Filter capable of performing far-end suppression

Abstract

The utility model relates to a filter capable of performing far-end suppression. The antenna comprises a cavity, a tuning mechanism and a zero point adjusting structure. At least six waveguide resonant cavities are arranged in the cavity, and loading columns are arranged on the waveguide resonant cavities; interstage coupling windows which are communicated are sequentially arranged between adjacent waveguide resonant cavities, and cross coupling windows are arranged between non-adjacent resonant cavities; the tuning mechanism comprises an adjusting screw rod, the adjusting screw rod extends into the waveguide resonant cavity and is opposite to the loading column, and the distance between the adjusting screw rod and the loading column is adjustable; the zero-point adjusting structure comprises a circular hole and a zero-point adjusting rod which are arranged in the interstage coupling window, the zero-point adjusting rod extends into the interstage coupling window and is opposite to the circular hole, and the distance between the zero-point adjusting rod and the circular hole is adjustable. Through the arrangement of the zero point adjusting structure, the phase of the coupling path in the cavity is offset, the near-band suppression degree of the filter can be improved, and a waveguide high-order mode signal at the far end of the filter can be effectively suppressed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of filters, and particularly relates to a filter capable of remote suppression. BACKGROUND

[0002] A waveguide filter is a two-port passive device, which realizes the filter function based on the characteristics of waveguide. The waveguide is a hollow metal tube capable of guiding electromagnetic wave transmission. By setting resonant cavities and coupling structures in the waveguide structure to change the transmission characteristics of electromagnetic waves, selective passing or suppression of different signals is realized.

[0003] Generally, the waveguide filter is very easy to pass through high-order modes, and usually presents many high-order mode parasitic passbands or spurious signals at the high end of the filter passband. In order to prevent the spurious interference of the communication system at the remote frequency signal to other microwave systems, the filter also requires a certain suppression degree in these frequency bands. At present, the commonly used method in the industry is to insert a evanescent mode filter, commonly known as a waveguide low-pass filter, into one end of the main filter to suppress it. Its use will increase the product size, which is not conducive to miniaturization and upgrading. In addition, due to its relatively high requirement for size tolerance, it increases the difficulty of product debugging and processing. For this reason, some other means of suppressing high-order modes are also disclosed in the prior art, such as adjusting the size of the resonant cavity close to the coaxial resonant cavity, adjusting the opening position of the coupling window between the cavities, and adjusting the depth of the adjusting screw during product debugging. For TEM mode coaxial cavities, spurious modes usually occur at 3 times the center frequency. If the waveguide cavity size is reduced to approach the coaxial cavity, high-order modes can be suppressed, but the result is a decrease in Q value, which increases the insertion loss and affects system use. SUMMARY

[0004] In view of the above problems existing in the prior art, the present application provides a filter capable of remote suppression, which can effectively suppress the remote harmonics of the filter.

[0005] To achieve the above-mentioned purpose, the technical scheme provided by the present application is as follows:

[0006] In a first aspect, the present application provides a filter capable of remote suppression, comprising a cavity, a tuning mechanism and a zero point adjusting structure; at least six waveguide resonant cavities are arranged in the cavity, and a loading column is arranged on the waveguide resonant cavity; interstage coupling windows are sequentially arranged between adjacent waveguide resonant cavities, and cross-coupling windows are arranged between non-adjacent resonant cavities; the tuning mechanism comprises an adjusting screw, the adjusting screw extends into the waveguide resonant cavity and is opposite to the loading column, and the distance between the adjusting screw and the loading column is adjustable; the zero point adjusting structure comprises a circular hole arranged in the interstage coupling window and a zero point adjusting rod, the zero point adjusting rod extends into the interstage coupling window and is opposite to the circular hole, and the distance between the zero point adjusting rod and the circular hole is adjustable.

[0007] Optionally, six waveguide resonant cavities are provided, and the six waveguide resonant cavities are sequentially connected between the input waveguide port and the output waveguide port; two cross-coupling windows are provided, one of which is a first cross-coupling window provided between the first waveguide resonant cavity and the third waveguide resonant cavity; and the other is a second cross-coupling window provided between the third waveguide resonant cavity and the sixth waveguide resonant cavity.

[0008] Optionally, the cavity is combined by a shell and a cover plate.

[0009] Optionally, the internal structures of the shell and the cover plate are combined to form the waveguide resonant cavities, the inter-stage coupling windows and the cross-coupling windows, respectively.

[0010] Optionally, the adjustment screw and the zero-point adjustment rod are arranged on the cover plate.

[0011] Optionally, the stepped surface of the inter-stage coupling window is higher than the bottom of the waveguide resonant cavity.

[0012] Optionally, the zero-point adjustment rod extends into the inter-stage coupling window to form an inductive coupling, thereby generating a zero point at the high end of the passband of the filter; and the zero-point adjustment rod extends into the circular hole to form a capacitive coupling, thereby moving the frequency position of the zero point from the high end of the passband to the low end of the passband.

[0013] Optionally, the filter has a rectangular structure, and the waveguide resonant cavities are circular.

[0014] Compared with the prior art, the present application has at least the following beneficial effects:

[0015] The present application can effectively suppress the far-end harmonic of the filter through the arrangement of the tuning mechanism and the zero-point adjustment structure. The extension of the zero-point adjustment rod into the circular hole causes the phase inversion of the entire coupling structure by 90°, thereby changing the inductive coupling into the capacitive coupling. Through the arrangement of the zero-point adjustment structure, the phase of the coupling path is cancelled in the cavity, thereby improving the near-band suppression of the filter and effectively suppressing the waveguide high-order mode signal of the far end of the filter. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0017] Figure 1 FIG. 1 is a structural schematic diagram of a filter capable of far-end suppression in an embodiment of the present application;

[0018] Figure 2A schematic diagram of the cavity structure in the embodiment of the present application;

[0019] Figure 3 A full-wave simulation curve of the filter when the second zero-adjusting rod is not inserted into the circular hole;

[0020] Figure 4 A full-wave simulation curve of the filter when the zero-adjusting rod is fully inserted into the circular hole;

[0021] Figure 5 A full-wave test curve of the filter when the zero-adjusting rod is fully inserted into the circular hole.

[0022] Explanation of reference numerals:

[0023] 1, shell; 2, cover plate; 3, waveguide resonant cavity; 4, inter-stage coupling window; 5, cross-coupling window; 6, loading column; 61, adjusting screw; 7, circular hole; 8, zero-adjusting rod; 81, first zero-adjusting rod; 82, second zero-adjusting rod; 9, input waveguide port; 10, output waveguide port. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use.

[0025] Embodiment 1

[0026] As shown in the drawings, Figure 1 A filter capable of remote suppression includes a cavity, a tuning mechanism, and a zero-adjusting structure. At least six waveguide resonant cavities 3 are arranged in the cavity. In this embodiment, six waveguide resonant cavities 3 (denoted as 31, 32, 33, 34, 35, and 36 in sequence) are arranged. The six waveguide resonant cavities 3 are connected in sequence between an input waveguide port 9 and an output waveguide port 10. A loading column 6 is arranged on the waveguide resonant cavity 3. Inter-stage coupling windows 4 are arranged in sequence between adjacent waveguide resonant cavities 3, and cross-coupling windows 5 are arranged between non-adjacent resonant cavities. The tuning mechanism includes an adjusting screw, which extends into the waveguide resonant cavity 3 and is opposite to the loading column 6. The distance between the adjusting screw and the loading column 6 is adjustable. The zero-adjusting structure includes a circular hole 7 arranged in the inter-stage coupling window 4 and a zero-adjusting rod 8. The zero-adjusting rod 8 extends into the inter-stage coupling window 4 and is opposite to the circular hole 7. The distance between the zero-adjusting rod 8 and the circular hole 7 is adjustable.

[0027] Through the structural design of the filter in this embodiment, the zero point adjusting rod extending into the circular hole causes the phase of the entire coupling structure to be reversed by 90°, changing from inductive coupling to capacitive; through the arrangement of the zero point adjusting structure, the phase of the coupling path inside the cavity is cancelled, which can improve the near-band suppression of the filter and effectively reduce the high-order mode signal at the far end of the filter band.

[0028] Embodiment 2

[0029] The difference between this embodiment and embodiment 1 is that the cavity is combined by a shell 1 and a cover plate 2. The internal structures of the shell 1 and the cover plate 2 are combined to form a waveguide resonant cavity 3, an inter-stage coupling window 4 and a cross-coupling window 5, respectively. The filter is a rectangular structure, and the waveguide resonant cavity 3 is circular.

[0030] In this embodiment, the waveguide resonant cavity 3 is a reduced-height waveguide, with a diameter of 15 mm, a depth of 6 mm, and a cylindrical loading column 6 arranged at the center of the bottom of the resonant cavity. The height of the loading column 6 is between 2-3 mm, and in this embodiment, the height of the loading column 6 is 2.5 mm, and the diameter is 5 mm.

[0031] In this embodiment, the inter-stage coupling window 4 is opened on the side of the adjacent two waveguide resonant cavities 3, and the step surface of the inter-stage coupling window 4 is 3 mm higher than the bottom of the waveguide resonant cavity 3, so that the entire channel exhibits a waveguide high-pass effect. Through the characteristics of the waveguide low-frequency cutoff, the high-order mode has a certain attenuation, and the width of the inter-stage coupling window 4 is between 6-8 mm.

[0032] In this embodiment, two cross-coupling windows 5 are provided, one being a first cross-coupling window 5 arranged between the first waveguide resonant cavity 31 and the third waveguide resonant cavity 33, and the other being a second cross-coupling window 5 arranged between the third waveguide resonant cavity 33 and the sixth waveguide resonant cavity 36. The width of the cross-coupling window 5 is 5.5 mm, and the depth is 2 mm. A circular hole 7 is arranged at the center of the bottom of the cross-coupling window 5, with a diameter of 3.8 mm and a depth of 4 mm. The circular hole 7 and the cross-coupling port form a capacitive-inductive switchable coupling structure. When the zero point adjusting rod 8 enters the circular hole 7, the phase of the entire coupling structure is reversed by 90°, becoming capacitive, which changes the polarity of the transmission zero point, thereby changing the properties of the zero point and meeting the actual suppression requirement of the filter.

[0033] The adjusting screw and the zero point adjusting rod 8 are arranged on the cover plate 2. By rotating the adjusting screw, the distance between the adjusting screw and the loading column 6 can be changed, the capacitance can be changed, and the resonant frequency of the filter can be changed.

[0034] By rotating the first zero point adjusting rod 81 to the direction close to the circular hole 7, it is adjusted into the cross-coupling window 5 (not into the circular hole 7), forming inductive coupling, which can produce a zero point in the high end of the filter's stop band; further deepening the screw rod into the circular hole 7 of the window, the frequency position of the zero point can be moved from the high end of the passband to the low end of the passband, realizing capacitive coupling, which can realize the free switching of the inductive and capacitive zero points.

[0035] The second zero point adjusting rod 82 can also realize the free switching of inductive and capacitive coupling, and by adjusting the second zero point adjusting rod 82 into the corresponding cross-coupling window 5, two transmission zero points can be produced simultaneously, which are distributed at the low end and the high end of the passband.

[0036] By studying the waveguide 10GHz waveguide filter, the out-of-band suppression requirement is less than 40dB, and the cutoff frequency is 26GHz. The Eigen mode of the resonant frequency is calculated by HFSS EM simulation. The frequency value is 10.5GHz under Model1 mode, and the two frequency values of the degenerate mode under Model2 and Model3 are almost the same, both of which are 23.42GHz; Model4 and Model5 are 24.5G and 27GHz respectively. The selected resonant cavity can keep the resonant cavity with a higher Q value, about 3000-3500. Theoretically, it is lower than the Q value of 5000 of the waveguide cavity resonance. According to the theoretical analysis of the amplitude-frequency curve of the 6-stage 3-transmission zero-point filter, the filter specification requirements can be met, and the corresponding topological structure is that the first cross-coupling window 5 realizes a zero point of CT structure, and the second cross-coupling window realizes two zero points of CQ structure. The generation of these zero points can greatly improve the near-band suppression of the filter, and can effectively suppress the waveguide high-order mode signal of the far end 22-26GHz of the filter. The principle is to achieve the purpose of attenuating high-order mode by phase cancellation in the cavity through the coupling path.

[0037] As shown in Figure 3 , the first zero point adjusting rod 81 is adjusted into the circular hole 7, and when the second zero point adjusting rod 82 is not adjusted into the circular hole 7, the filter in-band index can also meet the requirements, but the required filter out-of-band 20-26GHz frequency band amplitude is very high; on this basis, continue to adjust the second zero point adjusting rod 82 into the circular hole 7, two transmission zero points will be produced; at the same time, a large attenuation will be formed in the 20-26GHz frequency band, and the harmonic amplitude will be reduced to-40dB, as shown in Figure 4 . After the parts are processed, experimental verification is carried out under the same experimental conditions as Figure 4 , and the actual test structure is shown in Figure 5 . It can be seen that the actual test results and the simulation results can be well matched.

[0038] In the description of the application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0039] The above is only the preferred embodiment of the present application, and it should be pointed out that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, which should also be considered as the protection scope of the present application.

Claims

1. A filter capable of remote suppression, characterized in that, The system includes a cavity, a tuning mechanism, and a zero-point adjustment structure. The cavity contains at least six waveguide resonant cavities, each with a loading post. Interstage coupling windows are sequentially connected between adjacent waveguide resonant cavities, and cross-coupling windows are provided between non-adjacent resonant cavities. The tuning mechanism includes an adjusting screw that extends into the waveguide resonant cavity and is opposite to the loading post; the distance between the adjusting screw and the loading post is adjustable. The zero-point adjustment structure includes a circular hole and a zero-point adjusting rod disposed within the interstage coupling window. The zero-point adjusting rod extends into the interstage coupling window and is opposite to the circular hole; the distance between the zero-point adjusting rod and the circular hole is adjustable.

2. The remote-end suppression filter according to claim 1, characterized in that, The waveguide resonator is configured with six cavities, which are sequentially connected between the input waveguide port and the output waveguide port. Two cross-coupling windows are configured: one is a first cross-coupling window located between the first and third waveguide resonators; the other is a second cross-coupling window located between the third and sixth waveguide resonators.

3. The remote-end suppression filter according to claim 1, characterized in that, The cavity is composed of a matching shell and cover plate.

4. The remote-end suppression filter according to claim 3, characterized in that, The internal structures of the housing and cover plate are combined to form a waveguide resonant cavity, an interstage coupling window, and a cross-coupling window, respectively.

5. The remote-end suppression filter according to claim 3, characterized in that, Both the adjusting screw and the zero-point adjusting rod are arranged on the cover plate.

6. The remote-end suppression filter according to claim 1, characterized in that, The stepped surface of the interstage coupling window is higher than the bottom of the waveguide resonant cavity.

7. The remote-end suppression filter according to claim 1, characterized in that, The zero-point adjustment rod extends into the interstage coupling window, which can form inductive coupling and generate a zero at the high end of the filter's passband; the zero-point adjustment rod extends into the circular hole, which can form capacitive coupling and move the frequency position of the zero from the high end of the passband to the low end of the passband.

8. The remote-end suppression filter according to claim 3, characterized in that, The filter has a rectangular structure, and the waveguide resonant cavity is circular.

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