CN218215639U

CN218215639U - Coupler, calibration device and base station antenna

Info

Publication number: CN218215639U
Application number: CN202222877138.2U
Authority: CN
Inventors: 孙贵宇; 万方文
Original assignee: Commscope Technologies LLC
Current assignee: Commscope Technologies LLC
Priority date: 2022-10-31
Filing date: 2022-10-31
Publication date: 2023-01-03
Anticipated expiration: 2032-10-31

Abstract

The present disclosure relates to a coupler, comprising: an input port and an output port; a primary transmission line electrically connected in series between the input port and the output port of the coupler; a coupling port and an isolation port; and a secondary transmission line electrically connected in series between the coupled port and the isolated port of the coupler; the secondary transmission line has a first coupling section having a length less than or equal to 0.05 times a predetermined wavelength and spaced apart from the primary transmission line by a distance less than or equal to 0.05 times the predetermined wavelength, wherein the predetermined wavelength corresponds to a wavelength of a predetermined frequency point within an operating frequency band of the coupler, and a degree of coupling of the coupler is higher than 40dB. Furthermore, the present disclosure also relates to a calibration device for a base station antenna and an associated base station antenna.

Description

Coupler, calibration device and base station antenna

Technical Field

The present disclosure relates to wireless communications, and more particularly, to a coupler, a calibration device, and a base station antenna suitable for use in a wireless communication system.

Background

Couplers are widely used in microwave systems. The coupler may be configured as a power splitting device for splitting a single radio frequency signal into multiple radio frequency signals having predetermined amplitudes and phases. A coupler may typically include four ports, namely an input port, an output port, a coupled port, and an isolated port. When a radio frequency signal is input to the input port with a predetermined input power, a predetermined proportion of output power can be generated at the output port, a predetermined proportion of coupled power can be generated at the coupled port, and no power output should be generated at the isolated port in an ideal coupler. In practice, however, there is always some power leakage at the isolated port. It should be understood that, according to the principle of reciprocity, when a radio frequency signal is input from the "output port" described above, the "output port" is then converted into an input port of the coupler, the "input port" is converted into an output port of the coupler, the "isolated port" is converted into a coupled port of the coupler, and the "coupled port" is converted into an isolated port of the coupler.

The characteristics of a coupler can be characterized by a variety of parameters, such as coupling, isolation, directivity, and insertion loss. Assume a signal with power P1 is input at the input port, output power P2 at the output port, coupled power P3 at the coupled port, and leakage power P4 at the isolated port.

The "degree of coupling" of the coupler can be expressed as the ratio of the coupled power P3 to the input power P1. The degree of coupling of a coupler is usually expressed in dB and is negative. The larger the absolute value of the degree of coupling (hereinafter referred to as the degree of coupling should be understood as the absolute value of the degree of coupling), the smaller the amount of power output via the coupled port.

The "isolation" of the coupler can be expressed as the ratio of the leakage power P4 to the input power P1. The isolation of the coupler is usually expressed in dB and is negative. The greater the absolute value of the isolation (the isolation referred to below is to be understood as meaning the absolute value of the isolation), the less the amount of power that is leaked out via the isolated port, and thus the less the energy loss of the coupler.

The "directivity" of the coupler can be expressed as the ratio of the coupled power P3 to the leakage power P4. Directivity is a measure or figure of merit of the ability of a coupler to discriminate between incident and reflected waves. The following relationships may exist between the degree of coupling, isolation and directivity of the coupler: isolation = coupling + directivity. The coupling degree and the directivity can be set according to the use requirement, and then the expected value of the isolation degree can be calculated according to the coupling degree and the directivity. For example, coupling =30dB, directivity =25dB, then isolation =30db +25db =55db.

In some application scenarios, there are strict requirements on the degree of coupling of the coupler. For example, the coupling needs to be higher than 35dB, 40dB or 43dB, while the tolerance for the coupling needs to be lower than 1dB. The higher coupling degree can not only effectively improve the energy utilization rate, but also effectively reduce the load on the radio frequency device at the downstream of the coupling port of the coupler. Furthermore, the insertion loss, directivity and/or isolation of the coupler may also have stringent requirements. However, some known couplers do not meet the requirements in terms of coupling and its tolerance, directivity, isolation and/or insertion loss.

In some cases, the high degree of coupling may be achieved by a multistage coupler that may be a first coupler and a second coupler, the high degree of coupling being achieved by coupling ports of the first coupler and input ports of the second coupler being electrically connected to each other. Although the multi-stage coupler can meet the requirement of high coupling degree, the size is large, the insertion loss is high, and the cost is high.

In some cases, it is possible to use, the high degree of coupling can be achieved by a coupler integrated on the feed board printed circuit board (hereinafter referred to as feed board) of the base station antenna. A feed board refers to a printed circuit board on which one or more radiating elements are mounted and which transmits RF signals between these radiating elements and the feed network of the base station antenna. However, since the degree of coupling of the coupler integrated on the feeding board is not only related to the coupler itself but also to the feeding network upstream (including the possible phase shifting network), there may be a large degree of coupling tolerance. Typically, such couplers may have a large coupling tolerance (e.g., ± (2 to 3) dB). Therefore, it is difficult to satisfy the predetermined tolerance requirements.

SUMMERY OF THE UTILITY MODEL

It is an object of the present disclosure to provide a coupler, a calibration device and a base station antenna that overcome at least one of the drawbacks of the prior art.

According to a first aspect of the present disclosure, there is provided a coupler comprising: an input port and an output port; a primary transmission line electrically connected in series between the input port and the output port of the coupler; a coupling port and an isolation port; and a secondary transmission line electrically connected in series between the coupling port and the isolation port of the coupler, the secondary transmission line having a first coupling section, the length of the first coupling section of the secondary transmission line being less than or equal to 0.05 times a predetermined wavelength and the first coupling section being spaced apart from the primary transmission line by a distance less than or equal to 0.05 times the predetermined wavelength, wherein the predetermined wavelength corresponds to a wavelength of a predetermined frequency point within an operating frequency band of the coupler, and the degree of coupling of the coupler is higher than 40dB.

The coupler of the present disclosure can achieve a high degree of coupling and a low tolerance by a very short coupling section length between the primary transmission line and the secondary transmission line and a very small coupling spacing between the primary transmission line and the secondary transmission line.

According to a second aspect of the present disclosure, there is provided a calibration apparatus for a base station antenna, comprising: a dielectric substrate; calibration circuitry printed on a dielectric substrate, the calibration circuitry comprising a plurality of couplers, a power combiner, and a calibration port, wherein each coupler comprises: an input port configured to receive a radio frequency signal; an output port configured to output a radio frequency signal to the array of radiating elements; a primary transmission line electrically connected in series between an input port and an output port; a coupling port configured to extract a portion of the radio frequency signal from the input port and to transmit the extracted portion of the radio frequency signal to the power combiner; an isolated port; and a secondary transmission line electrically connected in series between the coupling port and the isolation port of the coupler, wherein the secondary transmission line has a first coupling section having a length less than or equal to 0.05 times a predetermined wavelength corresponding to a wavelength of a predetermined frequency point within an operating frequency band of the coupler and the first coupling section is spaced apart from the primary transmission line by a spacing less than or equal to 0.05 times the predetermined wavelength.

According to a third aspect of the present disclosure, there is provided a base station antenna comprising: a reflective plate; a feed board arranged on the front side of the reflection board and a radiation element array mounted on the feed board; a coupler according to some embodiments of the present disclosure or a calibration device according to some embodiments of the present disclosure disposed at a rear side of the reflection plate.

Other features of the present disclosure and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

Fig. 1 is a schematic diagram of a coupler according to some embodiments of the present disclosure.

FIG. 2 is a schematic diagram of a coupler according to other embodiments of the present disclosure.

Fig. 3 is a schematic diagram of a coupler, according to still further embodiments of the present disclosure.

Fig. 4 is a schematic diagram of a coupler according to still further embodiments of the present disclosure.

Fig. 5A, 5B, 5C are further exemplary plan layout variations of couplers according to some embodiments of the present disclosure.

Fig. 6 is a simplified schematic diagram of a base station antenna according to some embodiments of the present disclosure.

Fig. 7 is a schematic diagram of a calibration arrangement in the base station antenna of fig. 6.

Note that in the embodiments described below, the same reference numerals are used in common between different drawings to denote the same portions or portions having the same functions, and a repetitive description thereof will be omitted. In some cases, similar reference numbers and letters are used to denote similar items, and thus, once an item is defined in one figure, it need not be discussed further in subsequent figures.

For convenience of understanding, the positions, dimensions, ranges, and the like of the respective structures shown in the drawings and the like do not necessarily indicate actual positions, dimensions, ranges, and the like. Therefore, the present disclosure is not limited to the positions, dimensions, ranges, and the like disclosed in the drawings and the like.

Detailed Description

The present disclosure will now be described with reference to the accompanying drawings, which illustrate several embodiments of the disclosure. It should be understood, however, that the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, the embodiments described below are intended to provide a more complete disclosure of the present disclosure, and to fully convey the scope of the disclosure to those skilled in the art. It is also to be understood that the embodiments disclosed herein can be combined in various ways to provide further additional embodiments.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present disclosure. All terms (including technical and scientific terms) used herein have the meaning commonly understood by one of ordinary skill in the art unless otherwise defined. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

When an element is referred to herein as being "on," attached to, "" connected to, "coupled to," or "contacting" another element, etc., it can be directly on, attached to, connected to, coupled to or contacting the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly on," "directly attached to," directly connected to, "directly coupled to," or "directly contacting" another element, there are no intervening elements present. In this context, one feature being disposed "adjacent" another feature may refer to one feature having a portion that overlaps or is above or below the adjacent feature.

In this document, reference may be made to elements or nodes or features being "connected" together. Unless expressly stated otherwise, "connected" means that one element/node/feature may be mechanically, electrically, logically, or otherwise joined to another element/node/feature in a direct or indirect manner to allow for interaction, even though the two features may not be directly connected. That is, "connected" is intended to include both direct and indirect joining of elements or other features, including joining using one or more intermediate elements.

In this document, spatial relationship terms such as "upper", "lower", "left", "right", "front", "back", "high", "low", and the like may describe one feature's relationship to another feature in the drawings. It will be understood that the terms "spatially relative" encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, features originally described as "below" other features may be described as "above" other features when the device in the figures is inverted. The device may also be otherwise oriented (rotated 90 degrees or at other orientations) and the relative spatial relationships may be interpreted accordingly.

Herein, the term "a or B" includes "a and B" and "a or B" rather than exclusively including only "a" or only "B" unless otherwise specifically stated.

In this document, the term "exemplary" means "serving as an example, instance, or illustration," and not as a "model" that is to be reproduced exactly. Any implementation exemplarily described herein is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the detailed description.

In this document, the term "substantially" is intended to encompass any minor variations due to design or manufacturing imperfections, tolerances of the devices or components, environmental influences and/or other factors. The term "substantially" also allows for differences from a perfect or ideal situation due to parasitics, noise, and other practical considerations that may exist in a practical implementation.

In addition, "first," "second," and like terms may also be used herein for reference purposes only, and thus are not intended to be limiting. For example, the terms "first," "second," and other such numerical terms referring to structures or elements do not imply a sequence or order unless clearly indicated by the context.

It will be further understood that the terms "comprises/comprising," "includes" and/or "including," when used herein, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, and/or components, and/or groups thereof.

The present disclosure provides a coupler for a base station antenna, which can achieve a high degree of coupling and a low tolerance by a short coupling section length between a primary transmission line and a secondary transmission line and a small coupling distance between the primary transmission line and the secondary transmission line. A higher degree of coupling indicates a smaller amount of power output via the coupled port. The reduction of the power output through the coupling port can not only effectively improve the energy utilization rate, but also effectively reduce the load of the radio frequency device downstream of the coupling port of the coupler.

Furthermore, the coupler of the present disclosure can achieve high isolation and low insertion loss, such that the energy utilization of the coupler is high and the energy loss is small, e.g., insertion loss lower than 0.1dB.

In some embodiments, the degree of coupling of the coupler of the present disclosure may be higher than 36dB, 40dB, 43dB, or 50dB. Meanwhile, the tolerance of the coupling degree of the coupler of the present disclosure may be lower than 1dB. That is, the degree of coupling may vary from-1 dB to + 1dB.

In some embodiments, the directivity of the coupler of the present disclosure may be higher than 10dB, 13dB, 15dB, 20dB. The isolation of the coupler of the present disclosure may be higher than 50dB, 55dB, or 60dB.

Aspects in accordance with the present disclosure are now described in detail with reference to the drawings.

Fig. 1, 2, and 3 are each a schematic diagram of a coupler 10 according to some embodiments of the present disclosure.

As shown in fig. 1 to 3, the coupler 10 may be configured as a four-port coupler, which may include a primary transmission line 11 (which may also be referred to as a pass-through line), the primary transmission line 11 being electrically connected in series between an input port P _ in and an output port P _ out of the coupler 10; a secondary transmission line 12 (which may also be referred to as a coupled line), said secondary transmission line 12 being electrically connected in series between the coupled port P _ coup and the isolated port P _ iso of the coupler 10. The input port P _ in may receive a radio frequency signal from an upstream radio frequency device, e.g. via an input cable, the output port P _ out may output a radio frequency signal to a downstream radio frequency device, e.g. via an output cable, the coupled port P _ coup may extract a fraction of the radio frequency signal, and the isolated port P _ iso may be connected to a termination impedance. It should be understood that the input port P _ in/output port P _ out and the coupled port P _ coup/isolated port P _ iso of the coupler 10 may be adjusted according to the actual transmission direction of the radio frequency signal.

In order to achieve a high degree of coupling and a low tolerance, the secondary transmission line 12 may have a coupling section 21 (hereinafter referred to as a first coupling section for distinction), the length L of the first coupling section 21 is less than or equal to 0.05, 0.04, 0.03, 0.02, 0.01 times a predetermined wavelength and the first coupling section 21 is spaced apart from the primary transmission line 11 by a distance D that is less than or equal to 0.05, 0.04, 0.03, 0.02, 0.01 times the predetermined wavelength, the predetermined wavelength corresponding to a wavelength of a predetermined frequency point, for example, a center frequency point, within an operating frequency band of the coupler 10.

It is to be understood that the spacing D between the first coupling section 21 and the primary transmission line 11 may be understood as an average spacing between the first coupling section 21 and the primary transmission line 11. In some embodiments, as shown in fig. 1 to 3, the first coupling section 21 and the corresponding section of the primary transmission line 11 (hereinafter referred to as primary transmission line coupling section 31) may be substantially parallel to each other. In other embodiments, the first coupling section 21 may also extend at least partially at an angle to the primary transmission line coupling section 31.

Unexpectedly: the coupler 10 of the present disclosure advantageously achieves high coupling and low tolerance with extremely short coupling section lengths L and extremely small coupling spacing D. In some embodiments, the degree of coupling of coupler 10 may be up to-40 dB 1dB.

In the embodiment of fig. 1 to 3, the primary transmission line 11 of the coupler 10 may be designed as a non-linear primary transmission line 11. The secondary transmission line 12 of the coupler 10 may be designed as a non-linear secondary transmission line 12.

The primary transmission line 11 may comprise a primary transmission line coupling section 31 corresponding to the first coupling section 21 of the secondary transmission line 12. The primary transmission line 11 may further comprise a first primary transmission line segment 32 extending from the first end of the primary transmission line coupling segment 31 towards a direction away from the secondary transmission line 12 and a second primary transmission line segment 33 extending from the second end of the primary transmission line coupling segment 31 towards a direction away from the secondary transmission line 12, such that the first primary transmission line segment 32 and the second primary transmission line segment 33 are arranged further away from the secondary transmission line 12 relative to the primary transmission line coupling segment 31.

The secondary transmission line 12 comprises a first coupling section 21, a first secondary transmission line section 22 extending from a first end of the first coupling section 21 in a direction away from the primary transmission line 11, and a second secondary transmission line section 23 extending from a second end of the first coupling section 21 in a direction away from the primary transmission line 11, such that the first secondary transmission line section 22 and the second secondary transmission line section 23 are arranged further away from the primary transmission line 11 with respect to the first coupling section 21.

Thus, the primary transmission line 11 may comprise a first U-shaped portion formed by the first primary transmission line section 32, the primary transmission line coupling section 31 and the second primary transmission line section 33. The secondary transmission line 12 may comprise a second U-shaped portion formed by the first secondary transmission line segment 22, the first coupling segment 21 and the second secondary transmission line segment 23. The first and second U-shaped portions may be designed to advantageously achieve a high degree of coupling and a low tolerance.

In the embodiment of fig. 1, the cable for transmitting the radio frequency signal may be connected to the coupler 10 substantially parallel to the planar layout of the coupler 10 and electrically connected to the corresponding port. The cable can enclose the exposed inner conductor on both sides by means of a grounding clip. However, there may be relatively large energy leakage in this mode of electrical connection. In order to avoid undesired energy coupling between the input port P _ in and the coupled port P _ coup, the first primary transmission line section 32 may extend away from the secondary transmission line 12 substantially perpendicular to the first coupling section 21, and the first secondary transmission line section 22 may extend away from the primary transmission line 11 substantially perpendicular to the primary transmission line coupling section 31, such that the spacing between the input port P _ in and the coupled port P _ coup may be designed to be large, for example larger than 0.05 times, 0.1 times, or even 0.15 times the predetermined wavelength. In the current embodiment, the input cable may be connected to the input port P _ in of the coupler 10 substantially in a vertical direction, the output cable may be connected to the output port P _ out of the coupler 10 substantially in a horizontal direction, and the coupling cable may be connected to the coupling port P _ coup of the coupler 10 substantially in a vertical direction.

In the embodiment of fig. 2, unlike the embodiment of fig. 1, the input cable may be connected to the input port P _ in of the coupler 10 substantially in a horizontal direction, the output cable may be connected to the output port P _ out of the coupler 10 substantially in a horizontal direction, and the coupling cable may be connected to the coupling port P _ coup of the coupler 10 substantially in a horizontal direction.

In the embodiment of fig. 3, unlike the embodiment of fig. 2, a cable for transmitting radio frequency signals may be connected to the coupler 10 substantially perpendicular to the planar layout of the coupler 10, and the inner conductors of the cable may be threaded from the back side to the front side to be electrically connected with the respective ports. This mode of electrical connection can advantageously reduce energy leakage in the connection region. Thus, the distance between the input port P _ in and the coupling port P _ coup can be designed to be small relative to the embodiments of fig. 1 and 2, for example, greater than 0.03 or 0.05 times the predetermined wavelength, and thus a compact size of the coupler 10 is achieved. In some embodiments, the coupler 10 may be configured as a compact single stage coupler 10, the length of the single stage coupler 10 being less than or equal to 0.2 times the predetermined wavelength, and the width of the single stage coupler 10 being less than or equal to 0.1 times the predetermined wavelength.

Referring to fig. 4, a schematic diagram of a coupler 10 is shown, according to still further embodiments of the present disclosure. In contrast to the exemplary embodiments of fig. 1 to 3, the primary transmission line 11 of the coupler 10 can be designed as a linear primary transmission line 11. The first coupling section 21 of the secondary transmission line 12 may extend substantially parallel to the primary transmission line 11. At this time, a section of the primary transmission line 11 corresponding to the first coupling section 21 may be referred to as a primary transmission line coupling section 31. The linear primary transmission line 11 is advantageous because the linear primary transmission line 11 has low design difficulty and lower insertion loss, e.g. below 0.1dB.

Next, with reference to fig. 5A, 5B, 5C, further exemplary floor plan variations of coupler 10 according to some embodiments of the present disclosure are described.

To achieve a smooth coupling curve within a predetermined operating frequency band and/or to broaden the operating bandwidth of the coupler 10, the coupler 10 may be configured as a multi-stage coupler 10. In the present disclosure, a "multi-stage coupler 10" may be understood as a multi-stage coupler 10 that is sequentially cascaded by a plurality of basic coupling units, each of which may be designed in the form of a "single-stage coupler 10" as described in fig. 1 to 4. Advantageously, by cascading basic coupling elements with different degrees of coupling, the smoothness of the coupling curve of the whole coupler 10 can be improved, thereby expanding the operating bandwidth of the coupler 10.

As shown in fig. 5A and 5B, the coupler 10 may be configured as a two-stage coupler 10 (schematically separated by a dashed line) including two basic coupling units. In the embodiment of fig. 5A, the primary transmission line 11 is designed as a non-linear primary transmission line 11 and the secondary transmission line 12 is designed as a non-linear secondary transmission line 12. In the embodiment of fig. 5B, the primary transmission line 11 is designed as a linear primary transmission line 11 and the secondary transmission line 12 is designed as a non-linear secondary transmission line 12.

Advantageously, the first basic coupling unit 101 may have a different coupling degree index from the second basic coupling unit 102. Referring to fig. 5A and 5B, the non-linear secondary transmission line 12 of the coupler 10 may include a first coupling section 21 and a second coupling section 201. In one aspect, the length of the first and

second coupling sections

21, 201 may be less than or equal to 0.05 times the predetermined wavelength and the spacing of the first and

second coupling sections

21, 201 from the primary transmission line 11 may be less than or equal to 0.05 times the predetermined wavelength. On the other hand, the length of the first coupling section 21 may be different from the length of the second coupling section 201; and/or the first coupling section 21 may be spaced from the primary transmission line 11 by a different spacing than the second coupling section 201 is spaced from the primary transmission line 11. In some embodiments, the first coupling section 21 and the second coupling section 201 may be arranged parallel to each other staggered such that the first coupling section 21 is arranged closer to the primary transmission line 11.

As shown in fig. 5C, the coupler 10 may be configured as a three-stage coupler 10 including three

basic coupling units

101, 102, 103. It should be understood that two or three of the three basic coupling units may have different coupling degree indexes. Referring to fig. 5C, the non-linear secondary transmission line 12 of the coupler 10 may include a first coupling section 21, a second coupling section 201, and a third coupling section 301. In one aspect, the lengths of the first, second and

third coupling sections

21, 201 and 301 may be less than or equal to 0.05 times the predetermined wavelength and the spacing of the first, second and

third coupling sections

21, 201 and 301 from the primary transmission line 11 may be less than or equal to 0.05 times the predetermined wavelength. On the other hand, the length of the third coupling section 301 may be designed to be different from the length of the first and/or second coupling section 201; and/or the spacing at which the third coupling section 301 is spaced from the primary transmission line 11 may be designed to be different from the spacing at which the first and/or second coupling sections are spaced from the primary transmission line 11. In some embodiments, the first coupling section 21, the second coupling section 201 and the third coupling section 301 may be arranged offset parallel to each other.

It should be understood that the coupler 10 may be configured as a multi-stage coupler including more basic coupling units, such as a four-stage coupler, a five-stage coupler, a six-stage coupler, etc., and will not be described in detail herein.

In some embodiments, a coupling stub (not shown in the figures) may be provided between the secondary transmission line 12 and the corresponding primary transmission line 11 for tuning the coupling characteristics between the secondary transmission line 12 and the corresponding primary transmission line 11. The coupling stub may be configured to tune the coupling characteristics between the secondary transmission line and the respective primary transmission line 11. In some embodiments, the coupling stub may be integrally formed with the secondary transmission line 12.

Additionally or alternatively, other forms of coupling mechanisms, such as coupling slots, coupling holes, etc., may also be provided between the secondary transmission line 12 and the primary transmission line 11 in order to couple a portion of the radio frequency power of the primary transmission line 11 into the secondary transmission line 12. It is desirable that the radio frequency power coupled into the secondary transmission line 12 is transferred in the secondary transmission line 12 as far as possible to the coupled port P _ coup without leaking out of the isolated port P _ iso.

Next, the application of the coupler 10 according to some embodiments of the present disclosure in the base station antenna 100 is described with reference to fig. 6 and 7, where fig. 6 is a schematic diagram of the base station antenna 100 according to some embodiments of the present disclosure. Fig. 7 is a schematic diagram of the calibration device 130 in the base station antenna 100 of fig. 6.

As shown in fig. 6, the base station antenna 100 may include a feeding board 110 disposed at a front side of a reflection board (not shown) and a radiation element array 120 mounted on the feeding board 110. Further, the base station antenna 100 may further include a calibration device 130 disposed at the rear side of the reflection plate. It should be noted that the actual base station antenna 100 may also present other components, such as one or more of connectors, cables, phase shifters, remote electronic tilt units, duplexers, etc. To avoid obscuring the points of the present disclosure, the drawings do not show and other components are not discussed herein.

In a beamforming antenna, due to uncontrollable errors in the design, manufacture or use of the radio frequency control system (e.g. remote radio unit "RRU") or the antenna feeding network, the calibration apparatus 130 is usually required to compensate for phase and/or amplitude deviations of the radio frequency signals input at different radio frequency ports. This process is commonly referred to as "calibration".

As shown in fig. 6 and 7, the calibration device 130 may include: a dielectric substrate, a microstrip calibration circuit 140 disposed on a first surface of the dielectric substrate, and a ground metal layer (not shown) disposed on a second surface of the dielectric substrate. The calibration circuit 140 may be used to identify any undesired variations in the amplitude and/or phase of the radio frequency signals input to the different radio frequency ports of the antenna.

As shown in fig. 7, calibration circuit 140 may include a calibration port 142, a power splitter/combiner 143, and a plurality of couplers 10 as described in the present disclosure. The power splitter/combiner 143 may, for example, combine the coupled signals extracted by the coupler 10 and provide the combined signal to the calibration port 142.

In some embodiments, the input port P _ in of the coupler 10 may receive a Radio frequency signal from a corresponding port of a beamforming Radio (remote Radio unit).

The output port P out of each coupler 10 may be configured for outputting a radio frequency signal to a respective array of radiating elements 120 for generating a respective antenna beam.

The coupled port P _ coup of each coupler 10 may be configured to extract a portion of the radio frequency signal at the input port P _ in and output the extracted portion of the radio frequency signal to the power combiner 143. The power combiner 143 may combine the extracted Radio frequency signals into a calibration signal and communicate the combined calibration signal back to the beamforming Radio via the calibration port 142. The beamforming Radio may adjust the amplitude and/or phase of the Radio frequency signals to be input on the Radio frequency ports accordingly based on the calibration signals to provide optimized antenna beams. It should be appreciated that the calibration device 130 may include any suitable configuration and/or mode of operation and is not limited to the embodiments described above.

Based on the high coupling degree of the coupler 10, the calibration device 130 may allow the rf signal for the radiating element array to be extracted by the coupler 10 for only a relatively small portion, so that the energy utilization of the antenna system may be effectively improved, and the load of the calibration circuit 140 may be effectively reduced.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. The various embodiments disclosed herein may be combined in any combination without departing from the spirit and scope of the present disclosure. It will also be appreciated by those skilled in the art that various modifications may be made to the embodiments without departing from the scope and spirit of the disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A coupler, comprising:

an input port and an output port;

a primary transmission line electrically connected in series between the input port and the output port of the coupler;

a coupling port and an isolation port; and

a secondary transmission line electrically connected in series between the coupled port and the isolated port of the coupler,

wherein the secondary transmission line has a first coupling section, the length of the first coupling section of the secondary transmission line is less than or equal to 0.05 times of a predetermined wavelength and the first coupling section is spaced apart from the primary transmission line by a distance less than or equal to 0.05 times of the predetermined wavelength, wherein the predetermined wavelength corresponds to a wavelength of a predetermined frequency point within an operating frequency band of the coupler, and the degree of coupling of the coupler is higher than 40dB.

2. The coupler of claim 1, wherein the length of the first coupling section of the secondary transmission line is less than or equal to 0.03 times the predetermined wavelength and the first coupling section is spaced from the primary transmission line by a distance that is less than or equal to 0.02 times the predetermined wavelength.

3. The coupler of claim 1, wherein the length of the first coupling section of the secondary transmission line is less than or equal to 0.02 times the predetermined wavelength and the first coupling section is spaced from the primary transmission line by a distance that is less than or equal to 0.01 times the predetermined wavelength.

4. The coupler of claim 1, wherein the tolerance of the degree of coupling of the coupler is less than 1dB.

5. The coupler of claim 1, wherein the secondary transmission line of the coupler is configured as a non-linear secondary transmission line including a first secondary transmission line segment extending from the first end of the first coupling segment in a direction away from the primary transmission line and a second secondary transmission line segment extending from the second end of the first coupling segment in a direction away from the secondary transmission line, wherein the first secondary transmission line segment and the second secondary transmission line segment are disposed further away from the primary transmission line relative to the first coupling segment.

6. The coupler of claim 5, wherein the nonlinear secondary transmission line includes a second coupling section, wherein the length of the second coupling section is less than or equal to 0.05 times the predetermined wavelength and the second coupling section is spaced from the primary transmission line by a spacing that is less than or equal to 0.05 times the predetermined wavelength.

7. The coupler of claim 6,

the length of the first coupling section is different from the length of the second coupling section; and/or

The first coupling section is spaced apart from the primary transmission line by a different spacing than the second coupling section is spaced apart from the primary transmission line.

8. The coupler of claim 7, wherein the first coupling section and the second coupling section are parallel and staggered with respect to each other.

9. The coupler of claim 5, wherein the primary transmission line of the coupler is configured as a non-linear primary transmission line, the non-linear primary transmission line comprising: a primary transmission line coupling section corresponding to the first coupling section, a first primary transmission line section extending from a first end of the primary transmission line coupling section in a direction away from the secondary transmission line, and a second primary transmission line section extending from a second end of the primary transmission line coupling section in a direction away from the secondary transmission line, wherein the first primary transmission line section and the second primary transmission line section are disposed further away from the secondary transmission line relative to the primary transmission line coupling section.

10. The coupler of claim 9, wherein the first coupling section and the primary transmission line coupling section extend parallel to each other.

11. The coupler of claim 9, wherein the primary transmission line includes a first U-shaped portion formed by the first primary transmission line segment, the primary transmission line coupling segment, and the second primary transmission line segment, and the secondary transmission line includes a second U-shaped portion formed by the first secondary transmission line segment, the first coupling segment, and the second secondary transmission line segment.

12. The coupler of claim 1, wherein the primary transmission line of the coupler is configured as a linear primary transmission line.

13. The coupler of claim 1, wherein the coupler is configured as a single-stage coupler having a length less than or equal to 0.2 times the predetermined wavelength and a width less than or equal to 0.1 times the predetermined wavelength.

14. The coupler of claim 1, wherein the isolation of the coupler is greater than 60dB.

15. The coupler of claim 1, wherein the insertion loss of the coupler is less than 0.1dB.

16. The coupler of claim 1, wherein the coupler is configured as a printed metal pattern.

17. Calibration apparatus for a base station antenna, said calibration apparatus comprising:

a dielectric substrate;

calibration circuitry printed on a dielectric substrate, the calibration circuitry comprising a plurality of couplers, a power combiner, and a calibration port, wherein each coupler comprises:

an input port configured to receive a radio frequency signal;

an output port configured to output a radio frequency signal to the array of radiating elements;

a primary transmission line electrically connected in series between an input port and an output port;

a coupling port configured to extract a portion of the radio frequency signal from the input port and to transmit the extracted portion of the radio frequency signal to the power combiner;

an isolated port; and

wherein the secondary transmission line has a first coupling section having a length less than or equal to 0.05 times a predetermined wavelength and the first coupling section is spaced apart from the primary transmission line by a spacing less than or equal to 0.05 times the predetermined wavelength, the predetermined wavelength corresponding to a wavelength at a predetermined frequency within an operating frequency band of the coupler.

18. The calibration device for a base station antenna according to claim 17, wherein the degree of coupling of each coupler is higher than 40dB.

19. Calibration arrangement for a base station antenna according to claim 17, characterized in that each coupler is configured as a coupler according to one of claims 2 to 16.

20. A base station antenna, comprising:

a reflective plate;

a feed board arranged on the front side of the reflection board and a radiation element array mounted on the feed board;

coupler according to one of claims 1 to 16 or calibration device for a base station antenna according to one of claims 17 to 19 arranged on the rear side of a reflector plate.