WO2014181239A2 - Longitudinal-displacement passive phase-shifter - Google Patents

Longitudinal-displacement passive phase-shifter Download PDF

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Publication number
WO2014181239A2
WO2014181239A2 PCT/IB2014/061211 IB2014061211W WO2014181239A2 WO 2014181239 A2 WO2014181239 A2 WO 2014181239A2 IB 2014061211 W IB2014061211 W IB 2014061211W WO 2014181239 A2 WO2014181239 A2 WO 2014181239A2
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WO
WIPO (PCT)
Prior art keywords
phase
shifting system
conductive line
dielectric part
moving
Prior art date
Application number
PCT/IB2014/061211
Other languages
French (fr)
Other versions
WO2014181239A3 (en
Inventor
Jean-Pierre Harel
Original Assignee
Alcatel-Lucent Shanghai Bell Co.,Ltd
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Filing date
Publication date
Application filed by Alcatel-Lucent Shanghai Bell Co.,Ltd filed Critical Alcatel-Lucent Shanghai Bell Co.,Ltd
Publication of WO2014181239A2 publication Critical patent/WO2014181239A2/en
Publication of WO2014181239A3 publication Critical patent/WO2014181239A3/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/18—Phase-shifters
    • H01P1/184—Strip line phase-shifters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/30—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array
    • H01Q3/32—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array by mechanical means

Definitions

  • the present invention relates to a phase-shifting system with a longitudinal displacement for applying a phase-shift to radiating elements, or groups of radiating elements.
  • the invention is intended to particularly be used for radiating elements that belong to antennas for base stations of cellular communication networks (GSM, UMTS, etc.), but also for any other type of application that implements phase-shifting.
  • the purpose of phase-shifting is to adjust the direction of an antenna's main lobe, thereby attaining dynamic-tilt antennas, otherwise known as "variable-tilt antennas.” BACKGROUND
  • Base station antennas for telecommunication applications must have a high gain and radiation patterns in the horizontal plane and in the vertical plane that are free from parasitic radiation.
  • the requirements in terms of gain and radiation patterns in the vertical plane depend on the length of the antenna. These parameters are controlled by means of the feed network of the antenna's radiating elements.
  • Variable electric tilt, or VET antennas make it possible to vary the position of the main lobe relative to the horizon.
  • the tilt of the antenna in the vertical plane can be adjusted by different techniques applied to the antenna feed network, using active and/or passive devices, mainly by means of a phase-shifting device.
  • Phase-shifting systems are increasingly passive systems, meaning that they do not comprise any electronic components, making it possible to apply a relative phase differential between different access points of a radiofrequency feed network.
  • devices that use at least two dielectric domains: one domain formed of a solid dielectric material and one domain formed by air or a vacuum, for example.
  • Moving the solid dielectric material relative to the conductive line causes a phase variation.
  • the solid dielectric material is placed so as to cut off lines of current located between the conducting line and a ground plane, i.e. a grounded conducting plane.
  • the current structure of a phase-shifting system comprises parts made of a solid dielectric material that slide transversally, while the control unit is a central cylinder that moves in the axis of the antenna.
  • These additional mechanical parts have a cost.
  • they are sources of mechanical malfunctions, such as friction or clearance in the transmission of the movement (or "backlash"), which are created as a result of adding more mechanical parts and the corresponding tolerance levels.
  • each radiating element of a panel antenna for example, is individually phase-shifted.
  • phase-shifting system is assembled in order to form a single module, which comprises phase-shifters and current splitters.
  • a long case is required to house this module. It is expensive to manufacture and requires special tools for transportation, due to its dimensions.
  • This large case also requires a great deal of volume to be installed on the rear of the chassis of a panel antenna, which is not easy in a context of multiband antennas, in which several of those cases must be placed on the rear of an antenna chassis. Additionally, such a volume complicates and limits the options for assembling panel antennas, as antenna arrays generally have the same length as the chassis of a panel antenna.
  • This assembly into modules also makes repairs more complex: once assembly of the phase-shifting system is complete, it is no longer possible to directly access the components in the back of the feed system of the radiating elements, such as the feed cable connections, without destroying certain parts of the housing, such as the cover.
  • a passive phase-shifting system is proposed, of the type that uses dielectric materials, which is simpler to manufacture, more accessible, and less expensive than known phase-shifting systems.
  • the subject matter of the present invention is a unitary phase-shifting system that comprises at least one conductive feed line comprising an input portion connected to the phase-shifting system, said input portion connected to a source of electrical power, and an output portion connected to the output of the phase-shifting system, said output portion being connected to at least one antenna radiating element to be fed, a fixed dielectric part surrounding the input portion of the conductive line, a moving dielectric part surrounding the output portion of the conductive line, and a control unit rigidly connected to the moving dielectric part, said control unit being capable of longitudinally moving so as to cause the moving dielectric part to move longitudinally along the conductive line.
  • the conductive line comprises an input portion composed of three segments, the surface area of each segment being fixed.
  • the conductive line comprises an output portion composed of three segments, the relative surface area of each segment being variable.
  • the input portion and the output portion of the conductive line each comprise three segments, a central segment that carries out impedance matching and lateral segments respectively surrounded by a first dielectric domain and a second dielectric domain.
  • the first dielectric domain can be the surrounding air
  • the second dielectric domain can be a solid dielectric material chosen from a polymer and a ceramic.
  • the moving dielectric part moves longitudinally parallel to a fixed dielectric part that serves as its guide.
  • a further subject matter of the invention is a method for manufacturing a unitary phase-shifting system comprising the following steps:
  • a first half of the fixed dielectric part is placed near the input of the phase-shifting system and a first half of the moving dielectric part near the output of the phase-shifting system
  • a conductive line is placed on the first halves of the fixed and moving dielectric parts
  • each end of the conductive line is connected respectively to the input of the phase- shifting system and the output of the phase-shifting system
  • the first half of the fixed dielectric part is fastened onto the conductive line
  • a second half of the fixed dielectric part is fastened onto the input portion of the conductive line
  • a second half of the moving dielectric part is fastened onto the output portion of the conductive line
  • the second half of the fixed dielectric part is fastened onto the conductive line.
  • the first halves of the fixed and moving dielectric parts are placed in a housing cover and a housing bottom is placed onto the second halves of the fixed and moving dielectric parts.
  • a further subject matter of the invention is a method for manufacturing a stack of unitary phase-shifting systems comprising the following steps:
  • steps (b) and (c) are repeated as many times as desired
  • control units are placed on the same side of the stack.
  • a further subject matter of the invention is an antenna comprising a phase- shifting system placed inside a housing of which one of the faces is formed by the chassis of the antenna.
  • This simple, inexpensive phase-shifting system has many advantages. In particular, it allows the tilt of a panel antenna in the vertical plane to vary by a range of at least 12°
  • variable electric tilt (VET) panel radio antennas BRIEF DESCRIPTION
  • FIG. 1 illustrates a perspective top view of a unitary phase-shifting system
  • FIG. 2a to 2e illustrate a perspective top view of the steps of producing the phase- shifting system of Figure 1 ,
  • FIG. 3a to 3d illustrate a perspective view of different positions of the phase-shifting system of Figure 1 ,
  • FIG. 4 illustrates a schematic view of a feed network of a panel antenna comprising aligned radiating elements
  • FIG. 5 illustrates the impedance matching IM in dB as a function of the frequency F in GHz
  • FIG. 8a, 8b and 8c illustrate one embodiment of a stack of unitary phase-shifting systems
  • FIG. 1 depicts a unitary phase-shifting system 1 seen in a perspective view.
  • the phase-shifting system 1 comprises an input connected to a source of electrical power of the antenna, for example a coaxial input feed cable 2, and an output connected to a radiating element or a group of antenna radiating elements, for example a coaxial output feed cable 3.
  • the phase-shifting system 1 comprises a "stripline" conductive feed line 4, for example one made from copper or brass, which provides a connection between the input of the phase-shifting system connected to the input feed cable 2 and the output of the phase-shifting system connected to the output feed cable 3.
  • the dimensions of the conductive line 4 are adapted to abide by the desired input and output impedance within the system, normally on the order of 50 Ohms.
  • the coaxial feed cables 2 and 3 could be replaced with connectors or by an extension of the "stripline" conductive line 4.
  • a fixed dielectric part 5 is placed on an input portion 6 of the conductive line 4 which is connected to the input feed cable 2.
  • a moving dielectric part 7 is placed on an output portion 8 of the conductive line 4 which is connected to the output feed cable 3.
  • the moving dielectric part 7 can move longitudinally by mechanically sliding between two extreme positions along the output portion 8 of the conductive line 4.
  • the conductive stripline 4 is here made of a single part and can be broken down into multiple conductive segments.
  • the unitary phase-shifting system 1 is here supported by the bottom 9 of a conductive housing serving as a ground plane.
  • the housing can be mounted directly onto the chassis of the antenna, which in such a case forms one of the sides of the housing, for example the bottom 9.
  • the housing, or the housing's cover, onto the chassis of the antenna can be fastened by means of screws, rivets, clamps, or staples, for example.
  • a thin insulating layer may be placed on the bottom 9 of the housing, which may be the antenna's chassis, and disposed between the conductive bottom 9 and the phase-shifting system 1.
  • the thin insulating layer about 0.1 mm thick, may for example be a plastic film, a thin coat of paint or anodization, or others.
  • first segment 100 From the input of the phase-shifting system 1 connected to the input feed cable 2, there is a first segment 100 on the stripline feed 4.
  • the first segment 100 in contact with a dielectric domain that is ambient air, behaves like a 50 Ohm resistive line.
  • the first segment 100 is electrically connected, for example, to the central conductor of the coaxial input feed cable 2.
  • a second segment 101 used to enable correct impedance matching between the first segment 100 surrounded by air and a third segment 102 surrounded by solid dielectric material.
  • the area of the fixed dielectric part 5 that surrounds the second segment 101 can be made using multiple topologies, with the appropriate configuration being determined by calculations or simulations based on an equivalency of the dielectric medium composed of localized elements, meaning one foreseen as the succession of discrete elements R, L, and C.
  • the desired configuration is given by the presence of recesses 10 in a solid dielectric material, but it may also be obtained by altering the shape or size of the fixed dielectric part 5, or by a variation in the dielectric constant of the solid dielectric material that is used.
  • These recesses 10 have been depicted here as rectangular holes, but they may naturally have any other form depending on the expected result.
  • the entire surface of the third segment 102 is in contact with the solid dielectric material, which corresponds to a conductive line having a characteristic impedance that depends on the dimensions of the stripline segment 102 and the solid dielectric material used to form the fixed part 5.
  • the solid dielectric material can be a plastic or polymer material, such as, for example, polypropylene polyester (PPS RYTON ® ) having a dielectric constant ⁇ ⁇ on the order of 4 to 6. Though more expensive and requiring greater precision, it is also possible to use a plastic material containing certain types of ceramic as a dielectric material, whose dielectric constant ⁇ ⁇ is on the order of 10.
  • the segments 100, 101 , and 102 compose the input portion 6.
  • the surface of each segment 100, 101 , and 102 is constant because the dielectric part 5 is immobile.
  • the next three segments 103, 104, and 105 compose the output portion 8. Their relative surface area depends on the position of the moving dielectric part 7.
  • the fourth segment 103 is analogous to the third segment 102.
  • the entire surface of the fourth segment 103 is in contact with the solid dielectric material, which corresponds to a conductive line having a characteristic impedance that depends on the dimensions of the stripline segment 103 and the solid dielectric material used to make the moving part 7.
  • a fifth segment 104 is placed after the fourth segment 103.
  • the fifth segment 104 enables impedance matching between the fourth segment 103 surrounded by solid dielectric material and a sixth segment 105 surrounded by air.
  • the area of the moving dielectric part 7 that surrounds the fifth segment 104 can be made using multiple topologies, with the appropriate configuration being determined by calculations or simulations, as previously explained.
  • the sixth segment 105 analogous to the first segment 100, is electrically connected, for example, to the central conductor of the output feed cable 3.
  • the sixth segment 105 in contact with a dielectric domain that is ambient air, behaves like a 50 Ohm resistive line.
  • the movement of the moving dielectric part 7 along the portion 8 of the conductive stripline 4 leads to a decrease in the surface area of the fourth segment 103, it leads to a corresponding increase in the surface area of the sixth segment 105, and vice versa.
  • the fourth segment 103 and the sixth segment 105 are not in contact with the same dielectric domain, their phase speed is different.
  • the total electrical delay varies within the conductive line 4, between the input and the output of the phase-shifting system 1 , and therefore the phase-shifting of the radiating elements connected to it.
  • the number of segments as well as the nature and thickness of the solid dielectric material can be changed (segments 101 -104), as can the shape and dimensions of the recesses (segments 101 and 104).
  • the working frequency band is 1 .7-2.7 GHz.
  • a choice has been made to keep the thickness of the material constant for both dielectric parts 5, 7, and to use only two sections 101 , 102 and 103, 104 respectively in contact with the dielectric domain formed by the solid dielectric material, for the sake of simplicity and efficiency.
  • the movement of the moving dielectric part 7 can be controlled using a control unit such as a lever 11 , which can be associated with a gear and/or a rod for example, so as to be manually activated from outside.
  • a control unit such as a lever 11
  • Another solution could be to use stepper motors or independent linear actuators.
  • the movements therefore take place along the longitudinal axis, which helps simplify the phase-shifting system and improves its reliability.
  • the feed network of the radiating elements is therefore phase-shifted only by means of a direct link, without an intermediary between the control unit and the moving part that constitutes the core of the phase-shifting system.
  • Figures 2a to 2e depict the steps of assembling a unitary phase-shifting system in a housing.
  • Figure 2a depicts the cover 20 of the conductive housing protecting the phase-shifting system.
  • the cover of the housing can be constructed by different techniques.
  • a housing cover has been depicted that was obtained by folding a sheet of brass and copper, which makes it possible to weld the conductive shield, which here is braided, of the coaxial feed cables directly onto the cover of the housing in order to ensure it is grounded.
  • this housing cover could just as well be produced from crimped aluminum, from a molded alloy of zinc, aluminum, magnesium, or copper (Zamac), etc.
  • connection points 23 are connected to connection points 23, for example by directly welding them onto the cover of the housing or by means of connectors, as shown in Figure 2b.
  • FIG. 2c In the cover 20 of the housing, near the input feed cable 21 , an upper first half 24 of the fixed dielectric part is placed as shown in Figure 2c.
  • Figure 2d represents the next step, in which an upper first half 25 of the moving dielectric part is placed in the cover 20 of the housing, parallel to the upper first half 24 of the fixed dielectric part and near the output feed cable 22.
  • a conductive stripline 26 having an S-shaped notch is placed above the upper first halves 24, 25 of the fixed and moving dielectric parts so as to cover them both.
  • the particular shape of the conductive line 26 allows the moving dielectric part to move longitudinally, and it moves parallel to the fixed dielectric part, which in such a case serves as its guide.
  • each end of the conductive line 26 is connected, such as by welding, to the central conductor of the input feed cable 21 and that of the output feed cable 22, respectively.
  • the upper first half 24 of the fixed dielectric part is fastened onto the conductive line 26, such as by means of clamps or stables integrated into the conductive line 26.
  • the conductive line 26 is covered with a lower second half 28 of the fixed dielectric part.
  • the lower second half 28 is also fastened onto the conductive line 26 and mates with the upper first half 24 to form the fixed dielectric part.
  • the conductive line 26 has also been covered with a lower second half 29 of the moving dielectric part.
  • the lower second half 29 mates with the upper first half 25 to form the moving dielectric part.
  • the upper first half 25 is fastened to the lower second half 29, which allows the moving dielectric part to freely slide along the conductive line 26.
  • the bottom of the housing (not depicted) is placed onto the resulting assembly and fastened to the cover 20.
  • Figures 3a to 3e are perspective top views that show the different positions of the phase-shifting system while it is being used.
  • Figure 3a depicts a conductive housing enclosing a unitary phase-shifting system, which comprises a cover 30 made of folded brass sheets is fastened, such as by means of screws or rivets 31 , onto a bottom 32, such as the chassis of the antenna.
  • a coaxial input feed cable 33 and a coaxial output feed cable 34, whose braised shield is connected to the cover 30 of the housing, are placed on the lateral faces on either side of the cover 30.
  • a control lever 35 depicted in its middle position, extends outside the housing 30 to make it easier to handle.
  • Figure 3b similar to Figure 3a, shows the phase-shifting system in its middle position, the cover 30 of the housing being depicted as transparent in order to show the unitary phase-shifting system that it contains.
  • a conductive line 36 connects the input feed cable 33 to the output feed cable 34.
  • a fixed dielectric part 37 surrounds the input portion of the conductive line 36 electrically connected to the central conductor of the input feed cable 33.
  • a moving dielectric part 38 surrounds the output portion of the conductive line 36 electrically connected to the central conductor of the output feed cable 34. While the position of the fixed dielectric part 37 remains unchanged, the moving dielectric part 38 can move between two extreme travel path positions. Here, the moving dielectric part 38 is depicted in its middle position between those two extreme positions.
  • the moving dielectric part 38 can slide along the conductive line 36 when guided by the fixed dielectric part 37 and by the bent edge 39 of the cover 30 of the housing.
  • the moving dielectric part 38 is rigidly connected to the control lever 35, and its does not require any additional parts to move it.
  • the control lever 35 can be activated manually or by a stepper motor or linear actuator, or by any other means.
  • the phase-shifting system is in an extreme position corresponding to the minimum phase shaft.
  • the moving part 38 is mechanically stopped in the position furthest from the output of the phase-shifting system connected to the output feed cable 34.
  • the surface area of the conductive line 36 corresponding to the segment 103 is minimal, and its characteristic impedance is minimal.
  • the phase-shifting system is in an extreme position corresponding to the maximum phase shaft.
  • the moving part 38 is mechanically stopped in the position closest to the output feed cable 34.
  • the surface area of the conductive line 36 corresponding to the segment 103 is maximal, and its characteristic impedance is maximal.
  • Figure 4 schematically depicts a feed network for a panel antenna 40 comprising five aligned radiating elements 41 a-41e.
  • the radiating elements 41 a-41 e here are of the dual-polarization +457-45° type, a nd may, for example be dipole, spiral patch, periodic log, bow tie, cross bow tie, butterfly, etc.
  • the part of the feed network corresponding to one of the polarizations of the radiating elements 41a-41e of the antenna 40, comprises multiple unitary phase-shifting systems 42a-42e.
  • a coaxial input feed cable 43 is connected to the first current splitter 44a, which divides the incoming signal into three signal portions.
  • the first signal portion is sent into a unitary phase- shifting system 42a
  • the second portion of the signal is sent into another unitary phase- shifting system 42b
  • the third portion of the signal directly feeds a radiating element 41a.
  • the signal is sent into the current splitters 44b and 44c respectively.
  • Each current splitter 44b, 44c divides the incoming signal into two signal portions; the first signal portion is sent into a unitary phase-shifting system 42c, 42d and the second portion of the signal directly feeds a radiating element 41 b, 41d. Finally, the outgoing signal from the unitary phase-shifting systems 42c and 42d placed at the end of the circuit directly feed a radiating element 41c, 41e.
  • the feed network of the antenna must in such a case comprise as many splitters and unitary phase-shifting systems as needed in order to perform the phase-shifting and signal-splitting tasks in succession until all the radiating elements that make up the antenna have been fed.
  • the moving dielectric parts of the unitary phase-shifting systems 42 are moved inside a mechanical device 45 comprising a shared rod 46 rigidly connected to the control levers 47 of each phase-shifting system 42a-42d.
  • the phase shifts introduced via the feed network of the radiating elements 41 a-41 e are obtained by means of unitary phase-shifting systems 42a-42d that with a single motion make it possible to directly act on the conductive feed line.
  • phase-shifting systems 42 makes it possible to have an input on a lateral face, while the output is on the opposite lateral face. With this configuration, the total length of the coaxial cable needed to produce the antenna's feed network is less than when the inputs and outputs are placed on the major surfaces, upper and lower, of the phase-shifting system.
  • Figure 5 illustrates the variation in impedance matching IM (in dB) based on the position of the phase-shifter's moving dielectric part. In the present situation, we depicted a high-band ultra-broadband (HB UBB) antenna for frequencies F of between 1 .7 GHz and 2.7 GHz.
  • HB UBB high-band ultra-broadband
  • the dimensions of the housing containing phase-shifting system are, for example, 1 10 mm long by 25 mm wide by 8 mm high.
  • the dielectric material used here is a plastic material loaded with ceramic whose electrical properties are a dielectric constant ⁇ ⁇ equal to 8.25 and a loss tangent on the order of 0.001 .
  • the phase-shifting system could include other dielectric materials such as a polymer like polyethylene PE, polytetrafluoroethylene PTFE, or a ceramic such as alumina Al 2 0 3 .
  • the sizing of the housing and the RF result depend on the material used.
  • the input and output impedances of the unitary phase-shifting system are depicted for multiple mechanical positions of the moving dielectric part, illustrated by Figures 3b to 3d, from the extreme position corresponding to the minimum phase shift to the extreme position corresponding to the maximum phase shift, with the middle positions in between.
  • the amplitude of the movement of the moving dielectric part which here represents a movement of 30 mm, covers an impedance matching range IM of at least 17 dB in the frequency band of 1 .7 GHz to 2.7 GHz.
  • the curve 50a represents the input impedance value
  • the curve 50b represents the output impedance value for the position corresponding to the minimum phase shift
  • the curve 51 a represents the value of the input impedance
  • the curve 51 b represents the value of the output impedance for a movement of 5 mm relative to the position corresponding to the minimum phase shift.
  • the curves 52, 53, 54, 55 correspond respectively to a movement of 10 mm, 15 mm, 20 mm, and 25 mm relative to the position corresponding to the minimum phase shift.
  • the curve 56a represents the value of the input impedance and the curve 56b represents the value of the output impedance for a movement of 30 mm relative to the position corresponding to the maximum phase shift.
  • Figure 6 illustrates insertion loss IL (in dB) based on the position of the phase- shifter's moving dielectric part.
  • the insertion loss of the unitary phase-shifting system is depicted for multiple mechanical positions of the moving dielectric part, illustrated by Figures 3b to 3d, from the extreme position corresponding to the maximum phase shift to the middle position to the extreme position corresponding to the maximum phase shift. It is observed that, for the dielectric properties of the material mentioned previously, the insertion loss IL (also known as attenuation) is better than -0.35 dB for all cases between 1 .7 GHz and 2.7 GHz.
  • the curve 60 corresponds to the position of the moving dielectric part corresponding to the minimum phase shift.
  • the insertion losses are represented by the curves 61 , 62, 63, 64, 65 for 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm movements of the moving dielectric part, respectively.
  • the curve 66 corresponds to a 30 mm movement, i.e. the position of the moving dielectric part corresponding to the maximum phase shift.
  • Figure 7 illustrates the phase variation PV (in degrees) based on the position of the moving dielectric part of the phase-shifting system.
  • the phase variation is depicted for multiple mechanical positions of the moving dielectric part, illustrated by Figures 3b to 3d, from the extreme position corresponding to the maximum phase shift to the middle position to the extreme position corresponding to the maximum phase shift.
  • the phase shift between the extreme positions of the phase-shifter's moving dielectric part is better than 82°.
  • This cor responds to a variation in the tilt of the main lobe that can reach 15.5° for an HB UBB cross- polarization antenna with five radiating elements and 125 mm of space in between.
  • the curve 70 corresponds to the position of the moving dielectric part corresponding to the minimum phase shift.
  • the phase measurements are represented by the curves 71 , 72, 73, 74, 75 for 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm movements of the moving dielectric part, respectively.
  • the curve 76 corresponds to the phase measurement for the position of the moving dielectric part corresponding to the maximum phase shift, a 30 mm movement.
  • Figures 8a a 8c depict the steps of producing a stack of conductive housings each containing a unitary phase-shifting system.
  • a stack of two housings has been depicted and is described here, but it is understood that the steps described can be repeated in order to obtain a stack with more housings.
  • a first unitary phase-shifting system 80 is constructed in a manner similar to that depicted by Figures 2a-2e and described in detail earlier.
  • a lower first half 81 of the fixed dielectric part 82 and a lower first half 83 of the moving dielectric part 84 are placed on the bottom 85 of a first conductive housing.
  • the upper second half 89 of the fixed dielectric part 82 is placed on the conductive line 86 near its connection to the input feed cable 87.
  • the upper second half 90 of the moving dielectric part 84 is placed on the conductive line 86 near its connection to the output feed cable 88.
  • the moving dielectric part 84 is rigidly connected to a control lever 91 used to move it.
  • Figure 8b illustrates the step of closing the first conductive housing by means of a cover 92 that is fastened to the bottom 85 of the first housing.
  • perforated U-shaped hinges 93 have been used to connect the cover 92 and the bottom 85 of the housing by fastening means such as screws, rivets, clamps, staples, etc.
  • the cover 92 of the first housing covering the first unitary phase-shifting system 80 is in turn used as a bottom for a second conductive housing enclosing a second unitary phase-shifting system.
  • the second phase-shifting system is produced as depicted in Figure 8a and previously described in detail.
  • the second phase-shifting system comprises a conductive feed line placed between an input feed cable 94 and an output feed cable 95.
  • the second phase-shifting system also comprises a fixed dielectric part and a moving dielectric part 96 moved from outside by a control lever 97.
  • the second phase-shifting system is covered by a cover 98 fastened to the bottom 92 to form the second conductive housing.
  • this embodiment makes it possible to reduce both the number of steps needed to product the stack and the number of parts used, which makes it possible to reduce costs.
  • each unitary phase-shifting system 80, 90 comprises a control lever 87, 93.
  • the control levers 81 , 93 are preferably placed on the same side of the stack as depicted in Figure 9. For this reason, the control levers 81 , 93 can be activated simultaneously by connecting them to a shared rod, for example. However, each lever can be activated individually. For example, it is possible to envision disposing the levers in alternating order on one side of the stack and then the other, for example in stack of phase-shifting systems corresponding to the feed of the +45° polar ization and the feed of the -45° polarization.

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Abstract

The unitary phase-shifting system comprises at least one conductive feed line comprising an input portion connected to the phase-shifting system connected to a source of electrical power, and an output portion connected to the output of the phase- shifting system connected to at least one antenna radiating element to be fed, a fixed dielectric part surrounding the input portion of the conductive line, a moving dielectric part surrounding the output portion of the conductive line, and a control unit rigidly connected to the moving dielectric part capable of longitudinally moving so as to case the moving dielectric part to move longitudinally along the conductive line.

Description

Longitudinal-displacement passive phase-shifter
DOMAIN
The present invention relates to a phase-shifting system with a longitudinal displacement for applying a phase-shift to radiating elements, or groups of radiating elements. The invention is intended to particularly be used for radiating elements that belong to antennas for base stations of cellular communication networks (GSM, UMTS, etc.), but also for any other type of application that implements phase-shifting. The purpose of phase-shifting is to adjust the direction of an antenna's main lobe, thereby attaining dynamic-tilt antennas, otherwise known as "variable-tilt antennas." BACKGROUND
Base station antennas for telecommunication applications must have a high gain and radiation patterns in the horizontal plane and in the vertical plane that are free from parasitic radiation. The requirements in terms of gain and radiation patterns in the vertical plane depend on the length of the antenna. These parameters are controlled by means of the feed network of the antenna's radiating elements. Variable electric tilt, or VET antennas, make it possible to vary the position of the main lobe relative to the horizon. The tilt of the antenna in the vertical plane can be adjusted by different techniques applied to the antenna feed network, using active and/or passive devices, mainly by means of a phase-shifting device. Phase-shifting systems are increasingly passive systems, meaning that they do not comprise any electronic components, making it possible to apply a relative phase differential between different access points of a radiofrequency feed network. In particular, devices are known that use at least two dielectric domains: one domain formed of a solid dielectric material and one domain formed by air or a vacuum, for example. Moving the solid dielectric material relative to the conductive line (for example, a coaxial line, microstrip line, stripline, coplanar line, etc.) causes a phase variation. The solid dielectric material is placed so as to cut off lines of current located between the conducting line and a ground plane, i.e. a grounded conducting plane.
The current structure of a phase-shifting system comprises parts made of a solid dielectric material that slide transversally, while the control unit is a central cylinder that moves in the axis of the antenna. This means that the addition of special mechanical parts that enable the transmission of an axial movement to a transverse movement. These additional mechanical parts have a cost. Furthermore, they are sources of mechanical malfunctions, such as friction or clearance in the transmission of the movement (or "backlash"), which are created as a result of adding more mechanical parts and the corresponding tolerance levels.
In currently used phase-shifting systems, the solid dielectric parts slide along stripline feeds of the radiating elements. In this configuration, each radiating element, of a panel antenna for example, is individually phase-shifted. Although such antennas perform well in terms of value and stability of radiation in the vertical plane, several parameters still need improvement.
SUMMARY
Normally, a phase-shifting system is assembled in order to form a single module, which comprises phase-shifters and current splitters. A long case is required to house this module. It is expensive to manufacture and requires special tools for transportation, due to its dimensions. This large case also requires a great deal of volume to be installed on the rear of the chassis of a panel antenna, which is not easy in a context of multiband antennas, in which several of those cases must be placed on the rear of an antenna chassis. Additionally, such a volume complicates and limits the options for assembling panel antennas, as antenna arrays generally have the same length as the chassis of a panel antenna.
This assembly into modules also makes repairs more complex: once assembly of the phase-shifting system is complete, it is no longer possible to directly access the components in the back of the feed system of the radiating elements, such as the feed cable connections, without destroying certain parts of the housing, such as the cover.
A passive phase-shifting system is proposed, of the type that uses dielectric materials, which is simpler to manufacture, more accessible, and less expensive than known phase-shifting systems.
The subject matter of the present invention is a unitary phase-shifting system that comprises at least one conductive feed line comprising an input portion connected to the phase-shifting system, said input portion connected to a source of electrical power, and an output portion connected to the output of the phase-shifting system, said output portion being connected to at least one antenna radiating element to be fed, a fixed dielectric part surrounding the input portion of the conductive line, a moving dielectric part surrounding the output portion of the conductive line, and a control unit rigidly connected to the moving dielectric part, said control unit being capable of longitudinally moving so as to cause the moving dielectric part to move longitudinally along the conductive line.
According to a first aspect, the conductive line comprises an input portion composed of three segments, the surface area of each segment being fixed. According to a second aspect, the conductive line comprises an output portion composed of three segments, the relative surface area of each segment being variable.
According to a third aspect, the input portion and the output portion of the conductive line each comprise three segments, a central segment that carries out impedance matching and lateral segments respectively surrounded by a first dielectric domain and a second dielectric domain.
In such a case, the first dielectric domain can be the surrounding air, and the second dielectric domain can be a solid dielectric material chosen from a polymer and a ceramic.
According to a fourth aspect, the moving dielectric part moves longitudinally parallel to a fixed dielectric part that serves as its guide.
A further subject matter of the invention is a method for manufacturing a unitary phase-shifting system comprising the following steps:
- a first half of the fixed dielectric part is placed near the input of the phase-shifting system and a first half of the moving dielectric part near the output of the phase-shifting system,
- a conductive line is placed on the first halves of the fixed and moving dielectric parts,
- each end of the conductive line is connected respectively to the input of the phase- shifting system and the output of the phase-shifting system,
- the first half of the fixed dielectric part is fastened onto the conductive line, - a second half of the fixed dielectric part is fastened onto the input portion of the conductive line, and a second half of the moving dielectric part is fastened onto the output portion of the conductive line,
- the second half of the fixed dielectric part is fastened onto the conductive line. According to one embodiment, the first halves of the fixed and moving dielectric parts are placed in a housing cover and a housing bottom is placed onto the second halves of the fixed and moving dielectric parts.
A further subject matter of the invention is a method for manufacturing a stack of unitary phase-shifting systems comprising the following steps:
(a) a first unitary phase-shifting system is formed,
(b) the first unitary phase-shifting system is covered by a cover,
(c) a second unitary phase-shifting system is formed on the cover,
(d) steps (b) and (c) are repeated as many times as desired,
(e) the last unitary phase-shifting system is covered by a cover. According to one embodiment, the control units are placed on the same side of the stack.
A further subject matter of the invention is an antenna comprising a phase- shifting system placed inside a housing of which one of the faces is formed by the chassis of the antenna. This simple, inexpensive phase-shifting system has many advantages. In particular, it allows the tilt of a panel antenna in the vertical plane to vary by a range of at least 12°
The use of lightweight, low-volume housings containing a unitary phase-shifting system, which can be combined as needed and depending on how much space is available, provides great flexibility, easier access to the phase-shifting system and other parts of the antenna, particularly for maintenance, and a decreased production cost.
The invention particularly applies to variable electric tilt (VET) panel radio antennas. BRIEF DESCRIPTION
Other characteristics and advantages of the present invention will become apparent upon reading the following description of one embodiment, which is naturally given by way of a non-limiting example, and in the attached drawing, in which :
- Figure 1 illustrates a perspective top view of a unitary phase-shifting system,
- Figures 2a to 2e illustrate a perspective top view of the steps of producing the phase- shifting system of Figure 1 ,
- Figures 3a to 3d illustrate a perspective view of different positions of the phase-shifting system of Figure 1 ,
- Figure 4 illustrates a schematic view of a feed network of a panel antenna comprising aligned radiating elements,
- Figure 5 illustrates the impedance matching IM in dB as a function of the frequency F in GHz,
- Figure 6 illustrates the insertion loss IL in dB as a function of the frequency F in GHz, - Figure 7 illustrates the phase variation PV in dB as a function of the frequency F in GHz,
- Figures 8a, 8b and 8c illustrate one embodiment of a stack of unitary phase-shifting systems,
- Figure 9 illustrates a side view of the stack of Figures 8a-8c. DETAILED DESCRIPTION
Figure 1 depicts a unitary phase-shifting system 1 seen in a perspective view. The phase-shifting system 1 comprises an input connected to a source of electrical power of the antenna, for example a coaxial input feed cable 2, and an output connected to a radiating element or a group of antenna radiating elements, for example a coaxial output feed cable 3. The phase-shifting system 1 comprises a "stripline" conductive feed line 4, for example one made from copper or brass, which provides a connection between the input of the phase-shifting system connected to the input feed cable 2 and the output of the phase-shifting system connected to the output feed cable 3. The dimensions of the conductive line 4 are adapted to abide by the desired input and output impedance within the system, normally on the order of 50 Ohms. The coaxial feed cables 2 and 3 could be replaced with connectors or by an extension of the "stripline" conductive line 4. A fixed dielectric part 5 is placed on an input portion 6 of the conductive line 4 which is connected to the input feed cable 2. A moving dielectric part 7 is placed on an output portion 8 of the conductive line 4 which is connected to the output feed cable 3. The moving dielectric part 7 can move longitudinally by mechanically sliding between two extreme positions along the output portion 8 of the conductive line 4. The conductive stripline 4 is here made of a single part and can be broken down into multiple conductive segments.
The unitary phase-shifting system 1 is here supported by the bottom 9 of a conductive housing serving as a ground plane. The housing can be mounted directly onto the chassis of the antenna, which in such a case forms one of the sides of the housing, for example the bottom 9. The housing, or the housing's cover, onto the chassis of the antenna, can be fastened by means of screws, rivets, clamps, or staples, for example. In order to take intermodulation aspects into account, a thin insulating layer may be placed on the bottom 9 of the housing, which may be the antenna's chassis, and disposed between the conductive bottom 9 and the phase-shifting system 1. The thin insulating layer, about 0.1 mm thick, may for example be a plastic film, a thin coat of paint or anodization, or others.
From the input of the phase-shifting system 1 connected to the input feed cable 2, there is a first segment 100 on the stripline feed 4. The first segment 100, in contact with a dielectric domain that is ambient air, behaves like a 50 Ohm resistive line. The first segment 100 is electrically connected, for example, to the central conductor of the coaxial input feed cable 2. After the first segment 100 comes a second segment 101 used to enable correct impedance matching between the first segment 100 surrounded by air and a third segment 102 surrounded by solid dielectric material.
For the sake of obtaining suitable impedance matching, the area of the fixed dielectric part 5 that surrounds the second segment 101 can be made using multiple topologies, with the appropriate configuration being determined by calculations or simulations based on an equivalency of the dielectric medium composed of localized elements, meaning one foreseen as the succession of discrete elements R, L, and C. In the embodiment depicted here, the desired configuration is given by the presence of recesses 10 in a solid dielectric material, but it may also be obtained by altering the shape or size of the fixed dielectric part 5, or by a variation in the dielectric constant of the solid dielectric material that is used. These recesses 10 have been depicted here as rectangular holes, but they may naturally have any other form depending on the expected result. The entire surface of the third segment 102 is in contact with the solid dielectric material, which corresponds to a conductive line having a characteristic impedance that depends on the dimensions of the stripline segment 102 and the solid dielectric material used to form the fixed part 5. The solid dielectric material can be a plastic or polymer material, such as, for example, polypropylene polyester (PPS RYTON®) having a dielectric constant εΓ on the order of 4 to 6. Though more expensive and requiring greater precision, it is also possible to use a plastic material containing certain types of ceramic as a dielectric material, whose dielectric constant εΓ is on the order of 10.
The segments 100, 101 , and 102 compose the input portion 6. The surface of each segment 100, 101 , and 102 is constant because the dielectric part 5 is immobile. The next three segments 103, 104, and 105 compose the output portion 8. Their relative surface area depends on the position of the moving dielectric part 7.
The fourth segment 103 is analogous to the third segment 102. The entire surface of the fourth segment 103 is in contact with the solid dielectric material, which corresponds to a conductive line having a characteristic impedance that depends on the dimensions of the stripline segment 103 and the solid dielectric material used to make the moving part 7.
A fifth segment 104, analogous to the second segment 101 , is placed after the fourth segment 103. The fifth segment 104 enables impedance matching between the fourth segment 103 surrounded by solid dielectric material and a sixth segment 105 surrounded by air. For the sake of obtaining suitable impedance matching, the area of the moving dielectric part 7 that surrounds the fifth segment 104 can be made using multiple topologies, with the appropriate configuration being determined by calculations or simulations, as previously explained. The sixth segment 105, analogous to the first segment 100, is electrically connected, for example, to the central conductor of the output feed cable 3. The sixth segment 105, in contact with a dielectric domain that is ambient air, behaves like a 50 Ohm resistive line.
When the movement of the moving dielectric part 7 along the portion 8 of the conductive stripline 4 leads to a decrease in the surface area of the fourth segment 103, it leads to a corresponding increase in the surface area of the sixth segment 105, and vice versa. The fourth segment 103 and the sixth segment 105 are not in contact with the same dielectric domain, their phase speed is different. When the moving dielectric part 7 slides, the total electrical delay varies within the conductive line 4, between the input and the output of the phase-shifting system 1 , and therefore the phase-shifting of the radiating elements connected to it.
Depending on the frequency band for which impedance matching is carried out, and the desired level of adaption, the number of segments as well as the nature and thickness of the solid dielectric material can be changed (segments 101 -104), as can the shape and dimensions of the recesses (segments 101 and 104). Here, the working frequency band is 1 .7-2.7 GHz. A choice has been made to keep the thickness of the material constant for both dielectric parts 5, 7, and to use only two sections 101 , 102 and 103, 104 respectively in contact with the dielectric domain formed by the solid dielectric material, for the sake of simplicity and efficiency.
The movement of the moving dielectric part 7 can be controlled using a control unit such as a lever 11 , which can be associated with a gear and/or a rod for example, so as to be manually activated from outside. Another solution could be to use stepper motors or independent linear actuators. The movements therefore take place along the longitudinal axis, which helps simplify the phase-shifting system and improves its reliability. The feed network of the radiating elements is therefore phase-shifted only by means of a direct link, without an intermediary between the control unit and the moving part that constitutes the core of the phase-shifting system.
Figures 2a to 2e depict the steps of assembling a unitary phase-shifting system in a housing. Figure 2a depicts the cover 20 of the conductive housing protecting the phase-shifting system. The cover of the housing can be constructed by different techniques. Here, a housing cover has been depicted that was obtained by folding a sheet of brass and copper, which makes it possible to weld the conductive shield, which here is braided, of the coaxial feed cables directly onto the cover of the housing in order to ensure it is grounded. However, this housing cover could just as well be produced from crimped aluminum, from a molded alloy of zinc, aluminum, magnesium, or copper (Zamac), etc.
Respectively, on each end of the cover 20 of the housing, the braided shields of the coaxial input feed cable 21 and the coaxial output feed cable 22 are connected to connection points 23, for example by directly welding them onto the cover of the housing or by means of connectors, as shown in Figure 2b.
In the cover 20 of the housing, near the input feed cable 21 , an upper first half 24 of the fixed dielectric part is placed as shown in Figure 2c. Figure 2d represents the next step, in which an upper first half 25 of the moving dielectric part is placed in the cover 20 of the housing, parallel to the upper first half 24 of the fixed dielectric part and near the output feed cable 22. A conductive stripline 26 having an S-shaped notch is placed above the upper first halves 24, 25 of the fixed and moving dielectric parts so as to cover them both. The particular shape of the conductive line 26 allows the moving dielectric part to move longitudinally, and it moves parallel to the fixed dielectric part, which in such a case serves as its guide. As a result, the total length of the phase- shifting system is decreased without reducing the travel path of the moving dielectric part, and therefore without reducing the range of tilt. Each end of the conductive line 26 is connected, such as by welding, to the central conductor of the input feed cable 21 and that of the output feed cable 22, respectively. The upper first half 24 of the fixed dielectric part is fastened onto the conductive line 26, such as by means of clamps or stables integrated into the conductive line 26. A control lever 27, connected to the upper first half 25 of the moving dielectric part and accessible from outside, makes it possible to longitudinally displace the moving dielectric part. In Figure 2e, the conductive line 26 is covered with a lower second half 28 of the fixed dielectric part. The lower second half 28 is also fastened onto the conductive line 26 and mates with the upper first half 24 to form the fixed dielectric part. The conductive line 26 has also been covered with a lower second half 29 of the moving dielectric part. The lower second half 29 mates with the upper first half 25 to form the moving dielectric part. The upper first half 25 is fastened to the lower second half 29, which allows the moving dielectric part to freely slide along the conductive line 26. Finally, the bottom of the housing (not depicted) is placed onto the resulting assembly and fastened to the cover 20.
Figures 3a to 3e are perspective top views that show the different positions of the phase-shifting system while it is being used.
Figure 3a depicts a conductive housing enclosing a unitary phase-shifting system, which comprises a cover 30 made of folded brass sheets is fastened, such as by means of screws or rivets 31 , onto a bottom 32, such as the chassis of the antenna. A coaxial input feed cable 33 and a coaxial output feed cable 34, whose braised shield is connected to the cover 30 of the housing, are placed on the lateral faces on either side of the cover 30. A control lever 35, depicted in its middle position, extends outside the housing 30 to make it easier to handle.
Figure 3b, similar to Figure 3a, shows the phase-shifting system in its middle position, the cover 30 of the housing being depicted as transparent in order to show the unitary phase-shifting system that it contains. A conductive line 36 connects the input feed cable 33 to the output feed cable 34. A fixed dielectric part 37 surrounds the input portion of the conductive line 36 electrically connected to the central conductor of the input feed cable 33. A moving dielectric part 38 surrounds the output portion of the conductive line 36 electrically connected to the central conductor of the output feed cable 34. While the position of the fixed dielectric part 37 remains unchanged, the moving dielectric part 38 can move between two extreme travel path positions. Here, the moving dielectric part 38 is depicted in its middle position between those two extreme positions. In this embodiment, the moving dielectric part 38 can slide along the conductive line 36 when guided by the fixed dielectric part 37 and by the bent edge 39 of the cover 30 of the housing. The moving dielectric part 38 is rigidly connected to the control lever 35, and its does not require any additional parts to move it. The control lever 35 can be activated manually or by a stepper motor or linear actuator, or by any other means.
In Figure 3c, the phase-shifting system is in an extreme position corresponding to the minimum phase shaft. The moving part 38 is mechanically stopped in the position furthest from the output of the phase-shifting system connected to the output feed cable 34. The surface area of the conductive line 36 corresponding to the segment 103 is minimal, and its characteristic impedance is minimal.
In Figure 3d, the phase-shifting system is in an extreme position corresponding to the maximum phase shaft. The moving part 38 is mechanically stopped in the position closest to the output feed cable 34. The surface area of the conductive line 36 corresponding to the segment 103 is maximal, and its characteristic impedance is maximal. Figure 4 schematically depicts a feed network for a panel antenna 40 comprising five aligned radiating elements 41 a-41e. The radiating elements 41 a-41 e here are of the dual-polarization +457-45° type, a nd may, for example be dipole, spiral patch, periodic log, bow tie, cross bow tie, butterfly, etc. The part of the feed network, corresponding to one of the polarizations of the radiating elements 41a-41e of the antenna 40, comprises multiple unitary phase-shifting systems 42a-42e. A coaxial input feed cable 43 is connected to the first current splitter 44a, which divides the incoming signal into three signal portions. The first signal portion is sent into a unitary phase- shifting system 42a, the second portion of the signal is sent into another unitary phase- shifting system 42b, and the third portion of the signal directly feeds a radiating element 41a. At the output of the phase-shifting systems 42a and 42b, the signal is sent into the current splitters 44b and 44c respectively. Each current splitter 44b, 44c divides the incoming signal into two signal portions; the first signal portion is sent into a unitary phase-shifting system 42c, 42d and the second portion of the signal directly feeds a radiating element 41 b, 41d. Finally, the outgoing signal from the unitary phase-shifting systems 42c and 42d placed at the end of the circuit directly feed a radiating element 41c, 41e. Naturally, what has just been described for an antenna 40 comprising five radiating elements 41a-41e may be applied to any other antenna comprising more or fewer radiating elements. The feed network of the antenna must in such a case comprise as many splitters and unitary phase-shifting systems as needed in order to perform the phase-shifting and signal-splitting tasks in succession until all the radiating elements that make up the antenna have been fed.
The moving dielectric parts of the unitary phase-shifting systems 42 are moved inside a mechanical device 45 comprising a shared rod 46 rigidly connected to the control levers 47 of each phase-shifting system 42a-42d. The phase shifts introduced via the feed network of the radiating elements 41 a-41 e are obtained by means of unitary phase-shifting systems 42a-42d that with a single motion make it possible to directly act on the conductive feed line.
The configuration of such phase-shifting systems 42 makes it possible to have an input on a lateral face, while the output is on the opposite lateral face. With this configuration, the total length of the coaxial cable needed to produce the antenna's feed network is less than when the inputs and outputs are placed on the major surfaces, upper and lower, of the phase-shifting system. Figure 5 illustrates the variation in impedance matching IM (in dB) based on the position of the phase-shifter's moving dielectric part. In the present situation, we depicted a high-band ultra-broadband (HB UBB) antenna for frequencies F of between 1 .7 GHz and 2.7 GHz. In this situation, the dimensions of the housing containing phase-shifting system are, for example, 1 10 mm long by 25 mm wide by 8 mm high. The dielectric material used here is a plastic material loaded with ceramic whose electrical properties are a dielectric constant εΓ equal to 8.25 and a loss tangent on the order of 0.001 . Naturally, the phase-shifting system could include other dielectric materials such as a polymer like polyethylene PE, polytetrafluoroethylene PTFE, or a ceramic such as alumina Al203. The sizing of the housing and the RF result depend on the material used.
The input and output impedances of the unitary phase-shifting system are depicted for multiple mechanical positions of the moving dielectric part, illustrated by Figures 3b to 3d, from the extreme position corresponding to the minimum phase shift to the extreme position corresponding to the maximum phase shift, with the middle positions in between. The amplitude of the movement of the moving dielectric part, which here represents a movement of 30 mm, covers an impedance matching range IM of at least 17 dB in the frequency band of 1 .7 GHz to 2.7 GHz.
For example, the curve 50a represents the input impedance value, and the curve 50b represents the output impedance value for the position corresponding to the minimum phase shift. The curve 51 a represents the value of the input impedance and the curve 51 b represents the value of the output impedance for a movement of 5 mm relative to the position corresponding to the minimum phase shift. Likewise, the curves 52, 53, 54, 55 correspond respectively to a movement of 10 mm, 15 mm, 20 mm, and 25 mm relative to the position corresponding to the minimum phase shift. The curve 56a represents the value of the input impedance and the curve 56b represents the value of the output impedance for a movement of 30 mm relative to the position corresponding to the maximum phase shift.
Figure 6 illustrates insertion loss IL (in dB) based on the position of the phase- shifter's moving dielectric part. The insertion loss of the unitary phase-shifting system is depicted for multiple mechanical positions of the moving dielectric part, illustrated by Figures 3b to 3d, from the extreme position corresponding to the maximum phase shift to the middle position to the extreme position corresponding to the maximum phase shift. It is observed that, for the dielectric properties of the material mentioned previously, the insertion loss IL (also known as attenuation) is better than -0.35 dB for all cases between 1 .7 GHz and 2.7 GHz. The curve 60 corresponds to the position of the moving dielectric part corresponding to the minimum phase shift. The insertion losses are represented by the curves 61 , 62, 63, 64, 65 for 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm movements of the moving dielectric part, respectively. The curve 66 corresponds to a 30 mm movement, i.e. the position of the moving dielectric part corresponding to the maximum phase shift.
Figure 7 illustrates the phase variation PV (in degrees) based on the position of the moving dielectric part of the phase-shifting system. The phase variation is depicted for multiple mechanical positions of the moving dielectric part, illustrated by Figures 3b to 3d, from the extreme position corresponding to the maximum phase shift to the middle position to the extreme position corresponding to the maximum phase shift. At the frequency of 2 GHZ, the phase shift between the extreme positions of the phase-shifter's moving dielectric part is better than 82°. This cor responds to a variation in the tilt of the main lobe that can reach 15.5° for an HB UBB cross- polarization antenna with five radiating elements and 125 mm of space in between. The curve 70 corresponds to the position of the moving dielectric part corresponding to the minimum phase shift. The phase measurements are represented by the curves 71 , 72, 73, 74, 75 for 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm movements of the moving dielectric part, respectively. The curve 76 corresponds to the phase measurement for the position of the moving dielectric part corresponding to the maximum phase shift, a 30 mm movement.
Figures 8a a 8c depict the steps of producing a stack of conductive housings each containing a unitary phase-shifting system. A stack of two housings has been depicted and is described here, but it is understood that the steps described can be repeated in order to obtain a stack with more housings. As depicted in Figure 8a, a first unitary phase-shifting system 80 is constructed in a manner similar to that depicted by Figures 2a-2e and described in detail earlier. A lower first half 81 of the fixed dielectric part 82 and a lower first half 83 of the moving dielectric part 84 are placed on the bottom 85 of a first conductive housing. It should be noted that it can be advantageous to use the chassis of the antenna as the bottom of the conductive housing, which makes it easier to access the phase-shifting systems and other internal parts of the antenna later on. The lower first halves 81 , 83 of the fixed 82 and moving 84 dielectric parts with a conductive feed line 86, here a stripline. Each end of the conductive line 86 is respectively connected to the central conductor and to a coaxial input feed cable 87 and coaxial output feed cable 88. The upper second half 89 of the fixed dielectric part 82 is placed on the conductive line 86 near its connection to the input feed cable 87. The upper second half 90 of the moving dielectric part 84 is placed on the conductive line 86 near its connection to the output feed cable 88. The moving dielectric part 84 is rigidly connected to a control lever 91 used to move it.
Figure 8b illustrates the step of closing the first conductive housing by means of a cover 92 that is fastened to the bottom 85 of the first housing. In the present situation, for example, perforated U-shaped hinges 93 have been used to connect the cover 92 and the bottom 85 of the housing by fastening means such as screws, rivets, clamps, staples, etc.
The cover 92 of the first housing covering the first unitary phase-shifting system 80 is in turn used as a bottom for a second conductive housing enclosing a second unitary phase-shifting system. The second phase-shifting system is produced as depicted in Figure 8a and previously described in detail. The second phase-shifting system comprises a conductive feed line placed between an input feed cable 94 and an output feed cable 95. The second phase-shifting system also comprises a fixed dielectric part and a moving dielectric part 96 moved from outside by a control lever 97. As depicted in Figure 8c, the second phase-shifting system is covered by a cover 98 fastened to the bottom 92 to form the second conductive housing. It should be noted that this embodiment makes it possible to reduce both the number of steps needed to product the stack and the number of parts used, which makes it possible to reduce costs. However, it is also possible to stack individually created housings, like the one depicted in Figure 3a, each possessing a bottom and a cover.
The shape of these housings is adapted to allow them to be stacked. In particular, each unitary phase-shifting system 80, 90 comprises a control lever 87, 93. The control levers 81 , 93 are preferably placed on the same side of the stack as depicted in Figure 9. For this reason, the control levers 81 , 93 can be activated simultaneously by connecting them to a shared rod, for example. However, each lever can be activated individually. For example, it is possible to envision disposing the levers in alternating order on one side of the stack and then the other, for example in stack of phase-shifting systems corresponding to the feed of the +45° polar ization and the feed of the -45° polarization. It is possible to form two stacks, each equipped with a shared rod that makes it possible to activate the control levers that correspond to feeds with the same polarity. It is also possible to form a single stack by alternating between phase-shifting systems corresponding to the feeds for each polarity and by disposing the control levers in alternating order on one side of the stack and then the other. A shared rod makes it possible to activate the control levers on the same side of the stack. In a multiband antenna system where multiple feed networks are required, this solution is advantageous for allowing the antenna's chassis to be installed on a smaller surface.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

1 . A unitary phase-shifting system comprising at least
- a conductive feed line comprising an input portion connected to the phase-shifting system, said input portion being connected to a source of electrical power, and an output portion connected to the output of the phase-shifting system, said output portion being connected to at least one antenna radiating element to be fed,
- a fixed dielectric part surrounding the input portion of the conductive line,
- a moving dielectric part surrounding the output portion of the conductive line,
- and a control unit rigidly connected to the moving dielectric part, said control unit being capable of longitudinally moving so as to cause the moving dielectric part to move longitudinally along the conductive line.
2. A phase-shifting system according to claim 1 , wherein the conductive line comprises an input portion made up of three segments, with the surface area of each segment being fixed.
3. A phase-shifting system according to one of the claims 1 and 2, wherein the conductive line comprises an output portion made up of three segments, with the relative surface area of each segment being variable.
4. A phase-shifting system according to one of the claims 1 to 3, wherein the input portion and the output portion of the conductive line each comprises three segments, a central segment providing the impedance matching and lateral segments respectively surrounded by a first dielectric domain and a second dielectric domain.
5. A phase-shifting system according to claim 4, wherein the first dielectric domain is the surrounding air and the second dielectric domain is a solid dielectric material chosen from among a polymer and a ceramic.
6. A phase-shifting system according to one of the preceding claims, wherein the longitudinal movement of the moving dielectric part is parallel to the fixed dielectric part that serves as its guide.
7. A method for manufacturing a unitary phase-shifting system according to one of the preceding claims, comprising the following steps:
- a first half of the fixed dielectric part is placed near the input of the phase-shifting system and a first half of the moving dielectric part near the output of the phase-shifting system,
- a conductive line is placed on the first halves of the fixed and moving dielectric parts,
- each end of the conductive line is connected respectively to the input of the phase- shifting system and the output of the phase-shifting system,
- the first half of the fixed dielectric part is fastened onto the conductive line,
- a second half of the fixed dielectric part is fastened onto the input portion of the conductive line, and a second half of the moving dielectric part is fastened onto the output portion of the conductive line,
- the second half of the fixed dielectric part is fastened onto the conductive line.
8. A method according to claim 7, wherein the first halves of the fixed and moving dielectric parts are placed in a housing cover and a housing bottom is placed on the second halves of the fixed and moving dielectric parts.
9. A method for manufacturing a stack of unitary phase-shifting systems according to one of the claims 1 to 6, comprising the following steps:
(a) a first unitary phase-shifting system is formed,
(b) the first unitary phase-shifting system is covered by a cover,
(c) a second unitary phase-shifting system is formed on the cover,
(d) steps (b) and (c) are repeated as many times as desired,
(e) the last unitary phase-shifting system is covered by a cover.
10. A method for manufacturing according to claim 9, wherein the control units are placed on the same side of the stack.
1 1 . An antenna comprising a phase-shifting system according to one of the preceding claims, wherein the phase-shifting system is placed in a housing of which one of the faces is formed by the chassis of the antenna.
PCT/IB2014/061211 2013-05-06 2014-05-05 Longitudinal-displacement passive phase-shifter WO2014181239A2 (en)

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US11101558B2 (en) 2018-08-28 2021-08-24 Nokia Solutions And Networks Oy Apparatus for a phase shifter and a method of manufacture of an apparatus for a phase shifter

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CN109638391B (en) * 2018-11-09 2020-07-07 华南理工大学 Medium moving type phase shifter and base station antenna
CN111293383A (en) * 2018-12-06 2020-06-16 中兴通讯股份有限公司 Dielectric phase shifter and base station antenna
CN112652869A (en) * 2019-10-10 2021-04-13 中兴通讯股份有限公司 Phase shifter, electrically tunable antenna, network equipment and phase shifter manufacturing method
CN111063999A (en) * 2019-12-31 2020-04-24 京信通信技术(广州)有限公司 Antenna, phase-shifting feed device and cavity structure

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US11101558B2 (en) 2018-08-28 2021-08-24 Nokia Solutions And Networks Oy Apparatus for a phase shifter and a method of manufacture of an apparatus for a phase shifter

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