Medium cavity filtering coupler for indoor distribution system

Abstract

The invention discloses a dielectric cavity filtering coupler for an indoor distribution system, particularly relates to the technical field of wireless communication, and solves the technical problems that in the prior art, a filter and a coupler need to be arranged separately as independent devices, the circuit size is large after cascade connection, and the space utilization rate is low. According to the technical scheme, the filter and the coupler are integrally designed and integrated, and the circuit structure is multiplexed. According to the invention, connecting lines and interfaces between discrete devices can be eliminated, cascade loss and insertion loss are reduced, the circuit performance is improved, the system architecture is more simplified through multifunctional integration, and the reliability is improved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and particularly to a dielectric cavity filter coupler for an in-building distribution system. Background Art

[0002] In modern wireless communication systems, filters and couplers, as key components for signal selection and energy distribution, are of great importance. To meet the combined requirements of filtering characteristics and directional coupling functions, it is often necessary to physically cascade two types of devices. This discrete architecture directly leads to an increase in the volume of the RF link, which is not conducive to the miniaturization of the system. Summary of the Invention

[0003] Therefore, the present invention solves the technical problems in the prior art that filters and couplers need to be separately arranged as independent devices, and the circuit size is large and the space utilization rate is low after the two types of devices are cascaded. A dielectric cavity filter coupler for an in-building distribution system provided by the present invention integrates the filter and the coupler into one design, and the circuit structure is reused. Compared with the traditional design where filters and couplers need to be separately arranged as independent devices, the circuit size can be significantly reduced and the space utilization rate can be improved after integration. At the same time, the connection lines and interfaces between discrete devices can be eliminated, reducing the cascade loss and insertion loss, and improving the circuit performance. The multi-functional integration also simplifies the system architecture and improves the reliability. In addition, the number of connection components after integration is reduced, so the material cost is reduced, which is conducive to large-scale mass production.

[0004] The present invention provides a dielectric cavity filter coupler for an in-building distribution system. The dielectric cavity filter coupler involved includes a first dielectric block, a second dielectric block, a third dielectric block, a fourth dielectric block, a metal cavity, and a metal top cover. The first dielectric block, the second dielectric block, the third dielectric block, and the fourth dielectric block are all octagonal (non-regular octagon) structures of the same size. Each octagonal dielectric block can be regarded as obtained by cutting off 4 corners of a square dielectric block (each corner is cut off an isosceles triangle). The four octagonal dielectric blocks are arranged in a 2×2 array and inserted into the metal cavity. There are corresponding octagonal cavities inside the metal cavity, and the octagonal dielectric blocks are inserted into these cavities and are pressed by the metal top cover.

[0005] Furthermore, the surfaces of the four dielectric blocks are not silver-plated, and each has a metallized through hole along its central axis from top to bottom for fine-tuning the operating frequency. The metallized through hole is along the x-axis and is offset a certain distance from the outer wall of the nearest dielectric block.

[0006] Furthermore, the first dielectric block and the second dielectric block are energy-coupled through the first type of air cavity, and the third dielectric block and the fourth dielectric block are also energy-coupled through the first type of air cavity. The first dielectric block and the fourth dielectric block are energy-coupled through the second type of air cavity, and the second dielectric block and the third dielectric block are also energy-coupled through the second type of air cavity. Both the first type of air cavity and the second type of air cavity act as coupling windows. The length of the first type of air cavity in the x direction extends beyond the edge of the dielectric block, which is used to compensate the coupling amount between the two dielectric blocks, so as to meet the requirements of the filter passband for the coupling coefficient.

[0007] Furthermore, in the middle of each octagonal dielectric block, a pair of differential ports are fixedly arranged up and down. There are cylindrical through holes on both the bottom of the metal cavity and the metal top cover, so that the cylindrical connectors of each port can pass through the through holes and are finally pressed against the corresponding dielectric block. There is a cylindrical probe in the middle of the port, and the probe is directly inserted into the dielectric block. Starting from the upper left corner, the coupler rotates clockwise, and 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.

[0008] In the above technical solution, the technical effects and advantages provided by the present invention are as follows:

[0009] 1. A dielectric cavity filter coupler for in-building distribution system provided by the present invention integrates the filter and the coupler design into one, and the circuit structure is reused. Compared with the traditional design where the filter and the coupler are independent devices and need to be separately laid out, the integrated design can significantly reduce the circuit size and improve the space utilization rate; at the same time, the connection lines and interfaces between discrete devices can be eliminated, reducing the cascade loss and insertion loss, and improving the circuit performance.

[0010] 2. A dielectric cavity filter coupler for in-building distribution system provided by the present invention simplifies the system architecture through multi-functional integration, and the reliability is improved; in addition, the number of connection components after integration is reduced, so the material cost is reduced, which is beneficial to large-scale mass production.

[0011] 3. The dielectric cavity filter coupler provided by the present invention slows down the propagation speed of electromagnetic waves and shortens the wavelength by inserting dielectric blocks into the metal cavity. As a result, the size of the dielectric cavity resonator designed in the present invention is smaller than that of the traditional air cavity resonator (the size of the resonator is proportional to the wavelength of the electromagnetic wave), and good transmission performance can be maintained. This characteristic is beneficial to the miniaturization of the in-building distribution system while ensuring the communication quality. Since the periphery of the dielectric block is wrapped with a metal cavity and a metal top cover for electromagnetic energy shielding, the power capacity and mechanical strength of this filter coupler are significantly greater than those of a pure dielectric waveguide circuit. At the same time, compared with the integrally sintered dielectric waveguide device, the present invention adopts the structure of "discrete dielectric blocks plus air coupling cavities", and the processing difficulty is significantly reduced. 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 to be used in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0013] Figure 1 Schematic diagram of the overall structure of the present invention;

[0014] Figure 2 Top view of the present invention;

[0015] Figure 3 Front view of the present invention;

[0016] Figure 4 Side view of the present invention;

[0017] Figure 5 For TE 110 Electric field amplitude distribution diagram of the mode in an octagonal dielectric cavity resonator with metallized vias;

[0018] Figure 6 Amplitude-frequency response diagram of the dielectric cavity filter coupler of the present invention.

[0019] Description of the reference numerals:

[0020] 1. Metal cavity; 2. Metal top cover; 3. First dielectric block; 4. Second dielectric block; 5. Third dielectric block; 6. Fourth dielectric block; 7. Metallized via; 8. First type of air cavity; 9. Second type of air cavity; 10. Probe; 11. Input end; 12. Through end; 13. Coupling end; 14. Isolation end. Detailed Embodiments

[0021] 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.

[0022] Embodiment 1:

[0023] This embodiment provides a dielectric cavity filter coupler for an in-building distribution system, as Figures 1 to 4 shown, comprising a first dielectric block 3, a second dielectric block 4, a third dielectric block 5, a fourth dielectric block 6, a metal cavity 1, and a metal top cover 2. The first dielectric block 3, the second dielectric block 4, the third dielectric block 5, and the fourth dielectric block 6 are all octagonal (non-regular octagon) structures of the same size. Each octagonal dielectric block can be regarded as obtained by cutting off 4 corners of a square dielectric block (each corner is cut off an isosceles triangle); the four octagonal dielectric blocks are arranged in a 2×2 array and inserted into the metal cavity 1. There are corresponding four octagonal cavities inside the metal cavity 1, and the octagonal dielectric blocks are inserted into these cavities and pressed by the metal top cover 2.

[0024] In this embodiment, the surfaces of the four dielectric blocks are not silver-plated, and each has a metallized through-hole 7 along its central axis from top to bottom for fine-tuning the operating frequency. The metallized through-hole 7 is offset a certain distance along the x-axis and close to the outer wall of the nearest dielectric block.

[0025] In this embodiment, the first dielectric block 3 and the second dielectric block 4 are energy-coupled through a first type of air cavity 8, and the third dielectric block 5 and the fourth dielectric block 6 are also energy-coupled through the first type of air cavity 8. The first dielectric block 3 and the fourth dielectric block 6 are energy-coupled through a second type of air cavity 9, and the second dielectric block 4 and the third dielectric block 5 are also energy-coupled through the second type of air cavity 9. The first type of air cavity 8 and the second type of air cavity 9 both act as coupling windows. The length of the first type of air cavity 8 in the x-direction exceeds the edge of the dielectric block to compensate for the coupling amount between the two dielectric blocks, so as to meet the requirements of the filter passband for the coupling coefficient.

[0026] In this embodiment, a pair of differential ports are fixed up and down in the middle of each octagonal dielectric block. There are cylindrical through-holes on the bottom of the metal cavity 1 and the metal top cover 2, so that the cylindrical joints of each port can pass through the through-holes and are finally pressed on the corresponding dielectric block. There is a cylindrical probe 10 in the middle of the port, and the probe 10 is directly inserted into the dielectric block. Starting from the upper left corner, the coupler rotates clockwise, and the port sequence is the input end 11, i.e., differential port 1 (including port 1 at the upper end of the first dielectric block 3 + and port 1 at the lower end - ), the through end 12, i.e., differential port 2 (including port 2 at the upper end of the second dielectric block 4 + and port 2 at the lower end -) The coupling end 13, i.e., differential port 3 (including port 3 at the upper end of the third dielectric block 5 + and port 3 at the lower end - ) The isolation end 14, i.e., differential port 4 (including port 4 at the upper end of the fourth dielectric block 6 + and port 4 at the lower end - ).

[0027] In the specific circuit design process, the present invention inserts an octagonal dielectric block into the metal cavity 1, and then presses and seals it with the metal top cover 2 to form a dielectric cavity resonator. Figure 5 Shows the electric field distribution diagram of a single dielectric cavity resonator. The metallized vias 7 introduced in the dielectric block perturb the TE 110 mode inside to a certain extent, causing the resonant frequency of the resonator to shift to a higher frequency band.

[0028] In addition, by adjusting the size of the chamfers around the dielectric block, its resonant frequency can also be adjusted. When the chamfer is larger, the resonant frequency is higher. Generally speaking, the chamfers around the dielectric block are used for the initial determination of the resonant frequency, and the metallized vias 7 are used for fine-tuning the frequency during product testing (for example, after appropriately enlarging the holes and plating silver, the operating frequency increases). In the present invention, the relative dielectric constant of the dielectric block is selected as 9.8.

[0029] In the embodiment, it includes a pair of differential input ends 11 (port 1 + and port 1 - ), a pair of differential through ends 12 (port 2 + and port 2 - ), a pair of differential coupling ends 13 (port 3 + and port 3 - ), and a pair of differential isolation ends 14 (port 4 + and port 4 - ). Each pair of differential ports is placed face to face, parallel to the electric field direction, ensuring that the currents in the upper and lower pair of ports (for example, port 1 + and port 1 - ) are equal in amplitude and opposite in phase. Since the ports adopt a differential form, compared with a single-ended circuit, this solution has stronger anti-interference ability.

[0030] Embodiment 2:

[0031] This embodiment provides a dielectric cavity filter coupler optimized based on the above-mentioned Embodiment 1. Its dimensional parameters are shown in Table 1. In addition, the chamfered edges (the lengths of the waists of the cut isosceles triangles) of all dielectric blocks are 6 mm, and the height of the dielectric blocks is 8 mm. The diameters of all feeding probes 10 inserted into the dielectric blocks are 1.3 mm, and the insertion depths are all 2.1 mm. The diameter of the metallized through-hole 7 is 0.8 mm. The outer wall of the metal cavity 1 and the four corners on the metal top cover 2 are also chamfered, and the chamfered edge is 8 mm.

[0032] Table 1: Dimensional Parameter Table of This Embodiment

[0033] Parameter <![CDATA[l1]]> <![CDATA[l2]]> <![CDATA[l3]]> <![CDATA[l4]]> <![CDATA[d1]]> Value (mm) 20 8 6 34 12.2 Parameter <![CDATA[d2]]> <![CDATA[d3]]> <![CDATA[d4]]> <![CDATA[h1]]> <![CDATA[h2]]> Value (mm) 2 3.8 2 8 12

[0034] The amplitude-frequency response of the dielectric cavity filter coupler is as Figure 6 shown. The center frequency of the passband is 3.63 GHz. The in-band insertion loss of the direct-end signal is better than 0.4 dB, and the return loss of the input-end signal is better than 25 dB. The output of the coupled end is -(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. It can be seen that the input signal is mainly output from the direct end, and a small part of the energy is output from the coupled end.

[0035] The present invention uses the shared resonator technology to integrate the filter and the coupler in design and realizes differential excitation, reducing the circuit size while ensuring the communication quality. The simulation results show that this dielectric cavity filter coupler has low insertion loss and good common-mode rejection effect, and has application value in the base station communication system.

[0036] 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 to other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A dielectric cavity filter coupler for in-building distribution system, characterized in that It includes a metal cavity (1) with a dielectric block disposed therein; a metal top cover (2) is provided on the top of the metal cavity (1), and the metal top cover (2) is used to press the dielectric block tightly within the metal cavity (1).

2. The dielectric cavity filter coupler for in-building distributed antenna system according to claim 1, wherein There are four groups of the dielectric blocks, namely a first dielectric block (3), a second dielectric block (4), a third dielectric block (5), and a fourth dielectric block (6); the first dielectric block (3), the second dielectric block (4), the third dielectric block (5), and the fourth dielectric block (6) are all octagonal dielectric blocks of the same size, and each octagonal dielectric block is obtained by cutting off four corners of a square dielectric block; the four octagonal dielectric blocks are arranged in a 2×2 array.

3. The dielectric cavity filter coupler for in-building distribution system according to claim 2, characterized in that The surfaces of the first dielectric block (3), the second dielectric block (4), the third dielectric block (5), and the fourth dielectric block (6) are not silver-plated.

4. The dielectric cavity filter coupler for in-building distributed antenna system according to claim 3, characterized in that A metallized through hole (7) is provided on the central axis of each of the first dielectric block (3), the second dielectric block (4), the third dielectric block (5), and the fourth dielectric block (6) from top to bottom for fine-tuning of the operating frequency.

5. The dielectric cavity filter coupler for in-building distribution system according to claim 4, wherein The metallized through holes (7) are all offset along the x-axis towards the outer sidewall of the corresponding dielectric block.

6. The dielectric cavity filter coupler for in-building distribution system according to claim 5, characterized in that The first dielectric block (3) and the second dielectric block (4), as well as the third dielectric block (5) and the fourth dielectric block (6), are energy-coupled through a first type of air cavity (8); the first dielectric block (3) and the fourth dielectric block (6), as well as the second dielectric block (4) and the third dielectric block (5), are energy-coupled through a second type of air cavity (9).

7. The dielectric cavity filter coupler for in-building distribution system according to claim 6, characterized in that, Both the first type of air cavity (8) and the second type of air cavity (9) are used to act as coupling windows; the length of the first type of air cavity (8) in the x-axis direction exceeds the edge of the dielectric block.

8. The dielectric cavity filter coupler for in-building distribution system according to claim 7, characterized in that A pair of differential ports are provided in the middle regions on both the upper and lower sides of the first dielectric block (3), the second dielectric block (4), the third dielectric block (5), and the fourth dielectric block (6); cylindrical through holes are provided on both the bottom of the metal cavity (1) and the metal top cover (2) for the cylindrical connectors of each port to pass through and be pressed tightly on the corresponding dielectric block.

9. The dielectric cavity filter coupler for in-building distribution system according to claim 8, characterized in that, Probes (10) are provided within the differential ports, and the probes (10) are inserted into the dielectric blocks.

10. The dielectric cavity filter coupler for in-building distributed system according to claim 9, wherein, The ports on the four groups of dielectric blocks are respectively an input end (11), a through end (12), a coupling end (13), and an isolation end (14).

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