WO2015042974A1

WO2015042974A1 - Broadband phase shifter and broadband beam-forming network

Info

Publication number: WO2015042974A1
Application number: PCT/CN2013/084760
Authority: WO
Inventors: 张关喜; 赵建平; 谢中山
Original assignee: 华为技术有限公司
Priority date: 2013-09-30
Filing date: 2013-09-30
Publication date: 2015-04-02
Also published as: CN103947037A

Abstract

Provided are a broadband phase shifter and a broadband beam-forming network. The broadband phase shifter comprises a dielectric material board, a ground board and a micro-strip transmission line, wherein the ground board and the micro-strip transmission line are respectively located at the two sides of the dielectric material board, the ground board is grounded, and the two ends of the micro-strip transmission line are an input port and an output port of the broadband phase shifter, respectively. The micro-strip transmission line comprises at least one open-circuit branch or short-circuit branch. The broadband phase shifter and the broadband beam-forming network provided in the embodiments of the present invention are used for realizing the broadband of a phase shifter and the broadband of a beam forming network.

Description

Wideband phase shifter and wideband beam-explicable network

Technical field

Embodiments of the present invention relate to wireless communication technologies, and in particular, to a wideband phase shifter and a broadband beam-based adaptive network. Background technique

With the development of wireless communication technologies, wireless communication devices need to transmit more and more data, so wireless communication devices are required to operate at a wider bandwidth. Accordingly, the antennas of wireless communication devices also need to support wider bandwidth.

In the prior art wireless communication devices, such as base stations, the antenna is fed by a multi-beam shaped feed network, and the multi-beam adaptive feed network is composed of a phase shifter and a hybrid orthogonal network. The phase shifter in the prior art multi-beam adaptive feeding network is a narrow-band phase shifter, which results in a multi-beam adaptive feeding network exhibiting a narrow-frequency characteristic, so that the antenna of the wireless communication device also exhibits a narrow-frequency characteristic. Summary of the invention

Embodiments of the present invention provide a wideband phase shifter and a wideband beam-explicable network for implementing broadbandization of a phase shifter and widening of a beam-explicable network.

A first aspect provides a broadband phase shifter comprising a dielectric material board, a floor and a microstrip transmission line, the floor and the microstrip transmission line are respectively located on two sides of the dielectric material board, the floor is grounded, the micro The two ends of the strip transmission line are respectively an input port and an output port of the wideband phase shifter; the microstrip transmission line includes at least one open branch or shorted stub.

In a first possible implementation of the first aspect, the microstrip transmission line includes two open branches or shorted branches.

In conjunction with the first aspect or the first possible implementation of the first aspect, in a second possible implementation, the open branch or shorted branch is in an "L" shape.

In conjunction with the first aspect, the possible implementation of the second possible implementation of the first aspect, in a third possible implementation, the length of the open stub is one-half wavelength.

Combining the first aspect to any one of the possible implementations of the second possible implementation of the first aspect In a fourth possible implementation manner, the length of the short-circuiting branch is a quarter wavelength. A second aspect provides a wideband beam-exclusive network comprising a wideband phase shifter and a broadband orthogonal hybrid network as described in any of the possible implementations of the first aspect.

The wideband phase shifter and the wideband beam-explicative network provided by the embodiments of the present invention change the phase change law in the microstrip transmission line by adding a short-circuit branch or an open branch in the uniform microstrip transmission line, thereby realizing a wide frequency band. The purpose of phase shifting within. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description of the drawings used in the embodiments or the prior art description will be briefly described below. Obviously, the drawings in the following description It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any inventive labor.

Figure 1 is a frequency-phase graph of a conventional microstrip phase shifter;

2A and FIG. 2B are schematic structural diagrams of Embodiment 1 of a wideband phase shifter according to an embodiment of the present invention;

2C is a 50 Ω uniform transmission microstrip line compared with the wideband phase shifter shown in FIG. 2B; FIG. 2D is a frequency-phase difference curve of the wideband phase shifter shown in FIG. 2B and the microstrip transmission line shown in FIG. 2C. Figure

FIG. 2 is a schematic structural diagram of another embodiment of a wideband phase shifter according to an embodiment of the present invention; FIG. 3A to FIG. 3C are schematic structural diagrams of Embodiment 2 of a wideband phase shifter according to an embodiment of the present invention;

3D is a frequency-phase difference diagram of the wideband phase shifter shown in FIG. 3A and the wideband phase shifter shown in FIG. 3B, the wideband phase shifter shown in FIG. 3A, and the microstrip line shown in FIG. 3C;

4 is a schematic structural diagram of a broadband beam-based adaptive network according to an embodiment of the present invention;

Figure 5 is a frequency-attenuation curve of the wideband beam-explicable network shown in Figure 4;

6 is a frequency-phase graph of the wideband beam-explicable network of FIG. 4. The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is apparent that the described embodiments are a part of the embodiments of the invention, rather than all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

The wideband phase shifter provided by the embodiment of the invention is a phase shifter based on a microstrip line design. In the conventional phase shifter design idea, one branch is a 50 Ω uniform transmission line, and the other branch has a nonlinear phase, By changing the length of the 50 Ω uniform transmission line, a certain amount of phase shift can be obtained compared to the two branches. This conventional phase shifter performs better at the center frequency, but the farther the phase shift performance is from the center frequency, the greater the bandwidth characteristics.

In a wireless communication system, the characteristic impedance of the components is generally 50 Ω. Therefore, the parameters of the phase and attenuation of the electromagnetic wave signal in a uniform transmission line with a characteristic impedance of 50 Ω are linear, for example, a length of / 2 is 50. The Ω uniform transmission line can have a phase shift of 180° at the frequency of / = c / zl, and the phase difference varies linearly with frequency in the frequency band near the frequency point. Therefore, the conventional phase shifter can achieve phase shifting by changing the length of the 50 Ω uniform transmission line, and broadband cannot be realized.

Figure 1 is a frequency-phase plot of a conventional microstrip phase shifter with a center frequency of 2.2 GHz and curve 11 a frequency-phase curve of a branch with a phase shift value of -67.5 ° phase shift. Fig., curve 12 is a frequency-phase curve of a branch with a phase shift value of -22.5 ° phase shift. It can be seen from Fig. 1 that at the center frequency of 2.2 GHz, the phase shifter can reach the designed phase shift amplitude, but the phase shifting performance of the phase shifter gradually deteriorates as it deviates from the center frequency. It can be obtained from curve 11. When the frequency is 1.7 GHz, the phase shift value of the phase shifting branch with a phase shift value of -67.5 ° is designed to be about -52.5 °. When the frequency is 2.7 GHz, the phase shift value of the design is -67.5 °. The phase shift value of the phase shifting branch is about -82.5 °, and the peak-to-peak error of the phase shift value reaches 30° in the 1.7 GHz to 2.7 GHz band. It can be obtained from curve 12 that when the frequency is 1.7 GHz, the phase shift value of the phase shifting branch with a phase shift value of -22.5 ° is designed to be about -17.5 °, and when the frequency is 2.7 GHz, the phase shift value of the design is -67.5 °. The phase shift value of the phase shifting branch is about -27.5 °, and the peak-to-peak error of the phase shift value also reaches 10 ° in the 1.7 GHz to 2.7 GHz band. It can be seen that the conventional microstrip phase shifter does not have broadband performance, so the beam-based adaptive network composed of the conventional microstrip phase shifter does not have wide-band performance.

2A and FIG. 2B are schematic structural diagrams of a first embodiment of a wideband phase shifter according to an embodiment of the present invention, wherein FIG. 2A is a cross-sectional view of a wideband phase shifter according to an embodiment of the present invention. As shown in FIG. 2A, the present invention is implemented. The broadband phase shifter provided by the example is a microstrip line structure, including a dielectric material plate 21 and a floor 22 And the microstrip line 23, the floor 22 and the microstrip line 23 are respectively located on both sides of the dielectric material sheet 21, thus forming a microstrip line structure. The material of the dielectric material sheet 21 is not limited, and its dielectric constant is not limited. In order to form the microstrip line structure, the floor 22 needs to cover one side of the dielectric material sheet 21 and be grounded. The specific structure of the microstrip line 23 is as shown in Fig. 2B.

Since the phase of the electromagnetic wave signal is 360°, the phase shift value of the phase shifter is a relative concept. To illustrate the wideband phase shifter shown in Fig. 2B, it is necessary to introduce a microstrip line to be compared with it. Figure 2C is a 50 Ω uniform transmission microstrip line compared to the wideband phase shifter shown in Figure 2B. In the RF portion of the communication system, typically a 50 Ω transmission system, Figure 2C shows a 50 Ω uniform transmission microstrip. The cross-sectional structure of the line is as shown in FIG. 2A. The two ends of the microstrip line 201 are the input port 202 and the output port 203 of the microstrip transmission line respectively. According to the input port 202 and the output port 203 of the reciprocal theoretical microstrip line 201, exchange. The wideband phase shifter shown in Fig. 2B includes a microstrip line 204. The two ends of the microstrip line 204 are respectively an input port 205 and an output port 206 of the wideband phase shifter, which are also interchangeable according to the reciprocity theory. A short-circuit stub 207 is disposed in the middle of the microstrip line 204. The short-circuit stub 207 is a microstrip line. One end of the short-circuit stub 207 is connected to the microstrip line 204 and the other end is grounded.

The shorting stub 207 and the microstrip line 204 have a "T" shape, and the addition of the shorting stub 207 on the microstrip line 204 can create discontinuities on the microstrip line 204, thereby changing the phase from the input port 205 to the output port 206. The law of variation makes the phase change law from the input port 205 to the output port 206 slow, thereby achieving the purpose of phase shifting over a wider frequency band. The phase value from input port 205 to output port 206 can be varied by adjusting the length and line width of shorting stub 207. The wideband phase shifter shown in Fig. 2B achieves a phase shift of -45 ° compared to the microstrip line shown in Fig. 2C.

2D is a frequency-phase difference diagram of the wideband phase shifter shown in FIG. 2B and the microstrip transmission line shown in FIG. 2C. The center frequency of the wideband phase shifter shown in FIG. 2B is 2.2 GHz, and the curve 211 is shown in the figure. A plot of the difference between the phase from input port 205 to output port 206 and the phase from input port 202 to output port 203 as a function of frequency. As can be seen from the curve 211 in the figure, the wideband phase shifter shown in Fig. 2B achieves a phase shift of -45 ° in the 1.7 GHz to 2.7 GHz band, and the phase shift peak-to-peak error is less than 1.5 °. It can be seen that the wideband phase shifter shown in Figure 2B achieves a phase shift of -45 ° in the 1.7 GHz to 2.7 GHz band.

The shorting stub 207 shown in FIG. 2B is a section of the microstrip line of the "L" shape, but the shape of the shorting branch 207 is not limited thereto. For example, the shorting branch 207 may also be a section perpendicular to the microstrip line 204. With a line, or other shape. However, the "L" shaped shorting stub 207 shown in FIG. 2B saves the longitudinal dimension of the wideband phase shifter, thereby reducing the size of the entire wideband phase shifter, so that the electrical performance is satisfied, preferably shown in FIG. 2B. "L" shaped short-circuited branch.

In addition, as shown in the wideband phase shifter shown in Fig. 2B, in order to ensure the matching performance, the length of the short-circuiting branch 207 is preferably

2E is another schematic structural diagram of Embodiment 1 of a wideband phase shifter according to an embodiment of the present invention. As shown in FIG. 2E, the wideband phase shifter shown in FIG. 2E and FIG. 2B is different in the microstrip line 204. An open branch 208 is disposed in the middle, and the open branch 208 is a microstrip line. One end of the open branch 208 is connected to the microstrip line 204 and the other end is a free end. The open stub 208 and the microstrip line 204 have a "T" shape, and the addition of the open stub 208 to the microstrip line 204 can also create discontinuities on the microstrip line 204, thereby changing the input port 205 to the output port 206. The phase change law makes the phase change law from the input port 205 to the output port 206 slow, thereby achieving the purpose of phase shifting over a wider frequency band. The phase value from input port 205 to output port 206 can be varied by adjusting the length and line width of open branch 208. The open branch 208 shown in FIG. 2E is a "L" shaped microstrip line, but the shape of the open branch 208 is not limited thereto. For example, the open branch 208 may also be a microstrip line perpendicular to the microstrip line 204. , or other shapes. However, the "L" shaped open stub 208 shown in FIG. 2E saves the longitudinal dimension of the wideband phase shifter, thereby reducing the size of the entire wideband phase shifter, so that the electrical performance is satisfied, preferably as shown in FIG. 2E. "L" shaped open road branch. Further, as the wideband phase shifter shown in Fig. 2E, in order to ensure the matching performance, the length of the open stub 208 is preferably 1/2.

The wideband phase shifter provided in this embodiment achieves the purpose of phase shifting in a wide frequency band by adding a short-circuit branch or an open branch in the uniform microstrip transmission line to change the phase change law in the microstrip transmission line. .

3A to 3C are schematic structural views of a second embodiment of a wideband phase shifter according to an embodiment of the present invention, and the cross-sectional structure of FIG. 3A to FIG. 3C is as shown in FIG. 2A.

FIG. 3A illustrates another wideband phase shifter according to an embodiment of the present invention. As shown in FIG. 3A, the wideband phase shifter includes a microstrip line 301, and the two ends of the microstrip line 301 are respectively shifted by the broadband. The input port 302 and the output port 303 of the device are interchangeable according to the reciprocity theory. A short-circuit branch 304 and a short-circuit branch 305 are disposed in the middle of the microstrip line 301. The short-circuit branch 204 and the short-circuit branch 305 are respectively a microstrip line, and the short-circuit branch 304 and the short-circuit branch 305 have one end connected to the microstrip line 301, and another One end is grounded.

The short-circuiting branch 304 and the short-circuiting branch 305 and the microstrip line 301 each have a "T"-shaped structure, and the addition of the short-circuiting branch 304 and the short-circuiting branch 305 on the microstrip line 301 can cause discontinuity on the microstrip line 301, thereby changing the The phase change rule of the input port 302 to the output port 303 makes the phase change law from the input port 302 to the output port 303 slow, thereby achieving the purpose of phase shifting over a wider frequency band. The phase value from input port 302 to output port 303 can be varied by adjusting the length and line width of shorting stub 304 and shorting stub 305. By setting the shorting branch section 304 and the shorting branch section 305 to different lengths and line widths, the shorting branch section 304 and the shorting branch section 305 can respectively generate different phase shifting values, and the phase shifting value of the entire wideband phase shifter is the shorting branch section 304 and the short circuit. The sum of the phase shift values produced by branch 305.

The wideband phase shifter shown in Fig. 3B includes a microstrip line 306, which is respectively an input port 307 and an output port 308 of the wideband phase shifter, which are interchangeable according to the reciprocity theory. A short circuit branch 309 is disposed in the middle of the microstrip line 306. The short circuit branch 209 is a microstrip line. One end of the short circuit branch 309 is connected to the microstrip line 306 and the other end is grounded. The wideband phase shifter shown in Fig. 3B has the same structure as the wideband phase shifter shown in Fig. 2B, and both are provided with a shorting stub on a microstrip line.

Figure 3C is a section of a 50 Ω uniform transmission microstrip line as compared to the wideband phase shifter of Figure 3A, including a microstrip line 310 having input ports 311 and output ports 312, respectively.

Since the phase shifter phase shifts the electromagnetic wave signal is a relative concept, the wideband phase shifter shown in Fig. 3A needs to be used in conjunction with the wideband phase shifter shown in Fig. 3B and the microstrip line shown in Fig. 3C. The shorting branch 309 in the wideband phase shifter shown in FIG. 3B is the same as the shorting branch 305 in the wideband phase shifter shown in FIG. 3A, but since there is also a shorting stub 304 in the wideband phase shifter shown in FIG. 3A, The wideband phase shifter shown in FIG. 3B is the same as the insertion loss generated by the wideband phase shifter shown in FIG. 3B, and the microstrip line 306 of the wideband phase shifter shown in FIG. 3B needs to be appropriately extended to make the broadband shift shown in FIG. 3A. The phase loss generated by the phaser is the same, and the phase difference of the wideband phase shifter shown in Fig. 3A with respect to the wideband phase shifter shown in Fig. 3B is the phase difference produced by the shorting stub 304. Similarly, in order to ensure that the wideband phase shifter shown in FIG. 3A is the same as the insertion loss generated by the microstrip line shown in FIG. 3C, the length of the microstrip line 310 in FIG. 3C needs to be set to be the wideband phase shifter shown in FIG. 3A. The same, and the phase difference of the wideband phase shifter shown in FIG. 3A with respect to the microstrip line shown in FIG. 3C is the sum of the phase differences produced by the shorting stub 304 and the shorting stub 305.

Thus, the wideband phase shifter shown in FIG. 3A, the wideband phase shifter shown in FIG. 3B, and FIG. 3C can be used. The microstrip lines are used at the same time, and the above three structures are arranged on different branches of the system, so that the electromagnetic wave signals have the same signal strength and different phase values after passing through different branches. It can be seen that the wideband phase shifter provided in this embodiment is suitable for use in a beam-explicable network.

In Fig. 3A, the shorting stub 304 produces a phase shift of -22.5 ° and the shorting stub section 305 produces a phase shift of -45 °, i.e., the wideband phase shifter shown in Fig. 3A is compared to the microstrip line shown in Fig. 3C. 67.5 ° phase shift. In Fig. 3B, the shorting stub 309 produces a phase shift of -45 °, i.e., the wideband phase shifter shown in Fig. 3A produces a phase shift of -22.5 ° compared to the wideband phase shifter shown in Fig. 3B; the wideband shift shown in Fig. 3B The phaser produces a phase shift of -45 ° compared to the microstrip line shown in Figure 3C.

3D is a frequency-phase difference diagram of the wideband phase shifter shown in FIG. 3A and the wideband phase shifter shown in FIG. 3B, the wideband phase shifter shown in FIG. 3A, and the microstrip line shown in FIG. 3C, FIG. 3A and FIG. 3B. The wideband phase shifter shown has a center frequency of 2.2 GHz. Curve 321 shows a plot of the difference between the phase from input port 307 to output port 308 and the phase from input port 302 to output port 303 as a function of frequency. 322 represents a plot of the difference between the phase from input port 311 to output port 312 and the phase from input port 302 to output port 303 as a function of frequency. As can be seen from the curve 321 in the figure, the wideband phase shifter shown in Fig. 3A achieves a phase shift of -22.5 ° in the 1.7 GHz to 2.7 GHz band compared to the wideband phase shifter shown in Fig. 3B, and shifts. The peak-to-peak error is less than 3 °; as can be seen from curve 322 in the figure, the wideband phase shifter shown in Figure 3A is implemented in the 1.7 GHz to 2.7 GHz band, compared to the microstrip line shown in Figure 3C. 67.5 ° phase shift, and phase shift peak-to-peak error is less than 4. The short-circuit branch 304, the short-circuit branch 305, and the short-circuit branch 309 shown in FIGS. 3A and 3B are all "L"-shaped microstrip lines, but short-circuited branches The shape of the short circuit branch 305 and the short circuit branch 309 is not limited thereto. For example, the short circuit branch 304, the short circuit branch 305 and the short circuit branch 309 may also be a microstrip line perpendicular to the microstrip line 301 or the microstrip line 306, or Other shapes. However, the "L" shaped shorting stubs 304, the shorting stubs 305 and the shorting stubs 309 shown in Figures 3A and 3B save the longitudinal dimension of the wideband phase shifter, thereby reducing the size of the entire wideband phase shifter and thus satisfying On the premise of electrical performance, the "L" shaped short-circuiting branches shown in Figs. 3A and 3B are preferred.

In addition, as the wideband phase shifter shown in Figs. 3A and 3B, in order to ensure the matching performance, the lengths of the short circuit branch 304, the short circuit branch 305 and the short circuit branch 309 are preferably

Further, in the wideband phase shifter shown in FIG. 3A and FIG. 3B, the short-circuiting branch 304, the short-circuiting branch 305, and the short-circuiting branch 309 can also be implemented by an open branch, an implementation method of the open branch and The principle is similar to that in Figure 2E, and will not be described here. It should be noted that, in order to ensure matching performance, the length of the open branch is preferably

Further, the wideband phase shifter shown in Fig. 3A adopts a form in which two short-circuited branches are connected in series, but the wideband phase shifter provided by the present invention can also be implemented in the form of a short-circuited branch section connected in series with an open-circuit branch.

The wideband phase shifter provided by the embodiment of the present invention is not limited to the manner of providing a short circuit or an open branch on a microstrip line provided in the above embodiment, and is not limited to setting two short circuits or open branches on a microstrip line. the way. By adopting the same idea as the above embodiment, two or more short-circuit or open-circuit branches are arranged on a micro-strip line, and broadband phase shifting can also be realized, and multiple phase-shifting angles can be provided, since the implementation principle is similar to the above embodiment. , will not repeat them here.

4 is a schematic structural diagram of a broadband beam-based adaptive network according to an embodiment of the present invention. The broadband beam-forming network is a microstrip line structure, and its cross-sectional structure is still as shown in FIG. 2A. As shown in Figure 4, the wideband beam-explicative network includes a wideband phase shifter, a microstrip line, and an orthogonal hybrid network. Wherein, the 3dB coupler 41 can be an orthogonal hybrid network such as a 90° bridge, and the phase shifter 42 to the phase shifter 45 can be implemented by using a wideband phase shifter as shown in FIGS. 3A and 3B, and the phase shifter 42. The microstrip line 46 connected to the 3dB coupler 41 of the same layer of the phase shifter 45 can be implemented by using the microstrip line shown in FIG. 3C to ensure the insertion loss generated by the phase shifter 42 to the phase shifter 45, and The phase shifter 42 and the phase shifter 45 produce a phase shift of -67.5 ° with respect to the microstrip line 46, causing the phase shifter 43 and the phase shifter 44 to produce a phase shift of -22.5 ° with respect to the microstrip line 46; 47 to the phase shifter 50 can be implemented by using a wideband phase shifter as shown in FIG. 2B, and the microstrip line 51 connecting the 3dB coupler 41 of the same layer as the phase shifter 47 to the phase shifter 50 can adopt the method shown in FIG. 2C. The microstrip line is implemented to ensure that the insertion loss generated by the phase shifter 47 to the phase shifter 50 is uniform, and the phase shifter 47 to the phase shifter 50 are phase-shifted by -45° with respect to the microstrip line 51. Ports 401 through 408 are input ports, and ports 409 through 416 are outputs □.

5 is a frequency-attenuation curve of the wideband beam-explicable network shown in FIG. 4, and FIG. 6 is a frequency-phase curve of the wideband beam-explicable network shown in FIG. Referring to FIG. 5, curves 501 through 508 are frequency-attenuation curves between port 401 and port 409 to port 416, respectively. Since the different paths are required from the port 401 to the port 409 to the port 416, the attenuation values of each path can be made equal by using the wideband phase shifter provided by the embodiment of the present invention. As can be seen from FIG. 5, each strip The attenuation peak-to-peak difference of the path is less than 0.1 dB. Referring again to Figure 6, curves 601 through 608 are frequency-phase curves between port 401 and port 409 to port 416, respectively. It can be seen from FIG. 6 that although the path from port 401 to port 409 to 416 has experienced different paths, the phase change trend is basically the same in the frequency range of 1.7 GHz to 2.7 GHz, and broadbandization of the broadband beam-based adaptive network is realized. .

In FIG. 4, only the wideband beam-forming network of the 8×8 port implemented by the wideband phase shifter provided by the embodiment of the present invention is shown. However, the present invention is not limited thereto, and the wideband phase shifter provided by the embodiment of the present invention may be used. A wideband beam-explicable network that implements any port.

Finally, it should be noted that the above embodiments are only for explaining the technical solutions of the present invention, and are not intended to be limiting thereof; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that The technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

claims

1. A broadband phase shifter, including a dielectric material plate, a floor and a microstrip transmission line, characterized in that: the floor and the microstrip transmission line are located on both sides of the dielectric material plate, and the floor is grounded, so The two ends of the microstrip transmission line are respectively the input port and the output port of the broadband phase shifter; the microstrip transmission line includes at least one open-circuit stub or short-circuit stub.

2. The broadband phase shifter according to claim 1, characterized in that the microstrip transmission line includes two open-circuit stubs or short-circuit stubs.

3. The broadband phase shifter according to claim 1 or 2, characterized in that the open-circuit branches or short-circuit branches are in an "L" shape.

4. The broadband phase shifter according to any one of claims 1 to 3, characterized in that the length of the open-circuit branches is one-half wavelength.

5. The broadband phase shifter according to any one of claims 1 to 3, characterized in that the length of the short-circuit stub is a quarter wavelength.

6. A broadband beam-forming network, characterized by including any one of claims 1 to 5