Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
  • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
  • H01Q15/006—Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces
  • H01Q15/0066—Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces said selective devices being reconfigurable, tunable or controllable, e.g. using switches
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
  • H01Q19/28—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements
• • 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
  • H01Q3/44—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 electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
  • H01Q3/446—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 electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element the radiating element being at the centre of one or more rings of auxiliary elements
• • 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
  • H01Q3/44—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 electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
  • H01Q3/46—Active lenses or reflecting arrays

Definitions

• the present invention relates to a radio antenna which makes it possible to configure in space one or more lobes or beams, these terms being here equivalent, of emission / reception of electromagnetic waves and therefore of configuring its radiative diagram. It finds 10 applications in the field of transmission / reception in radio electromagnetic waves and in particular as a mobile telephone antenna. It allows in particular the conformation and switching of radioelectric beams or lobes within a base station of a telephone network or of radiocommunication data transmissions with mobile stations both in transmission and in reception (E / R).
• a steerable directional antenna a structurally directional antenna is produced on the one hand and, on the other hand, it is moved to orient it in space, generally in rotation, so that its diagram of electromagnetic radiation is oriented in the desired direction.
• the radiation pattern remains identical in shape throughout the rotation. It is therefore desirable to have non-mechanical means making it possible to modify the orientation of the radiation pattern in space. In addition, it also appears desirable to be able to modify the structure of the radiation diagram, in particular the number of emission / reception lobes and / or their shapes in space.
• Smart antennas made with adaptive antennas generally consist of a network of radiating elements controlled by a digital signal processor (or DSP, for "Digital Signal Processor”). They can automatically adapt their radiation pattern according to the external signals received.
• DSP Digital Signal Processor
• L ' set of rods forming the BIP material of this type of antenna is a periodic structure, called BIP structure, mainly composed of parallel conductors and in which a radiating element acts.
• BIP structure mainly composed of parallel conductors and in which a radiating element acts.
• the electromagnetic characteristics of this BIP structure depend mainly on the emission frequency / reception of the radiating element. Its frequency response to a plane wave alternately presents frequency bands authorizing or not the propagation through the BIP structure.
• the invention which is proposed has in particular the objective of overcoming the drawbacks of the state of the art concerning antennas of the type using a material with Photonic Forbidden Band (BIP material) and forming a determined structure which can be qualified of photonic crystal.
• the antenna of the invention can be used to orient (direction) and / or shape (shape) a single beam or several simultaneous beams. It can also be used to conform and switch different beams: we can then speak of beam-switching antenna.
• the antenna of the invention differs from antennas with a BIP structure known by the fact that the implantation of the elements (wires / bars) within the antenna and around the radiating element is not done. according to a square mesh but according to a distribution along closed curves concentric to each other at the center of which is the radiating element.
• the shape of the closed curves is preferably circular (circles) but it can be more complex in particular with the type of ellipse, cycloid or other rounded curves.
• the shape of the elements making up the antenna (radiating element and / or the wires / bars) is preferably linear but it can be different and in particular curved for the wires / bars.
• the invention relates to an antenna allowing the conformation of at least one beam of radio waves of at least one determined wavelength, of the type comprising at least one element radiating the waves, preferably passive, placed in a set of wires or bars reflecting the wave and substantially parallel to each other, made of a material with Photonic Forbidden Band (BIP) and forming a determined structure, said determined structure having defects so as to conform said at least one beam in a direction depending on the position and / or the configuration of said faults.
• the wires or bars and the faults are arranged on a set of N closed concentric curves of a plane, N being greater than or equal to one, the radiating element being disposed inside the most curved internal.
• the following means which can be combined according to all the technically possible possibilities, are used: - the curves are chosen from circles, ellipses, cycloids and, preferably, are all circles, the radiating element being placed substantially at the common center of the circles; - the maximum distance separating the innermost curve (in practice a wire / bar on the innermost curve) and the radiating element is less than or equal to a quarter of the wavelength (of the shortest wavelength in the case where several wavelengths are possible), - the distance separating the innermost curve and the radiating element is greater than a quarter of the wavelength (of the shortest wavelength in the case where several wavelengths are possible), in order to reduce the weight and / or the production cost and / or to facilitate the impedance adaptation, etc.
• the maximum distance separating two successive contiguous curves is less than or equal to a quarter of the length wavelength (of the shortest wavelength in the case where several wavelengths are possible)
• - the adjacent wires / bars or faults along a given curve are arranged at equidistant points transversely (corresponds to a constant transverse period in the case of a curve which is a circle);
• - the transverse distances of the adjacent wires / bars or defects are all equal for all the curves (corresponds to a constant and equal transverse period for all the circles in the case of curves which are circles);
• the curves are circles and the wires / bars or defects are arranged in at least two concentric circles around the radiant element that is substantially central according to a periodic transverse distribution which is constant and equal for all the circles;
• - the wires / bars or faults are arranged along distribution axes passing through the radiating element and in the
• the invention finally consists of a base station which comprises at least one beam-switching antenna according to one or more of the preceding characteristics.
• the invention therefore consists of a tunable electromagnetic material derived from photonic band gap materials (BIP) and preferably having a cylindrical symmetry. This material will hereinafter be called BIP Accordable Conformé material (BIPAC).
• BIP photonic band gap materials
• BIPAC BIP Accordable Conformé material
• the main destination of this material is the use as an active deflector in base station antennas, in particular for civil telecommunications networks (GSM and UMTS).
• the antenna is produced by surrounding an element radiating electromagnetic waves (preferably omnidirectional at least in an xy plane) with a structure of Faraday cage type with bars (or wires) which are perpendicular to the xy plane (and parallel to the radiating element), each of the bars of the cage being able to selectively be made conductive of the waves, it then appears as a reflector of the electromagnetic waves, in whole or by section (s) very long (continuous state) or be conductive only on very small segments (discontinuous state), the segments being separated from each other by insulators and the segments being of a length such that the bar then appears substantially transparent for the waves.
• the total length of the bars in the continuous state is large compared to the wavelength of the waves to be emitted or received because they then appear to be in a conductive state vis-à-vis -vis these waves which prevents (or limit) by reflection their exit outside the antenna. It is understood that in this very long case with controllable wires / bars (in particular by components which are diodes), it is necessary to use many components. However, it has been observed in practice that, surprisingly, shorter lengths of the wires / bars could be used advantageously and it is thus possible to use lengths of wires / bars greater than or equal to half the length d 'wave.
• each wire / bar is approximately 17 cm.
• the term “large” for the length of the wires / bars (or continuous conductive parts / reflectors of the waves) must be considered more in a functional aspect than in pure length since one can make antennas with wires / bars of a length which can be reduced to half the wavelength and whose continuous wires / bars behave well as wave conductors / reflectors.
• each of the bars can thus be made conductive / reflective (continuous state) or non-conductive / transparent (discontinuous state) vis-à-vis the waves is of the type with very small segments separated by radioelectric insulators with, in parallel with the insulators, switching means making it possible to connect electrically continuously and alternately or only alternately (capacitive connection for example) two by two adjacent segments of an insulator.
• the mean term of parallel switching of the insulator corresponds as well to the case where an insulator is always present (switch controlled in parallel with an insulating spacer), as to the case where the insulator becomes conductive (diode for example ).
• the terms wire or bar will be used interchangeably to designate conductive / reflective or non-conductive / transparent (radio) electric elements of the antenna structure. In practice, depending on the frequencies used by the antenna, it may be preferable to use bars for very high frequencies for which skin effects are present rather than wires.
• the bars can be hollow and internally allow the passage of in particular electrical connections for the control of active switching components between isolated segments of the bar, these connections can thus be partially shielded by the presence of the bar.
• the term (radio) electric is used to define the conductive / reflective or non-conductive / transparent state of the wires / bars overall and conductive or non-conductive of the active switching components specifically because if, at a minimum, conduction or non-conduction must concern radio waves (alternating), these elements can be more conductive or non-conductive towards a possible direct current.
• a capacitive link for example in an active switching element, is conductive for radio waves but insulating for DC, so a switching can be obtained by varying the value of the capacitance (varicap).
• an inductive link for example in an active switching element, is non-conductive for radio waves but conductive for direct current, a switching can therefore be obtained by varying the value of the inductor. It is also possible to associate capacitive and inductive components in plug circuits (non-conductive) forming active switching elements and the values of the components of which can be varied in order to make them conductive. In order to improve the behavior of the antenna, it is also possible to correct the presence of stray capacitances (in particular for the diodes) or stray self (in particular for the connections of the diodes), by additional corrective components, in particular chokes parasitic capacities and capacity against parasitic coils, see combinations of these components.
• These active switching components can for example be diodes which are turned on or off depending on whether or not a current is applied.
• the active switching components can be conductive or non-conductive at rest (a non-polarized diode, at rest, is non-conductive, neglecting its parasitic capacity).
• the antenna of the invention in the preferred case of a distribution of the layers of wires / bars in concentric circles is particularly well suited to excitations by cylindrical waves produced by a radiating element of the dipole type placed in its center. Depending on its configuration, it makes it possible to produce at least one radio beam (lobe) of any opening, which can rotate 360 °.
• the antennas must be capable of having a directional radiating beam orientable through 360 °, capable of following a user during his movement.
• the antenna of the invention in particular in its preferred configuration of circular (cylindrical) layers, is simple to implement and inexpensive. It is recalled that in the current antennas of the base stations, the direction of the beams is fixed and does not allow the operators to adapt to telephone traffic.
• the BIP structure according to the invention and preferably in its form with a cylindrical BIP structure and in the case where it can be controlled, makes it possible to obtain beam agility. This makes it possible to follow the mobiles, to dynamically modify the coverage areas according to the needs of the moment, to give priority to particular sectors during peak hours, etc.
• FIG. 1 which represents a cross-sectional view of an antenna comprising a BIP structure of the state of the art square mesh
• FIG. 2 which represents a first particular embodiment of a cylindrical BIP structure according to the invention
• FIG. 3 which represents a second particular embodiment of a cylindrical BIP structure according to the invention
• FIG. 4 which represents an example of antenna according to the invention comprising a cylindrical BIP structure according to the first embodiment illustrated in FIG. 2 and with faults obtained by withdrawal of wires / bars
• FIG. 5 which represents an example of antenna according to the invention comprising a cylindrical BIP structure according to the second embodiment illustrated in FIG.
• FIG. 6 which represents radiation patterns obtained for the antennas of FIGS. 4 and 5;
• FIG. 7 which represents a schematic perspective view of an antenna according to the invention comprising a cylindrical BIP structure;
• FIG. 8 which represents a real perspective view of an exemplary antenna according to the invention comprising a cylindrical BIP structure;
• FIG. 9 which illustrates the operation of a beam switching antenna, FIG.
• FIG. 10 which represents in (a) a perspective view of an antenna formed from a 90 ° BIPAC material, the wires / bars being arranged on spokes separated angularly by 90 ° and in (b) a top view of an antenna formed of a BIPAC material 30 °, the wires / bars being arranged on spokes separated angularly by 30 °,
• Figure 1 1 (a) to (d) which represents simulations of 45 ° BIPAC antennas for different distributions of continuous and discontinuous wires / bars
• FIG. 12 (a) to (d) which represents a simulation of a radiating element of dipole type alone
• FIG. 13 (a) to (d) which represents the simulation of a radiating element such as that of FIG.
• FIG. 14 (a) to (d) which represents the simulation of a radiating element such as that of Figure 12 but placed within an ante nne in 22.5 ° BIPAC material.
• FIG. 14 (a) to (d) which represents the simulation of a radiating element such as that of Figure 12 but placed within an ante nne in 22.5 ° BIPAC material.
• the antennas of the invention have a structure based on a distribution on circular curves (circle, ellipse or another circular closed curve) concentric son or bars each forming a layer around a radiating element substantially central to the curves.
• a radiating element in particular a simple dipole antenna
• a BIP structure is used, the distribution of the wires or bars of which is carried out on concentric circles around a center where the radiating element is substantially located.
• the radiating element and the wires / bars are perpendicular to a median xy plane of the structure which, in a basic operating mode, carries the major axes of the transmission / reception beams (lobes) which can be created (in other modes of operation, the main axes can be above or below), with a particular lobe shape and an angular position around the particular z axis depending on the distribution and the conductor / reflector or non-conductor states conductor / transparent wires / bars.
• the term radiating element is used here to designate both the final device for transmitting in the radio wave space of a transmitter and the device for collecting in space the electromagnetic waves of a receiver, devices which are of preferably assembled in a single structure (same device for emission and reception) but which, in certain configurations, can be formed of two distinct devices or be used only for emission or for reception (in the case of the creation of an antenna specializing in transmission or reception).
• the radiating element is for example a dipole, preferably passive. To cover a large bandwidth (for example the UMTS band), the radiating element can be a thick dipole or a folded dipole in printed technology.
• Each wire or bar is preferably made up of adjacent electrically conductive segments separated from each other by insulators comprising in parallel active switching components (active controlled components) capable of placing (radio) electrical continuity in the adjacent electrically conductive segments.
• each wire or bar can be conductive in sections or in its entirety (continuous state appearing conductive / reflective for the waves) or be left consisting of conductive segments isolated from each other (discontinuous state, appearing non-conductive / transparent for the wave).
• the possibility of conduction or not by sections of the wires / bars also makes it possible to orient the major axis of the lobe (s) in height with respect to the xy plane for volume scanning of the space.
• this reflection or transparency effect concerns the waves and the lengths of the wires / bars, of the segments and of the sections are adapted to the wavelengths involved so that these effects are indeed present vis-à-vis -vis waves.
• only part of the wires or bars is of the previous type consisting of conductive segments which can be connected
• An additional advantage of having separate electrically conductive segments of insulators which can be made conductive by section switching elements is to allow the creation of a broadband antenna or of the logarithmic type, the length of the section made conductive being suitable for a particular frequency.
• the operation of the antenna can optionally be adapted to a wide range of frequencies.
• the wires / bars of the antenna structure of the invention are arranged in concentric layers and, preferably, each circular (circle in the xy plane or cylinder in the xyz space) whose single center of the structure and circles correspond substantially to the radiating element.
• the wires / bars are arranged from one layer to the other in the xy plane along carrier axes in rays (distribution axes) passing through the center of the structure (or in zw planes in xyz space; w being a line centered in the xy plane).
• these bearing axes in radii are regularly angularly arranged in the xy plane, for example every 90 °, 45 °, 30 ° or 22.5 °, or even more or less and more generally any value corresponding to a division of the plane xy around the center in equal angular portions.
• the wires / bars of a layer are distributed around the center in equiangular positions (for example every 30 °), it is however considered the case of non-equiangular distributions, the wires / bars being able to be more tightened angularly in certain parts of the xy plane in order to increase the pointing accuracy of the lobe (s) in said parts relative to the others.
• a wire or bar is present at each intersection of a bearing axis in radius and a circle of a layer. It is understood that these circles (cylinders) and axes (planes) are virtual and intended to facilitate the explanation of the location of the wires or bars to form the structure.
• the wires / bars are arranged regularly with transverse distances between two adjacent wires / bars (distance along the straight line joining the two) of a given circle equal all along said circle and, possibly, for all circles. As previously, however, it is envisaged that in certain sectors the transverse distances are different.
• the wires or bars as well as the radiating element are held together by material means in order to keep a stable structural configuration. These means are typically spacers joining the wires / bars and the antenna or a common support. These means can be drilled discs through which the wires / bars are held relative to the radiating element. These means can still completely fill the structure of the antenna. These means are made of materials with low loss for the frequencies involved by the antenna and are in particular plastics, special glasses or special ceramics and, for example foams, expanded polystyrene, resins,
• TEFLON® TEFLON® ...
• the radiating element is a monopole (radiating element with ground plane)
• this ground plane as a means of holding the wires / bars which will then be fixed to one (lower) of their two ends. to said ground plane and preferably connected (or which can be electrically connected in particular by the switching components in the case of segment wires / bars) to the ground plane.
• ground plane signifies both a continuous surface and a discontinuous surface. Indeed, if from a theoretical point of view a continuous surface is ideal, it is also possible to implement wired or meshed ground planes without net degradation of the characteristics of the antenna.
• wired ground planes are presented as continuous horizontal conductive wires / bars, that is to say perpendicular to the radiating element and to the wires / bars of the BIP / BIPAC structure, joining the latter and grounded.
• the presence of ground planes at both high and low axial ends of the antenna makes it possible to limit the propagation of waves in these two directions.
• the distance between the layers of wires / bars and the length of the segments along the wires / bars depends on the emission wavelength of the antenna.
• the distances between the concentric layers will be equal to or different from each other, provided that these distances are clearly less than the wavelength and better still, less than a quarter of the length d 'wave.
• the wavelength in air is 30 cm.
• the length of a segment of a wire / bar is of the order of a few centimeters (2.5 cm in the example considered here).
• These wires / bars are arranged in concentric layers starting from the central axis of the antenna. These layers are separated by a distance which must be less than a quarter of a wavelength (7.5 cm for the example at 1 GHz).
• the wires / bars are preferably arranged along the radii of concentric cylinders.
• the number of these rays, and therefore the angle which separates them, is chosen according to the intended application and, in practice, the smaller the angle the more precision can be obtained on the shape and angular orientation of the / lobes.
• a radiating element is placed in the center of the antenna. The radiation of the antenna will be controlled by the BIPAC material.
• the arrangement of the rays, the number of layers and the number of wires / bars switched determine the shape (width) of the beam radiated by the antenna.
• the metal wires / bars have diodes between the segments which can be made conductive (state of a continuous wire / bar therefore conductive / reflective for waves) or non-conductive ( state of a discontinuous wire / bar therefore non-conductive / transparent for waves) by acting on the polarization of these diodes.
• Direct current polarizes these diodes. When the current is sufficient, the diodes are in the passing state, their internal resistance is low and the wire / bar is in a continuous state (conductor / radioelectric reflector). When this current is interrupted, the diodes are blocked and the wire becomes in a discontinuous state (non-conductive radioelectric, transparent for waves).
• the operating principle is as follows.
• the material behaves like a metallic BEEP operating in its first prohibited band.
• the metallic wires / bars that compose it are in the continuous state (passing diodes for example)
• the material is reflective and the radiation from the antenna placed in the center is confined inside.
• the wires / bars are in the discontinuous state (blocked diodes for example)
• the material becomes transparent for this radiation only in the region where these wires / bars are in the discontinuous state. If we can control the state of the switching components (diodes for example) between the adjacent segments of the wires / bars on the whole material, we can make all or part of this material transparent and therefore control the direction in which the antenna will transmit or receive.
• the wires / bars arranged along a single ray are all placed in the discontinuous state (transparent for the waves), the others being in the continuous state (conductor / reflector for the waves ).
• the antenna simulated uses a central radiating element of the dipole type operating at 1 GHz.
• the radiation pattern has a lobe which becomes thinner in the direction of radiation when the number of layers of wires / bars of the material is increased.
• the wires / bars can also be placed every 30 ° and made discontinuous along two directly adjacent spokes. If the number of layers is sufficient, the beam will be more directive than in the previous case of an angular arrangement at 45 °.
• the radioelectric radiating element is preferentially passive and it is placed at the heart of a set of wires / bar conductors substantially parallel to each other and made of a Photonic Forbidden Band (BIP) material and forming a determined structure of wires / bars.
• BIP Photonic Forbidden Band
• This antenna structure formed of wires / bars surrounding a radiating element has defects in the type of wires / bars having (radio) electrical characteristics different from the others, in particular conduction / reflection or non-conduction / transparency, so as to conform at least one beam (or lobe) in a direction depending on the position and / or configuration of said defects.
• said defects are achieved by the withdrawal of some of said conductive wires / bars, said at least one bundle being shaped in a direction depending on the position and / or configuration of the wires / bars removed.
• the withdrawal of a wire / bar can be carried out in whole or in part in order to also be able to orient the beam in height with respect to the xy plane.
• the conductive wires / bars are either actually continuous, or of the type with separate segments of insulators with active switching components and placed in a continuous state (conductor / reflector with respect to waves).
• the wires / bars are in several segments separated by insulators which can be short-circuited by active active components and allowing when the active components are in a passing state, in short -circuit (radio) electric, that the wire / bar behaves like a conductor / reflector (radio) electric (continuous state) and when the active components are in an insulating state, the wire / bar behaves like a non-conductor / transparent (radio) electric (discontinuous state) equivalent to a wire / bar at least partially removed.
• the antenna preferably comprises means for controlling said active switching components, making it possible to force certain of the segment wires / bars to behave like discontinuous wires / bars (non-conductive of waves, transparent) and others like continuous wires / bars (conductor / wave reflector).
• the defects here are wires / bars behaving like discontinuous wires / bars and a bundle can be shaped in a direction depending on the position and / or configuration of the discontinuous wires / bars.
• the BIP structure of the antenna is therefore active in that it makes it possible to dynamically and easily conform one or more beams or lobes (radiation patterns). No manual manipulation of wire / bar removal is necessary here.
• said means for controlling the active switching components form shaping and switching means between at least a first beam and at least a second beam, so that said antenna is a beam switching antenna.
• the beam switching antenna according to the invention makes it possible to produce one or more beam (s) of any opening, which can rotate (that is to say switchable) over 360 °, with a pitch and an angle of any function the angular distribution of the wires / bars within the BIP structure of the antenna.
• the wires / bars are arranged on circles according to an angular period constant, and consequently according to a variable transverse period, for each concentric layer.
• Many arrangements of the wires / bars, according to concentric layers along closed circular curves can be envisaged without departing from the scope of the present invention and we will now describe in more detail antennas with concentric circles layers of the BIP structure type cylindrical. In FIGS.
• the radiating element 2 and the wires / bars 1 are seen in cross section from above (or below) the xy plane, said plane being in the plane of the sheet on which the figures are made.
• the wires / bars are arranged along concentric circles or layers around the radiating element 2.
• the different parameters of the cylindrical BIP structure are: - P ⁇ : the angular period (in °), that is to say the angular distance between two adjacent wires / bars of a given circle; - Pt: the transverse period (in mm), that is to say the interval between two adjacent wires / bars of a given circle; - P r: the radial period (in mm), that is to say the interval between two adjacent circles; - d: the diameter of the conductive wires / bars (in mm); - n: the number of concentric circles (layers).
• the wires / bars are arranged periodically according to a constant radial period Pr and, for each concentric circle, according to a constant angular period P ⁇ (and consequently according to a variable transverse period Pt).
• the angular period P ⁇ is identical for all the concentric circles. Consequently, the transverse period Pt varies from one circle to another (Pt1 ⁇ Pt2).
• the inner circle has particularly tight wires / bars and in this type of configuration it is this inner circle which essentially controls the frequency characteristics of the antenna. Such an antenna structure is rather intended for single-band applications.
• a second embodiment illustrated in FIG.
• the cylindrical BIP structure must also contain faults (wires / rod in a discontinuous state, non-conductive of the waves and therefore transparent for these waves) so as to create (at least) a beam in a direction depending on the position and / or the configuration of these faults within a BIP structure essentially made up of wires / bars in a continuous state (conductor / reflector of waves).
• a first, simple technique for producing faults in the cylindrical BIP structure consists in removing metallic wires / bars locally. Depending on the position and configuration of the wires / bars removed (faults), the width, direction and number of useful beams can be chosen.
• Figures 4 and 5 illustrate the structures obtained by removing wires / bars in an angular sector of the BIP structure.
• the radiation diagram obtained for the antenna in FIG. 4 is referenced 61 in FIG. 6.
• the radiation obtained for the antenna of FIG. 5 is referenced 62 in FIG. 6. It will be seen from these diagrams that the antenna of FIG. 5 offers better directivity than that of FIG. 4.
• a second technique for producing faults in the cylindrical BIP structure consists in using metallic wires / bars which can be controlled, known as active wires / bars, by using active wires / bars comprising at least two conductive segments between which an insulator is inserted and in parallel from the insulator to the at least one active switching component (diode, transistor, MEMS, etc.) making it possible, depending on the state of the component (conductive or non-conductive) to connect (radio) the two segments electrically.
• the active wire / bar behaves as if it were in a continuous state (conductor / wave reflector) or a discontinuous state (non-conductor of waves and therefore transparent for waves).
• the wires / bars behaving like wires / bars of discontinuous state, therefore non-conductive at least for radio waves, constitute the faults.
• the antenna therefore comprises means for controlling the active switching components, making it possible, depending on the beam (s) to be created, to force certain of the active wires / bars to behave like wires / bars in a state discontinuous while the others are in a continuous state.
• active switching components networks of PIN diodes polarized by a direct current flowing in the metal wires / bars can be used.
• the control of these components can be carried out by angular sectors (for example three sectors separated by 90 ° to produce three lobes in three directions) of the cylindrical BIP structure.
• angular sectors for example three sectors separated by 90 ° to produce three lobes in three directions
• Photodiodes can also be used, the switching of which is obtained by light supplied by optical fiber.
• all the wires / bars can be of the type that can be controlled.
• the active switching components can be controlled as a block or individually or in sections.
• all the wire / bar will be made conductive / reflective or non-conductive / transparent depending on the order.
• it will be the section (s) ordered which will be made conductive / reflective or non-conductive / transparent according to the order (as indicated above, the length of the section must be large relative to the wavelength).
• the cylindrical BIP structure comprises three concentric circles on each of which are arranged a plurality of wires / bars 1.
• the conductive wires / bars are for example metallic wires / bars, placed in air or in a dielectric (in view of reducing the dimensions).
• the wires / bars are held by means of a support.
• This support is for example made of foam (permittivity equivalent to that of air).
• it comprises a horizontal plate or disc 6.
• FIG. 9 there are shown two examples of antenna made from BIPAC materials, the first in (a) with circular and radial distribution of angular pitch of 90 ° and the second in (b) of pitch of 30 °.
• the wires / bars are formed of segments 7 conductors separated by diodes 9 and can therefore be placed in a continuous state (conductor / reflector of the waves) or discontinuous (transparent for the waves) depending on the polarization or not of the diodes.
• the central radiating element is a dipole.
• this type of structure in the case where the diodes can be controlled selectively (in a wire / bar: individually, by group or globally), makes it possible to produce a wire / bar of which one (or more) section (s) (Fri) t be made discontinuous with respect to the rest of the wire / bar, a section corresponding to a portion (or all) of a wire / bar whose adjacent (contiguous) segments are isolated from each other others (discontinuous) electrically radio, the rest of the wire / bar being continuous.
• the dipole radiates at a frequency of 2 GHz within a BIPAC material whose wires / bars are arranged on concentric circles along rays spaced angularly by 45 °, all son being in a continuous state 10 (conductor / reflector of the waves) except those of a ray which are in a discontinuous state 1 1 (transparent for the waves) and in the direction of which ray will be formed a lobe of the radiation diagram.
• a quarter of the antenna is simulated ( Figure 13 (d)).
• Figure 13 (a) the far field radiation pattern forms a lobe in this perspective view.
• the dipole radiates at a frequency of 2 GHz within a BIPAC material, the wires / bars of which are arranged in concentric circles along rays spaced angularly by 22.5 °, all the wires being in a continuous state 10 (conductor / reflector of the waves) except those of two adjacent rays which are in a discontinuous state 1 1 (transparent for the waves) and in the direction of which rays will be formed a lobe of the radiation diagram .
• the control means can also constitute beam switching means. In other words, by modifying the control signals applied to the active components of the wires / bars of several elements, it is possible to switch between at least a first beam and at least a second beam.
• the beam switching antenna thus obtained can be implemented in particular, but not exclusively, in a base station of a radiocommunication system with mobile stations.
• the BIP elements of which are arranged regularly and in a circular distribution in a circle coaxially around a radiating element (simple omnidirectional dipole antenna) in order to simplify the explanations. and calculations.
• the radiating element being omnidirectional and the arrangement of the BIP elements regular in concentric circles, one can limit the modeling calculations to certain sectors of space, in particular angular. We can also deduce a symmetry in revolution of the behavior of the antenna.
• the radiating element alone can have a non-omnidirectional diagram and / or the BIP elements be arranged on elliptical curves (or even at the limit in a circle) with constant eccentricity or not as the element moves away radiant which is central. It is therefore understood that the simulation and the radiation patterns obtained can be more complex.
• This type of antenna can for example be used in a base station whose environment is inhomogeneous and includes obstacles to the waves and / or constructions with mirror effect on the waves (reflection, multiple paths) and / or promoting transmission (E / R by the sea: you can choose to favor / refine by default the transmission towards the interior of the land rather than towards the sea).
• a base station whose environment is inhomogeneous and includes obstacles to the waves and / or constructions with mirror effect on the waves (reflection, multiple paths) and / or promoting transmission (E / R by the sea: you can choose to favor / refine by default the transmission towards the interior of the land rather than towards the sea).
• z axis parallel to the radiating element
• the major axis is substantially perpendicular to the radiating element, thus allowing circular scanning of the major axis (s) of the lobe (s) in a plane also perpendicular to the radiating element.
• the BIP structure is with parallel / non-linear wires / bars and, preferably, with wires / bars which are at least on part of their paths substantially parallel to each other and on a curve circular of the circle type (wires / bars in arcs of circles), elliptical (wires / bars in arcs of ellipses).
• Such a structure in concentric spherical or elliptical shells of wires / bars in addition to the possibility of conformation of lobe (s) in a plane perpendicular to the radiating element (xy plane) allows better conformation of the lobes in height relative to the xy plane (the lobes are in zw planes; w being a centered axis traversing the xy plane), thus allowing a volume scanning of the major axis of the lobe (s) in space.
• the selection of the continuous or discontinuous state for a wire / bar is preferably carried out in sections according to a position determined in height.
• antennas can be produced in which wires or bars are arranged in spherical layers around an omnidirectional antenna.
• the antenna will only radiate in the directions in which wires / bars or sections of wires / bars are electrically non-conductive (radio). It is also possible, as we have seen, to sweep part of the space with one / several lobes even with linear wires / bars controlled by sections.
• the general shape of the wires / bars in particular towards their upper and / or lower ends, can depart from the forms indicated above (linear, circle or ellipse), in order to obtain an even more particular behavior of the / lobes up and / or down the antenna by implementing shapes of particular wires / bars and, for example, (associated or not with the preceding linear, circle, ellipse) in triangle, square or rectangle (in particular in the case where there are ground planes at the two axial ends of the antenna to limit the radiation up or down).
• the invention can be applied in combinations of antennas produced according to the distribution characteristics on circular curves (circle or ellipse or other curved closed shape) of wires / bars, wires / bars being common to two (or plus) separate radiating elements, the distribution curves for each of the radiating elements crossing at said common wires / bars.

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