CN114566776A

CN114566776A - Built-in broadband cavity duplexer of miniaturized base station antenna of high performance

Info

Publication number: CN114566776A
Application number: CN202210099961.7A
Authority: CN
Inventors: 陈国梁; 张刚; 杜军; 贾松
Original assignee: Hengerwei Technology Suzhou Co ltd
Current assignee: Hengerwei Technology Suzhou Co ltd
Priority date: 2022-01-27
Filing date: 2022-01-27
Publication date: 2022-05-31

Abstract

The invention discloses a high-performance miniaturized base station antenna built-in broadband cavity duplexer, which comprises a cavity, a radio frequency cable, an upper cover plate and a lower cover plate, wherein the upper cover plate and the lower cover plate are respectively arranged at the top and the bottom of the cavity; the cavity is internally provided with a low-frequency channel and a high-frequency channel, the low-frequency channel is internally provided with a first filter, the high-frequency channel is internally provided with a second filter and a non-resonant unit, the first filter and the second filter are both composed of a plurality of resonators, the first filter and the second filter are connected through a common cavity, the common cavity is a resonator, and the direction of the open end of the non-resonant unit is opposite to the direction of the open end of the resonator; the high-frequency channel is internally provided with a flying rod, the flying rod is bridged between nonadjacent resonators, a flying rod support is arranged at the joint of the flying rod and the resonators, the flying rod is made of metal materials, and the flying rod support is made of nonmetal materials. The invention realizes the miniaturization, light weight, low cost, high performance and wide bandwidth of the duplexer.

Description

Built-in broadband cavity duplexer of miniaturized base station antenna of high performance

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a built-in duplexer of a base station antenna.

Background

With the rapid development of mobile communication technology, the spectrum resource of communication signal transmission is increasingly tense, and it is expected to make more reasonable use of the current frequency and space without increasing the frequency bandwidth for mobile communication, and array frequency reuse and frequency selection techniques of base station antennas are increasingly used in this new requirement. Wherein the base station antenna built-in duplexer becomes the most critical part of the above requirements. The built-in duplexer of the base station antenna not only well solves the problem of frequency division of the antenna, but also greatly reduces the volume of the base station antenna. However, as the internal structure of the antenna is more and more complex, the internal space is more and more compact, and the requirements of miniaturization and light weight are provided for the built-in duplexer of the base station antenna; the frequency band of the base station antenna is wider and wider, and the frequency band requirement of the built-in duplexer of the base station antenna is also wider and wider. How to realize the miniaturization, light weight, low cost, high performance and wide bandwidth of the built-in duplexer of the base station antenna becomes an industrial problem.

Disclosure of Invention

The invention aims to provide a high-performance miniaturized base station antenna built-in broadband cavity duplexer, so as to realize miniaturization, light weight, low cost, high performance and broadband of the duplexer.

In order to realize the purpose, the invention adopts the following technical scheme:

a high-performance miniaturized base station antenna built-in broadband cavity duplexer comprises a cavity, a radio frequency cable, an upper cover plate and a lower cover plate, wherein the upper cover plate is arranged at the top of the cavity, and the lower cover plate is arranged at the bottom of the cavity; the cavity is internally provided with a low-frequency channel and a high-frequency channel, the low-frequency channel is internally provided with a first filter, the high-frequency channel is internally provided with a second filter and a non-resonant unit, the first filter and the second filter are both composed of a plurality of resonators, the first filter and the second filter are connected through a common cavity, the common cavity is a resonator, and the direction of the open end of the non-resonant unit is opposite to the direction of the open end of the resonator; the high-frequency channel is internally provided with a flying rod, the flying rod is bridged between nonadjacent resonators, a flying rod support is arranged at the joint of the flying rod and the resonators, the flying rod is made of a metal material, and the flying rod support is made of a nonmetal material; the number of the radio frequency cables is three, one end of each radio frequency cable is respectively connected with the first filter, the second filter and the public cavity, and the other end of each radio frequency cable is led out of the cavity.

The resonator comprises resonance rod and the loading electric capacity of connecting on resonance rod, has seted up the debugging hole in the loading electric capacity, and the debugging hole is the through-hole.

In the low-frequency channel, adjacent resonators are connected through first metal connecting ribs, and the first metal connecting ribs are respectively connected with the resonance rods of the adjacent resonators.

In the low-frequency channel, the distance between the resonators is adjustable.

The flying rod is made of brass, and the flying rod support is made of ultem 1000.

In the high-frequency channel, adjacent resonators are connected through second metal connecting ribs.

In the high-frequency channel, the height of the second metal connecting rib at the position where the flying rod is not arranged is adjustable, and the distance between every two three resonators associated with the flying rod is adjustable.

In the high-frequency channel, a part of the resonator, which is over the flying bar, is sunk near the flying bar.

Has the advantages that: compared with the prior art, the invention has the following advantages:

1. small volume: the invention adopts a smaller volume than the similar products in the market under the same frequency and index requirements, and the external dimension of the invention is as follows: 114.5X 40X 14 (length X width X height, unit: mm, without mounting hole size), reduced by about 1/3 from a comparable product size;

2. And (3) light weight: the invention realizes the following weight under the same frequency and index requirements: 150 (unit: g), a weight reduction of about 40% compared to a comparable product;

3. low loss, high isolation: the insertion loss of the duplexer is less than-0.6 dB, the return loss is less than-20 dB, and the mutual isolation between two pass bands is less than-32 dB;

4. high intermodulation: the invention has simple structure, good test effect of the third-order intermodulation, the third-order intermodulation is less than-155 dBc (2 multiplied by 20W), and the intermodulation passing rate is high;

5. wide bandwidth: the high-frequency channel covers a frequency range of 1920-2700MHz, achieves an absolute bandwidth of 780MHz and a relative bandwidth of nearly 35 percent, and well inhibits the frequency range of 1695-1880MHz of the low-frequency channel;

6. high mass productivity, low cost: the invention has simple structure, easy mass production, high passing rate and low cost.

Drawings

Fig. 1 is an assembly view of a high performance miniaturized base station antenna built-in broadband cavity duplexer of the present invention;

fig. 2 is an internal structure diagram (front side) of the high-performance miniaturized base station antenna built-in broadband cavity duplexer of the present invention;

fig. 3 is an internal structure diagram (reverse side) of the high-performance miniaturized base station antenna built-in broadband cavity duplexer of the present invention;

FIG. 4 is a graph of a product simulation of an embodiment;

FIG. 5 is a graph of the product test curves (1695 and 1880MHz band) of the example;

FIG. 6 shows the test curve (1920-2700MHz band) of the product of the example.

Detailed Description

The invention is further explained below with reference to the drawings.

As shown in fig. 1 to 3, the high-performance miniaturized base station antenna built-in broadband cavity duplexer of the present invention includes a cavity 2, a radio frequency cable 4, and an upper cover plate 1 and a lower cover plate 3 respectively disposed at the top and the bottom of the cavity 2; a low-frequency channel and a high-frequency channel are arranged in the cavity 2, a first filter is arranged in the low-frequency channel, a second filter and a non-resonant unit 13 are arranged in the high-frequency channel, the first filter and the second filter are both composed of a plurality of resonators, the first filter and the second filter are connected through a common cavity 12, and the common cavity 12 is a resonator; the number of the radio frequency cables 4 is three, one end of each radio frequency cable is respectively connected with the first filter, the second filter and the common cavity 12, and the other end of each radio frequency cable is led out of the cavity 2.

The resonator consists of a resonance rod 8 and a loading capacitor 7 connected to the resonance rod 8, the resonance rod 8 and the loading capacitor 7 form the resonator, the resonator has a high quality factor, the center frequency of 1790MHz in the resonator can reach more than 1200, and lower loss can be obtained under the same filter order; according to the theoretical formula: f is 1/(2pi × sqrt (L × C)), where f is the resonance frequency, C is the inductance, and L is the capacitance. The thickness and the width of the resonance rod 8 are reduced, namely the L is increased, so that the eigenfrequency of the resonator can be reduced under the same cavity volume; at the same frequency, a smaller volume can be obtained without a drastic deterioration of the quality factor; according to the theoretical formula: f is 1/(2pi × sqrt (L × C)), where f is the resonance frequency, C is the inductance, and L is the capacitance. The relative area between the loading capacitor 7 and the cavity wall and between the loading capacitor and the upper cover plate and the lower cover plate is increased, namely C is increased, so that the eigenfrequency of the resonator can be reduced under the same cavity volume; at the same frequency, a smaller volume can be obtained without a drastic deterioration of the quality factor.

A debugging hole 14 is formed in the loading capacitor 7, and the debugging hole 14 is a through hole; the tuning holes 14 are used to adjust the frequency of the filter, increasing the producibility of the product.

In the low-frequency channel, adjacent resonators are connected through first metal connecting ribs 9, and the first metal connecting ribs 9 are respectively connected with the resonance rods 8 of the adjacent resonators. Theoretically, there will be coupling between adjacent resonators and no coupling between non-adjacent resonators. However, in practical design, coupling occurs between non-adjacent resonators, and the coupling between non-adjacent resonators is called parasitic coupling. In conventional filter designs, such parasitic coupling is very weak and needs to be avoided, and too strong parasitic coupling may affect the overall performance of the filter, making the filter unable to meet the desired specifications. In the low-frequency channel of the invention, the linear arrangement of the resonators is adopted to generate stronger parasitic coupling, and the first metal connecting ribs 9 between the resonators can be used for enhancing and controlling the size of the parasitic coupling and flexibly controlling the position of the parasitic coupling, so that the stronger parasitic coupling can generate a stronger inductive transmission zero point on the right side of the passband of the filter, and the rectangular coefficient of the filter is increased. Thus, by combining the two filters into a duplexer, a higher degree of isolation can be achieved. Theoretically, with this structure, an N-th order filter can generate (N-1) transmission zeros. Compared with the traditional product, more transmission zero points and higher out-of-band rejection can be obtained. More transmission zeros also means that higher performance can be achieved with fewer filter orders, which greatly reduces the size of the filter. The low-frequency channel has great advantages in the number of transmission zero points, and no additional inductive coupling structure is added in the low-frequency channel, so that the production cost is greatly reduced, and the production consistency and reliability of products are improved.

In the low frequency path the spacing 15 between the resonators is adjustable. Due to the design idea, the parasitic coupling of the filter is ingeniously used to generate a transmission zero point, so that the size of the filter is greatly reduced, and the production pressure is reduced. However, this method also has a certain limitation, when a wider bandwidth is required, the distance 15 between two resonators needs to be reduced to obtain a larger coupling coefficient, and due to the difficulty of actual machining and the limitation of process level, it is impossible to make the distance between the resonators infinitely small to meet the requirement of a wideband filter, so this method is only suitable for filters with a relative bandwidth of 0.5% -15%. When the relative bandwidth of the filter is larger than 15%, the filter realized by the method is difficult to process and realize and has no producibility.

A flying rod 5 is arranged in the high-frequency channel, the flying rod 5 is bridged between nonadjacent resonators, a flying rod support 6 is arranged at the joint of the flying rod 5 and the resonators, and the adjacent resonators are connected through second

metal connecting ribs

10 and 11. The flying rod 5 is made of a metal material, preferably brass, and the flying rod support 6 is made of a non-metal material, preferably ultem 1000. When a broadband filter needs to be realized, a new idea needs to be provided to solve the problem of wide bandwidth, the flying bar 5 made of metal materials and the cavity 2 are separated by the flying bar support 6, so that capacitive coupling can be generated between the flying bar 5 and the cavity 2 only in a surface coupling mode, and a transmission zero point with adjustable strength can be formed on the left side of a passband of a high-frequency channel by controlling the thickness of the flying bar support 6 and the position in the cavity 2. When the external capacitive flying rod is introduced, the action of the second metal connecting rib 10 is changed, at the moment, the relative position of the second metal connecting rib 10 does not adjust the strength of the transmission zero point generated by the filter any more, and the relative position of the second metal connecting rib in the cavity only influences the size of the coupling coefficient between two adjacent high-frequency resonators. If the broadband of the filter is to be realized, the metal connecting ribs between the resonators only need to move towards the open circuit direction of the resonators. However, for the second metal connecting ribs 11 between each two of the three resonators associated with the flying bar, they not only determine the coupling coefficient between each two of the three resonators, but also form a transmission zero having the same polarity as that of the flying bar. By adjusting the positions of the two metal connecting ribs, not only can the coupling coefficient between the resonators be changed, but also the strength of the transmission zero point can be adjusted. That is, we introduce a fly rod inside the filter to generate capacitive coupling, which generates two capacitive couplings, and form two transmission zeros on the left side of the filter channel. Theoretically, with this structure, an N-th order filter can generate (N-1) transmission zeros (N is an odd number); the filter of M order can generate (M-2) transmission zeros (M is an even number, and M is more than or equal to 4); compared with the traditional product, more transmission zero points and higher out-of-band rejection can be obtained. More transmission zeros also means that higher performance can be achieved with fewer filter orders, which greatly reduces the size of the filter. By adopting the structure, the gap 17 between the high-frequency channel resonators can not play a role in adjusting the coupling coefficient, so that the wide bandwidth can be realized without adopting a small physical space, and the production cost is greatly saved. However, for the metal connecting ribs between every two three resonators associated with the flying bar, the metal connecting ribs can not only adjust the coupling coefficient, but also control the strength of the transmission zero point generated by the metal connecting ribs, so that in order to obtain a stronger transmission zero point, the distance 18 between every two three resonators can be properly reduced, the coupling coefficient between every two resonators can be increased, and more second metal connecting ribs 11 between the three resonators can be used for adjusting the strength of the transmission zero point. By adopting the structure, the high-frequency channel in the invention realizes a broadband filter with 1920-2700MHz, realizes the absolute bandwidth of 780MHz and the relative bandwidth of nearly 35 percent, and forms two stronger transmission zero points at the left side of the passband, thereby forming good inhibition on the low-frequency channel;

Similarly, if the low-frequency channel needs to realize wide bandwidth, and the transmission zero is on the right side of the passband of the low-frequency channel, and when the high-frequency channel needs to be suppressed, the inductive flying rod can be introduced, the inductive flying rod has various types and abundant realization forms, and the transmission zero similar to the embodiment can also be formed on the right side of the passband.

The high-frequency channel in the invention is provided with the non-resonance unit 13, and the resonance frequency of the non-resonance unit 13 is adjusted to the left side of the high-frequency passband, so that a transmission zero point is formed. The mode of generating transmission zero point by adopting the non-resonance unit comprises the following steps: the transmission zero point is easy to realize strong transmission zero point and controllable transmission zero point position, and the transmission zero point realized by the same non-resonant unit can be placed on the left side of the passband and also can be placed on the right side of the passband, and the advantages of flexible and changeable position, simple realization mode, large adjustable space and the like are achieved. The high-frequency channel adopts the non-resonant unit to generate the transmission zero point, so that the inhibition of the high-frequency channel on the low-frequency channel is improved, the isolation degree is increased, a plurality of flying rods are prevented from being introduced for realizing a plurality of transmission zero points, and the design and production difficulty is reduced;

the common cavity 12 of the invention adopts the form of a resonator, and combines two filters into a duplexer, and the form of the common cavity can improve the isolation of the duplexer and reduce the mutual interference between the two filters, and has simple structure and easy production;

The radio frequency cable adopts an RG-401 radio frequency cable which is used as a 50 omega port for connection, and is easier to switch in the base station antenna.

The invention has simple structure, and the simple internal structure can not only obtain higher third-order intermodulation, but also improve the production consistency, thereby reducing the production cost.

The present invention will be further described with reference to the following examples.

Examples

The working frequency of the duplexer of the embodiment is 1695MHz-1880MHz/1920MHz-2700 MHz. 1695MHz-1880MHz band, 5-order filter composed of 5 resonators; in the frequency range of 1920MHz-2700MHz, a 7-order filter is adopted, and the filter consists of 7 resonators and a non-resonant unit 13.

For the frequency band of the low-frequency channel 1695mhz-1880MHz, the resonators are connected with each other by the first metal connecting rib 9, so that the overall structural strength of the duplexer can be enhanced, the parasitic coupling between non-adjacent resonators can be enhanced, a strong transmission zero point is generated near a pass band, and the generated transmission zero point just falls on the right side of the pass band by adjusting the height of the metal connecting rib. The height of the metal connecting ribs is adjusted, and the positions of transmission zero points generated by parasitic coupling can also be adjusted to be distributed in sequence, so that a better stop band inhibition effect is achieved. The 4 cross-couplings generated by the 1695mhz-1880MHz frequency bands are all placed on the right side of the pass band according to the requirement of the index. By adjusting the distance 15 between the low-frequency channel resonators, the coupling coefficient between adjacent resonators can be changed, and the filter can reach the bandwidth required by indexes. The benefit of cross-coupling with parasitic coupling: 1: the parts required by adding cross coupling are reduced, so that the filter structure is simpler; 2: the polarity of the cross coupling can be adjusted by the intensity of the parasitic coupling, so that not only inductive coupling but also capacitive coupling can be generated, and the position of the generated cross coupling can be adjusted at will, and stronger cross coupling 3: the N-order filter can generate (N-1) cross couplings, so that the filter can obtain better rectangular coefficients, and the order of the filter can be saved under the same index requirement, thereby not only greatly reducing the size of the filter, but also reducing the insertion loss of the filter and ensuring that the performance of the filter is better.

For the frequency band of the high-frequency channel of 1920MHz-2700MHz, connect 7 resonators with the second metal connecting bar 10 between the resonators, adjust the height of the metal connecting bar, can change the coupling coefficient between the resonators of adjacent chambers, because the adjustable height range of the metal connecting bar is larger, when the height is close to the open end of the resonator, namely close to the top end of the resonator, the coupling coefficient that can be realized is very large, so can realize the wider transmission channel. When the second metal connecting rib 10 is only used for changing the coupling coefficient between the resonators and is not used for adjusting the transmission zero point, the gap 17 between the high-frequency channel resonators is not used for changing the coupling coefficient between the resonators, so that the distance can be greatly increased, and the processing cost is reduced. The high-frequency channel adopts a flying rod 5 and a flying rod support 6 which is arranged below the flying rod and used for playing a physical isolation role to realize capacitive coupling, and a transmission zero point is generated on the left side of a high-frequency pass band. Due to parasitic coupling between the introduced flying rod and the associated resonator, the filter simultaneously generates a transmission zero with the same polarity as the transmission zero generated by the flying rod, and the strength of the transmission zero can be controlled by the second metal connecting rib 11 of the resonator associated with the flying rod, and the coupling coefficients of the three resonators can be adjusted by the coupling distance 18. The invention introduces a flying bar, and two strong transmission zeros are generated on the left side of the high-frequency channel passband. Under the condition of the same filter order, the structure in the invention can obtain better out-of-band rejection. The coupling between the flying bar and the resonator is reduced by partial sinking of the flying bar across the resonator, and the depth of the sinking portion 16 is 1mm, so as to minimize the influence of the introduced flying bar on the standing wave in the filter band. The two transmission zero points generated by the flying bar cannot completely meet the requirement of out-of-band rejection of a high-frequency channel, so that the non-resonant unit 13 is adopted to generate another transmission zero point in the invention. The resonance frequency of the non-resonance unit is arranged at the first strongest zero position on the left side of the high-frequency channel, and the two zero points generated by the flying rod are respectively arranged at the second zero position and the third zero position on the left side of the high-frequency channel, so that the filter can have better power resistance under the condition of high-power signal input. As shown in fig. 2, the direction of the open end of the non-resonant unit 13 is opposite to that of other resonant units, so that the parasitic coupling of the non-resonant unit to the resonant unit can be effectively reduced, and the opposite open direction can obtain a larger coupling coefficient under the same distance, thereby increasing the distance between the resonators and facilitating the production.

The resonator comprises a loading capacitor 7 and a resonance rod 8, and the thickness and the width of the resonance rod 8 are reduced to 3mm on the basis of ensuring the mechanical strength and the producibility; the distance between the loading capacitor 7 and the inner wall of the cavity is reduced to 1.5mm, and the distance between the loading capacitor 7 and the upper cover plate and the lower cover plate is reduced to 0.5mm, so that the width and the height of the filter can be greatly reduced under the same eigenfrequency, and the quality factor is not greatly deteriorated.

In the invention, the loading capacitor 7 is provided with the through hole 14 with the thickness of 4.5mm, so that a debugging screw can be added on the upper cover plate of the duplexer to adjust the resonance frequency of each resonator, and the producibility is increased.

The invention adopts the common cavity 12 to connect the filter of 1695MHz-1880MHz band with the filter of 1920MHz-2700MHz band, so as to form the duplexer, thereby greatly reducing the mutual influence between the two filters, improving the isolation of the duplexer, simplifying the structure of the duplexer, improving the passing rate of third-order intermodulation and lowering the production cost.

The RG-401 radio frequency cable is adopted as an input/output port to be connected with three ports of the duplexer, and the RG-401 radio frequency cable is mostly used in the base station antenna to connect with a complex feed network, so that the port form can be better connected with the feed network in the antenna, and mismatching generated in the switching process of various ports is avoided. As shown in fig. 3, three RG-401 rf cables are respectively welded to the welding points A, B and C inside the cavity, and this connection mode is strong, simple in structure and easy to produce.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and amendments can be made without departing from the principle of the present invention, and these modifications and amendments should also be considered as the protection scope of the present invention.

Claims

1. The utility model provides a built-in broadband cavity duplexer of miniaturized base station antenna of high performance which characterized in that: the radio frequency cable comprises a cavity (2), a radio frequency cable (4), an upper cover plate (1) and a lower cover plate (3), wherein the upper cover plate (1) and the lower cover plate (3) are respectively arranged at the top of the cavity (2); a low-frequency channel and a high-frequency channel are arranged in the cavity (2), a first filter is arranged in the low-frequency channel, a second filter and a non-resonant unit (13) are arranged in the high-frequency channel, the first filter and the second filter are both composed of a plurality of resonators, the first filter and the second filter are connected through a common cavity (12), the common cavity (12) is a resonator, and the direction of the open end of the non-resonant unit (13) is opposite to the direction of the open end of the resonator; the high-frequency channel is internally provided with a flying rod (5), the flying rod (5) is bridged between nonadjacent resonators, a flying rod support (6) is arranged at the joint of the flying rod (5) and the resonators, the flying rod (5) is made of a metal material, and the flying rod support (6) is made of a non-metal material; the number of the radio frequency cables (4) is three, one end of each radio frequency cable is connected with the first filter, the second filter and the common cavity (12), and the other end of each radio frequency cable is led out of the cavity (2).

2. The high-performance miniaturized base station antenna built-in broadband cavity duplexer of claim 1, wherein: the resonator comprises resonance rod (8) and loading electric capacity (7) of connecting on resonance rod (8), has seted up debugging hole (14) in loading electric capacity (7), and debugging hole (14) are the through-hole.

3. The high-performance miniaturized base station antenna built-in broadband cavity duplexer of claim 1, wherein: in the low-frequency channel, adjacent resonators are connected through first metal connecting ribs (9), and the first metal connecting ribs (9) are respectively connected with the resonance rods (8) of the adjacent resonators.

4. The high-performance miniaturized base station antenna built-in broadband cavity duplexer of claim 1, wherein: in the low frequency channel, the spacing (15) between the resonators is adjustable.

5. The high-performance miniaturized base station antenna built-in broadband cavity duplexer of claim 1, wherein: the flying rod (5) is made of brass, and the flying rod support (6) is made of ultem 1000.

6. The high-performance miniaturized base station antenna built-in broadband cavity duplexer of claim 1, wherein: in the high-frequency channel, adjacent resonators are connected through second metal connecting ribs (10) and (11).

7. The high-performance miniaturized base station antenna built-in broadband cavity duplexer of claim 6, wherein: in the high-frequency channel, the height of the second metal connecting rib (10) at the position where the flying rod (5) is not arranged is adjustable, and the distance (18) between every two three resonators associated with the flying rod (5) is adjustable.

8. The high-performance miniaturized base station antenna built-in broadband cavity duplexer of claim 1, wherein: in the high-frequency channel, on the resonator spanned by the flying bar (5), the part of the resonator close to the flying bar (5) sinks.

9. The high-performance miniaturized base station antenna built-in broadband cavity duplexer of claim 1, wherein: the first filter in the low frequency channel is a 5 th order filter; the second filter in the high frequency channel is a 7 th order filter.