EP4131654A1 - Mechanisch abtastende antenne mit niedrigem profil mit reduzierter nebenkeule und gitterkeulen und grosser abtastdomäne - Google Patents

Mechanisch abtastende antenne mit niedrigem profil mit reduzierter nebenkeule und gitterkeulen und grosser abtastdomäne Download PDF

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Publication number
EP4131654A1
EP4131654A1 EP21425038.3A EP21425038A EP4131654A1 EP 4131654 A1 EP4131654 A1 EP 4131654A1 EP 21425038 A EP21425038 A EP 21425038A EP 4131654 A1 EP4131654 A1 EP 4131654A1
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EP
European Patent Office
Prior art keywords
refractive index
deflector
wave
antenna
inclusions
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EP21425038.3A
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English (en)
French (fr)
Inventor
Francesco CAMINITA
Giovanni Toso
Cristian DELLA GIOVAMPAOLA
Massimo Nannetti
Gabriele MINATTI
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Wave Up Srl
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Wave Up Srl
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Priority to EP21425038.3A priority Critical patent/EP4131654A1/de
Publication of EP4131654A1 publication Critical patent/EP4131654A1/de
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/32—Adaptation for use in or on road or rail vehicles
    • 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
    • H01Q15/02—Refracting or diffracting devices, e.g. lens, prism
    • H01Q15/10—Refracting or diffracting devices, e.g. lens, prism comprising three-dimensional array of impedance discontinuities, e.g. holes in conductive surfaces or conductive discs forming artificial dielectric
    • 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
    • H01Q3/12—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems
    • H01Q3/14—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems for varying the relative position of primary active element and a refracting or diffracting device
    • 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
    • H01Q3/22—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 orientation in accordance with variation of frequency of radiated wave

Definitions

  • This invention belongs to the technical field of mechanical beam scanning antenna systems.
  • the object of this invention is to produce a new architecture for the implementation of phase gradient planar deflectors for antenna beam scanning, designed to work in an environment with refractive index • greater than one and fitted with transition devices (or equivalently called matching devices) that manage the gradual passage of radiation from a medium .with refractive index greater than one to air (refractive index one) and vice versa.
  • This new architecture of phase gradient planar deflectors allows the secondary lobes and the grating lobes to be reduced to levels never before obtained with conventional design techniques while the main beam is scanned within a wide angular range, all with a solution that is simultaneously reliable, space-saving and structurally simple.
  • Such a target may, for example, be a moving node of a point-to-point communication system or a moving object in the context of a radar application or a satellite.
  • the direction of the antenna beam in general can be changed, for example, electronically, by acting on the reciprocal phase shift of the radiating elements that make up the antenna without changing its position.
  • the direction of the antenna beam can be changed mechanically by moving a part or the entire antenna system.
  • each antenna has transversal (indicated, for example, with the Cartesian coordinates X and Y) and longitudinal dimensions (indicated, for example, with the Cartesian coordinate Z). While the transverse dimensions depend on the technical requirements of the antenna (and therefore are difficult to modify once the requirements have been set), the longitudinal dimensions may vary according to the platform where the antenna is installed and according to the application. For example, if the antenna is to be installed on a car or on the roof of a train or bus, minimizing its thickness, i.e. reducing its profile, is essential even if it involves losses in terms of performance.
  • Low footprint and low profile are critical aspects, for example, whenever the antenna needs to be positioned on a fast moving vehicle, such as a train or plane, or in a vehicle that has limited space for the communication system, such as a tourism coach.
  • the dielectric wedges are replaced by planar deflectors, parallel to the radiant aperture of the antenna, implemented by stacking multiple layers with many small inclusions (pixels), structured in a regular lattice, having dimensions and/or shapes that change or rotate gradually within a pattern that is periodic (modulation period) or almost periodic in the case in which the beam is not only deflected but also collimated.
  • the dimensions of the modulation period depend on the angle of deflection or phase gradient that the deflector must produce and are typically greater than the value of the wavelength of the antenna's electromagnetic signal. For this reason, in the antenna's radiation pattern, after the deflection produced by the deflection system, some undesired grating lobes appear which reduce the signal strength associated with the antenna's main lobe and can cause unwanted interference. The level of these grating lobes tends to increase compared to the level of the main lobe, the more the main lobe points in directions away from the longitudinal axis of the antenna.
  • the radiation pattern of an antenna represents the spatial trend of the electromagnetic field generated in transmission (or received in reception) by the antenna itself. It consists of a main lobe, which represents the desired signal, and a series of side lobes and grating lobes which depend on the size and shape of the antenna and on the way in which the aperture field of the antenna is possibly sampled.
  • an antenna must comply with certain regulations in order to be commercialized.
  • the regulations (produced as recommendations by international organizations such as ETSI, FCC and ITU, for example) also require that an antenna meets certain limits in terms of maximum power output (depending on the direction of observation and the frequency band of the antenna) in order to be effectively used in commercial applications, such as satellite communications.
  • the level of the power radiated by the antenna must be reduced to a value that allows these specifications to be respected, thus limiting the telecommunication system's performance.
  • Beam scanning antennas based on the planar implementation of Risley prisms, typically suffer from high levels of secondary lobes and grating lobes under certain pointing conditions, this therefore imposes limits on their performance in order to comply with the regulations.
  • optimization of the geometries and materials that make up the entire structure using conventional techniques, in order to eliminate these secondary beams, is impractical due to the combination of electrically large overall dimensions of each single deflector and the large number of electrically small details of the inclusions - the number of parameters that the optimizer would have to manage would be prohibitively large and would require prohibitively long analysis times (simulations).
  • Optimization techniques limited to the modulation period alone actually reduce the computational burden and therefore the resources and analysis times (simulations), but the optimal solutions known so far still have unsatisfactory levels of secondary lobes and grating lobes, in particular when the beam is deflected in radiant directions away from the antenna's longitudinal axis.
  • This publication describes an antenna consisting of a first stationary lens on which two rotating lenses are superimposed, these in turn being superimposed on each other (see, for example, Figure 1 of the article).
  • the two rotating lenses rotate around the vertical axis Z. Scanning of the beam is obtained by rotating the said two lenses independently of each other.
  • the phase gradient impressed on the beam is obtained by making inclusions in the two rotating lenses, these inclusions are positioned in the lens to form a grid in which, when moving, for example, along a column, they are progressively rotated, as shown, for example, in figure 3 of said scientific article.
  • a further object of this invention is to provide an apparatus in which the level of the secondary lobes and the grating lobes is minimized within limits compatible with the provisions of the regulations, in particular for important communications such as satellite communications.
  • This assembly includes:
  • said deflector is configured to operate in an environment with refractive index "n" greater than 1, for example, being immersed in a medium with refractive index greater than one.
  • the deflection system has, for at least one part thereof, refractive index greater than 1.
  • the deflection system may have the classic deflector comprising the inclusions and with said deflector immersed in a medium with refractive index greater than 1, for example, coated externally with a medium with refractive index greater than 1 ( Figure 1A shows the solution of the deflector between two layers with refractive index greater than 1).
  • the deflection system is matched to the surrounding environment by means of one or more transition or matching devices, each of said transition or matching devices composed of one or more transition layers (also called matching layers).
  • the matching device can be arranged, for example, at the inlet to and/or outlet from said deflection system.
  • the proposed solution provides a new architecture based on phase gradient planar deflectors designed to work in an environment with refractive index greater than one (for example, immersed in a medium with refractive index greater than one) and fitted with transition (or matching) devices that manage gradual passage of radiation from a medium with refractive index greater than 1 to air (refractive index one) and/or vice versa.
  • This solution is able to minimize the value of the secondary lobes and grating lobes to levels compatible with the standards foreseen, allowing the disturbances associated with them to be reduced with compact and functional construction solutions.
  • said inclusions scattered in said planar deflector are designed to work in an environment with refractive index n greater than 1.
  • these matching devices are therefore configured to match the at least one planar deflector operating in an environment with refractive index greater than 1 to air (refractive index one).
  • matching devices can be provided whose conformation and/or choice of material (for example, dielectric) is such as to allow a variation of the refractive index throughout their thickness.
  • material for example, dielectric
  • Such deflector therefore allows the direction of the incident radiation to be varied, depending on the appropriate design in the medium with refractive index greater than 1 of the periodic arrangement of the elements.
  • the radiation strikes and is transmitted with angles closer to the longitudinal axis than to air, based on the refraction phenomenon governed by Snell's law.
  • One or more transition or “matching” devices are then added (for example, at the inlet and/or outlet of the deflector).
  • They are preferably formed by one or more matching layers which, complying with the conservation conditions of the transverse electromagnetic field phase, manage an additional deflection of the radiation from the medium with refractive index greater than one to that with refractive index one and vice versa, i.e. from angles close to the longitudinal axis to grazing angles and vice versa; if this deflection is achieved gradually, preferably by using numerous transition layers, the presence of reflected waves is considerably reduced even on relatively wide frequency bands. Consequently, the additional deflection introduced by the transition or matching layers extends the scanning range without altering performance of the side lobes and grating lobes of the deflected radiation pattern, which remain those optimized for the medium with refractive index greater than 1.
  • This system is therefore a beam scanning system, having a low profile, which maintains low levels of side lobes and grating lobes minimal and compatible with the provisions of the regulations while redirecting the beam in a wide angular scanning range, within a wide band of frequencies.
  • Each deflection system is therefore in fact a planar deflector composed of one or more layers where these inclusions are disseminated and then immersed or included in a medium with refractive index greater than one (as in figure 1A , for example).
  • the lens is therefore a low profile lens in a dimensional range preferably, but not exclusively, between 0.8 and 1.7 wavelengths relative to a medium with refractive index one.
  • each deflection system further cooperates with one or more transition or matching devices configured to match each deflector to air, i.e. to a medium with refractive index 1, different from that of the design, having refractive index greater than 1; thus producing a gradual transition from the design medium to air, the transition devices greatly reduce the presence of reflected waves due to discontinuities of the various media.
  • the wave launcher which cooperates with the deflection system and the matching devices presented above is also part of the system object of the invention.
  • this invention also relates to an antenna comprising the system according to one or more of the preceding characteristics.
  • This invention also relates to a method of manufacturing an antenna which comprises the steps of:
  • the inclusions disseminated in the deflector are therefore configured to work in a medium with refractive index greater than 1.
  • a method is also described here for the production of planar deflectors in which a plurality of inclusions are disseminated, the design of which is carried out for a medium with refractive index greater than 1 and wherein the deflector is immersed in a medium with refractive index greater than one and includes the addition of at least one transition or matching device, preferably two transition or matching devices, for the gradual subsequent deflection of radiation from the medium with refractive index greater than one to air (refractive index one) and vice versa.
  • This new architecture is able to maintain levels of side lobes and grating lobes in the deflected radiation pattern that are minimal and compatible with the requirements of the regulations while the main beam is redirected in a wide angular range.
  • one possible configuration could include one or an array of wave launchers arranged side by side, preferably with an axis having a different inclination with respect to one another or with respect to the axis of the deflector system, preferably but not exclusively dedicated to increasing the deflection angle of the beams.
  • the launcher could be composed of an array of launchers operating at the same frequency or at different frequencies, preferably with the possibility of working together in said array, to increase the maximum gain of the antenna system and/or widen the operating bandwidth, or with the possibility of working separately.
  • each deflector having its own modulation period for the inclusions, so that the beams produced by each launcher can be deflected in arbitrary or combined directions to produce a beam shaped depending on the deflector being illuminated.
  • a deflection system with one or more aligned deflectors and a plurality of launchers, rotatable or fixed, each of these providing a wave in a particular direction, so that the waves produced by the wave launchers can be further deflected in arbitrary directions or combined to produce a shaped beam.
  • An antenna assembly comprising:
  • said deflector is immersed in a medium with refractive index greater than one.
  • said matching devices are arranged at least at the outlet from the deflection system in such a way as to manage passage of the wave at least from said deflection system with refractive index greater than 1 to a medium with refractive index one, for example, air.
  • said medium with refractive index one is air.
  • This invention also relates to a method of manufacturing an antenna which comprises the steps of:
  • the medium with refractive index one can be air.
  • said deflector can be arranged in the medium with refractive index greater than 1.
  • said arrangement of the deflector in the medium having refractive index greater than one can optionally comprise at least one of the following solutions:
  • Also described here is a method for deflecting an electromagnetic wave from a wave launcher, the method comprising passage of the wave emitted by the wave launcher through a deflector which adds a phase gradient to the wave coming from said wave launcher and with said deflector working in an environment with refractive index greater than one and wherein is included subsequent passage of the wave through at least one matching device configured to manage at least passage of the wave from a medium with refractive index greater than one to a medium with refractive index one and/or vice versa.
  • the medium having refractive index one being air.
  • This invention relates to a new architecture for the implementation of deflectors, preferably planar and therefore having a flat shape, with phase gradient for scanning the antenna beam, designed to work in an environment with refractive index greater than one.
  • each deflector is arranged in a medium with refractive index greater than one.
  • transition devices which manage gradual passage of radiation from a medium with refractive index greater than one to air (refractive index one) and vice versa.
  • the transition device is preferably arranged at least at the outlet from the deflector thereby allowing transition of the wave from a medium with refractive index greater than one to a medium with refractive index one (in this case air).
  • transition device can be provided at the inlet to and/or outlet from the deflector.
  • FIG. 1A A schematic is presented in figure 1A .
  • Figure 1A shows an assembly formed by the deflection system (described immediately below) and cooperating with one or more matching devices (or transition devices).
  • Figure 1A therefore shows a standard deflector having inclusions, as also clarified below.
  • a design medium with refractive index greater than one In particular, it is coated externally, that is in correspondence with its two faces, by a medium with refractive index greater than one (for example a dielectric) so that, overall, producing a deflector device (or deflection system) which in fact has for at least one part thereof (essentially a predetermined, thick section) refractive index greater than 1.
  • the matching devices are preferably in the form of superimposed layers and are such as to allow the gradual passage from the design medium of the deflector with refractive index greater than one to the external environment, i.e. the air, or vice versa.
  • Figure 1A therefore shows the entire deflection system comprised between two matching devices and of which each matching device is in the form of several matching layers.
  • Figure 1B shows the wave pattern as it passes through air - transition layers - deflection system - transition layers - air.
  • This new architecture makes it possible to produce a low profile apparatus for a mechanical beam scanning antenna, comprising a primary wave launcher and one or more mechanically rotatable beam deflection systems, capable of redirecting the beam produced by the primary launcher in an arbitrary direction in azimuth and in elevation, minimizing the level of the secondary lobes and above all of the grating lobes within limits compatible with the provisions of the regulations, in particular for important communications such as satellite communications.
  • This invention also relates to the production of beam deflectors made of inclusions arranged in a regular grid (Cartesian, hexagonal, triangular), with variable geometries and/or rotated according to a periodic pattern.
  • a regular grid Cartesian, hexagonal, triangular
  • the inclusions are designed to work in an environment with refractive index greater than one (n > 1), therefore included in the medium having refractive index greater than one.
  • the beam deflection systems are equipped with matching devices to match the deflectors to work in air, i.e. in an environment with refractive index one and therefore different from that greater than one of the design.
  • a new architecture is produced for the realization of phase gradient planar deflectors, in which advantageously the design of the inclusions (pixels) is carried out in a medium with refractive index greater than one, therefore included in the medium with refractive index greater than one, and transition devices formed by one or more transition layers are added for the gradual subsequent deflection of radiation from the medium with refractive index greater than one to air (refractive index one) and vice versa.
  • This apparatus for scanning of the antenna beam is able to maintain levels of side lobes and grating lobes that are minimal and compatible with the provisions of the regulations while the main beam is redirected within a wide angular range.
  • This new architecture while the main beam is redirected within a wide angular range, is able to keep the secondary lobes and grating lobes at lower levels than any other solution known so far and compatible with the applicable regulations, particularly for important communications such as satellite communications.
  • the apparatus In a first configuration (see, for example, Figure 1 ), the apparatus is composed of a wave launcher (or primary antenna) and by two assemblies (20, 30) each formed by a deflection system coupled with the relative one or more matching devices exactly according to the architecture presented above in figure 1A .
  • the primary antenna is a directional antenna, with a fixed beam in the longitudinal direction (broadside), which produces a beam of circular or linear polarization, in line with the antenna, at the inlet to the deflectors.
  • the beam deflectors are two planar structures, aligned along the same axis, rotatable independently and able to deflect the beam produced by the antenna in an arbitrary direction (in elevation and azimuth) when suitably rotated.
  • Each deflector is composed of one or more planar layers (see, for example, Figure 3 or 4 ), each layer comprising a plurality of small elements (pixels or inclusions) which add to the phase of the incident wave or incident radiation a phase gradient in a medium with refractive index greater than 1.
  • Each deflector is, as mentioned, designed to work in an environment with refractive index greater than 1 and therefore is immersed in a medium with refractive index greater than one.
  • the matching layers (see, for example, Figure 1A ) which manage the subsequent gradual deflection of radiation from a medium with refractive index greater than 1 to the air (refractive index one) and/or vice versa.
  • the direction of the outgoing beam is determined by the relative angular orientation of the two deflectors.
  • a second configuration (see, for example, Figures 8 and 9 ), is similar to the first configuration described but, in this case, the primary antenna is not fixed but can rotate around its own axis. It produces a circularly or linearly polarized beam, inclined with respect to the antenna axis, which enters a single assembly formed by the deflection system with relative matching devices (one or more than one) (and not to two assemblies such as in the first configuration) placed above the antenna and therefore made according to the new architecture presented above.
  • This single deflector therefore comprises one or more layers having the inclusions of the first configuration, immersed in a medium with refractive index greater than one and to which one or more matching devices are added at the outlet and/or at the inlet (as for the first configuration) and is also rotatable around its own axis, the latter aligned with the axis of the antenna.
  • the beam can be directed in an arbitrary direction (in elevation and azimuth) determined by the relative angular position between the primary antenna and the beam deflector.
  • each deflector is designed to operate in a medium with refractive index greater than 1.
  • the design of the deflector with refractive index greater than one can be obtained, for example, by coating the deflector at its upper and lower surfaces (above and below) with a spatially homogeneous dielectric material with refractive index > 1. The matter will also be addressed later.
  • each deflector requires, above and below, matching devices composed of one or more matching layers which avoid wave reflections when the apparatus operates in the real environment with refractive index one.
  • Figure 1 structurally describes a first configuration of the invention.
  • This launcher therefore has a fixed beam in the longitudinal direction (broadside) and is aligned with a first and a second assembly (20, 30) formed, according to Figure 1A , by a deflector immersed in a medium with refractive index greater than one and having one or more transition devices.
  • the first assembly 20 superimposed on the wave launcher is on the same axis as it, and the second assembly 30 superimposed on the first assembly 20 is still on the same axis as the wave launcher 10.
  • Both the assemblies are rotatable about their central axis of symmetry. They are rotatable independently of each other.
  • the perimeter shape of the assemblies is typically circular but can also have other shapes (for example, elliptical or square or polyhedral).
  • Figure 1 therefore shows the initial beam which starts from the fixed wave launcher in the longitudinal direction (broadside) and which is deflected on exiting from the second deflector.
  • each deflector comprises inclusions designed to work in an environment with refractive index greater than 1 and which inclusions add, according to their arrangement, a phase gradient to the wave coming from the wave launcher, whereby they orient said wave in a certain direction in elevation and azimuth.
  • the second configuration of the invention differs from the first, with reference to Figures 8 and 9 , in that there is only one rotatable assembly 220 which is superimposed and on the same axis as the wave launcher 210, also rotatable, and in that the launcher radiates a wave not on the same axis as the deflector.
  • the deflector and wave launcher can therefore be rotated independently of each other.
  • Both Figure 8 and Figure 9 show a variation in the inclination of the wave beam thanks to the two combined rotations.
  • the rotation of the wave launcher determines a first rotation of the wave which is then deflected through passage of the wave in the deflector immersed in the medium having refractive index greater than one and fitted with a transition device.
  • This assembly 220 further rotates and therefore determines the deflection of the beam in a direction which depends on the relative rotation of the launcher with respect to the deflector.
  • inclusions designed to work in an environment with refractive index greater than 1, which inclusions determining, based on their arrangement, a phase gradient in the wave coming from the wave launcher whereby they orient said wave in a certain direction in elevation and azimuth.
  • the essentially common parts for the two configurations concern the structure of the deflectors immersed in a medium with refractive index greater than one with relative inclusions.
  • the deflectors are designed to operate in an environment with refractive index greater than one (n > 1) and are therefore included in a medium with refractive index greater than one.
  • the deflectors include or are composed of a plurality of inclusions 300, for example, in the form of superimposed layers, that may have various shapes.
  • each deflector may, for example, consist of at least two or more superimposed layers, each layer having such inclusions disseminated therein.
  • At least a part of the deflector, or its entire surface is therefore made up of such inclusions, which are disseminated according to an orientation that is progressively rotated in a certain direction (phase gradient direction) or with variable dimensions in a certain direction (phase gradient direction).
  • figure 7A shows an enlarged view of a direction of progression and it can be seen how, along this direction, all the inclusions present in the deflector are progressively rotated according to a pattern of rotation that is repeated with a certain frequency.
  • a grid of inclusions were created, made up of rows and columns in which the arrangement of the inclusions in the columns follows a certain order such that, for example, in the first column the inclusions have a certain arrangement, in the second column they have an arrangement rotated with respect to the previous one and so on until completing the 360° rotation so that, returning to the starting position of the first column, the sequence starts repeating.
  • Figure 7A shows an enlarged portion of the deflector in an enlarged image showing the inclusions 300 (in this example marked with a "+").
  • the columns are shown and it is evident how the inclusion arrangement sequence is repeated according to a predetermined pattern every three columns.
  • the first column therefore has an arrangement according to a certain angle of the inclusions.
  • the second column has an arrangement rotated by a certain angle of the inclusions and the third column has a further rotated angle of said inclusions.
  • the pattern then repeats periodically, as shown in figure 7A .
  • figure 7A is not to be considered limiting in the sense that the inclusions can be of different shapes, as shown in figures 3 and 4 and the arrangement pattern can be different from that of figure 7A , in the sense that the rotation angles may differ from column to column so that, moreover, the pattern can be replicated, for example, every four columns or according to any number of columns.
  • the inclusions made are rotated or of variable size, they are designed to work in an environment with refractive index greater than 1 and, consequently, there are transition or matching devices to make the antenna work in the real environment, i.e. with refractive index one.
  • the deflectors redirect the beam by means of the gradual (adiabatic) rotation presented above, or variation in size, of the inclusions 300 which are small geometric elements capable of adding an appropriate and accurate phase gradient to the beam at the deflector inlet.
  • both deflectors and therefore the individual inclusions, are designed to operate in an environment with refractive index greater than 1, therefore included in the medium with refractive index greater than 1, with the consequent necessary presence of "matching devices” to make the deflector adapt to operate in air (refractive index one).
  • Accurate setting of the phase gradient allows a beam to be produced that emerges from the deflector pointed in the desired direction maintaining the level of the side lobes and especially of the grating lobes at levels compatible with the provisions of the regulations, in particular for important communications such as satellite communications.
  • each deflector uses small inclusions of generally the same shape and size, gradually rotated in the direction of progression of the phase gradient that is added to the input beam, as already described in Figure 7 , or inclusions of gradually different size such as described in figure 7B .
  • the length of the period of rotation or scaling of the dimensions of the inclusions determines the direction of the beam exiting from each deflector.
  • the beam points in a direction ⁇ 0 .
  • the period is covered by eight inclusions, then the beam exiting from the deflector is directed in a direction ⁇ 1 different from ⁇ 0 .
  • the rotation of the deflectors with respect to each other and with respect to the launcher (configuration 1), or the rotation of the deflector and the launcher (configuration 2) are the basis of the beam scanning or re-pointing mechanism.
  • the fact that the single deflector deflects the incident wave depends on the rotation of the single inclusions within a periodic pattern or on the change in size of the same (depending on the configuration).
  • the number of rotated inclusions that make up the rotation period determines the direction in which the beam is deflected.
  • the wave is deflected in the direction ⁇ 2
  • the period were covered by a different number of inclusions, then the wave would be deflected in the direction ⁇ 3 .
  • the rotation of the inclusions cannot be changed once the deflector has been made. However, in the design stage, depending on requirements, one could opt to cover a rotation period with a certain number of inclusions instead of another.
  • each deflector is implemented in such a way that the co-polar component of the signal incident on one side of the deflector and the co-polar component of the signal emerging on the opposite side of the deflector have circular orthogonal polarizations.
  • the beam entering the deflector is produced by the launcher (10; 210) formed by a directional antenna.
  • this launcher can be a short focal parabolic reflector (to keep the profile low), or a modulated metasurface antenna or a slotted antenna (RLSA) or a pillbox antenna.
  • RLSA slotted antenna
  • the embodiment examples of wave launcher are shown in figure 5 and are valid for all configurations. All these solutions must be understood as possible alternatives for the launcher and must not be seen as a limitation.
  • Each deflector is formed by planar structures, generally of several layers (see for this purpose, figures 3 and 4 ), composed of a plurality of inclusions (pixels) placed inside a regular grid (Cartesian, hexagonal, triangular).
  • an important element of the invention which contributes to obtaining the desired technical effects, consists of the fact that the inclusions are designed to work with refractive index > 1 and are therefore included in the medium with index of refraction greater than 1.
  • the deflectors are therefore designed to operate in an environment with refractive index greater than one and therefore immersed in the medium with refractive index greater than 1 in order to reduce the minimum elevation that can be reached by the beam without degradation and keeping the level of the side lobes and above all of the grating lobes at minimal levels compatible with the provisions of the regulations, in particular for important communications such as satellite communications.
  • the design in a medium with refractive index greater than 1 allows pixels to be designed in an environment in which, compared to an environment with a refractive index one, the electromagnetic wave, when it enters the medium with refraction index greater than 1, is refracted (i.e. deflected) in a direction closer to the direction of the longitudinal axis of the deflectors which coincides with the normal to the surface of the interface between the two media.
  • the electromagnetic wave when it enters the medium with refraction index greater than 1
  • the electromagnetic wave when it enters the medium with refraction index greater than 1
  • refracted i.e. deflected
  • the deflector immersed in a medium with refractive index greater than one suitably equipped with matching devices at the interface with the air, must deflect the wave by a smaller angle compared to what it should do if it was working in an environment with refractive index one.
  • the wave will in fact be further deflected as it propagates from the medium with refractive index greater than 1 to that with refractive index one (air).
  • the aforementioned reduction of the angle of deflection that the deflector must produce therefore, translates into two very important aspects relating to performance enhancement listed below. 1)
  • the phase gradient that the deflector must implement is less steep, i.e.
  • the spatial variation of the pixels is slower, thus allowing an enhancement of performance in terms of reduction of the level of the side lobes and of the grating lobes in the deflected radiation pattern; 2) the waves incident on the deflector have angles of incidence included in a smaller range, consequently the inclusions that make up the deflector have a very stable transmission coefficient in amplitude (close to one) and in phase depending on the direction of incidence (in both azimuth and elevation); if the pixel transmission coefficient is stable depending on the direction of incidence (in both azimuth and elevation), the phase gradient created by the deflector by distributing the pixels in a periodic pattern (modulation period) will be very stable depending on the direction of incidence of the wave and very similar to the ideal condition required to achieve a deflection in the absence of side lobes and grating lobes. All this obviously translates into a significant enhancement of performance in terms of reduction of the side lobes and, in particular, of the grating lobes in the radiation pattern deflected
  • the deflector Since the deflector is designed to work in an environment with refractive index greater than one and is therefore included in the medium with refractive index greater than one, it is necessary to introduce one or more "transition” or “matching” devices that gradually manage the passage of the waves to the air, i.e. to a medium with refractive index one, and different from the design index.
  • inclusions are disseminated, according to what has been described above, in said medium (generally in the form of a layer or plane) and are designed (i.e. configured) to work at their best in said refractive index > 1, i.e. adding the required phase gradient.
  • the design of the deflector with refractive index greater than one can be obtained, for example, by coating the deflector at its upper and lower surfaces (above and below) with a spatially homogeneous dielectric material with refractive index > 1.
  • PCB multilayer printed circuit
  • initial and final dielectric layers with refractive index > 1 or by bonding a dielectric material with refractive index > 1 above and below or even by co-molding the deflector in a plastic material with refractive index > 1.
  • Figure 1A therefore shows the deflection system obtained by immersing the deflector in a medium with refractive index greater than 1 according to one of the production methods indicated above.
  • the system working with refractive indices > 1, requires the presence of matching devices.
  • the invention therefore provides for an assembly formed by a deflection system that cooperates with at least one matching device.
  • each deflector must preferably include at least one or more matching devices which avoid wave reflections that would be present if the deflectors operated in the real environment with refractive index one.
  • the matching device could be present only at the outlet of the deflection system and therefore with such matching device superimposed on the deflection system.
  • the matching devices in other configurations, could be composed of several matching layers both at the inlet and at the outlet of the deflector and, for example, such that said deflector is interposed, i.e. included or packaged, between said multiple matching layers both at the inlet and outlet of the deflector.
  • the wave emerging from the deflector would then be incident on the interface with the first matching layer and then cross through both the first and the second matching layer and then all the other matching layers present to finally go towards the air. Conversely, the incident wave coming from the air would follow the reverse path to reach the medium with refractive index greater than 1 and be incident on the deflector.
  • each deflector there is therefore at least one matching device composed of one or more matching layers which guarantees low insertion losses and facilitates the deflection of the beam in a grazing direction, very inclined with respect to the longitudinal axis of the system and vice versa.
  • These matching layers completely cover the deflector and can be implemented by means of one or more dielectric layers with different refractive index and different thickness.
  • each dielectric layer may or may not include metallic or dielectric inclusions, for example, having geometries of the same type as those shown in the Figures 7 which are to be considered merely by way of example and in no way limiting.
  • inclusions unlike the inclusions used for the deflector, are identical in their geometric parameters in order to obtain the most suitable refractive index of the matching layer.
  • the number of matching layers to be used depends on the performance required. In fact, the use of several matching layers can, for example, enable a widening of the operating frequency band and an enhancement of the performance in terms of reducing reflected waves in the transition from medium with refractive index greater than one to medium with refractive index one and vice versa.
  • Some matching device solutions are shown in Figures 15-18 merely by way of example and in no way limiting.
  • matching devices are shown made by means of a dielectric layer perforated with mono or multi-diameter cylindrical ( figure 15 and 17 ) or conical ( figure 16 ) shaped pass-through holes, matching layers made with metallic inclusions ( figure 18 ), for example, square-shaped in a uniform dielectric environment, matching layers made with square-shaped metallic inclusions in a spatially non-uniform dielectric environment in the longitudinal direction.
  • the selection of material for example, dielectric layer
  • its conformation holes and/or inclusions, etc.
  • each deflector adds a phase gradient to the wave striking it.
  • the phase of the transmission coefficient (insertion phase) of the deflector has a trend that is "sawtooth" in one direction (for example the "x” direction) and uniform in the orthogonal direction (the "y” direction). Except for the aforementioned phase change, each deflector is in any case mostly transparent to the incident radiation, to the extent that it introduces low losses in the signal passing through the deflector, i.e. ideally the transmission coefficient has unitary amplitude.
  • rotation of the deflector (and of the wave launcher) can be obtained through independent drive units and a controller to control the value of rotation according to the desired pointing direction.
  • the second deflector is placed on top and is typically (but not necessarily) identical to the first deflector, except for the angle of rotation ⁇ 2 which in general is different from ⁇ 1 . It can be shown that the combination of the phase shifts produced by the two deflectors gives rise to a change in the pointing direction of the beam in both azimuth and elevation ( Figure 1 ).
  • one deflector can be missing and the launcher can rotate around the "z" axis in order to provide at the deflector inlet a beam inclined with respect to the axis of the launcher ( Fig. 7 ).

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EP21425038.3A 2021-08-03 2021-08-03 Mechanisch abtastende antenne mit niedrigem profil mit reduzierter nebenkeule und gitterkeulen und grosser abtastdomäne Pending EP4131654A1 (de)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1976062A1 (de) * 2007-03-30 2008-10-01 Itt Manufacturing Enterprises, Inc. Hochfrequenzlinse und Verfahren zur Unterdrückung von Nebenkeulen
US20080291101A1 (en) * 2007-03-30 2008-11-27 Itt Manufacturing Enterprises, Inc Method and apparatus for steering and stabilizing radio frequency beams utilizing photonic crystal structures
US20140320361A1 (en) * 2011-07-26 2014-10-30 Kuang-Chi Innovative Technology Ltd. Front feed microwave antenna
FR3043499A1 (fr) * 2015-11-06 2017-05-12 Thales Sa Antenne compacte a faisceau orientable

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1976062A1 (de) * 2007-03-30 2008-10-01 Itt Manufacturing Enterprises, Inc. Hochfrequenzlinse und Verfahren zur Unterdrückung von Nebenkeulen
US20080291101A1 (en) * 2007-03-30 2008-11-27 Itt Manufacturing Enterprises, Inc Method and apparatus for steering and stabilizing radio frequency beams utilizing photonic crystal structures
US20140320361A1 (en) * 2011-07-26 2014-10-30 Kuang-Chi Innovative Technology Ltd. Front feed microwave antenna
FR3043499A1 (fr) * 2015-11-06 2017-05-12 Thales Sa Antenne compacte a faisceau orientable

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Y. SUNF. DANGC. YUANJ. HEQ. ZHANGX. ZHAO: "A Beam-Steerable Lens Antenna for Ku-Band High-Power Microwave Applications", IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 68, no. 11, November 2020 (2020-11-01), pages 7580 - 7583, XP011817303, DOI: 10.1109/TAP.2020.2979282
ZHAO: "All-Metal Beam Steering Lens Antenna for High Power Microwave Applications", IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 65, no. 12, December 2017 (2017-12-01), pages 7340 - 7344, XP011673507, DOI: 10.1109/TAP.2017.2760366

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