant slot and a ridge waveguide resonator with a tuning column. Compared with the bandpass filter utilizing metal waveguide and traditional ridge waveguide, the present design introduces tuning columns and half-wavelength metal resonant slots to have a smaller size and a wider upper stopband. Due to the poor stray characteristics brought by the dielectric, the present design has a wider upper stopband compared with the bandpass filter designed using dielectric waveguide and dielectric resonator.

[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 2.72-10.38GHz stopband suppression >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 drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded 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 The internal structure of the present invention is shown in FIG. Figure 1 ;

[0018] Figure 3 The internal structure of the present invention is shown in FIG. 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

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

[0022] Figure 7 The present invention has Figure 1 Sectional view at point C;

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

[0024] Fig. 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] Fig.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 of the first high-order mode resonant frequency to the fundamental mode resonant frequency n and the tuning column extension length h c Relationship diagram;

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

[0027] Fig.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] Embodiment 1:

[0032] In this embodiment, a ridge waveguide resonator 2, a tuning column 3 and a half-wavelength resonant groove on a metal baffle 4 are loaded in a rectangular cavity 1 with a length of 32.8 mm, a width of 25.2 mm and a height of 12.6 mm. A rectangular groove 201 extending downward from the upper surface is present at the center of the ridge waveguide resonator 2. The lower bottom surface of the rectangular groove 201 does not reach the bottom of the ridge waveguide resonator 2. The rectangular groove 201 is 6 mm long, 3 mm wide and 8.3 mm high. The tuning column 3 extends downward from the upper surface of the filter cavity. The lower bottom surface of the tuning column does not reach the lower bottom surface of the rectangular groove 201. The tuning column 3 is 5 mm long, 2 mm wide and 7.5 mm high. The ridge waveguide resonator 1 and the tuning column 3 together constitute one of the basic resonant units of the filter; the half-wavelength metal resonant groove is placed between two ridge waveguide resonators 2 embedded in the tuning column 3, and its slot length is half of the filter working wavelength, constituting another basic resonant unit of the filter. This embodiment is set to achieve a third-order filter passband with a ripple factor of 0.03dB, a center frequency of 2.2GHz, and a relative bandwidth of 19%. It can be fitted through 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 According to 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 groove, 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 groove is set to 7.1 mm.

[0033] like Figure 3 As shown, this design has two ports, namely probes 5 at both ends. The signal is input from port 1 and output from port 2. The working 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 TE mode decreases and 102 The resonant frequency of the mode is almost unchanged. It is worth noting that when the depth of tuning column 3 reaches a threshold, the coaxial mode of tuning column 3 replaces TE 102 mode becomes the first harmonic, but due to the fundamental mode TE 101The resonant frequency of the mode still decreases with the increase of the depth of the tuning column 3. Therefore, in this case, while reducing the resonant frequency of the fundamental mode of the resonator, the upper stopband range can still be widened. After determining the size of the ridge waveguide resonator 2 and the embedded tuning column 3 according to the center frequency, we constructed a half-wavelength metal resonant slot between the two ridge waveguide resonators 2, whose length is determined by the center frequency, and constructed a resonant unit with the half-wavelength metal resonant slot. Due to the introduction of the half-wavelength metal resonant slot, a three-pole bandpass filter can be composed of 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 = 2.2 GHz, the frequency range is 2.04 GHz-2.48 GHz, where |S 11 |Less than -17dB, insertion loss less than 0.45dB.

[0035] Embodiment 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 slot. The size of the ridge waveguide resonator 2, tuning column 3, and half-wavelength metal resonant slot 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 Fig. 9 The fundamental mode resonant frequency f0 of the ridge waveguide resonator and the extension length h of the tuning rod are given as 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 Fig.10 The ratio n of the first high-order mode resonant frequency to the fundamental mode resonant frequency is obtained. The size of the half-wavelength metal resonant slot can be calculated according to the required center frequency of the passband.

[0038] Step 2: The present invention sets a third-order filter passband with a ripple factor of 0.03dB, a center frequency of 2.2GHz, and a relative bandwidth of 19%. It can be fitted through 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, such as Fig.11 , Fig.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; Fig.11 Know Q e Follow p Increases or l1 decreases and increases. Fig.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 only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A miniaturized wide stopband cavity bandpass filter for satellite communications, characterized in that: 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 regions inside the rectangular cavity (1), a metal baffle (4) is arranged in the middle region, and a half-wavelength resonance 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 communication 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 communication 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 communication according to claim 3, characterized in that: A tuning column (3) is arranged 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 communication 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 communication 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 communication according to claim 6, characterized in that: The opening length of the half-wavelength resonance slot on the metal baffle (4) is half of the working wavelength of the filter, forming a second basic resonance unit.

8. The miniaturized wide stopband cavity bandpass filter for satellite communication according to claim 7, characterized in that: The filter is made of aluminum as a whole.

9. The method for manufacturing a miniaturized wide stopband cavity bandpass filter for satellite communication 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) operates at TE within the target frequency band. 10 model; S2: Set a third-order filter passband with a ripple factor of 0.03dB, a center frequency of 2.2GHz, and a relative bandwidth of 19%, fit it through the Chebyshev low-pass prototype filter circuit, and use the formula to calculate the theoretically required coupling coefficient and quality factor; extract the quality factor and the coupling coefficient between adjacent resonant cavities through 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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