WO2007073638A1

WO2007073638A1 - A phase shifter for continuous phase modification

Info

Publication number: WO2007073638A1
Application number: PCT/CN2006/000813
Authority: WO
Inventors: Binlong Bu; Fengzhang Xue; Shanqiu Sun; Guoqing Xie; Songdong Fang
Original assignee: Comba Telecom Technology (Guangzhou) Ltd.
Priority date: 2005-12-26
Filing date: 2006-04-26
Publication date: 2007-07-05
Also published as: BRPI0608588A2; CN2859838Y

Abstract

A phase shifter for continuous phase modification, which is used in base-station antenna to adjust beam tilt, includes a metallic cavity and a pair of fixed transmission lines and a movable transmission line in the cavity, said movable transmission line appears U-shape on the whole, one end of each fixed transmission line is provided with a lengthwise slot, two arms of said movable transmission line are respectively set in the slot of each fixed transmission line, wherein, the cross section of the two arms of said movable transmission line both appear rectangle, the cross section of the slot of each fixed transmission line appears one-side-removed rectangular-frame shape. The fixed transmission line is easy to achieve machining or flank stripping at the premise of keeping a whole , moreover, after the cross-section structure is changed from roundness to rectangle, the cross-section structure may be pressed into oblong to reduce the volume of the phase shifter so as to facilitate its use, at the same time, the present invention also can inhibit passive-intermodulation product and avoid from the phenomenon of high-power striking fire.

Description

Phase-variable phase shifter

[Technical Field]

The present invention relates to a phase-variable phase shifter, and more particularly to a phase shifter for a base station antenna to adjust beam tilt.

【technical background】

The base station antenna in the mobile communication system needs to be reasonable in order to optimize the coverage of the radio signal of the own cell, and to suppress the radio interference (referred to as the same-frequency interference) from other cells having the same working frequency (referred to as the same-frequency cell for short). Adjust the beam direction of the vertical plane pattern of the base station antenna so that its pointing angle is appropriately tilted downward in the horizontal direction (also called beam downtilt). Since the range of signal coverage and the situation of co-channel interference are constantly changing in many complicated practical application scenarios, the angle of beam downtilt (also called beam scanning) also needs frequent changes in time and in angular position. On the continuous change, this type of antenna is called a continuously adjustable beam electric down-tilt base station antenna.

The phase shifter is a key component of the continuously adjustable beam electrical down-tilt base station antenna.

It is usually required that a plurality of phase shifters form a continuously variable beamforming network to realize beam electrical downtilt of the base station antenna, and the principle is derived from the well-known phased array radar antenna beam scanning principle. Unfortunately, the phase shifter used in the beamforming network of the phased array radar antenna is a quantized digital phase shifter, which is expensive to manufacture, and the quantized digital phase shifter will bring the pointing deviation of the beam downtilt angle and The angle of the beam downtilt cannot be continuously changed.

In order to realize the function of the beam electric down-tilt base station antenna, the key is to require an inexpensive phase changer with continuously variable phase. In the prior art, a continuous patent is proposed in the 1950 US Patent (US 2,502,359). The changing phase shifter is shown in Figure 1.

Referring to Figure 1: the metal cavity 390 is formed by a plurality of screws 391 secured by two portions 390A and 390B that are mirror-symmetrical to each other. Signals enter the metal cavity 390 from the coaxial connector 304, pass through a fixed transmission line 397, and a movable transmission line. 396. The fixed transmission line 398 reaches the coaxial connector 306. One end of the cylindrical fixed transmission lines 397 and 398 has a hollow ring shape, and both ends of a large "U" type movable transmission line 396 having a cylindrical cross section are inserted into the hollow rings of the fixed transmission lines 397 and 398, respectively. By rotating a drive handle 318, the synchronous rotation of the screw 316 thereon will drive the linear movement of the nut 314 at the right end of the shield block 392, thereby causing the linear movement of the movable transmission line 396 due to the synchronous movement of the dielectric block 392, thereby causing the transmission line. 397, 396, 398 total length change, confirmation Finally, a change in the phase of the transmitted signal between the coaxial connector 304 and the coaxial connector 306 is achieved.

The above continuously variable phase shifters have been modified to make them more practical, as described in U.S. Patent Nos. 3,763,445 and 4,755,778. With continued reference to FIG. 1, the improvement is: adding a medium support structure 302; adding a compensation ring 300 to compensate for the impedance discontinuity transition between the fixed transmission line 397 or 398 and the movable transmission line 396; adding a transmission guide rail 394, positioning and guiding the movement of the transmission block 392 by 394; adding a screw 330 having a terminal 332, when the transmission block 392 moves close to the left end limit position, the spring 332 is compressed to gradually accumulate stress to prevent excessive movement of 318. Damage to the phase shifter; a spring is added to the left side of the guide hole 322. When the right end 310 of the transmission block 392 moves closer to the right end limit position, the spring 328 is compressed by 314 to gradually accumulate stress to prevent excessive movement of the 318 and damage the phase shift. A plurality of longitudinal slits 388 are added to the ends of the fixed transmission line 397 or 398. The slits 388 can be resiliently positioned to provide a better contact between the fixed transmission line 397 or 398 and the movable transmission line 396.

One of the disadvantages of the above phase shifter is that only the slit 388 can produce a certain elasticity, however, in repeated use, it is difficult to ensure good contact between the fixed transmission line 397 or 398 and the movable transmission line 396, and the two metals This non-fastening connection between the two may cause sparking at high power, and it is difficult to avoid passive intermodulation products due to poor contact.

The second disadvantage of the phase shifter described above is that the cylindrical transmission lines 397, 398, and 396 have a larger thickness dimension of the corresponding cavity 390 in order to satisfy a certain impedance characteristic. ·

The third disadvantage of the above phase shifter is: When the phase shifter is applied to a similarly continuously adjustable beam electric down-tilt base station antenna, it is usually necessary to use multiple phase shifter integration at the same time. Thus, due to the structural layout relationship, the cylinder The hollow rings of the transmission lines 397 and 398 are not easy to machine, and the mold production is not convenient for the demolding process.

Examples of the application of the third disadvantage are in the published literature Crone, GAE; Rispoli, R; Wolf, Η·; Clarricoats, PJB; "Technology advances in reconfigurable contoured beam reflector antenna in Europe", Proc. of 13-th AIAA International Conference on Communications Satellite Systems, 1990, pp. 255-263 can be seen: According to the description of Fig. 10 in the above document, the schematic diagram of the structure of a variable power splitter is shown in Fig. 2.

Referring to Fig. 2, the input signal is decomposed from the port 51 through the 54a arm of the splitter 54 to 54b and 54c, and then through the large "U" type phase shifters 55 and 56, respectively, to the 3dB branch line orientation. The two input terminals 58 and 59 of the coupler 57, when a pair of "U" type phase shifters 55 and 56 having the same structure and facing each other move in the same direction, a phase shifter will generate a positive differential phase. The other phase shifter will produce a negative differential phase, so that, according to the well-known microwave network principle, the two outputs 52 and 53 of the branch line directional coupler 57 will eventually achieve a continuous change in the power distribution ratio, and the corresponding phase. The output remains constant. It can be seen that two "U" type phase shifters are used in this example, and correspondingly 54b and 54c or 58 and 59 require integral machining, wherein the hollow ring cross section clearly causes inconvenience in processing.

[Summary of the Invention]

The object of the present invention is to overcome the deficiencies of the prior art described above, and to provide a phase-variable phase shifter capable of realizing continuous phase change, which can be conveniently applied to continuously adjustable while overcoming the above three disadvantages. The beam is electrically tilted down the base station antenna.

The object of the present invention is achieved by the following technical solutions: The phase-variable phase shifter of the present invention comprises a metal cavity and a pair of fixed transmission lines and a movable transmission line located inside the metal cavity, the movable transmission line as a whole" a U"-shaped, one end of each of the fixed transmission lines is provided with a vertically long slot, and the two arms of the movable transmission line are respectively placed in the slots of the fixed transmission lines, wherein the cross sections of the movable transmission lines are rectangular The cross section of each fixed transmission line slot has a rectangular frame shape with only one side removed.

The cross-section of both arms of the movable transmission line is a rectangular shape which is compressed, and correspondingly, the cross section of each fixed transmission line slot has a rectangular frame shape with only one side removed and being flattened. .

In order to ensure the impedance characteristics of the transmission line, the cross section of the movable transmission line is positioned within the fixed transmission line slot and does not protrude beyond the edge of the slot.

Further, the present invention further includes a mechanical transmission device provided with an insulating portion connected to the movable transmission line for continuously moving the movable transmission line to achieve continuous phase change.

In order to ensure that the phase shifter does not produce passive intermodulation products, the movable transmission line is not in contact with the fixed transmission line to maintain signal transmission in a capacitive coupling manner.

The surface of the movable transmission line is coated with a high temperature resistant and high power resistant protective layer, the protective layer being polytetrafluoroethylene.

The fixed transmission line and the movable transmission line are provided with convex portions on upper and lower inner walls of the metal cavity corresponding to the left and right sides parallel to the direction of the transmission signal.

The upper and lower inner wall surface positions of the metal cavity in which the movable transmission line is located are opposite to the fixed position The upper and lower inner wall surfaces of the metal cavity in which the transmission line is located are convex.

Compared with the prior art, the invention has the advantages that: the fixed transmission line is easy to realize mechanical processing under the premise of being kept as a whole, or the slot structure of the rectangular frame shape is removed when the mold process is used, and the side is convenient to realize the side Moreover, after the cross-sectional structure of the transmission line is changed from a circular shape to a rectangular shape, the improvement of the flattening rectangle can be used to reduce the volume of the phase shifter and make it close to use, and the invention can also suppress the passive intermodulation. The product and avoid high power ignition.

[Description of the Drawings]

1 is a schematic structural view of a phase shifter in the prior art;

2 is a schematic plan view showing the structure of a continuously variable power divider in the prior art;

3 is a schematic perspective view of a three-dimensional structure of an embodiment of the present invention, in which only the connection relationship between the fixed transmission line and the movable transmission line and the metal cavity is disclosed;

Figure 4 is a partial schematic view of the section 4-4 of Figure 3, showing the convex portion of the upper and lower surfaces of the metal cavity;

5 is a partial schematic view of a 5- 5 section of FIG. 3, wherein the upper and lower surfaces of the metal cavity are corresponding to the corresponding fixed transmission line at the position corresponding to the movable transmission line;

Figure 6 is a schematic view of a second embodiment of the present invention;

Figure 7 is a schematic view of a third embodiment of the present invention;

Figure 8 is a schematic view of a fourth embodiment of the present invention.

【detailed description】

The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

Referring to FIG. 3, FIG. 4 and FIG. 5, the phase-variable phase shifter of the present invention comprises a metal cavity 400, a pair of fixed transmission lines 411 and 413 located inside the metal cavity 400, a movable transmission line 412, and Mechanical transmission (not shown).

Each of the fixed transmission lines 411, 413 is provided with an elongated slot, and the cross section of the slot has a rectangular frame shape with only one side removed (see FIG. 6), and the remaining portion of the slot The cross section can be round or square, and has the same small "u" shape. The two arms of the movable transmission line 412 are rectangular in cross section, respectively placed in the slots of each of the fixed transmission lines 411, 413, and the cross section of the intermediate section between the arms of the movable transmission line 412 can be Round, rectangular, etc.

Two coaxial joints 401, 402 are disposed on the side walls of the metal cavity 400 with their respective core wires passing through The sidewall of the cavity 400 is connected to one end of the non-arranged slot of the fixed transmission line 411; the core of the coaxial connector 402 is connected to the non-arranged slot of the fixed transmission line 413 after passing through the sidewall of the cavity 400. One end. In addition, by providing a well-known mechanical transmission (not shown in FIG. 3, see FIG. 1), and connecting the predetermined insulating portion of the mechanical transmission to the movable transmission line 412, The movable transmission line 412 can be continuously moved, and the total length of the transmission lines composed of the fixed transmission lines 411, 413 and the movable transmission line can be changed, thereby achieving continuous phase change between the coaxial joint 401 and the coaxial joint 402.

In order to ensure that the impedance characteristic of the transmission line of the movable transmission line 412 in the present invention is equivalent to the performance of the cylindrical transmission line in FIG. 1, the two arms of the movable transmission line 412 need to be positioned on the rectangular frame of the fixed transmission line 411, 413. The small "u" shaped slot is located and the upper edge of the movable transmission line 412 must not protrude above the upper edge of the small "u" shaped slot of the fixed transmission line 411, 413.

In order to suppress the passive intermodulation products of the phase shifter, the movable transmission line 412 and the fixed transmission lines 411, 413 transmit signals by non-contact capacitive coupling.

In order to define the relative position of the movable transmission line 412 and the fixed transmission line 411, 413, and in order to achieve the high power capacity of the phase shifter, a surface of the movable transmission line is coated with a high temperature resistant and high power resistant protective layer, the protective layer A known polytetrafluoroacetone can be used as the dielectric material. Thus, the small "u" type groove size of the fixed transmission lines 411, 413 can be appropriately designed according to the outer contour size of the movable transmission line 412 and the thickness of the protective layer.

Referring to FIG. 4, the fixed transmission line 411, 413 or the movable transmission line 412 is provided with a convex portion 421 on the upper and lower inner walls of the metal cavity 400 on the left and right sides parallel to the direction of the transmission signal, and is convex with respect to the original cavity inner wall position 422. The inner wall position 421 facilitates isolation of signal coupling between the parallel fixed transmission line 411 and the fixed transmission line 413, or, in the case of equivalent signal isolation, the distance between the fixed transmission line 411 and the fixed transmission line 413 can be narrowed, thus, The volume of the cavity 400 can be reduced under the premise of ensuring electrical performance.

Referring to FIG. 5, the upper and lower inner wall surface positions 423 of the metal cavity 400 corresponding to the movable transmission line 412 are raised relative to the upper and lower inner wall surface positions 422 of the metal cavity 400 corresponding to the fixed transmission lines 411, 413, so that The characteristic impedance of the moving transmission line 412 becomes smaller as the cross section becomes smaller, and the impedance characteristic change due to the transition between the fixed transmission line 411, 413 and the movable transmission line 412 is compensated.

Referring to FIG. 6 , which is a second embodiment of the present invention, this embodiment discloses that the fixed frame 411 or the fixed transmission line 413 may be a rectangular frame. On the one side, the rectangular frame in Fig. 4 is removed from the right side, and the left side can also be removed. In Fig. 6, the upper side is removed, and the lower side can be removed in the same manner. The direction of the removed side edges is entirely dependent on the ease of processing of the plurality of phase shifters in a practical application due to the particular structural layout. Obviously, grooving from the outer structural layout to the outside facilitates processing.

Please refer to FIG. 7, which is a third embodiment of the present invention, which is different from the first embodiment (see FIG. 4) in that: the fixed transmission line 411 and the movable transmission line transmission line 412 are both squashed into The rectangular structure, at this time, as long as the right side of the movable transmission line 412 does not exceed the fixed transmission line 411, the right edge of the rectangular frame shape, the phase shifter satisfying the electrical performance requirement can also be designed, and thus, the thickness of the metal cavity 400 H can be further reduced.

A further modification of the structure of the second embodiment disclosed in Fig. 6 forms a fourth embodiment. Referring to Fig. 8, similarly, the transmission lines 411, and 412 are fixed in the thickness H direction of the cavity 400, and are flattened from a square to a rectangle. At this time, as long as the upper side of the movable transmission line 412 in FIG. 8 does not exceed the fixed transmission line 411, and the rectangular frame is a short "u" type upper edge, a phase shifter that satisfies the electrical performance requirement can also be designed. The thickness H of the metal cavity 400 can also be further reduced.

The phase-variable phase shifter constructed by the above embodiment has the characteristics of low passive intermodulation and high power capacity, and has the advantages of simple structure, small size, easy processing, low cost, and can be applied to various working frequency bands. The continuously adjustable beam electric down-tilt base station antenna has wide application value in the cellular mobile communication system.

Claims

Claim

A phase-variable phase shifter comprising a metal cavity (400) and a pair of fixed transmission lines (411, 413) and a movable transmission line (412) located inside the cavity, the movable transmission line (412) The whole is in a "U" shape, and one end of each of the fixed transmission lines (411, 413) is provided with a vertically long slot, and the arms of the movable transmission line (412) are respectively placed in the slots of the fixed transmission lines (411, 413). The second embodiment of the movable transmission line ('412) has a rectangular cross section, and the cross section of each of the fixed transmission lines (411, 413) has one side and only one side is removed. Rectangular frame shape.

The phase-variable phase shifter according to claim 1, wherein: the cross-section of both arms of the movable transmission line (412) is a flattened rectangle, and correspondingly, each of the fixed The cross section at the slot of the transmission line (411, 413) also has a rectangular frame shape with only one side removed and flattened.

3. A phase-continuously variable phase shifter according to claim 2, wherein: said cross section of said movable transmission line (412) is positioned within said slot of said fixed transmission line (411, 413) and Does not protrude from the edge of the slot.

A phase-variable phase shifter according to any one of claims 1 to 3, wherein: the present invention further comprises a mechanical transmission, wherein the mechanical transmission is provided with an insulating portion, the insulating portion and The movable transmission line (412) is connected, and continuously moving the movable transmission line (412) realizes continuous change of phase.

The phase-continuously variable phase shifter according to claim 4, wherein: said movable transmission line (412) is in contact with said fixed transmission line (411, 413) to maintain transmission in a capacitive coupling manner. signal.

6. A phase-continuously variable phase shifter according to claim 5, wherein: the surface of said movable transmission line (412) is coated with a high temperature resistant and high power resistant protective layer. The phase-continuously variable phase shifter according to claim 6, wherein the protective layer is polytetrafluoroethylene.

The phase-continuously variable phase shifter according to claim 7, wherein: said fixed transmission line (411, 413) and said movable transmission line (412) are on the left and right sides parallel to the direction of the transmission signal. A corresponding convex portion (421) is provided on the upper and lower inner walls of the corresponding metal cavity (400).

The phase-continuously variable phase shifter according to claim 8, wherein: the upper and lower inner wall surface positions (423) of the metal cavity (400) where the movable transmission line (412) is located are opposite to The upper and lower inner wall surface positions of the metal cavity (400) where the fixed transmission line (411, 413) is located

(422) Raised. ·