WO2013079552A1

WO2013079552A1 - Antenna comprising a tunable array of radiating elements

Info

Publication number: WO2013079552A1
Application number: PCT/EP2012/073872
Authority: WO
Inventors: Jean-Pierre Harel
Original assignee: Alcatel Lucent
Priority date: 2011-11-30
Filing date: 2012-11-28
Publication date: 2013-06-06
Also published as: FR2983358B1; FR2983358A1

Abstract

The object of the present invention is an antenna comprising at least one row of fed radiating elements. At least one of the radiating elements is placed in a moving cell. The antenna comprises at least one mechanical device whose rotation causes the longitudinal displacement of the moving cell in order to alter the spacing of the radiating elements. The mechanical device may comprise at least one threaded rod portion cooperating with a fixed threaded hole joined with a moving cell.

Description

Antenna comprising a tunable array of radiating elements

CROSS-REFERENCE

This application is based on French Application N° 1 1 ,60,960 filed on November 30, 201 1 , the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is hereby claimed under 35 U.S.C. §1 19.

BACKGROUND

The present invention pertains to an array of radiating elements forming an antenna, in particular a broadband or ultrabroadband antenna.

The dimensions of broadband or ultra broadband antennas, such as the distance between the radiating elements for instance, are chosen so as to represent an acceptable compromise with respect to radio performance desired over the frequency band. Naturally, this compromise is based on average performance over the entire frequency band and cannot be optimal for each portion of the frequency band. Additionally, these geometric dimensions are initially fixed by construction, and there is no way for the end user to modify this compromise.

However, for various clients in the field of high-speed communications using broadband or ultra broadband antennas, the compromise that is considered the best is not the same in most cases. A geometric design based on one client's needs might be ill- suited for most others. At present, the only solution is to offer a wide range of different products so as to best meet the desires of different clients. However, this no longer meets the goal of encouraging ultra broadband products that can meet the needs of a large market.

SUMMARY

The purpose of the present invention is to propose a mechanical device that makes it possible to alter the spacing between the radiating elements of an antenna, so as to alter the radiation pattern in the vertical plane. The purpose of the invention is also to enable the altering of the radiating elements' positions while the antenna is operating, without its operation being disrupted as a result.

The object of the present invention is an antenna comprising at least one row of fed radiating elements in which at least one of the radiating elements is placed in a moving cell joined with a mechanical device whose rotation causes the longitudinal displacement of the moving cell in order to alter the distance between the radiating elements.

According to one aspect, the antenna comprises a reflector common to all of the radiating elements. The common reflector forms the antenna's chassis and ensures its mechanical sturdiness. The moving cell is capacitively coupled to the common reflector, which is separated from it by a dielectric layer. The moving cells are thereby electrically insulated from one another. Fixed or moving barriers may be added in order to assist in separating the radiating elements. According to another aspect, each of the radiating elements is placed in an individual moving cell that serves as a reflector for that radiating element. In such a case, the individual moving cells are electrically insulated from one another. Barriers separate the radiating elements.

According to one embodiment, the mechanical device comprises at least one threaded rod portion cooperating with a fixed threaded hole joined with a moving cell.

According to a first variant, the threaded rod portion is controlled by means of a rotating rod equipped with a handle.

According to a second variant, the threaded rod portion is controlled by means of a motor controlled by an electronic system. The antenna may comprise at least two rows of radiating elements disposed perpendicularly, each row comprising a radiating element placed within a moving cell and at least one mechanical device that makes it possible to move the moving cell.

One advantage of the present invention is to make it possible to propose a single type of antenna that can operate under good conditions on multiple frequency bands, particularly broadband ones. The operator is thereby capable of choosing the best compromise for its intended use. The manufacturing cost is reduced through the elimination of many specific variants in favor of a single, higher-quantity product.

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 schematically depicts a top view of an antenna of the prior art comprising a row of radiating elements,

- Figure 2 is the radiation pattern in the vertical plane of the antenna in Figure 1 ,

- Figures 3a and 3b schematically depict a first embodiment of an antenna, Figure 3a is a top view and Figure 3b is a cross-section along A-A of Figure 3a,

- Figures 4a and 4b schematically depict one variant of the first embodiment of an antenna, Figure 4a is a partial cross-section view and Figure 4b is a perspective view, - Figure 5 schematically depicts, in a side view and partial cross-section view, the mechanical device for moving the radiating elements of the first embodiment of an antenna,

- Figures 6a and 6b schematically depict, in a top view, the moving of the radiating elements of the first embodiment of an antenna,

- Figures 7a and 7b schematically depict, in a top and bottom perspective view, respectively, the arrangement of the radiating elements corresponding to Figure 6a of the first embodiment of an antenna,

- Figures 8a and 8b schematically depict, in a top and bottom perspective view, respectively, the arrangement of the radiating elements corresponding to Figure 6a of the first embodiment of an antenna,

- Figures 9a, 9b and 9c depict the radiation pattern in the vertical plane of the first embodiment of an antenna with no tilt in the main lobe for a 125 mm distance between elements at the frequencies 1.7 GHz, 2.2 GHz and 2.7 GHz respectively,

- Figures 10a, 10b and 10c depict the radiation pattern in the vertical plane of the first embodiment of an antenna with a 10° tilt in the main lobe for a 125 mm distance between elements at the frequencies 1.7 GHz, 2.2 GHz and 2.7 GHz respectively, - Figures 1 1 a, 1 1 b and 1 1 c depict the radiation pattern in the vertical plane of the first embodiment of an antenna with a 10° tilt in the main lobe for a 1 10 mm distance between elements at the frequencies 1.7 GHz, 2.2 GHz and 2.7 GHz respectively,

- Figure 12 schematically depicts, in a top view, another arrangement of the radiating elements of the first embodiment of an antenna,

- Figures 13a, 13b and 13c depict the distribution of amplitude A in dBc based on the position D of the radiating elements for an antenna according to Figures 6a, 6b and 12 respectively,

- Figures 14a and 14b depict the radiation pattern in the vertical plane of the first embodiment of an antenna for a constant distance (Fig.6a) or different distance (Fig.12) between radiating elements, respectively,

- Figures 15a and 15b schematically depict, in a partial top and bottom perspective view, a second embodiment of an antenna,

- Figures 16a and 16b schematically depict, in a top view, the moving of the radiating elements of the second embodiment of an antenna,

- Figures 17a and 17b schematically depict, in a top and bottom perspective view, the initial position corresponding to Figure 16a of the radiating elements of the second embodiment of an antenna,

- Figures 18a and 18b schematically depict, in a top and bottom perspective view, the initial position corresponding to Figure 16a of the radiating elements of the second embodiment of an antenna,

In Figures 2, 9a, 9b, 9c, 10a, 10b, 10c, 1 1 a, 1 1 b, 1 1 c, 14a and 14b, the radiation level R in dBc (for "decibels relative to the carrier") is given on the y-axis, and the angle a of radiation in the plane in question is given in degrees on the x-axis. DETAILED DESCRIPTION

For example, a known antenna 1 , illustrated by Figure 1 , comprises ten radiating elements 2, powered by an outside source of energy, which are aligned and arranged at an equal distance from one another on a common reflector 3. The radiating element 2 is, for example, a dual-polarization radiating element formed from two radiating dipoles. Each dipole of each polarization is made up of two co-linear conductor threads, and it is fed by a coaxial cable connected to a feed line. The radiating elements 2 are separated by a distance d between elements, for example d = 125 mm, which is set during the construction of the antenna, and which cannot be modified afterward.

The radio radiation pattern 20 in the vertical plane, as depicted by Figure 2, shows the radiation level R of the antenna 1 in the vertical plane based on the angle a of radiation for a given frequency F, here F = 2.6 GHz for example, when the signal is in the same phase and amplitude for all radiating elements 2.

Figures 3a and 3b depict a first embodiment of an antenna 30. The radiating elements 31 of the antenna 30 are aligned and placed in a moving cell 32. The radiating elements 31 possess a common reflector 33. A moving cell 32 is represented here by a flat rectangular plate disposed beneath the common reflector 33, facing an opening built into the common reflector 33, that opening 34 accommodating the foot 35 of the radiating element 31 which is fastened thereto. As depicted in cross-section view in Figure 3b, the moving cell 32 is capacitively coupled to the common reflector 33. The moving cell 32, whose dimensions are slightly larger than the opening, is separated from the common reflector 33 by a thin dielectric layer 36, such as a plastic film or insulating paint.

Figures 4a and 4b depicts one variant of the antenna according to the first embodiment of Figures 3a and 3b. Additional parts are commonly present in such an antenna, particularly metal barriers or parasitic elements. These additional parts may be fastened onto the common reflector or into the moving cells.

For an antenna 40, a barrier 41 may be fastened, for example, into the moving cell 42. The moving cell 42 is electrically insulated by a dielectric layer from the common reflector 46 that constitutes the antenna's chassis. The moving cell 42 may be moved by means of a mechanical device 43 placed beneath the moving cells 42. Couplings between the dual-polarization radiating elements 44 may substantially reduce the performance of the antenna 40. In order to reduce those couplings, and thereby to increase the insulation between the feed connectors of the antenna 40, the radiating elements 44 are separated by metal barriers 41. Other barriers 45 may also be added, or parasitic elements that may be fastened onto the common reflector 46, for example, or into the moving cells 42 as needed.

The term parasitic element, or director, refers to a conductive element that is not fed, neither directly nor by means of the radiating element. The addition of parasitic elements offers an increase in the antenna's performance, such as insulation between channels (one channel per antenna polarization), the antenna's bandwidth and its gain. An example mechanical device 50 allowing the moving cells to move is depicted in Figure 5. This figure depicts a simple case in which some radiating elements 51A are fastened directly onto the reflector 52, while other radiating elements 51 B, 51 C are disposed within the moving cells 53B, 53C.

The mechanical device 50 for moving the radiating elements 51 B, 51 C comprises a longitudinal rotating rod 54 bearing at least one threaded portion 55B, 55C, a fixed threaded hole 56B, 56C, for example a nut, is disposed on a moving cell 53B, 53C. Each threaded portion 55B, 55C cooperates with a fixed nut 56B, 56C respectively placed on the moving cells 53B, 53C. Each fixed nut 56B, 56C is therefore associated with a moving cell 53B, 53C and with a threaded portion 55B, 55C. The rotation of the rotating rod 54 rotationally drives the threaded portion 55B, 55C, which causes the translational movement of the threaded portions 55B, 55C into the threaded holes 56B, 56C respectively, and therefore of the moving cells 53B, 53C bearing the radiating elements 51 B, 51 C. Consequently, each element 51 B, 51 C sees its position change with respect to the antenna's fixed components such as the reflector 52 or the fixed radiating element 51A.

In the present situation, a radiating element 51A, fastened directly onto the common reflector 52, is surrounded by at least two radiating elements 51 B and 51 C disposed within moving cells 53B and 53C respectively. The rotating rod 54 is fastened by two fastening parts 58 onto the common reflector 52. The rotating rod 54 support the first threaded portion 55B associated with a first fixed nut 56B related to the first moving cell 53B and a second threaded portion 55C associated with a second fixed nut 56C related to the second moving cell 53C. The first threaded portion 55B has a right-hand thread (clockwise), while the second threaded portion 55C has a left-hand thread (counterclockwise).

This mechanical device 50, which can be motorized, has the advantage of being accessible and controllable from outside antenna, for example by means of a protruding handle 57. It should noted that control is performed easily using a single gesture that causes rotation, and requires no option of disassembling/reassembling fastening parts such as screws or nuts. Finally, the mechanical device 50 may be manually or remotely activated, for example by means of an outside device such as an ACU (for "Antenna Control Unit") module used to control the tilt of a VET (for "Vertical Electrical Tilt") antenna, for example. This first embodiment has been described assuming an odd number of radiating elements, but naturally the antenna may comprise an odd or even number of radiating elements. Likewise, the antenna may comprise a variable number of fixed and moving radiating elements, as well as only moving radiating elements. Figures 6a and 6b depict one example adjustment of the spacing of the radiating elements of an antenna according to the first embodiment described above. The antenna comprises for moving radiating elements disposed on either side of a fixed radiating element placed in the center.

The antenna in the configuration 60A, here depicted by the Figure 6a, comprises four moving radiating elements 61 A, 61 B, 61 D, 61 E disposed on either side of a fixed radiating element 61 C in the center, so that the five radiating elements 61 A, 61 B, 61 C, 61 D and 61 E are separated by a constant distance d between elements.

Each moving radiating element 61 A, 61 B, 61 D, 61 E is placed within a moving cell 62A, 62B, 62D, 62E of its own. Moving metal barriers 63A, 63E and fixed metal barriers 64B, 64D make it possible to separate the radiating elements 61A, 61 B, 61 C, 61 D and 61 E.

Using a mechanical device 65, similar to the mechanical device 50 of Figure 5 for example, each moving radiating element 61 A, 61 B, 61 D, 61 E is moved in the direction of the fixed radiating element 61 C in the center, so as to reduce the distance between elements by a length ε.

This results in an antenna in the configuration 60B as depicted in Figure 6b, whose radiating elements 61 A, 61 B, 61 C, 61 D and 61 E are separated by a distance between elements (d-ε).

Based on the same principle, it is equally possible to increase the distance between elements d in order to achieve a distance between elements (d+ε) for example.

Altering the distance between elements makes it possible to alter the antenna's radiation pattern in the vertical plane.

The antenna in the configuration 60A according to the first embodiment is illustrated by Figures 7a and 7b, by a top perspective view and a bottom perspective view, respectively.

Each moving radiating element 61 A, 61 B, 61 D, 61 E is disposed within a moving cell 62A, 62B, 62D and 62E. The mechanical device 65 to move the moving cells 62A, 62B, 62D and 62E comprises a rotating rod 66, longitudinally disposed along the entire length of the antenna, suspended beneath the common reflector 67 by fastening parts 68 and terminated by a handle 69 protruding from the antenna 60A in order to make it possible to manually activate the rotating rod 66. A fixed nut 70A, 70B, 70D and 70E is joined with each moving cell 62A, 62B, 62D and 62E and respectively associated with each of the corresponding threaded portions supported by the rotating rod 66.

Figures 8a and 8b depict the antenna in the configuration 60B from a top perspective view and a bottom perspective view, respectively.

Each moving radiating element 61 A, 61 B, 61 D, 61 E is disposed within a moving cell 62A, 62B, 62D and 62E. The moving cells 62A, 62B, 62D and 62E have moved towards the fixed radiating element 61 C, placed in the center, by a length ε in order to reach the configuration 60B.

The threaded holes or fixed nuts 70B and 70D joined with the moving cells 62B and 62D respectively must have opposite threading directions so that the moving cells 62B and 62D move towards or away from one another at the same time, as well as with respect to the fixed radiating element 61 C in the center. Likewise, the fixed nuts 70A and 70E joined with the moving cells 62A and 62E must have an opposite threading direction for the same reasons. However, when the rotating rod 66 is activated, the moving cells 62B and 62D move apart on either side of the fixed radiating element 62C by the same distance x. The moving cells 62A and 62E must then also move apart by a distance x with respect to the moving cells 62B or 62D respectively. If it is desired that all the moving cells 62A, 62B, 62D, 62E move apart from one another by the same distance x when the common rotating rod 66 is activated, the moving cells 62B and 62D must move by a distance x while the cells 62A and 62E must move by twice as great a distance 2x. Consequently, it is understood that the pitch of the threaded portions must proportionally increase the further one gets from the central fixed radiating element 61 C. The pitch is defined as the relative distance translationally traveled by a screw with respect to its nut during one full turn. Now consider an ultrabroadband antenna working in the 1 .7 to 2.7 GHz frequency range. For the lower part of that frequency band, a distance of about 130 mm between the radiating elements would be suitable. However, for the upper part of the frequency band, the most suitable distance between elements would be about 120 mm. Consequently, an average distance between elements of about 125 mm appears to be the best compromise to cover the entire frequency band.

Figures 9a, 9b and 9c illustrate radiation patterns in the vertical plane of such an antenna with zero tilt for a distance between elements of about 125 mm, each of the radiating elements here being fed with a signal of the same phase and amplitude.

Figure 9a is a radiation pattern 100 in the vertical plane in the lower part of the frequency band around a frequency of about 1.7 GHz.

Figure 9b is a radiation pattern 101 in the vertical plane in the central part of the frequency band around a frequency of about 2.2 GHz.

Figure 9c is a radiation pattern 102 in the vertical plane in the upper part of the frequency band around a frequency of about 2.7 GHz.

A sidelobe 103 of about -13 dBc in the upper part of the frequency band, compared to the reference value of 0 dBc corresponding to the radiation level R for the main beam 104. Figures 10a, 10b and 10c depict radiation patterns in the vertical plane of the same antenna as Figures 9a, 9b and 9c, but with an electrical tilt of 10° from the vertical (also known as pointing). In order to obtain an electrical tilt, the radiating elements are fed with a signal of the same amplitude, but with a different phase. For example, in order to obtain a 10° tilt at a frequency of 2.7 GHz, the first radiating element may be fed by a phase of 0° (taken as the reference radiating element), a phase of 72° for the second radiating element, a phase of 144° for the third radiating element, a phase of 216° for the fourth radiating element and a phase of 288° for the fifth radiating element.

Figure 10a is a radiation pattern 110 in the vertical plane in the lower part of the frequency band around a frequency of about 1.7 GHz.

Figure 10b is a radiation pattern 111 in the vertical plane in the central part of the frequency band around a frequency of about 2.2 GHz.

Figure 10c is a radiation pattern 112 in the vertical plane in the upper part of the frequency band around a frequency of about 2.7 GHz.

A particularly developed sidelobe 113, on the order of -7 dBc, in the upper part of the frequency band compared to the main beam 114. Consequently, for example, for LTE ("Long Term Evolution"), applications, a distance of 125 mm between elements is not satisfactory, particularly in the event that high tilt values are imposed, given the energy that is lost within those sidelobes 113 and assuming that those sidelobes 113 may interfere with the neighboring antennas.

It is understood that the ease of being able to alter the distance that separates the antenna's radiating elements offers a heretofore unknown option for considerably improving an antenna's performance.

Figures 1 1 a, 1 1 b and 1 1 c detect radiation patterns in the vertical plane of an antenna similar to that of Figures 10a, 10b and 10c with a tilt of 10°, but with a distance between elements of about 1 10 mm.

Figure 1 1 a is a radiation pattern 120 in the vertical plane in the lower part of the frequency band around a frequency of about 1.7 GHz.

Figure 1 1 b is a radiation pattern 121 in the vertical plane in the central part of the frequency band around a frequency of about 2.2 GHz.

Figure 1 1 c is a radiation pattern 122 in the vertical plane in the upper part of the frequency band around a frequency of about 2.7 GHz.

The sidelobe 123, on the order of -10 dBc relative to the main lobe 124, has decreased compared to what was observed in Figure 10c. This level of value for the sidelobe is commonly accepted by telecommunications network designers.

However, it must be noted that lowering the distance between elements from 125 mm to 1 10 mm may have other consequences. In particular, in the present situation: - the angular width of the main lobe in the vertical plane VBW (for "Vertical BeamWidth") increases from a value of about 4.6° (frequency 2.7 GHz, tilt 10°) for a distance of about 125 mm between elements, to a value of about 5.2° for a distance between elements of about 1 10 mm under the same conditions;

- the insulation level between the antenna's ports, in the event of dual-polarization antennas or multiband antennas, is reduced, as the coupling factor between the radiating elements increases when the distance between elements decreases;

- the phases of the various signals applied to the radiating elements, which are needed to suitably feed the radiating elements, may vary slightly in order to make it possible to achieve a fixed tilt value that may be slightly different.

In the present situation of 10° tilt, a 1.3° deviation in tilt may occur if the same phases maintained when changing from one value representing the distance between elements to another. For example, for an antenna with five radiating elements fed by a signal of the same amplitude, separated by a constant distance equal to 125 mm, the difference in phase between the feed signals needed to obtain a 10° tilt at the frequency of 2.7 GHz is 0° for the first radiating element (taken as the reference radiating element), 72° for the second radiating element, 144° for the third radiating element, 216° for the fourth radiating element, and 288° for the fifth radiating element. Whenever the distance between elements decreases and reaches a value of 1 10 mm, the difference in phase between the radiating elements being unchanged, the resulting tilt will be 1 1.3°.

Figure 12 depicts an antenna 130 according to the first embodiment described above. Unlike the previous examples, the space between radiating elements is not constant: for this reason, the radiating elements 131 and 132 are separated by a distance d; the radiating elements 132 and 133 are separated by a distance e, the radiating elements 133 and 134 are separated by a distance f; and the radiating elements 134 and 135 are separated by a distance g, the distances d, e, f and g being different.

In the case of a passive antenna, meaning one whose radiating elements are fed with the same amplitude distribution, the effective amplitude distribution A along the antenna will be different for the antennas 60A, 60B and 130 as depicted in Figures 13a, 13b and 13c which depict the amplitude distribution A based on the position D of the radiating elements along the antenna expressed by the distance between elements.

Figure 13a corresponds to the antenna in the configuration 60A. The curve 141 represents the amplitude levels (in dBc) of the signals applied to each of the radiating elements 61 A, 61 B, 61 C, 61 D and 61 E for a distance between elements d.

Figure 13b corresponds to the antenna in the configuration 60B. The curve 142 represents the amplitude levels (in dBc) of the signals applied to each of the radiating elements 61 A, 61 B, 61 C, 61 D and 61 E for a distance between elements d-. The curve 141 represents the initial amplitude levels (in dBc) of signals applied to each of the radiating elements 61 A, 61 B, 61 C, 61 D and 61 E.

Figure 13c corresponds to the antenna in the configuration 130. The curve 143 represented the new distribution of the amplitude levels (in dBc) of the signals applied to each of the radiating elements 61 A, 61 B, 61 C, 61 D and 61 E for a distance between elements d, e, f, g that is no longer constant. The curve 141 represents the initial amplitude levels (in dBc) of signals applied to each of the radiating elements 61A, 61 B, 61 C, 61 D and 61 E.

It is observed that the distribution of power along the antenna has been altered with the distance between elements. Figures 14a and 14b depict radiation patterns in the vertical plane of an antenna for a tilt of 10° and a frequency of about 2.7 GHz. The curves 150 and 151 of Figures 14a and 14b respectively correspond to the radiation patterns obtained in the configuration 60B of Figure 6b and in the configuration 130 of Figure 12.

A decrease in the sidelobe 152 compared to the main lobe 153 is observed between Figures 14a and 14b.

The radiating elements may be fed by a so-called passive system, comprising passive power splitters, or fed dynamically in active antennas. For active antennas in which the amplitudes and feed phases of the radiating elements may be accurately set as a function of frequency by electronic devices, being able to mechanically move the radiating elements in order to place it into the exact desired location creates an additional variable parameter that can be adjusted in order to improve the active antenna's capabilities and performance.

In the second embodiment, depicted in Figures 15a and 15b, the antenna 160 comprises radiating elements 161 which are each respectively placed in a moving cell 162. The moving cells 162 are unitary and independent, and electrically insulated from one another. Each moving cell 162 serves as a reflector for the radiating element 161 that it accommodates. Once assembled, the moving cells 162 form the structure of the antenna 160 itself.

The mechanical device 163 here comprises a rotating rod 164 that connects threaded portions 165 to one another. Guides 166 held in fixed brackets 167 fastened onto each moving cell 162 make it possible to control the longitudinal sliding of the moving cells 162.

However, each moving cell may comprise its own individually-moving mechanical device. Each individually-moving device may be activated independently of the others, and for this reason the space separating the moving cells may be individually adjusted for each pair of neighboring moving cells, which allows their usage in both active and passive patch antennas. These movement devices make it possible to achieve total flexibility between the different possible arrangements.

Whether they are individual or active multiple moving cells, the movement devices may be passive as previously described, i.e. manually activated by a handle, for example. The movement devices may also be active, in which the threaded portions are associated with motorized commands, for example a step-by-step motor block, which are activated by an electronic command system. Naturally, the motorization may be remotely controlled.

Figures 16a and 16b depict an example adjustment of the space between the radiating elements of an antenna according to the second embodiment.

The antenna in the configuration 170A depicted in Figure 16a, comprises five radiating elements 171. Each radiating element 171 is placed in a moving cell 172 of its own. The moving cells 172 are separated by a distance d₀ that is roughly equal to zero here, the moving cells 172 being adjacent.

Using a mechanical device 173, similar to the mechanical device 163 of the figures 16a and 16b for example, each moving cell 172 is moved in order to achieve a distance di between the moving cells 172 that is greater than d₀. The result is an antenna in the configuration 170B as depicted in Figure 16b.

Figures 17a and 17b depict, in top and bottom perspective views, the antenna in the configuration 170A of Figure 16a before moving the moving cells.

The mechanical device 173 comprises a rotating rod 174 that connects threaded portions 175 to one another, each threaded portion being joined to a moving cell 172. Two guides 176 make it possible to control the longitudinal sliding of the moving cells 172. The guides 176 are held in brackets 177 fastened to each moving cell 172. Each moving cell 172 comprises four brackets 177 placed within each corner of the cell. Here, the brackets 177 of two adjacent moving cells 172 are attached. Each of the guides 176 traverses two aligned brackets 177 of each moving cell 172.

Figures 18a and 18b depict, in top and bottom perspective views, the antenna in the configuration 170A of Figure 16a after moving the moving cells.

When the device 173 is activated, the adjacent brackets 177 slide apart around the guides 176, which causes the moving cells 172 to separate.

Naturally, the present invention is not limited to the described embodiments, but is, rather, subject to many variants accessible to the person skilled in the art without departing from the spirit of the invention. In particular, it is possible, without departing from the scope of the invention, to alter the spacing of the radiating elements, insert fixed radiating elements, and vary the ratio of fixed radiating elements to moving radiating elements. The different embodiments that have just been described for a row of radiating elements altering the radiation pattern in the vertical plane. These embodiments also apply to a row of radiating elements that have a different direction, in order to alter the antenna's radiation pattern in the horizontal plane. Likewise, these embodiments may be applied to an antenna that comprised both rows of radiating elements altering the radiation pattern in the vertical plane and rows (or columns) of radiating elements, disposed perpendicularly, that alter the radiation pattern in the horizontal plane.

Claims

THERE IS CLAIMED:

1 . An antenna comprising at least one row of fed radiating elements in which at least one of the radiating elements is placed in a moving cell joined with a mechanical device whose rotation causes the longitudinal displacement of the moving cell in order to alter the distance between the radiating elements.

2. An antenna according to claim 1 , comprising a reflector common to all the radiating elements.

3. An antenna according to claim 2, in which the moving cell is separated from the common reflector by a dielectric layer to which it is capacitively coupled.

4. An antenna according to claim 1 , in which each of the radiating elements is placed into an individual moving cell that serves as a reflector for that radiating element.

5. An antenna according to one of the preceding claims, in which the moving cells are electrically insulated from one another.

6. An antenna according to one of the preceding claims, in which the barriers make it possible to separate the radiating elements.

7. An antenna according to one of the preceding claims, in which the mechanical device comprises at least one threaded rod portion cooperating with a fixed threaded hold joined with a moving cell.

8. An antenna according to claim 7, in which the threaded rod portion is controlled by means of a rotating rod equipped with a handle.

9. An antenna according to claim 7, in which the threaded rod portion is controlled by means of a motor controlled by an electronic system.

10. An antenna according to one of the preceding claims, comprising at least two rows of radiating elements disposed perpendicularly, each row comprising at least one radiating element placed within a moving cell and at least one mechanical device that makes it possible to move the moving cell.