EP1522119B1 - Phase shifter for continuous phase modification - Google Patents

Abstract

The inventive phase shifter comprises two dielectric plates which are arranged in such a way that they are movable in a selected direction inside a metallic box and clamp a main metallic segment in order to form a dephasing cell whose terminals (E, S) are situated on the extremities thereof. Said main segment is provided with two conductive sections (T1, T2) which are arranged in parallel to each other, transversally and longitudinally spaced from each other with respect to the selected direction and provided with a conductive link (T3). The dielectric plates are provided with orifices which determine mobile windows (f1, f2), detecting in a variable manner the sections (T1, T2) according to the motion of the dielectric plates in the box, thereby concomitantly modifying the phase shift between the terminals of the cell. Said phase shifter is used, in particular for an antenna network with nondirectional beam.

Description

The present invention relates to variable phase shifters of antenna arrays that can be used in particular in the base stations of GSM or UMTS cellular radio communication networks for example.

où Θo est l'angle de dépointage du faisceau par rapport à l'horizon. Suivant la relation (1) le faisceau est pointé à l'horizon pour Θo=0 lorsque toutes les sources du réseau sont en phase c'est à dire pour Φ=0. La variation de Φ par un moyen de déphasage ajustable induit un dépointage du faisceau d'un angle Θo. Par exemple pour p=0,9λ et Θo=-10° le déphasage Φ vaut environ 56,3°. Dans les réseaux de radiocommunication cellulaires précités l'amplitude du déphasage Φ vaut typiquement 60° mais, il peut en cas de besoin, atteindre de 90° environ.In order to satisfy the ever-increasing increase in traffic which leads to an increase in the density of base stations in a given territory and to a reduction in the area occupied by the cells forming a cellular radiocommunication network, the antenna networks equipping the stations Bases must be able to radiate directional beams steerable in elevation, typically from 0 ° to -10 ° with respect to the horizon line. As antenna arrays are generally located at the top of pylons or buildings, a decrease in the misalignment angle between 0 ° and -10 ° makes it possible to reduce the ground range of radiated radio waves. These antenna arrays are generally formed by a vertical alignment of elementary sources spaced apart by a distance (p) forming the pitch of the grating which is a multiple, generally less than 1, of the wavelength of the median frequency the frequency band to cover. The elementary sources are fed according to a linear distribution law of phase, two adjacent sources being out of phase of: $$\mathrm{\Phi }\mathrm{=}\mathrm{-}\mathrm{2}\mathrm{\pi }\left(\mathrm{p}\mathrm{/}\mathrm{\lambda }\right)\mathrm{sin\; \Theta o}$$

where Θo is the angle of misalignment of the beam with respect to the horizon. According to relation (1), the beam is pointed on the horizon for Θo = 0 when all the sources of the network are in phase, that is to say for Φ = 0. The variation of Φ by an adjustable phase shift means induces a misalignment of the beam by an angle Θo. For example for p = 0.9λ and Θo = -10 ° the phase shift Φ is about 56.3 °. In the aforementioned cellular radiocommunication networks, the amplitude of the phase shift Φ is typically 60 °, but can, if necessary, reach about 90 °.

The misalignment of the beam can be done manually by tilting the antenna or automatically from a remote control on the ground. These adjustment modes depend for a great deal on the technology used in the production of phase shifters.

It is known to orient the beam of the electromagnetic wave radiated by an antenna array to use ferrite phase shifter devices or PIN diode phase shifter devices. For the realization of antenna arrays, these devices have the particularity that they allow a remote adjustment of the beam misalignment angle by applying a suitable bias current on the ferrites or PIN diodes, they have by cons the disadvantages of presenting nonlinearities and of generating inter-modulation noise in multi-carrier transmission.

It is also known to use coaxial telescopic phase shifters with metal to metal friction or else phase shifters comprising a triplate structure comprising an electrically conductive track composed of several non-aligned segments, the segments being covered in whole or in part by at least one blade. dielectric material moving between two conductive planes along the electrical track.

However, the coaxial telescopic phase shifters with metal-to-metal friction have the disadvantage of being sensitive to corrosion and of presenting micro non-linearities at high powers which are essentially due to the contact resistances.

In the phase shifters with a triplate structure, such as the phase shifter described in FR-A1-2813445 , the variable recovery of the conductive track by the dielectric plates changes the electrical length of the conductive track which produces a mismatch thereof and generally makes this type of phase shifter unsuitable for the supply of antenna networks with high phase shift. The phase excursion can however be improved by adding, for example, to the ends of the conductive track segments of determined length which cancel out the mismatches produced by the dielectric overlays. However, this type of embodiment greatly increases the size of the phase shifters and makes them difficult to use in GSM or UMTS antenna networks. On the other hand, this embodiment requires the introduction, at each phase-shifter of the network, of displacement control devices dielectric plates which further increases their size, and limits their use to networks with only a reduced number of antennas.

The object of the invention is to provide a phase shifter device capable of continuous variation by single mechanical control with a low insertion loss and operating in a wide frequency band to be integrated for example in a network of radiating elements. aligned to form a steerable beam directional antenna.

The invention proposes, for this purpose, a phase-shifter, comprising two plates of dielectric material, slidably mounted in a direction selected inside a metal casing, and sandwiching a metal main segment, to form a phase shift cell. whose terminals are at the ends of the main segment. According to one aspect of the invention, the main segment comprises two substantially parallel conductor sections, spaced apart from one another both transversely and longitudinally with respect to the selected direction, with a conductive connection between them, while the dielectric plates have openings defining mobile windows, varyingly discovering the sections, depending on the sliding of the dielectric plates in the housing, which at the same time changes the phase difference between the terminals of the cell.

The length of each of the windows may be equal to the length of a section increased by a length slightly greater than the half-length of the conductive connection in projection on the chosen direction. This characteristic makes it possible to maintain the electrical length and the impedance of the conductive connection constant irrespective of the position of the dielectric plates, and the phase characteristics depend only on the covering of the first and second sections by the windows.

Good linearity of the phase shift cell can be obtained for lengths of the sections less than 0.12 times the working wavelength of the cell and for a length of the conductive connection less than 0.25 times the length of the cell. working wave of the cell.

The phase shifter may comprise, between the dielectric plates and the housing, a slot arrangement and guide rod, able to jointly define the excursion of the two slidable plates.

According to one embodiment of the invention, directly applicable to the realization of a antenna array, the phase shifter comprises a group of at least two main segments, substantially parallel to the selected direction and connected in series to form a multiple phase shift cell whose terminals are at the free ends of the main segments, while the plates dielectric devices have apertures, defining movable windows, for each section of each main segment.

This arrangement of the invention makes it possible to directly control the orientation of the wave beam emitted by the antenna array by performing a single displacement of the dielectric plates. This displacement can be performed via a single electric motor type "Step" for example controlled remotely which facilitates the development.

The phase shifter may further comprise at least two groups of main segments connected in series, mounted symmetrically with respect to a plane perpendicular to the selected direction, to form two phase shift cells having a common terminal and two opposite terminals located at the ends of the groups.

Alternatively, the phase shifter may comprise an assembly defined by at least two groups of main segments connected in series and placed side by side to form two phase shift cells having a common terminal and two end terminals located at the ends of these groups.

Finally, the invention makes it possible to produce antenna arrays with a phase shifter block, the distribution block being composed of two sets of main segments connected in series, mounted symmetrically with respect to a plane perpendicular to said selected direction.

The proposed phase shifter device makes it possible to achieve relatively large phase shifts in a small footprint while having a low insertion loss and good impedance matching in a wide frequency band. Another advantage is that it has a very good linearity in phase control. In applications to antenna arrays operating in the GSM900, GSM1800 and UMTS frequency bands, the impedance matching is better than 1.3 of ROS in each of the frequency bands and for any position of the phase shifter. The linearity of the phase shifts measured as a function of Displacement of the plates and the frequency is excellent, the non-linearity is better than +/- 5 ° in the frequency band. The insertion losses are extremely low of the order of 0.13dB for a double cell generating a phase shift of 60 ° in the 2GHz frequency band.

• La figure 1A représente une vue de dessus suivant la coupe I-I d'une cellule élémentaire de déphasage selon l'invention.
• Les figures 1B et 1C représentent respectivement des vues suivant les coupes AA et BB de la figure 1A.
• La figure 1D représente une vue suivant la coupe II-II de la figure 1B.
• La figure 2 montre un mode de réalisation de la piste conductrice de la cellule de déphasage représentée aux figures 1A, 1B, 1C, et 1D
• La figure 3 représente une vue de dessus d'un déphaseur comprenant deux cellules élémentaires en cascade selon l'invention.
• La figure 4 représente une vue de dessus d'un déphaseur répartiteur symétrique formé par deux cellules élémentaires selon l'invention.
• La figure 5 représente une vue de dessus d'un déphaseur répartiteur formé par trois cellules élémentaires en cascade selon l'invention.
• La figure 6 représente une vue de dessus d'un bloc déphaseur répartiteur symétrique formée de cellules élémentaires en cascade selon l'invention.
• Les figures 7, 8, 9 représentent des modes de répartition de dispositifs déphaseurs selon l'invention dans des réseaux d'antennes.
• La figure 10 représente une vue de dessus d'un bloc déphaseur répartiteur selon un mode de réalisation particulier de l'invention.

Other characteristics and advantages of the invention will appear in the detailed description below, made with reference to the appended drawings, in which:

• The Figure 1A represents a top view along section II of an elementary phase shift cell according to the invention.
• The Figures 1B and 1C respectively represent views according to sections AA and BB of the Figure 1A .
• The figure 1D represents a view along section II-II of the Figure 1B .
• The figure 2 shows an embodiment of the conductive track of the phase shift cell shown in FIGS. FIGS. 1A, 1B, 1C , and 1D
• The figure 3 represents a top view of a phase shifter comprising two elementary cells in cascade according to the invention.
• The figure 4 represents a top view of a symmetrical splitter phase-shifter formed by two elementary cells according to the invention.
• The figure 5 represents a top view of a splitter phase shifter formed by three cascaded elementary cells according to the invention.
• The figure 6 represents a top view of a symmetrical splitter phase shifter block formed of elementary cells in cascade according to the invention.
• The Figures 7, 8, 9 represent modes of distribution of phase-shifter devices according to the invention in antenna arrays.
• The figure 10 represents a top view of a splitter phase shifter block according to a particular embodiment of the invention.

The drawings contain, for the most part, elements of a certain character. They can therefore not only serve to better understand the description, but also contribute to the definition of the invention if necessary.

The elementary phase shift cell which is represented in FIGS. 1A, 1B, 1C and 1D comprises a main segment sandwiched between two plates of dielectric material 2 and 3, of relative permittivity ξr greater than 1. The plates 2 and 3, here in the form of a rectangular parallelepiped, are held together against each other inside a metal housing 4, in which they slide in the longitudinal direction of the housing between two open ends thereof.

As will be seen, the main segment is part of a "center line" 1 of the phase shifter. In fact, except where the context otherwise requires, the term "central line" in principle covers several main segments.

The conductive housing 4 is formed of a U-shaped base 5 which serves as a guide for the dielectric plates 2 and 3 and a closing conductive plate 6 in the form of a cover. The large size of the base 5 defines the direction of movement of the plates. To allow the displacement of the dielectric plates 2 and 3 in the housing, the latter are traversed by a rod 7 guided by two longitudinal slots g1 and g2 opposite in the base 5 and the cover 6. The length of the slots g1 and g2 limits the amplitude of displacement of the plates 2 and 3. The simultaneous driving of the dielectric plates 2 and 3 can be carried out thanks to one or more rods not shown, integral with the rod 7 and actuated either manually or with the aid of an electric motor.

The central line is composed, as shown more particularly by the figure 2 , of several sections S1, T1, T2, T3, S2. The sections S1 and S2 constitute the entry and exit lines of the phase shift cell. As known to those skilled in the art, the inputs and outputs can be inverted in a reciprocal phase shifter, therefore, we can consider indifferently an input or an output as a terminal of the phase shifter.

The sections T1 and T2 intermediate between the sections S1 and S2, are in extension along two parallel directions xx 'and yy'. They are offset relative to each other, and interconnected by a 90 ° elbow shaped conductive connection forming the section T3. It is mainly on the sections T1, T2 and T3 that the phase shift cell is formed.

To do this, the dielectric plates 2 and 3 comprise openings defining movable windows f1, f2 and f'1 of generally rectangular shape. Each window f1, f2 and f'1 has an opening in a plate, and, substantially in facing relation, an opening in the other plate (alternatively, a window could be defined by an opening in only one of the two plates). The windows f1, f2 are respectively aligned with the active sections T1 and T2 and are dimensioned so as to cover them partially or wholly depending on the position of the dielectric plates 2 and 3 in the housing 4. According to one aspect of the invention, the T1 and T2 sections also have a generally rectangular general shape. The window f'1 is aligned with a portion of the output section S2 of the central line 1. It should be noted that the window f'1 serves only to cascade the cell with another cell as it will appear in FIG. Following the description, it is not necessary for the achievements requiring a phase shift cell. In the example described, the respective width of the windows and their respective lengths are at least equal to those of the corresponding sections. The rectangular shape of the windows substantially matches that of the corresponding sections.

Referring to the Figure 1A the outgoing signal at (S) is out of phase (delayed) with respect to the incoming signal at (E). This phase shift depends, in a substantially proportional manner, on the surface of the sections T1 and T2 covered by the dielectric plates or, in an equivalent manner, the displacement of the dielectric plates 2 and 3 materialized by the distance (d) which separates the straight edges of the windows f1 and f2 and the right end edges of corresponding sections T1 and T2. The minimum position of the phase-shifter corresponds to d = 0, the maximum position of the phase-shifter corresponds to d = 1, "1" being the predefined common length of the sections T1 and T2, so that the maximum stroke of the phase shifter is equal to the common length "1" of said sections.

The maximum achievable phase shift is substantially proportional to "1". The main role of the slots g1 and g2 is precisely to limit the travel of the plates 2 and 3 between an initial position for which for example d = 0 and a final position for which d = 1, depending on the desired phase shifts.

The role of the windows f1 and f2 formed in the dielectric plates is to cover a distance of a portion of the sections T1 and T2 by discovering the other part of these same sections over a distance d-1. The portion covered with sections T1 and T2 is surrounded by the dielectric medium of dielectric constant ξr greater than 1 and the uncovered portion bathes in the air of dielectric constant equal to 1 in the manner of a suspended line. The length of the window f2 is such that the section T2 can be completely ventilated in the minimum position of the phase shifter module which is obtained for d = 0 and that the bent portion of the section T3 at the end of the section T2 is also ventilated in this position. In other words, the length of the window f2 is at least equal to a length f as indicated on the figure 2 comprising the length 1 of the section T2 increased by a length corresponding to the portion of the section T3 falling at the end of the window. This portion has a length slightly greater than the half length of the conductive connection (T3) in projection on the direction of movement of the plates and comprises a certain longitudinal length, a bend and finally a certain transverse length. It is the same for the window f1 with respect to sections T1 and S1. In this way, the electrical length and the impedance of the section T3 connecting the sections T1 and T2, part of which is in the air and the other part is embedded in the dielectric, are kept invariable whatever the position of the plates. In the end, only the electrical properties of the active sections T1 and T2 are variable as a function of the position of the dielectric plates 2 and 3 and all the other sections or connecting sections such that T3, S1 and S2 retain their initial properties during the phase adjustment of the cell.

To maintain the alignment of the windows f1, f2, f'1 with respective corresponding sections T1, T2, S2 the dielectric plates 2 and 3 are guided in the slide formed in the base 4 in cooperation with the slots g1 and g2 and the driving rod 7. The width of a window is substantially equal to the width of a corresponding line section. It may however be slightly higher or lower without this having a consequence on the proper functioning of the phase shift cell. The material of the dielectric plates is chosen for its good radio and mechanical qualities. By way of non-limiting example, it may be used polyethylene or polytetrafluoroethylene which are well known for their good slip qualities and loss tangent at radio frequencies.

With reference to the figure 2 which represents the track 1 with its different sections, the active sections are not aligned on the same axis. The axis offset is larger than the width of the windows so that adjacent windows do not intersect. The length 1 of the active sections T1 and T2 is short in front of the working wavelength, for example equal to one-tenth of the wavelength, and the respective widths W1, W2 are preferably substantially equal. However for impedance matching purposes W1 and W2 widths may differ slightly. The widths and lengths of the active sections determine the maximum phase shift achievable by the phase shift cell.

$$\mathrm{Cotg}\left(\mathrm{\theta }\right)\mathrm{\simeq }\left(\mathrm{Zc}\mathrm{/}\mathrm{Zco}\right)\left(\mathrm{2}\mathrm{\pi }\mathrm{1}\mathrm{/}\mathrm{\lambda }\right)\left(\mathrm{\xi r}\mathrm{+}\mathrm{1}\right)\mathrm{/}\mathrm{2}$$

The section T3 interconnects the two sections T1 and T2 and has at least two elbows, these elbows are not necessarily straight. The characteristic impedance Zc of the section T3 and its equivalent electrical length θ substantially determine the impedance matching state with respect to the impedances Zo of the input and output lines of the phase shifter, these being generally 50 Ohms . For given dimensions of the sections T1 and T2, there exists at least one equivalent electrical length θ and one impedance Zc of the section T3 which are optimal in the sense that they allow the best impedance matching of the phase-shifter in a given frequency band. The impedance Zc determines the width of the section. Approximately, these quantities are determined by the following relationships: $$\mathrm{Zc}\simeq \mathrm{zo}$$

$$\mathrm{cotg}\left(\mathrm{\theta }\right)\mathrm{\simeq }\left(\mathrm{Zc}\mathrm{/}\mathrm{zco}\right)\left(\mathrm{2}\mathrm{\pi }\mathrm{1}\mathrm{/}\mathrm{\lambda }\right)\left(\mathrm{\xi r}\mathrm{+}\mathrm{1}\right)\mathrm{/}\mathrm{2}$$

où Zo est l'impédance des lignes d'entrée et de sortie, généralement de 50 Ohms; Zco est l'impédance dans l'air des tronçons T1 et T2 supposées identiques et de longueur mécanique 1 et λ est la longueur d'onde dans l'air correspondant à la fréquence centrale de la bande de fréquence à couvrir. Le déphasage Δϕ mesure la différence de phase du signal sortant entre l'état final du déphaseur où les tronçons T1 et T2 sont entièrement recouverts par les plaques diélectriques 2 et 3 lorsque d=1 et l'état initial où les tronçons sont dans l'air pour d=0.The maximum phase shift Δφ achievable under these adaptation conditions is approximately given by the following relation: $$\mathrm{Tang}\left(\mathrm{\Delta \phi }\mathrm{/}2\right)\mathrm{\simeq }\left(\mathrm{Zc}\mathrm{/}\mathrm{zco}\right)\left(\mathrm{2}\mathrm{\pi }\mathrm{1}\mathrm{/}\mathrm{\lambda }\right)\left(\mathrm{\xi r}-\mathrm{1}\right)\mathrm{/}\mathrm{2}$$

where Zo is the impedance of the input and output lines, usually 50 Ohms; Zco is the impedance in the air of sections T1 and T2 assumed to be identical and of mechanical length 1 and λ is the wavelength in air corresponding to the central frequency of the frequency band to be covered. The phase shift Δφ measures the phase difference of the outgoing signal between the final state of the phase shifter where the sections T1 and T2 are completely covered by the dielectric plates 2 and 3 when d = 1 and the initial state where the sections are in the air for d = 0.

For example at the frequency 2045MHZ and for 1 = 14.7 mm (ie 1 / λ = 0.1) and Zco = 67 Ohms, with ξr = 2.3, we obtain: Zc ≃Zo = 50 Ohms, θ = 52 , 2 ° is an equivalent length of the section T3 equal to 0.145λ (or 21.3 mm in the air) and finally a phase shift Δφ ≃34 °. Such a phase-shifter has a relative bandwidth close to 25%, ie a frequency band between 1700 MHz and 2200 MHz for a stationary wave ratio (ROS) of less than 1.2. In a triplate with a thickness of 4.6 mm, for example with a 0.2 mm thick track, the sections T1 and T2 would have a width of 3.9 mm and the section T3 a width of 3.2 mm in the constant dielectric. 2,3 or 6mm in the air.

In practice, it is not mandatory to adopt the values derived from relationships (2) and (3) which are based on simplifying assumptions that make it possible to obtain estimates. For example, considering that the section T3 is partly in the air and partly in the dielectric it should have two sections of different width to maintain a homogeneous impedance equal to Zc. Or it may be more convenient to keep constant the width of this section to simplify the realization of the elbows which implies that the impedance Zc is not constant over its entire length. Under these conditions the precise definition of the section T3 in order to obtain a good impedance matching in the frequency band can be treated in a more global way by taking into account the real topology of the circuit, by means of a software tool of CAD suitable for microwave circuits, such as for example the software marketed under the name ADS by the company AGILENT or the software marketed under the designation SERENAD by ANSOFT Corporation. Also, the input and output impedance matching can be improved by the addition of matching circuits, for example, performing one or more quarter-wave transformations.

The relation (4) shows that the phase difference is proportional to the length 1 covered by the dielectric plates 2 and 3 and that it varies substantially linearly as a function of the displacement d of the dielectric plates 2 and 3, which facilitates the adjustment or the phase shifter calibration. The relation (4) also shows that the phase shift is proportional to the frequency.

The relation (4) also makes it possible to estimate the phase shift achievable with an elementary cell comprising three sections T1, T2 and T3 of the type of that described above. Typically, the phase shift can be close to 30 ° by using dielectric substrates with a constant close to 2, which is advantageous in terms of bandwidth and in terms of radio frequency losses. Also, to achieve higher phase shifts of 60 °, 90 ° or more and be able to control the misalignment of the beam of a network antenna according to the relationship (1) it is necessary to cascade two or three or more elementary cells, each realizing 30 ° phase shift as shown in figures 4 and 5 .

In addition, the relations (3) and (4) also make it possible to appreciate the overall small overall size of the phase-shifter, both in length and in width, since the section T3 with its two elbows has a typical equivalent length close to 0.15λ and generally lower. at 0.25λ and the sections T1 and T2 have a typical length of 0.1λ and generally less than 0.12λ.

The figure 3 where the elements homologous to those of Figures 1A to 1D have the same references shows a top view of the phase shifter the removed cover, comprising two cascaded elementary cells comprising a central line, composed of four sections referenced T1, T2, T'1, T'2, of identical lengths, the sections d the odd indices being aligned on the axis xx "and the even subscript sections being aligned on the axis yy 'In this configuration the sections T1 and T2 form the first cell and the sections T'1 and T'2 form the second cell, these two cells constituting a double phase-shifting cell The dielectric plates 2 and 3 comprise four windows f1, f2, f'1, f'2, respectively covering all or part of the sections T1, T2, T'1, T'2 The phase difference obtained is 2Δφ, which is twice that of Δφ of an elementary cell The connection between the two cells is made by means of line sections whose electrical properties remain invariable as a function of the position of the plates This embodiment is easily generalized to obtain a phase shift multiple cell composed of three or more elementary cells.

The figure 4 where the elements homologous to those of the preceding figures bear the same references, shows a view from above of a symmetrical splitter phase-shifter comprising an input E and two outputs S1 and S2 whose phases are conjugate, that is to say equal and of signs contrary, the phase shift sections on either side of a median plane PP ', perpendicular to the direction of movement of the plates, comprising a double cell of the type shown in FIG. figure 3 . This phase-shifter can for example be used to excite antenna arrays of the type represented in FIGS. Figures 8 and 9 . The structure of the central line 1 is symmetrical with respect to the plane PP ', so that a displacement d of the plates 2 and 3 to the left of this plane for example, makes the active sections of the section on the right uncovered by dielectric , equal surface discovered and covered respectively. The outgoing phase shift at S1 is proportional to the displacement d of the dielectric plates and the phase shift of the outgoing signal at S2 is proportional to (1-d), where l is the length of the sections T1 and T2 as before, the two signals being in phase with the median position d = 1/2. With respect to this median position taken as a reference, the two signals have equal and opposite phases and the maximum phase shift between the two signals is equal to the phase shift achievable by two cascaded elementary cells, ie substantially 2Δφ, where Δφ is the maximum phase shift for a cell. By equalizing the phases of the two output signals in an extreme position of the phase shifter taken as a reference, for example for d = 0, the maximum phase shift between the two outputs will be 4 Δφ and the two signals will have equal and opposite phases for any position phase shifter from d = 0 to d = 1. The equalization of the phases consists simply of lengthening in a way not represented on the figure 4 , the output line S1 of an electrical length equivalent to the phase shift Δφ. Alternatively, such a symmetrical splitter phase shifter can be made from multiple cells instead of double cells.

The figure 5 where the elements homologous to those of the preceding figures bear the same references, represents a view from above of a phase-shifter comprising a common input E and three outputs S1, S2, S3, phase-shifted relative to one another phase shift, generated by double cells, assumed to be identical, of the type represented in figure 3 . These double cells are connected in series and placed side by side to form two phase shift cells.

In this embodiment, the central line 1 is folded in zigzag each branch of the zigzag corresponding to a double cell section. By traversing the figure from bottom to top, the output S1 is out of phase with a quantity (φo + 2Δφ) with respect to the input E, the output S2 is out of phase with (φ1 + 2Δφ) with respect to the output S1 and the output S3 is shifted by (φ2 + 2Δφ) with respect to the output S2, φo, φ1, φ2 being the residual phase shifts corresponding to the paths traveled by the incoming wave in E to reach the respective outputs for a given position of the phase shifter taken as a reference. By equalizing the phases in this reference position by the elongation of the shortest output lines, for example S2 and S3, these residual phase shifts can be compensated so that in this reference position the outputs are all in phase. The phase difference between two consecutive outputs is then the same and equal to 2Δφ. In a variant, each branch of the zigzag may comprise a multiple cell. Moreover, the zigzag is not limited to three branches. This principle can be generalized for any number of outputs.

This phase shifter can be used to realize a symmetrical splitter phase shifter. For the sake of clarity, only the left part of the splitter phase shifter is represented on the figure 5 . This symmetrical splitter phase shifter can for example be used in the network antenna architecture diagram shown in FIGS. Figures 8 and 9 .

The figure 6 represents a splitter phase shifter block comprising an input E and ten outputs referenced respectively S1, S2 ..... S5, S-1, S-2, ..... S-5. The outputs have two to two of the conjugate phases and the input power is distributed unbalanced between the ten outputs. On either side of a median plane PP 'are four double phase shift cells of the type of the figure 3 producing a phase shift 2Δφ between the outputs S1 and S2, S2 and S3, S4 and S5 and the symmetrical phase shift between the outputs S-1 and S-2, S-2 and S-3, etc., the outputs S1 and S -1 keeping the same fixed phase shift taken as reference 0 °. These symmetrical phase shifts are obtained by means of two separate blocks 8 and 9 of dielectric plates 2 and 3, disposed on either side of the median plane PP 'and moving together by a mechanism for adjusting the phase shifter not shown. The portions of the conductive tracks 10 located in the space between the two removable blocks 8 and 9 and at the ends of the blocks are sandwiched by two facing plates 11 made of insulating material, for example foam with very low loss. and a dielectric constant close to that of the air.

Examples of embodiments of antennas organized in a uniform network that may comprise phase shifters according to the invention are shown in FIGS. Figures 7 to 9 .

On the figure 7 the network is formed by a series of sources A1 to AN aligned vertically and spaced with a constant pitch p. These sources are fed in parallel by means of a balanced or unbalanced power distributor or divider, each branch of the divider supplying a source of rank n (n = 1, 2, .... N) with a phase difference equal to (n -1) Φ with respect to the first source, taken as 0 ° phase reference. In this embodiment the amplitude of the phase shift on the last source which is equal to (N-1) Φ can become very important if N is large. However, the size of the phase shifters limits this embodiment to a very limited number of sources.

The figure 8 shows the same network of sources but this time fed in series so that the phase shifts are cumulative from one source to the next and the distribution law of the phases is linear along the network. In this series architecture, each node of the network comprises three branches, an input branch and two output branches, and it is possible to easily produce a specific distribution law of the power on the radiating sources, for example in order to produce a diagram. of radiation shaped or having a low level of sidelobes. It is also clear that the circuit consisting of phase shifters and power dividing nodes can advantageously be embodied as a single box both distributor and phase shifter, or at least if the available space does not allow it. not, a small number of such boxes. Such a housing which may be of the type described in figures 5 and 6 will have an input and several outputs supplying the elementary sources A-2, A-1, A0, A1, A2. It will also be equipped with the adjustment means of the phase shifters. Note that on the diagram of the figure 8 , the phase-shifts are symmetrical with respect to the entry point M of the network, the phase-shifts are upwardly positive and are negative towards the bottom of the point M. This arrangement is only a particular case that is advantageous in practical terms. The entry point of the network can indeed be positioned at any point in the network, the essential thing is that the phase difference between two successive sources is equal to Φ. As shown in figure 9 the network is formed by an even number of sources with a feed point M positioned at the center of the network which provides symmetrical phase shifts as on the figure 2 .

The figure 10 represents a splitter phase shifter block, according to a particular embodiment of the invention, wherein the housing 4 comprises 2 compartments 4a and 4b aligned and interconnected by a coaxial cable 30 having a characteristic resistance generally of 50 ohms. Each compartment comprises a set of phase shift cells having a common terminal and end terminals located at the lateral ends of the compartments. So, in the example of the figure 10 , each compartment has four double phase shifters of the type of the figure 3 . The compartments 4a and 4b in particular have substantially identical dimensions.

The phase shifter block shown on the figure 10 has a common input E and 9 outputs S1 to S5 and S-2 to S-5. These inputs / outputs are generally adapted to an impedance of 50 ohms.

The input / output cables are connected to the casing 4 by means of input / output cable supports 20, 21, 22 and 23, made of conductive material, fastened to the lateral ends of each compartment by screwing on the casing. . The housing is in particular metallic.

Thus, the compartment 4a is provided with an input / output cable holder 20 on its left-hand side end and an input / output cable holder 21 on its right-hand side end. The compartment 4b is provided with an input / output cable holder 22 on its left-hand side end and an input / output cable holder 23 on its right-hand side end. The coaxial cable 30 connects the cable support 22 of the compartment 4a to the cable support 23 of the compartment 4b.

The outputs Si and S-i for i = 2 to 5 have conjugate phases. The output S1 keeps the same fixed phase shift taken as reference 0 °.

These symmetrical phase shifts are obtained by means of two pairs of separate blocks {8,9} and {8 ', 9'}, symmetrical with respect to an axis (P ₁ P ₁ ') perpendicular to the chosen direction. Each block consists of dielectric plates 2 and 3. The pair of blocks {8,9} is located in the compartment 4a and the pair of blocks {8 ', 9'} is located in compartment 4b.

The phase shift is modified by a guide rod 7 integrated in the housing 4 and passing through each compartment 4a and 4b. The guide rod 7 is directed in the chosen direction defined above and is integral with the dielectric plates 2, 3.

The housing 4 according to this embodiment of the invention is a metal housing, for example aluminum, manufactured by an extrusion process. The dielectric plates 2 and 3 can be made by molding.

The manufacture of a phase shifter block of given length L is more complex than the manufacture of a two-compartment phase shifter block L / 2 length twice smaller. As a result, the structure of the housing 4 in two compartments 4a and 4b, as described above, simplifies the manufacture of the phase shifter with respect to the embodiments described above.

Furthermore, since the housing 4 is made of a single block by extrusion and all the inputs / outputs are disposed at the ends of the housing, the assembly of the phase shifter block can be achieved by threading each pair of blocks {8,9 } (respectively {8 ', 9'}) in the corresponding compartment 4a (respectively 4b). Thus the assembly of the phase shifter block according to this embodiment is also simplified with respect to the embodiments described above.

The dephaser described with reference to the figure 10 also makes it possible to eliminate the direct connection of input / output cables to the housing 4 (ie the direct contacts between the coaxial sheath and the housing) thanks to the introduction of the cable supports and therefore the number of potential sources passive intermodulation products (IMPs).

The phase shifter according to the invention is used, in particular, for the production of antenna arrays with detachable beams, by moving the plates 2 and 3. The input / output terminals then form connection points of the elements. antennas.

Moreover, the invention is not limited to the embodiments described. These include different possibilities of symmetry that can be arranged differently by removing any unnecessary elements.

Similarly, there has been described a single cell then multiple, in particular double. The number of stages of a cell may depend on the phase shift range desired for it.

The means described for limiting the sliding excursion of the plate or plates are not limiting. In this regard, instead of providing a single pair of plates for a set of phase shift cells, it would be possible to provide several pairs of plates moved independently. Finally, this displacement could comprise at least partially a rotation.

Claims (19)

1. Phase shifter comprising two plates of dielectric material (2, 3) mounted to be slidable in a selected direction inside a metal housing (4) and sandwiching between them a main metallic segment (1) to form a phase- shift cell the terminals of which are at the ends of the main segment, the main segment (1) comprising two substantially parallel conductive sections (T1, T2) spaced from one another both transversely and longitudinally relative to said selected direction, having a conductive connection (T3) between them, characterised in that the dielectric plates (2, 3) comprise openings (f1, f2) defining movable windows that variably uncover said sections (T1, T2), as a function of the sliding of the dielectric plates (2, 3) in the housing (4), thus at the same time modifying the phase shift between the terminals of the cell.
2. Phase shifter according to claim 1, characterised in that each window comprises an opening in a plate and, substantially opposite, an opening in the other plate.
3. Phase shifter according to one of claims 1 and 2, characterised in that the conductive connection (T3) comprises a part which is substantially perpendicular to said selected direction, particularly in the shape of an elbow.
4. Phase shifter according to claim 1, characterised in that the sections (T1, T2) are substantially shorter in length than the working wavelength (λ) of the phase shifter.
5. Phase shifter according to one of claims 2 to 4, characterised in that the sections (T1, T2) have lengths which are less than 0.12 times the working wavelength (λ) and the length of the conductive connection (T3) is less than 0.25 times the working wavelength (λ)
6. Phase shifter according to one of claims 1 to 5, characterised in that it comprises, between the dielectric plates (2, 3) and the housing (4), an arrangement with slots (g1, g2) and a guide rod (7), jointly capable of limiting the excursion of the two sliding plates (2, 3).
7. Phase shifter according to one of claims 1 to 6, characterised in that the length (f) of each of the windows is equal to the length (1) of a section, augmented by a length slightly greater than half the length of the conductive connection (T3) projected in the selected direction.
8. Phase shifter according to one of claims 1 to 7, characterised in that the windows (f1, f2) and the sections (T1, T2) have a substantially rectangular geometry with substantially equal widths (W1, W2).
9. Phase shifter according to one of claims 1 to 8, characterised in that it comprises a group of at least two main segments, substantially parallel to the selected direction and connected in series to form a multiple phase-shift cell the terminals of which are at the free ends of said main segments, the dielectric plates (2, 3) comprising openings, defining movable windows (F1, f2, f'1, f'2) for each section (T1, T2) of each main segment.
10. Phase shifter according to claim 9, characterised in that it comprises at least two groups of main segments connected in series, mounted symmetrically with respect to a plane perpendicular to said selected direction, to form two phase-shift cells having one common terminal (E) and two opposing terminals (S1, S2) located at the ends of said groups.
11. Phase shifter according to one of claims 9 and 10, characterised in that it comprises an assembly defined by at least two groups of main segments connected in series and placed side by side to form two phase-shift cells having one common terminal (E) and two opposing terminals (S1, S2) located at the ends of said groups.
12. Phase shifter according to claim 11, characterised in that it comprises two sets of main segments connected in series, mounted symmetrically with respect to a plane (PP') perpendicular to said selected direction.
13. Phase shifter according to claim 11, characterised in that the housing (4) comprises two compartments of substantially identical dimensions (4a, 4b) connected to one another by a coaxial cable, each compartment of the housing (4a, 4b) comprising a set of main segments connected in series, to form phase-shift cells having one common terminal (E) and extreme terminals (S1, S2, S-2,S3, S-3,S4, S-4, S5, S-5) located at the lateral ends of said compartments.
14. Phase shifter according to claim 13, characterised in that each compartment of the housing (4a, 4b) comprises two inlet/outlet cable supports (20, 21, 22, 23) consisting of a conductive material and fixed to the lateral ends of the compartment, the terminals being connected to inlet/outlet cables via said cable supports.
15. Phase shifter according to claim 14, characterised in that the coaxial cable connects the two compartments of the housing (4a, 4b) by one of their respective inlet/outlet cable supports (20, 21, 22, 23).
16. Phase shifter according to one of claims 13 to 15, characterised in that the housing (4) is produced by an extrusion process.
17. Phase shifter according to one of claims 13 to 16 taken together with claim 6, characterised in that the guide rod (7) is directed in said selected direction and is fixedly attached to the dielectrics (2, 3).
18. Phase shifter according to one of claims 13 to 17, characterised in that the dielectrics (2, 3) are produced by a moulding process.
19. Use of the phase shifter according to one of claims 1 to 17 with terminals forming connection points for elements of antennas, for producing arrays of antennas with a de-aimable beam, by movement of the plates (2, 3).

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