CN209767534U - t-shaped bias circuit and calibration board for base station antenna - Google Patents

Abstract

t-shaped bias circuits and calibration plates for base station antennas are disclosed. One of the T-shaped bias circuits comprises: a synthesis path configured to transmit a synthesized signal via the synthesis path, the synthesized signal comprising a combination of a radio frequency signal and a direct current signal; a radio frequency path configured to transmit a radio frequency signal contained in the composite signal via the radio frequency path; a direct current path configured to transmit a direct current signal included in the synthesized signal via the direct current path; and an impedance transformer connected between the first end of the composite path, the first end of the radio frequency path, and the first end of the direct current path and configured such that reflection coefficients of the radio frequency signal transmitted between the composite path and the radio frequency path have resonant modes at least two frequencies in a radio frequency band of operation.

Description

T-shaped bias circuit and calibration board for base station antenna

Technical Field

The present disclosure relates to the field of radio frequency communications, and in particular to a Bias-T (Bias-Tee) circuit for use in the field.

Background

the base station antenna using beam forming can improve the channel reuse rate and the base station coverage area of a mobile communication system, and overcome increasingly serious interference problems such as co-channel interference, multipath fading and the like. When using a beamforming antenna, the antenna array must be calibrated to ensure that the phase relationship between the different RF paths is known and can be calculated in the beamforming operation. The operating frequency bands of beamforming antennas are also increasing, and techniques suitable for calibrating wideband beamforming antennas are needed.

a Bias-T (Bias-Tee) circuit is often used inside the base station antenna to allow low frequency AISG signals and/or DC power signals to be transmitted to the antenna via the same coaxial cable used to transmit RF signals to the antenna, thereby reducing the number of cables and the loading of the antenna tower.

SUMMERY OF THE UTILITY MODEL

One of the objectives of the present invention is to provide a new T-type bias circuit and a calibration board for a base station antenna including the same.

according to a first aspect of the present invention, there is provided a T-shaped bias circuit, comprising: a composite path having a first end and a second end and configured to transmit a composite signal comprising a combination of a radio frequency signal and a direct current signal; a radio frequency path having a first end and a second end and configured to transmit a radio frequency signal contained in the composite signal; a direct current path having a first end and a second end and configured to transmit a direct current signal contained in the composite signal; and an impedance transformer connected between the first end of the composite path, the first end of the radio frequency path and the first end of the dc path and configured such that a reflection coefficient of the radio frequency signal transmitted between the second end of the composite path and the second end of the radio frequency path has at least two resonant modes in a radio frequency band of operation.

According to a second aspect of the present invention, there is provided a calibration plate for a base station antenna, comprising: a T-bias circuit, calibration port, dc bias port, and power divider as described above. A second end of a composite path in the T-shaped bias circuit is connected to the calibration port and configured to input a calibration signal as the composite signal, a second end of the radio frequency path is connected to an input of the power divider and configured to output the radio frequency signal to the power divider, and a second end of the dc path is connected to the dc bias port and configured to output the dc signal for driving RET.

According to a third aspect of the present invention, there is provided a T-shaped bias circuit, comprising: a DC port; a radio frequency port; a composition port; and an impedance transformer configured to pass a direct current signal received at the combining port to the direct current port and to substantially prevent a radio frequency signal received at the combining port from passing to the direct current port, and configured to pass a radio frequency signal received at the combining port to the radio frequency port and to substantially prevent a direct current signal received at the combining port from passing to the radio frequency port; wherein the impedance transformer comprises a closed loop connecting the composite port to both the dc port and the rf port.

Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments of the invention, 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 invention and together with the description, serve to explain the principles of the invention.

The invention will be more clearly understood from the following detailed description, with reference to the accompanying drawings, in which:

FIG. 1 is a simplified schematic diagram of a conventional T-shaped bias circuit;

fig. 2 is a schematic diagram of a T-type bias circuit according to some exemplary embodiments of the present invention;

Fig. 3 is a more detailed schematic diagram of a T-type bias circuit in accordance with some exemplary embodiments of the present invention;

FIG. 4A is a schematic plan view of an exemplary implementation of the T-bias circuit of FIG. 3;

FIG. 4B is a graphical illustration of return loss versus frequency for the T-bias circuit of FIGS. 1 and 4A;

fig. 5-7 are schematic diagrams of other configurations of T-bias circuits according to various embodiments of the present invention;

Fig. 8 is a schematic diagram of a specific structure of a calibration board for a base station antenna according to an exemplary embodiment of the present invention.

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, sizes, ranges, and the like of the respective structures shown in the drawings and the like do not sometimes indicate actual positions, sizes, ranges, and the like. Therefore, the present invention is not limited to the positions, dimensions, ranges, and the like disclosed in the drawings and the like.

Detailed Description

The invention will be described with reference to the accompanying drawings, which illustrate several embodiments of the invention. It should be understood, however, that the invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, the embodiments described below are intended to provide a more complete disclosure of the present invention and to fully convey the scope of the invention 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 be limiting of the invention. 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.

Fig. 1 is a simplified schematic diagram of a conventional T-bias circuit. As shown in fig. 1, the conventional T-bias circuit includes three conductive paths commonly connected at point d, i.e., paths 1-3, which respectively transmit three signals, i.e., a composite signal (DC signal + RF signal) on path 1, an RF signal on path 2, and a DC signal on path 3. In some cases, a DC + RF signal is input at one end of the path 1, i.e., a point a in fig. 1, and ideally, the RF signal in the composite signal is losslessly transmitted to a point c, and the DC signal therein is losslessly transmitted to a point b. But the access of path 3 has an impact on the transmission of RF signals between points a, b, so some of the incoming RF energy at point a may be reflected back instead of passing to point c. The return loss between points a and b may be reduced or minimized by making the connection between points d and b appear as an open circuit to the transmitted RF signal. In case the T-bias circuit is implemented with a microstrip transmission line on a Printed Circuit Board (PCB), this can be achieved by setting the length of path 3 to λ/4, where λ corresponds to the center frequency of the operating band of the RF signal. This is because, according to the formula of calculation of the reflection coefficient from point a to b, this reflection coefficient exhibits a resonant mode at a length λ/4 of the path 3, i.e. has a local minimum value, but it remains low only in a narrow range around the center frequency of the operating band to which this local extreme value corresponds. The T-bias circuit will exhibit good return loss performance over a relatively narrow frequency range.

As discussed above, in the conventional T-bias circuit shown in fig. 1, in order to make the transmission of the RF signal between the ends a and c have no loss, the path 3 should be equivalent to an open circuit at the point b of the connection. The impedance transformation may be performed by designing the length or impedance of the path 3 such that the path 3 appears as an open circuit at the connection point b, but this can only be achieved at a single frequency. The conventional T-type bias circuit can also have a good return loss characteristic over a frequency range near the frequency point, but a frequency range over which the return loss is still small is narrow because the reflection coefficient of the RF signal between the points a and c has only one resonance mode. As a result, the conventional T-type bias circuit can transmit the RF signal from the point a to the point c only within a very narrow frequency band with a low return loss. However, in practice, a T-bias circuit with a wide operating band may be desirable.

According to embodiments of the present invention, the frequency range over which the T-bias circuit will exhibit low return loss can be extended by adding an impedance transformer between the three paths included in the conventional T-bias circuit of fig. 1. The impedance transformer can be designed to match the impedances of the three terminals, thereby introducing one or more new resonant modes that broaden the operating frequency bandwidth of the T-bias circuit (i.e., the bandwidth over which the T-bias circuit provides acceptable return loss performance). The impedance transformer may be designed such that at and near two frequencies corresponding to the resonant modes, the DC path appears as an open circuit (or nearly an open circuit) along the two (or more) paths through which the RF signal passes, and the reflection coefficient for the RF signal also decreases within the frequency band between the two resonant frequency points due to the interaction of the two relatively adjacent resonant modes. Therefore, the reflection coefficient for the RF signal is small at two resonance frequencies in the operating frequency band, and the reflection coefficient in the frequency band between the two resonance frequencies is also small. That is, the impedance transformer may make the reflection coefficient for the RF signal low within a band, thereby extending the operating band of the RF signal. Of course, it will be understood by those skilled in the art that the addition of the impedance transformer not only brings about two resonant modes, but also introduces more resonant modes as needed, thereby further expanding the operating frequency band and/or reducing the reflection coefficient within the frequency band.

fig. 2 is a schematic diagram of a T-type bias circuit according to some exemplary embodiments of the present invention.

As shown in fig. 2, the T-bias circuit includes a composite path, a radio frequency path and a dc path, and an impedance transformer 210 connected between the three paths. The composite path has a first end a1 and a second end a2, and is configured to transmit a composite signal that is a composite signal (DC + RF) of a radio frequency signal and a direct current signal. The dc path has a first end b1 and a second end b2, and is configured to transmit a dc signal contained in the composite signal. The radio frequency path has a first end c1 and a second end c2, and is configured to transmit a radio frequency signal contained in the composite signal.

The impedance transformer connection 210 is between the first end a1 of the composite path, the first end b1 of the dc path, and the first end c1 of the radio frequency path, and is configured such that a reflection coefficient of an RF signal transmitted between the second end a2 of the composite path and the second end c2 of the radio frequency path has at least two resonant modes in an operating frequency band of the RF signal.

It should be noted that the present invention does not limit the direction of signal flow in the T-bias circuit. The T-shaped bias circuit according to the present invention can receive the combined signal at the port a2 of the combined path and output the DC and RF signals from the other two ports b2, c2, respectively, can receive the DC and RF signals at the ports b2, c2, respectively, and output the combined signal DC + RF at the port a2, and can be designed to be adapted to signal bidirectional flow. Therefore, the reflection coefficient of the RF signal transmitted between the second end a2 of the composite path and the second end c2 of the RF path may be determined by the flow direction of the RF signal, for example, when the RF signal flows from the composite path to the RF path, the reflection coefficient is the reflection coefficient of the RF signal from the input end a2 of the composite path to the output end c2 of the RF path, and has at least two resonance modes, i.e., local minima, in the operating frequency band. In other embodiments, the reflection coefficient is a reflection coefficient of the RF signal from the input c2 of the RF path to the output a2 of the composite path when the RF signal flows from the RF path to the composite path, and has at least two resonant modes, i.e., local minima, in the operating band.

In some embodiments, the operating band may be a 2.3-2.7GHz band.

The invention will be described below mainly with reference to a specific impedance converter structure incorporating two resonance modes as an example, but in view of the present disclosure, a person skilled in the art can easily develop other impedance converter structures comprising more than two resonance modes without inventive effort, and those should also be included within the scope of the invention.

Fig. 3 is a more detailed schematic diagram of a T-type bias circuit according to some exemplary embodiments of the present invention.

As shown in fig. 3, the impedance transformer 310 comprises first to third conductive lines 311-313, wherein the first conductive line 311 is connected between the first end a1 of the composite path and the first end b1 of the dc path, the second conductive line 312 is connected between the first end a1 of the composite path and the first end c1 of the rf path, and the third conductive line 313 is connected between the first end c1 of the rf path and the first end b1 of the dc path.

Compared to the prior art structure of fig. 1, the structure of fig. 3 adds a bypass conductive line, so that the path through which the dc signal passes and the rf signal have one more connection point, and there are two parallel branches to each connection point. As a result of this design, the impedance transformer 310 has a closed loop structure. The deficiency of the unity of the impedance transformation using a single branch can be made up by the impedance compensation of the parallel connection of the two branches. For example, at one frequency in the desired operating band, when the dc path presents an inductive impedance at the connection point via one branch, the dc path may be caused to present a capacitive impedance at the connection point via the other branch by adjustment of various parameters (e.g., length) of the other branch. The impedance transformer 310 can cause the dc path to appear open (or nearly open) at one frequency at the connection point a1, and also appear open (or nearly open) at another frequency at the connection point c1, according to the principle of mutual compensation of capacitance and inductance in the microwave circuit. In other words, the impedance transformer 310 may be configured to introduce two resonant modes in a desired radio frequency band, such that there is a smaller reflection coefficient over a wider frequency band between the two resonant frequencies. In some embodiments, to achieve a higher operating bandwidth, the impedance transformer 310 may include additional connected conductive lines, thereby introducing more branches to compensate for the impedance matching limitations of a single branch, as will be discussed in detail later in connection with fig. 5-7. In some embodiments, by adjusting the length of the cables of the two branches, the capacitance or the inductance of the impedance presented via the two branches can be alternated.

as shown in fig. 3, the first conductive line 311 forms a first branch connected between the composite path and the dc path, the second conductive line 312 and the third conductive line 313 together form a second branch connected between the composite path and the dc path, and the two branches may be designed such that the dc path presents a capacitive impedance and an inductive impedance at the first end a1 of the composite path via the two branches, respectively. Any branch connecting the composite path and the dc path may present a capacitive impedance and the other branch may present an inductive impedance, as long as the capacitive impedances compensate each other so that the effect of the dc path at point a1 is as equivalent as an open circuit (i.e., causing resonance) as possible at the desired frequency point.

In addition, the third conductive line 313 forms a first branch connected between the dc path and the radio frequency path, the first conductive line 311 and the second conductive line 312 together form a second branch connected between the dc path and the radio frequency path, and the two branches may be arranged such that the dc path presents a capacitive impedance and an inductive impedance at the first end c1 of the radio frequency path via the two branches, respectively. Any branch connecting the dc path and the rf path may present a capacitive impedance and the other branch may present an inductive impedance, as long as the capacitive impedances compensate each other such that the effect of the dc path at point c1 at the desired frequency point is equivalent to an open circuit as much as possible.

the parameters of the three conductive lines 311 and 313 can be designed according to practical application by various ways such as theoretical formula, experience, experiment, simulation software, etc.

Note that the curves in fig. 3 are merely schematic and are not intended to define or limit the shape of the respective conductive lines.

In some embodiments, the three paths and the first to third conductive lines are microstrip transmission lines or stripline transmission lines.

fig. 4A is a schematic plan view of a specific example of implementing the T-type bias circuit in fig. 3 with a microstrip transmission line.

Although not shown in the drawings, it will be understood by those skilled in the art that the microstrip transmission line of fig. 4A may further include an electrically insulating substrate and a conductive ground member, wherein the conductive ground member is disposed on one side of the electrically insulating substrate, and the metal pattern shown in fig. 4A is disposed on the other side of the electrically insulating substrate. Note that the synthesized path, the dc path, the rf path, and the shapes, lengths, widths, etc. of the first to third conductive lines 411 and 413 in fig. 4A are merely exemplary and are not intended to limit the present invention.

Fig. 4B is a graph comparing the return loss performance (in dB) of the conventional T-type bias circuit of fig. 1 (curve 401) and the T-type bias circuit of fig. 4A (curve 402) according to an embodiment of the present invention. Curves 401 and 402 show the return loss of the simulated RF signal from the composite path to the radio frequency path, which is merely exemplary and is primarily intended to visually compare the shape of the return loss curves for two different configurations, and is not intended to show specific values. Those skilled in the art will understand that the return loss RL is 20lg (Rho) dB, where Rho is the magnitude of the reflection coefficient, and therefore the return loss curve indicates the magnitude of the reflection coefficient.

as can be seen from the curve 401 in fig. 4B corresponding to the prior art T-bias circuit of fig. 1, the return loss has only one resonant mode, and has an appropriate value only in a narrow band around the resonant frequency, and thus a narrow operating band. On the contrary, as can be seen from the curve 402 corresponding to the T-type bias circuit of the embodiment of the present invention, the return loss thereof has a resonant mode near the 2.3GHz and 2.6GHz frequencies, and is at a local minimum, and the curve between the two resonant frequencies presents a flatter depression, so the T-type bias circuit according to the embodiment of the present invention has a smaller reflection coefficient at least on the frequency band between the two resonant frequencies, thereby widening the operating frequency band.

As mentioned before, more branches can be introduced in the impedance converter of fig. 3 in order to obtain a larger operating bandwidth.

in some embodiments, the impedance converter according to the present invention may further comprise a fourth conductive line, wherein one end of the fourth conductive line is connected to the first end of the dc path and the other end is connected to the first end of the composite path or the first end of the rf path. In other embodiments, one end of the fourth conductive line may be connected to the first end of the dc path and the other end is connected to a point other than the end on any one of the first to third conductive lines. In still other embodiments, both ends of the fourth conductive line may be connected to a point other than the ends on any two of the first to third conductive lines, respectively. Of course, it will be understood by those skilled in the art that the present invention is not limited to the above-described structure, and more conductive wires may be added to the impedance converter as needed.

Fig. 5-7 are schematic diagrams of some examples of the above-described modified configurations of the T-bias circuit of fig. 3, respectively.

As shown in fig. 5, a conductive line 514 is added between the first end a1 of the composite path and the first end b1 of the dc path.

As shown in fig. 6, a conductive line 614 is added between the first end b1 of the dc path and a non-end point on the second conductive line 612. Thus, the connection points of the direct current path and the path through which the RF signal passes become three, and resonance modes can be introduced at three different frequencies, thereby further widening the operating band.

As shown in fig. 7, a conductive line 714 is added between a non-end point on the first conductive line 711 and a non-end point on the third conductive line 713.

The magnitude of the reflection coefficient of the RF signal and the operating frequency band can be further optimized by designing the shape, length, position of the connection point, etc. of each of the conductive lines in fig. 5-7.

note that the impedance converter according to the embodiments of the present invention is not limited to the types and structures discussed above as long as the impedance converter can introduce at least two resonance modes within the operating frequency band.

it should be noted that although the background art refers to implementing the T-shaped bias circuit on a calibration board for a base station antenna, the T-shaped bias circuit of the present invention may also be applied elsewhere within the antenna, such as on a feed back board or a phase shifter printed circuit board, or on its own printed circuit board.

Fig. 8 illustrates one scenario of implementing a T-bias circuit on a calibration board according to some exemplary embodiments of the present invention.

As shown in fig. 8, the calibration board for the base station antenna is a PCB board, which includes the T-shaped bias circuit, the calibration port, the dc bias port, the power divider, and the plurality of couplers shown in fig. 4A. The Remote Electrical Tilt (RET) unit shown in fig. 8 is not part of the calibration board, but refers to an actuator unit included in the antenna for adjusting electromechanical phase shifters included in the antenna, which are used to change the electrical downtilt of the antenna beam produced by the antenna.

In some embodiments, one end of the synthesis path in the T-bias circuit may be connected to a calibration port, and a calibration signal may be input as the synthesis signal. One end of the rf path is connected to the input terminal of the power divider, and outputs the rf signal to the power divider, which then divides the rf signal to each coupler. One end of the dc path is connected to the dc bias port and outputs a dc supply signal for powering the RET unit. Therefore, it is possible to simultaneously input the DC signal and the RF signal without interfering with each other with only one cable, and the T-type bias circuit according to the present invention extends the operating frequency band of the transmitted RF signal.

Note that 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 "coupled" together. Unless expressly stated otherwise, "coupled" 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, to "couple" is intended to include both direct and indirect joining of elements or other features, including connection with 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, the invention is not limited by any expressed or implied theory presented in the preceding technical field, background, utility model content, or 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, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

in addition, embodiments of the present invention may further include the following examples:

1. a T-bias circuit, comprising:

a composite path having a first end and a second end and configured to transmit a composite signal, the composite signal comprising a combination of a radio frequency signal and a direct current signal,

a radio frequency path having a first end and a second end and configured to transmit a radio frequency signal contained in the composite signal,

a DC path having a first end and a second end and configured to transmit a DC signal contained in the composite signal, an

an impedance transformer connected between the first end of the composite path, the first end of the radio frequency path and the first end of the direct current path and configured such that a reflection coefficient of the radio frequency signal transmitted between the second end of the composite path and the second end of the radio frequency path has at least two resonant modes in a radio frequency band of operation.

2. The T-bias circuit of claim 1, wherein the impedance transformer includes first through third conductive lines, wherein the first conductive line is connected between the first end of the composite path and the first end of the dc path, the second conductive line is connected between the first end of the composite path and the first end of the rf path, and the third conductive line is connected between the first end of the rf path and the first end of the dc path.

3. The T-bias circuit of claim 2, wherein the first conductive line forms a first branch connected between the composite path and the dc path,

The second conductive line and the third conductive line together form a second branch connected between the composite path and the dc path,

the first and second branches are arranged such that the dc path presents one of an inductive and a capacitive impedance at the first end of the composite path via the first branch and the other of an inductive and a capacitive impedance at the first end of the composite path via the second branch.

4. The T-bias circuit of claim 3, wherein the third conductive line forms a first branch connected between the DC path and the RF path,

the first conductive line and the second conductive line together form a second branch connected between the dc path and the rf path,

The first and second branches are arranged such that the dc path presents one of an inductive and a capacitive impedance at the first end of the radio frequency path via the first branch and the other of an inductive and a capacitive impedance at the first end of the radio frequency path via the second branch.

5. the T-bias circuit of claim 2, wherein the impedance transformer further comprises a fourth conductive line, wherein one end of the fourth conductive line is connected to the first end of the dc path and the other end is connected to the first end of the composite path or the first end of the rf path.

6. The T-bias circuit of claim 2, wherein the impedance transformer further comprises a fourth conductive line, wherein one end of the fourth conductive line is connected to the first end of the dc path and the other end is connected to a point other than the end on any one of the first through third conductive lines.

7. The T-bias circuit of claim 2, wherein the impedance transformer further comprises a fourth conductive line, wherein both ends of the fourth conductive line are connected to a point other than the ends of any two of the first through third conductive lines, respectively.

8. the T-bias circuit of claim 2, wherein the first through third conductive lines are all microstrip transmission lines or stripline transmission lines.

9. The T-bias circuit of claim 1, wherein said operating radio frequency band is 2.3-2.7 GHz.

10. The T-bias circuit of claim 1, wherein the combining path is configured to input a combined signal from a second end of the combining path,

The radio frequency path is configured to output the radio frequency signal included in the composite signal from a second end of the radio frequency path,

The DC path is configured to output the DC signal contained in the composite signal from a second end of the DC path, an

The impedance transformer is configured such that a reflection coefficient of the radio frequency signal output from the radio frequency path has at least two resonant modes in a frequency band of operation.

11. The T-bias circuit of claim 1, wherein the RF path is configured to input the RF signal from a second end of the RF path,

The DC path is configured to input the DC signal from a second end of the DC path,

The synthesis path is configured to output the synthesized signal obtained by synthesizing the radio frequency signal and the direct current signal from a second end of the synthesis path, an

The impedance transformer is configured such that a reflection coefficient of the radio frequency signal in the synthesized signal output from the synthesis path has at least two resonance modes in a frequency band of operation.

12. A calibration plate for a base station antenna, comprising:

The T-bias circuit of any one of claims 1-11,

The calibration of the ports is carried out by means of,

a DC bias port, and

The power divider is used for dividing the power into a plurality of power components,

wherein a second end of a synthesis path in the T-shaped bias circuit is connected to the calibration port and is configured to input a calibration signal as the synthesis signal,

A second end of the radio frequency path is connected to an input of the power divider and configured to output the radio frequency signal to the power divider,

A second end of the dc path is connected to the dc bias port and is configured to output the dc signal for driving RET.

13. A T-bias circuit, comprising:

a DC port;

a radio frequency port;

A composition port; and

An impedance transformer configured to pass a direct current signal received at the combining port to the direct current port and to substantially prevent a radio frequency signal received at the combining port from passing to the direct current port, and configured to pass a radio frequency signal received at the combining port to the radio frequency port and to substantially prevent a direct current signal received at the combining port from passing to the radio frequency port,

Wherein the impedance transformer comprises a closed loop connecting the composite port to both the dc port and the rf port.

14. The T-bias circuit of claim 13, further comprising:

a composition path connecting the composition port to the closed loop;

a radio frequency path connecting the radio frequency port to the closed loop; and

A DC path connecting the DC port to the closed loop.

15. the T-bias circuit of claim 14, wherein the closed loop comprises first through third conductive lines, wherein the first conductive line is connected between a first intersection of the composite path and the closed loop and a second intersection of the dc path and the closed loop, wherein the second conductive line is connected between the first intersection of the composite path and the closed loop and a third intersection of the rf path and the closed loop, and wherein the third conductive line is connected between the second intersection of the dc path and the closed loop and the third intersection of the rf path and the closed loop.

16. The T-bias circuit of claim 15, wherein the first conductive line comprises a first branch of the closed loop and the combination of the second conductive line and the third conductive line comprises a second branch of the closed loop, an

Wherein the first and second legs are arranged such that the direct current path presents one of an inductive and a capacitive impedance at the first intersection of the composite path and the closed loop via the first leg and the other of an inductive and a capacitive impedance at the first end of the composite path via the second leg.

although some specific embodiments of the present invention have been described in detail by way of illustration, it should be understood by those skilled in the art that the above illustration is only for purposes of illustration and is not intended to limit the scope of the invention. The embodiments disclosed herein may be combined in any combination without departing from the spirit and scope of the present invention. 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 invention. The scope of the invention is defined by the appended claims.

Claims (16)

1. A T-bias circuit, comprising:

a composite path having a first end and a second end and configured to transmit a composite signal, the composite signal comprising a combination of a radio frequency signal and a direct current signal,

A radio frequency path having a first end and a second end and configured to transmit a radio frequency signal contained in the composite signal,

a DC path having a first end and a second end and configured to transmit a DC signal contained in the composite signal, an

an impedance transformer connected between the first end of the composite path, the first end of the radio frequency path and the first end of the direct current path and configured such that a reflection coefficient of the radio frequency signal transmitted between the second end of the composite path and the second end of the radio frequency path has at least two resonant modes in a radio frequency band of operation.

2. The T-bias circuit of claim 1 wherein said impedance transformer includes first through third conductive lines, wherein a first conductive line is connected between a first end of said composite path and a first end of said dc path, a second conductive line is connected between a first end of said composite path and a first end of said rf path, and a third conductive line is connected between a first end of said rf path and a first end of said dc path.

3. The T-bias circuit of claim 2, wherein the first conductive line forms a first branch connected between the composite path and the DC path,

The second conductive line and the third conductive line together form a second branch connected between the composite path and the dc path,

The first and second branches are arranged such that the dc path presents one of an inductive and a capacitive impedance at the first end of the composite path via the first branch and the other of an inductive and a capacitive impedance at the first end of the composite path via the second branch.

4. The T-bias circuit of claim 3, wherein the third conductive line forms a first branch connected between the DC path and the RF path,

the first conductive line and the second conductive line together form a second branch connected between the dc path and the rf path,

the first and second branches are arranged such that the dc path presents one of an inductive and a capacitive impedance at the first end of the radio frequency path via the first branch and the other of an inductive and a capacitive impedance at the first end of the radio frequency path via the second branch.

5. The T-bias circuit of claim 2, wherein the impedance transformer further comprises a fourth conductive line, wherein one end of the fourth conductive line is connected to the first end of the dc path and the other end is connected to the first end of the composite path or the first end of the rf path.

6. the T-bias circuit of claim 2, wherein the impedance transformer further comprises a fourth conductive line, wherein one end of the fourth conductive line is connected to the first end of the dc path and the other end is connected to a point on any one of the first through third conductive lines other than the end.

7. the T-bias circuit of claim 2, wherein the impedance transformer further comprises a fourth conductive line, wherein both ends of the fourth conductive line are connected to a point other than the ends of any two of the first through third conductive lines, respectively.

8. The T-bias circuit of claim 2, wherein said first through third conductive lines are each a microstrip transmission line or a stripline transmission line.

9. the T-bias circuit of claim 1, wherein said operating radio frequency band is 2.3-2.7 GHz.

10. The T-bias circuit of claim 1, wherein the synthesis path is configured to input a synthesized signal from a second end of the synthesis path,

The radio frequency path is configured to output the radio frequency signal included in the composite signal from a second end of the radio frequency path,

the DC path is configured to output the DC signal contained in the composite signal from a second end of the DC path, an

The impedance transformer is configured such that a reflection coefficient of the radio frequency signal output from the radio frequency path has at least two resonant modes in a frequency band of operation.

11. The T-bias circuit of claim 1, wherein the radio frequency path is configured to input the radio frequency signal from a second end of the radio frequency path,

the DC path is configured to input the DC signal from a second end of the DC path,

The synthesis path is configured to output the synthesized signal obtained by synthesizing the radio frequency signal and the direct current signal from a second end of the synthesis path, an

The impedance transformer is configured such that a reflection coefficient of the radio frequency signal in the synthesized signal output from the synthesis path has at least two resonance modes in a frequency band of operation.

12. A calibration plate for a base station antenna, comprising:

the T-bias circuit of any of claims 1-11,

The calibration of the ports is carried out by means of,

a DC bias port, and

the power divider is used for dividing the power into a plurality of power components,

wherein a second end of a synthesis path in the T-shaped bias circuit is connected to the calibration port and is configured to input a calibration signal as the synthesis signal,

A second end of the radio frequency path is connected to an input of the power divider and configured to output the radio frequency signal to the power divider,

a second end of the dc path is connected to the dc bias port and is configured to output the dc signal for driving RET.

13. a T-bias circuit, comprising:

a DC port;

A radio frequency port;

A composition port; and

An impedance transformer configured to pass a direct current signal received at the combining port to the direct current port and to substantially prevent a radio frequency signal received at the combining port from passing to the direct current port, and configured to pass a radio frequency signal received at the combining port to the radio frequency port and to substantially prevent a direct current signal received at the combining port from passing to the radio frequency port,

Wherein the impedance transformer comprises a closed loop connecting the composite port to both the dc port and the rf port.

14. The T-bias circuit of claim 13, further comprising:

A composition path connecting the composition port to the closed loop;

a radio frequency path connecting the radio frequency port to the closed loop; and

a DC path connecting the DC port to the closed loop.

15. the T-bias circuit of claim 14, wherein the closed loop comprises first through third conductive lines, wherein a first conductive line is connected between a first intersection of the composite path and the closed loop and a second intersection of the dc path and the closed loop, a second conductive line is connected between the first intersection of the composite path and the closed loop and a third intersection of the rf path and the closed loop, and a third conductive line is connected between the second intersection of the dc path and the closed loop and the third intersection of the rf path and the closed loop.

16. The T-bias circuit of claim 15, wherein the first conductive line comprises a first branch of the closed loop, and the combination of the second conductive line and the third conductive line comprises a second branch of the closed loop, and

Wherein the first and second legs are arranged such that the direct current path presents one of an inductive and a capacitive impedance at the first intersection of the composite path and the closed loop via the first leg and the other of an inductive and a capacitive impedance at the first end of the composite path via the second leg.