Medium cavity filtering coupler with adjustable center frequency

Abstract

The invention discloses a medium cavity filtering coupler with an adjustable center frequency, particularly relates to the technical field of wireless communication, and solves the problems that in the prior art, the fusion design between a coupler and a filter of the same type is mainly adopted, most designs are low-power planar circuits, and the cost is low. The technical problem of lack of fusion design of an adjustable cavity filter and a coupler is solved. According to the technical scheme, a metal stepped shaft assembly is inserted into a non-metallized through hole of a medium cavity in a segmented mode, disturbance of different magnitudes is generated on a TE110 mode electric field in the medium cavity, and then the resonant frequency of the medium cavity is shifted; the effect of flexibly regulating and controlling the center frequency of the filtering coupler can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and particularly to a dielectric cavity filter coupler with adjustable center frequency. Background Art

[0002] Modern wireless communication systems often include multiple transmission channels and need to be compatible with multiple communication frequencies. Therefore, couplers and various filters are widely used. In traditional design schemes, these two types of devices are cascaded with each other. However, in a multi-frequency system, due to the inclusion of filters with different operating frequencies, when various filters are cascaded with a coupler, the system scale will increase significantly. Integrating the coupler and various filters in a combined design can effectively reduce the number of devices in the system and simplify the system architecture, and thus has received increasing attention.

[0003] However, the disclosed technical solutions mainly focus on the combined design between a coupler and the same type of filter. When a multi-frequency system needs to switch between different frequencies, such solutions cannot meet the requirements. In addition, most of the disclosed designs are low-power planar circuits and cannot meet the application scenarios with medium and high power capacities. Summary of the Invention

[0004] The present invention solves the technical problem in the prior art that the combined design mainly focuses on the combination between a coupler and the same type of filter, and such solutions cannot meet the requirements when a multi-frequency system needs to switch between different frequencies. The present invention provides a dielectric cavity filter coupler with adjustable center frequency. By reusing the resonator method, the coupler and the filter are integrated into one entity, eliminating the cascading loss between the devices and improving the overall performance. By inserting the stepped shaft assembly of metal into the non-metallized through holes of the dielectric cavity in sections, different magnitudes of perturbations are generated on the TE 110 mode electric field in the dielectric cavity, thereby shifting the resonant frequency of the dielectric cavity and achieving the effect of flexibly adjusting the center frequency of the filter coupler. The present invention can effectively alleviate the problems of large usage amounts of couplers and different-frequency filters and complex system architecture in a multi-frequency and multi-channel communication system, and is applicable to in-building distribution signal communication in the N78 frequency band.

[0005] The present invention provides a dielectric cavity filter coupler with adjustable center frequency, which includes a dielectric cavity, a lead screw, a fixed seat, a four-arm top beam, a stepped shaft assembly, a stop block, an upper fixing nut, and a lower fixing nut. The dielectric cavity contains four octagonal (non-regular octagon) dielectric resonators of the same size. Each octagonal dielectric resonator is obtained by cutting off four corners of a square dielectric resonator (each corner is cut off an isosceles triangle). The four octagonal dielectric resonators are arranged in a 2×2 array, and are coupled to each other through rectangular dielectric sheets (coupling windows), and the widths of the dielectric sheets along the x-axis and y-axis directions are different. Among them, the width of the rectangular dielectric sheet between the two pairs of resonators arranged along the y-direction exceeds the edge of the dielectric resonator in the x-direction, which is used to compensate the coupling amount between the resonators, so as to meet the requirements of the coupling coefficient for the filtering passband.

[0006] Further, a non-metallized through hole runs from top to bottom on the central axis of each octagonal dielectric resonator. The non-metallized through hole is along the x-axis and offset by a certain distance from the side wall of the nearest resonator. In the middle of each octagonal dielectric resonator, a pair of differential ports are fixedly installed above and below. There is a cylindrical probe in the middle of the ports, and the probe is directly inserted into the dielectric block. Starting from Figure 2 the upper left corner and rotating clockwise, the port sequence is the input end, i.e., differential port 1, the through end, i.e., differential port 2, the coupling end, i.e., differential port 3, and the isolation end, i.e., differential port 4. The contact surface between the dielectric cavity and the feeding port is not silver-plated, the inside of the non-metallized through hole is not silver-plated, and the rest of the surfaces are silver-plated.

[0007] Further, both ends of the fixed seat are tightly adhered to the tops of two rectangular dielectric sheets that exceed the edge of the dielectric resonator. A lead screw is fixed above it. The circular hole in the center of the four-arm top beam passes through the lead screw, and it is locked and fixed by the upper fixing nut and the lower fixing nut in the opposite direction above and below. The four-arm top beam includes four cross beams that bend and diverge around. The bottom of the end of each cross beam is threadedly connected to the top of a stepped shaft assembly.

[0008] Further, the stepped shaft assembly includes three metal cylinders (probes) of the same length but different diameters. From bottom to top, the diameters of the three segmented metal cylinders gradually increase. The length of each metal cylinder is the same as the height of the dielectric cavity. The four stepped shaft assemblies are all inserted into the non-metallized through holes. A stop block is welded to the end of the bottom, i.e., the thinnest metal cylinder, of the stepped shaft assembly. By inserting different segments of the stepped shaft assembly into the non-metallized through holes respectively, the center frequency of the passband can be adjusted, and three-level adjustment can be performed.

[0009] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0010] 1. A dielectric cavity filter coupler with adjustable center frequency provided by the present invention integrates the coupler and the filter into one entity by multiplexing resonators, eliminating the cascading loss between devices and improving the overall performance. By inserting the stepped shaft assembly of metal into the non-metallized through-holes of the dielectric cavity in sections, different magnitudes of perturbation are generated to the TE 110 mode electric field in the dielectric cavity, thereby shifting the resonance frequency of the dielectric cavity and achieving the effect of flexibly regulating the center frequency of the filter coupler.

[0011] 2. A dielectric cavity filter coupler with adjustable center frequency provided by the present invention can effectively alleviate the problems of large usage of couplers and different-frequency filters and complex system architecture in a multi-frequency and multi-channel communication system, and is applicable to in-building distribution signal communication in the N78 frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings.

[0013] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0014] Figure 2 It is a top view of the present invention;

[0015] Figure 3 It is a front view of the present invention;

[0016] Figure 4 It is a side view of the present invention;

[0017] Figure 5 On the left side is the electric field amplitude distribution diagram of the TE 110 mode in the octagonal dielectric cavity resonator without through-holes and metal probes, and on the right side is the electric field amplitude distribution diagram of the TE 110 mode in the octagonal dielectric cavity resonator with through-holes and metal probes;

[0018] Figure 6 It is a schematic diagram of the structure of the stepped shaft assembly of the present invention in different working states;

[0019] Figure 7 It is the amplitude-frequency response diagram of the filter coupler of the present invention in the first working state, that is, when the diameter Φ of the cylinder inserted into the through-hole is 0.8 mm;

[0020] Figure 8 It is the amplitude-frequency response diagram of the filter coupler of the present invention in the second working state, that is, when the diameter Φ of the cylinder inserted into the through-hole is 2 mm;

[0021] Figure 9 This is the amplitude-frequency response diagram of the filter coupler of the present invention in the third working state, i.e., when the cylindrical diameter Φ of the inserted through-hole is 3 mm.

[0022] Figure 10 This is the comparison diagram of the amplitude-frequency responses of the filter coupler of the present invention in three working states.

[0023] Description of reference numerals:

[0024] 1. Dielectric cavity; 2. Lead screw; 3. Fixed seat; 4. Four-arm top beam; 5. Step shaft assembly; 6. Stop block; 7. Upper fixing nut; 8. Lower fixing nut; 9. Non-metallized through-hole; 10. Input end; 11. Through end; 12. Coupling end; 13. Isolation end. Detailed implementation manners

[0025] 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 introduced in detail below with reference to the accompanying drawings.

[0026] Embodiment 1:

[0027] This embodiment provides a dielectric cavity filter coupler with adjustable center frequency as Figures 1 to 4 shown, which includes a dielectric cavity 1, a lead screw 2, a fixed seat 3, a four-arm top beam 4, a step shaft assembly 5, a stop block 6, an upper fixing nut 7, and a lower fixing nut 8. The dielectric cavity 1 contains four octagonal (non-regular octagon) dielectric resonators of the same size. Each octagonal dielectric resonator is obtained by cutting off four corners of a square dielectric resonator (each corner is cut off an isosceles triangle). The four octagonal dielectric resonators are arranged in a 2×2 array, and are coupled to each other through rectangular dielectric sheets (coupling windows), and the widths of the dielectric sheets in the x-axis and y-axis directions are different. Among them, the width of the rectangular dielectric sheet between the two pairs of resonators arranged in the y direction exceeds the edge of the dielectric resonator in the x direction, so as to compensate the coupling amount between the resonators, thereby meeting the requirements of the filter passband for the coupling coefficient.

[0028] In this embodiment, each octagonal dielectric resonator contains a non-metallized through-hole 9 from top to bottom on its central axis. The non-metallized through-hole 9 is offset a certain distance along the x-axis and close to the side wall of the nearest resonator. In the middle of each octagonal dielectric resonator, a pair of differential ports are fixed up and down. There is a cylindrical probe in the middle of the ports, and the probe is directly inserted into the dielectric block. Starting from Figure 2 the upper left corner and rotating clockwise, the port order is the input end 10, i.e., differential port 1, the through end 11, i.e., differential port 2, the coupling end 12, i.e., differential port 3, and the isolation end 13, i.e., differential port 4. The contact surface between the dielectric cavity 1 and the feeding port is not silver-plated, and the inside of the non-metallized through-hole 9 is not silver-plated, and the rest of the surfaces are silver-plated.

[0029] In this embodiment, both ends of the fixed seat 3 are tightly adhered to the tops of two rectangular dielectric sheets that extend beyond the edge of the dielectric resonator. A lead screw 2 is fixed above it. The circular hole in the center of the four-arm top beam 4 passes through the lead screw 2, and it is locked and fixed by an upper fixing nut 7 and a lower fixing nut 8 in opposite directions above and below respectively. The four-arm top beam 4 includes four cross beams that bend and diverge around. The bottom of the end of each cross beam is threadedly connected to the top of a stepped shaft assembly 5.

[0030] In this embodiment, the stepped shaft assembly 5 includes three metal cylinders (probes) with the same length but different diameters. From bottom to top, the diameters of the three-segment metal cylinders gradually increase. For example, Figure 3 , the length of each segment of the metal cylinder is 8 mm. From top to bottom, the diameters of each segment are 3 mm, 2 mm, and 0.8 mm respectively. The length of each metal cylinder is the same as the height of the dielectric cavity 1. The four stepped shaft assemblies 5 are all inserted into the non-metallized through holes 9, and a stop block 6 is welded to the end of the thinnest metal cylinder at the bottom of the stepped shaft assembly 5. By inserting different segments of the stepped shaft assembly 5 into the non-metallized through holes 9 respectively, the center frequency of the passband can be adjusted, and three-level adjustment can be performed.

[0031] In the specific circuit design process, the dielectric constant of the dielectric cavity 1 is selected as 9.8. Figure 5 Shows the electric field distribution diagram of the TE 110 mode in a single dielectric resonator. When the surface of the resonator is silver-plated and the inside is all dielectric material, the electric field of the TE 110 mode is evenly distributed, showing the characteristic of isotropy. When the resonator contains non-metallized through holes 9 and metal probes, the electric field on one side of the through hole and the metal probe is squeezed, that is, the effective space of the resonator is reduced, which will inevitably increase the resonance frequency. At the same time, the resonance frequency of the resonator will also increase with the increase of the diameter of the metal probe.

[0032] In this embodiment, as Figures 1 to 4 shown, it includes a pair of differential input terminals 10 (including port 1 at the upper end of the octagonal resonator + and port 1 at the lower end - ), a pair of differential through terminals 11 (including port 2 at the upper end of the octagonal resonator + and port 2 at the lower end - ), a pair of differential coupling terminals 12 (including port 3 at the upper end of the octagonal resonator + and port 3 at the lower end - ), and a pair of differential isolation terminals 13 (including port 4 at the upper end of the octagonal resonator + and port 4 at the lower end - ). Each pair of differential ports is placed face to face, parallel to the electric field direction, to ensure that the upper and lower pair of ports (for example, port 1+ and Port 1 - ) have equal amplitude and opposite phase. Since the ports adopt a differential form, compared with a single-ended circuit, this solution has stronger anti-interference ability.

[0033] Such as Figure 6 shown, schematic diagrams of the stepped shaft assembly 5 in different working states (descending to different positions). Since the length of each metal cylinder (probe) in the stepped shaft assembly 5 is the same as the height of the dielectric cavity 1, when one of the metal cylinders is completely inserted into the non-metallized through hole 9 (representing a working state), a frequency adjustment is achieved. Because the stepped shaft assembly 5 includes three metal cylinders with gradually increasing diameters from bottom to top, by adjusting the positions of the upper fixing nut 7 and the lower fixing nut 8 to move the stepped shaft assembly 5 up and down (corresponding to different working states), three-stage frequency adjustment of this filter coupler can be realized. It should be noted that in the third working state, the lower fixing nut 8 needs to be removed so that the four-arm top beam 4 is closely attached to the top of the dielectric cavity 1, thereby ensuring that the third metal cylinder probe is completely inserted into the through hole of the dielectric resonator.

[0034] The above method actually changes the effective resonance space of the resonator by adjusting the diameter of the metal probe inserted into the through hole of the resonator, and then adjusts the resonance frequency of this filter coupler.

[0035] Embodiment 2:

[0036] This embodiment provides a dielectric cavity filter coupler optimized based on the above Embodiment 1. Its dimensional parameters are shown in Table 1. In addition, all chamfered edges (the length of the waist of the cut isosceles triangle) of the dielectric cavity 1 are 6 mm, the height of the dielectric cavity 1 is 8 mm, and the diameter of the non-metallized through hole 9 is 3.2 mm. The diameters of all port feeding probes are 1.3 mm, and the insertion depths into the dielectric cavity are all 2.1 mm. From bottom to top, the diameters of the three cylinders in the stepped shaft assembly are 0.8 mm, 2 mm, and 3 mm respectively.

[0037] Table 1: Dimensional parameter table of this embodiment

[0038] Parameter <![CDATA[d1]]> <![CDATA[d2]]> <![CDATA[d3]]> <![CDATA[d4]]> Value (mm) 12.2 2 3.8 2 Parameter <![CDATA[l1]]> <![CDATA[l2]]> <![CDATA[l3]]> Value (mm) 20 8 6

[0039] Figures 7 - 9 respectively show the amplitude-frequency responses of this center frequency adjustable dielectric cavity filter coupler in three working states. Such as Figure 7As shown, in the first working state, the center frequency of the filter coupler is 3.63 GHz. The input signal is mainly output from the through-end 11, with an in-band insertion loss better than 0.4 dB and a return loss better than 25 dB. The amplitude of the signal output from the coupled-end 12 is within -(20 ± 1) dB, that is, the coupling degree is 20 ± 1 dB. The common-mode rejection performance is better than -94 dB in a relatively wide frequency band. As Figure 8 shown, in the second working state, the center frequency of the filter coupler is 3.73 GHz. The in-band insertion loss of the signal output from the through-end 11 is better than 0.4 dB, and the amplitude of the signal output from the coupled-end 12 is within -(20 ± 1) dB, that is, the coupling degree is 20 ± 1 dB. As Figure 9 shown, in the third working state, the center frequency of the filter coupler is 3.82 GHz. The in-band insertion loss of the signal output from the through-end 11 is better than 0.5 dB, and the amplitude of the signal output from the coupled-end 12 is still within -(20 ± 1) dB, that is, the coupling degree remains at 20 ± 1 dB.

[0040] In order to more intuitively show the characteristic that the center frequency of the dielectric cavity filter coupler is adjustable, the return loss characteristics of the input-end 10 and the transmission characteristics of the through-end 11 in three working states are compared in one figure, as Figure 10 shown. The results show that in this embodiment, by inserting metal cylinders with different diameters in the stepped shaft assembly into the non-metallized through-holes 9, the center frequency of the passband can be switched among three frequency points, and the performance of the through-end 11 and the coupled-end 12 is hardly affected.

[0041] The present invention integrates the filter and the coupler in a design, sharing the same resonator, which improves the system integration. By inserting metal cylinders with different diameters into the through-holes of the resonator, the effect of adjustable center frequency is achieved. The design of the differential port effectively improves the common-mode rejection ratio of the circuit. The present invention has application value in multi-frequency communication systems.

[0042] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A dielectric cavity filter coupler with adjustable center frequency, characterized in that, Comprising a dielectric cavity (1), the dielectric cavity (1) includes four octagonal resonators; the four octagonal resonators are arranged in a 2×2 array; a frequency adjustment mechanism is provided on the dielectric cavity (1), and the frequency adjustment mechanism is used to adjust the center frequency of the passband in the coupler.

2. The dielectric cavity filter coupler with adjustable center frequency according to claim 1, characterized in that, Each octagonal dielectric resonator is obtained by cutting off four corners of a square dielectric resonator. The octagonal dielectric resonators are coupled to each other by rectangular dielectric sheets, and the widths of the rectangular dielectric sheets along the x-axis and y-axis directions are different; among them, the length of the rectangular dielectric sheet between the two octagonal resonators arranged along the y-axis exceeds the inner edge of the octagonal dielectric resonator in the x-axis direction.

3. The dielectric cavity filter coupler with adjustable center frequency according to claim 2, characterized in that, A pair of differential ports are provided in the middle regions on the upper and lower sides of each octagonal dielectric resonator, and cylindrical probes are provided in the ports, and the cylindrical probes are inserted into the dielectric cavity (1).

4. The dielectric cavity filter coupler with adjustable center frequency according to claim 3, characterized in that, The frequency adjustment mechanism includes a fixed seat (3) provided on the rectangular dielectric sheet exceeding the edge of the dielectric resonator; a lead screw (2) is provided on the fixed seat (3); a four-arm top beam (4) is provided on the lead screw (2), and a circular hole in the center of the four-arm top beam (4) passes through the lead screw (2); the four-arm top beam (4) is locked and fixed in the reverse direction by an upper fixing nut (7) and a lower fixing nut (8) respectively above and below.

5. The dielectric cavity filter coupler with adjustable center frequency according to claim 4, characterized in that The four-arm top beam (4) includes four cross beams that bend and extend around. A stepped shaft assembly (5) is provided at the bottom of the end of each cross beam; the stepped shaft assembly (5) includes three metal cylinders with the same length and different diameters, and the diameters of the three metal cylinders gradually increase from bottom to top; the length of each metal cylinder is the same as the height of the dielectric cavity (1).

6. The dielectric cavity filter coupler with adjustable center frequency according to claim 5, characterized in that, A non-metallized through hole (9) is provided on the central axis of each octagonal dielectric resonator from top to bottom, and the non-metallized through hole (9) is offset along the x-axis towards the outer wall of the corresponding octagonal resonator; the four stepped shaft assemblies (5) are respectively inserted into the non-metallized through holes (9) provided on the four octagonal resonators.

7. The dielectric cavity filter coupler with adjustable center frequency according to claim 6, characterized in that, A stop block (6) is provided at the bottom of the stepped shaft assembly (5).

8. The dielectric cavity filter coupler with adjustable center frequency according to claim 7, characterized in that The ports on the four octagonal dielectric resonators are respectively an input end (10), a through end (11), a coupling end (12) and an isolation end (13).

9. The dielectric cavity filter coupler with adjustable center frequency according to claim 8, wherein The diameters of the three metal cylinders in the stepped shaft assembly (5) are not greater than the diameter of the non-metallized through hole (9).

10. The dielectric cavity filter coupler with adjustable center frequency according to claim 9, characterized in that, The length of the stop block (6) is greater than the diameter of the non-metallized through hole (9).

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