High-selectivity wideband cavity bandpass filter for low-orbit satellite communication and manufacturing method thereof

Abstract

The application discloses a kind of high selectivity wideband cavity band-pass filters and preparation method for low-orbit satellite communication, specifically relates to communication technology field, solve the structure loss of periodic metal strip loaded on microstrip transmission line and substrate integrated waveguide in prior art, the selectivity of lower stop band of artificial surface plasmon constructed by loading periodic unit in metal waveguide is poor and the characteristics that metal waveguide is not flexible enough;And existing metal waveguide artificial surface plasmon cannot effectively achieve the technology problem that upper stop band is wide enough;Its technical scheme is that: on the basis of the band-pass filter of artificial surface plasmon etched inverted T-shaped groove on the center ridge, a pair of symmetric folded groove structure is etched to form 1 / 4 wavelength resonator, for generating zero point in lower stop band, improve the selectivity of band-pass filter, at the same time, by controlling the length of grating, the characteristics of wide stop band are realized;The application has lower loss, realizes relatively wide stop band.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, in particular to a high-selectivity wideband cavity bandpass filter for low-orbit satellite communication and a manufacturing method thereof. BACKGROUND

[0002] In recent years, the rapid development of computer, micro-electromechanical, advanced manufacturing and other industries has promoted the upgrading of communication technology and micro-satellite technology, thus making the cost of satellite communication decrease, and low-orbit satellite communication highlights a wide application prospect. Around 2015, several large-scale low-orbit satellite communication systems were proposed at home and abroad. With the rapid development of low-orbit satellite communication, the demand for high-performance and wide-band bandpass filters is gradually increasing. Due to the inherent low-pass characteristic and flexible upper cutoff frequency, artificial surface plasmonic polaritons (artificial surface plasmonic polaritons) are widely researched and developed for designing various wide-band bandpass filters (bandpass filters). Due to the low loss and high power handling capability of waveguides, artificial surface plasmonic polaritons are often combined with artificial surface plasmonic polaritons for designing high-performance artificial surface plasmonic polariton bandpass filters. Especially in metal waveguides, such as rectangular waveguides, gap waveguides and ridge waveguides, etc. Among them, the ridge waveguide has a lower cutoff frequency than the same size waveguide, which is beneficial to realize the miniaturization of the circuit, and at the same time, a wider single-mode working bandwidth is obtained.

[0003] In the existing technology, although the structure of loading periodic metal strips on the microstrip transmission line and the substrate integrated waveguide is flexible, it has high loss and is difficult to meet the application requirement of low loss. The artificial surface plasmonic polaritons constructed by loading periodic units in the metal waveguide have poor lower stopband selectivity and the metal waveguide is not flexible enough; and the existing bandpass filter composed of metal waveguide and artificial surface plasmonic polaritons cannot effectively achieve the technical problem of wide enough upper stopband. SUMMARY

[0004] Therefore, the present application solves the technical problems in the prior art that although the structure of loading periodic metal strips on a microstrip transmission line and a substrate integrated waveguide has great flexibility, it has great loss and cannot meet the application requirement of low loss; the lower cutoff characteristic of an artificial surface plasmon constructed by loading periodic units in a metal waveguide only depends on the cutoff characteristic of the waveguide and the design is not flexible enough, which cannot meet the requirement of small size and good lower stopband roll-off performance; and the existing metal waveguide artificial surface plasmon bandpass filter cannot effectively achieve the effect of wide stopband suppression; the present application provides a high-selectivity wideband cavity bandpass filter for low-orbit satellite communication and a manufacturing method, a basic wideband bandpass filter is designed by etching a reverse T-shaped groove on a center ridge, and the characteristics of the artificial surface plasmon are discussed. Secondly, a pair of symmetrical folded grooves are etched on both ends of the center ridge of the ridge waveguide to form a 1 / 4 wavelength resonator, a new zero point is successfully introduced below the passband for increasing the roll-off degree of the lower edge of the passband. At the same time, by controlling the length of the grating, the effect of wide stopband is achieved. The present application realizes a wideband bandpass structure of 3.3GHz-5.8GHz. The return loss is below -15dB and the insertion loss is 0.25dB in the passband. Low loss and small size are realized in a wideband of 55%, and a zero point is introduced in the ridge waveguide artificial surface plasmon bandpass filter, which can change with the length of the folded groove. At the same time, the suppression level of the upper stopband of -30dB is expanded from 5.95GHz to 20GHz, and good stopband suppression effect is achieved. In addition, the center ridge has a low impedance and can be directly connected to a coaxial connector, so that the overall size is more compact.

[0005] The present application provides a high-selectivity wideband cavity bandpass filter for low-orbit satellite communication, which comprises a shell, a cavity is formed in the shell, a center ridge is arranged in the cavity, horizontal transition shafts are arranged at both ends of the shell, and the horizontal transition shafts are connected to both ends of the center ridge. A plurality of reverse T-shaped grooves are formed on the upper surface of the center ridge. The plurality of reverse T-shaped grooves form artificial surface plasmons, and transition artificial surface plasmon grooves are formed on the left and right sides of the reverse T-shaped grooves.

[0006] Further, a pair of folding grooves are formed on both sides of the bottom of the center ridge, the folding grooves are formed by slitting one end of the center ridge, penetrating the ridge and folding upward, a plurality of vertical columns are arranged on the cavity side walls of the front and rear sides of the center ridge, the plurality of vertical columns form a double-grating structure, and the length of the vertical columns gradually decreases in the horizontal direction.

[0007] Further, the artificial surface plasmons and the double-grating structure form a passband, and the two folding grooves are left-right symmetrical.

[0008] Further, the filter is made of aluminum.

[0009] In the above technical solutions, the application provides technical effects and advantages:

[0010] 1. The application provides a high-selectivity wideband cavity bandpass filter for low-orbit satellite communication, which realizes the design of a high-selectivity wideband ridge waveguide bandpass filter by using artificial surface plasmons and a folded groove etched on a center ridge. Compared with an artificial surface plasmon bandpass filter made on a dielectric plate, the design uses a metal waveguide and has lower loss. Since the flexibility of the metal waveguide in designing the filter is not high, the structure cannot be increased at will on the dielectric plate to increase the zero point. Therefore, a pair of folded grooves etched on the center ridge is designed to form a 1 / 4 wavelength resonator to increase a zero point that can be moved at will and is easy to manufacture in the lower stopband of the filter.

[0011] 2. The application provides a high-selectivity wideband cavity bandpass filter for low-orbit satellite communication, which has an insertion loss of less than 0.25 dB in the working frequency band, a bandwidth of up to 55%, a return loss of less than -15 dB, and a suppression of -30 dB or lower in the upper stopband reaching 20 GHz, and realizes a relatively wide stopband. DETAILED DESCRIPTION

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0013] Figure 1 It is a schematic diagram of the overall structure of the application.

[0014] Figure 2 It is a side view of the application. Figure 1 ;

[0015] Figure 3 It is a top view of the application. Figure 1 ;

[0016] Figure 4 It is a side view of the application. Figure 2 ;

[0017] Figure 5 It is a top view of the application. Figure 2 ;

[0018] Figure 6 It is a bandpass filter S parameter diagram of the application.

[0019] Figure 7 It is an insertion loss diagram of the application.

[0020] Figure 8Figure for influence of length change of folding groove on zero point position change of the present application;

[0021] Figure 9 Figure for influence of depth change of artificial surface plasmon on passband bandwidth of the present application;

[0022] Figure 10 Figure for influence of length change of grating structure on passband bandwidth of the present application.

[0023] Explanation of reference signs:

[0024] 1, center ridge; 2, artificial surface plasmon; 3, folding groove; 4, double grating structure; 5, horizontal transition axis; 6, shell; 7, cavity. DETAILED DESCRIPTION

[0025] In order to make the skilled in the art better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings.

[0026] Example 1

[0027] Figures 1-3 The 3D structure diagram, side view and top view of the high-selectivity wideband cavity bandpass filter for low-orbit satellite communication provided by the present embodiment are respectively shown, which contains the inverted T-shaped groove etched on the center ridge 1 to form the artificial surface plasmon 2 structure and the etched symmetrical folding groove 3 structure, which has progressive depths hs1 and hs2 for use as transition artificial surface plasmons, and the double grating structure 4 loaded at both ends of the center ridge 1. The ridge waveguide is fed by the horizontal transition axis 5. The entire invention is made of metal aluminum.

[0028] As shown in Figure 4 , first, according to the value of the center frequency, the initial size of the overall ridge waveguide is determined, and then the inverted T-shaped groove is etched on the center ridge 1 to form the artificial surface plasmon 2. Then a pair of symmetrical folding grooves 3 are etched at both ends of the center ridge 1. At the same time, the double grating structure 4 is loaded with two rows of pillars on both sides of the center ridge 1 as shown in Figure 5 . The two ends of the center ridge 1 are connected with the horizontal transition axis 5 as shown in Figure 5 . Finally, a high-selectivity wideband bandpass filter is made.

[0029] As shown in Figure 5As shown, the design has two ports, which are the horizontal transition shafts 5 at both ends. The signal is input from the left port, transmitted to the center ridge 1 through the coaxial, and then transmitted to the middle standard artificial surface plasmon 2 through the transition artificial surface plasmon to realize impedance matching, realize the band-pass characteristic, and finally the signal is output from the right port. The working frequency range of the filter is 3.3GHz-5.8GHz. The etched folded slot makes the waveguide transmission concentrated in the left etched folded slot at 2.9GHz, so that the entire filter has no wave transmission, which introduces a zero point below the passband to increase the lower edge of the passband. After determining the size of the ridge waveguide according to the center frequency, the artificial surface plasmon with low-pass characteristic is loaded to form the upper stop band. In order to realize the performance of widening the stop band, the length of the grating is increased in the design, so that the electric field at the ridge closest to the grating is perpendicular to the transmission direction, so that the high-order mode of the artificial surface plasmon cannot be effectively excited. Thus, the design of a high-selectivity wideband band-pass filter can be realized.

[0030] The design etches a pair of 1 / 4 wavelength folded slots 3 at both ends of the center ridge 1 to increase a zero point below the passband, which can be moved with the overall length of the slot. It is proved that the etched folded slot 3 has the excellent characteristic of increasing the roll-off degree of the passband. The inverted T-shaped slot artificial surface plasmon 2 is directly connected to the horizontal transition shaft 5 through the transition artificial surface plasmon at both ends to achieve good matching characteristics.

[0031] The simulation results of the high-selectivity wideband band-pass filter design of the ridge waveguide loaded with artificial surface plasmon in the present example are shown in Figures 6-10 , the center frequency is f0=4.5GHz, the frequency range is 3.3GHz-5.8GHz, and the S 11 is less than-15dB, and the insertion loss is less than 0.25dB. Figure 6 The overall S parameter graph of the filter is shown in the figure, the overall selectivity of the filter is high, and the overall return loss is-15dB; Figure 7 The performance of the filter passband is shown, which has a smooth insertion loss S 21 in the passband; Figure 8 The position of the zero point moves to low frequency with the increase of the length of the folded slot 3 (represented by the parameter l1); Figure 9 The effect of the depth parameter hs of the inverted T-shaped slot on the upper cutoff frequency of the filter is shown. With the increase of hs, the upper cutoff frequency of the filter decreases; Figure 10 The effect of the length lg of the double grating structure 4 on the lower cutoff frequency is shown. With the increase of the length of the grating, the lower cutoff frequency increases.

[0032] Example 2:

[0033] The embodiment provides a manufacturing method of the high-selectivity wide-band cavity band-pass filter for low-orbit satellite communication.

[0034] S1: first, the size of the ridge waveguide is determined, the size of the cavity 7 and the internal center ridge 1 is determined through the target working frequency band center frequency, so that the ridge waveguide works in the TE 10 mode in the target frequency band;

[0035] S2: a reverse T-shaped groove is etched downward on the center ridge 1, and a grating structure is loaded on both sides of the center to realize the band-pass characteristic, the upper cutoff frequency is controlled by adjusting the depth of the groove, the appropriate depth of the groove (the depth of the groove hs is 5.2mm in the design, the transition depths hs1 and hs2 of the artificial surface plasmon on both sides of the middle section are used for transition) is found by adjusting, the order and size of the double-grating structure 4 are determined, the lower cutoff frequency is realized by adjusting the order and the length of the double-grating 4 (the length of the grating lg is 4.6mm in the design, the grating with the transition lengths lg1 and lg2 is used for transition);

[0036] S3: a pair of folding grooves 3 is etched on the two sections of the center ridge 1, which is used for generating an arbitrarily movable zero point in the lower stop band (the length of each groove is 1 / 4 of the wavelength at the zero point);

[0037] S4: the related parameters are optimized to achieve the best matching result, as shown in Table 1;

[0038] Table 1: filter parameter table

[0039]

[0040]

[0041] The above only describes some exemplary embodiments of the application in a descriptive manner, undoubtedly, for ordinary skilled in the art, the described embodiments can be modified in various ways without departing from the spirit and scope of the application. Therefore, the above figures and description are illustrative in nature and should not be understood as limiting the scope of protection of the claims of the application.

Claims

1. A high-selectivity wideband cavity bandpass filter for low earth orbit satellite communications, characterized by, Including shell (6), the cavity (7) is opened in the shell (6) inside;The center ridge (1) is arranged in the cavity (7);The horizontal transition shaft (5) is arranged at the both ends of the shell (6);The horizontal transition shaft (5) is connected with the both ends of the center ridge (1); The plurality of inverted T-shaped grooves are formed artificial surface plasmon (2); The bottom of the center ridge (1) is provided with folding groove (3) on both sides; The plurality of the column is formed double grating structure (4). The artificial surface plasmon (2) and double grating structure (4) form passband.

2. The high-selectivity wideband cavity bandpass filter for low earth orbit satellite communication of claim 1, wherein, The two folding grooves (3) are left-right symmetrical.

3. The high-selectivity wideband cavity bandpass filter for low earth orbit satellite communication of claim 2, wherein, The filter as a whole adopts aluminum material.

4. The high-selectivity wideband cavity bandpass filter for low earth orbit satellite communication of claim 3, wherein, Including the following steps:

5. The high-selectivity wideband cavity bandpass filter for low earth orbit satellite communication of claim 4, wherein, S2: etching inverted T-shaped groove on the center ridge (1) and loading grating structure on both sides of the center as the basis of band-pass filter, then etching a pair of folding groove (3) on both ends of the center ridge (1) to constitute 1 / 4 wavelength resonator, for generating a zero point that can be moved arbitrarily in lower stopband; 6. The method of making a high-selectivity wideband cavity bandpass filter for low earth orbit satellite communications according to any one of claims 1 to 5, wherein, S3: adjusting the length of etching folding groove (3) to control the position of zero point in lower stopband;Adjusting the depth of groove to control the upper cutoff frequency, adjusting the appropriate depth of groove to determine the order and size of double grating structure (4), adjusting the order and length of double grating structure (4) to realize the control of lower cutoff frequency; S1 : First, the dimensions of the ridge waveguide are determined, the dimensions of the cavity (7) and the inner central ridge (1) are determined by the target operating frequency band center frequency, so that the ridge waveguide works in the TE 10 mode in the target frequency band; S4: optimizing related parameters to achieve the best matching result. ​ ​

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