Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/0087—Apparatus or processes specially adapted for manufacturing antenna arrays
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
  • H01Q21/22—Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array

Definitions

• the present invention concerns a plane antenna, in particular employable in fixed and mobile terminals adapted for reception of satellite TV and for multimedia satellite links, that is reliable, simple and efficient, having a wide operation bandwidth, a very limited volumetric dimensions, and being extremely inexpensive with reference to the manufacturing, installation, and maintenance costs.
• the present invention further concerns the process of manufacturing such plane antenna.
• reflector antennas are presently normally used for reception of satellite TV and multimedia satellite links, for instance belonging to the Internet.
• reflector antennas suffer from some drawbacks, such as an insufficient aperture efficiency, significant volumetric dimensions, the need of an accurate electric adjustment, and high manufacturing, installation, and maintenance costs.
• this type of antennas suffers from some drawbacks, substantially due to the fact that this antenna architecture has considerable combination losses of the feeding network or BFN (Beam Forming Network) of the individual radiating elements.
• BFN Beam Forming Network
• a plane antenna benefits in terms of antenna gain from the coherent sum of the contributions due to the individual elements constituting the plane antenna. Such contributions must be coherently added through a Radio Frequency or RF combiner.
• microstrip approach entails advantages in terms of dimensions, ensuring very small thicknesses, microstrip plane antennas have significant losses due to ohmic dissipation of the same microstrip lines.
• the ohmic loss associated with the BFN that grows with the increase of the antenna dimensions, limits the attainment of the antenna gain, at the same time making the same antenna inefficient. This means that the antenna does not fully exploit its size.
• an active element such as a Low Noise Amplifier or LNA, a Solid State Power Amplifier or SSPA, or a transmitter/receiver or Tx/Rx module, further allows to control, for instance through the use of phase shifters, the shape and the aim of the antenna radiation pattern.
• active antennas suffer form the drawback of being particularly complex and, consequently, expensive.
• use of active elements requires an accurate tracking in amplitude and phase (tuning) of the same, that is hard to achieve and it depends on environmental parameters (for instance temperature), especially with the increase of the operating frequency.
• a further antenna type is the slotted array antenna one.
• These antennas essentially consist in a wave guide provided with suitably designed slots which interrupt the current lines present onto the same guide and which consequently become small radiating elements.
• the wave guide structure may terminate with either a resistive termination, and in this case there is a so-called traveling wave antenna, or a simple short circuit termination, and this case there is a resonant antenna.
• this antenna architecture substantially achieves a linear, not planar, antenna.
• this antenna architecture in the case when a planar antenna is required, it is necessary to have a set of linear slot antennas provided with a series of combiners which allow the coherent sum of the inputs/outputs of the individual linear antennas. Consequently, the resulting planar antennas are complex, they have significant ohmic losses, and their dimensions are increased by the thickness required by the various components.
• the aim of the radiation pattern peak moves with frequency.
• the operating bandwidth is limitated to few percents, of the order of 3-5%, around the central frequency, and a very high accuracy in manufacturing the slots is also necessary.
• an array plane antenna comprising a set of at least two reception and/or transmission radiating elements fed by means of at least one beam forming network or BFN of parallel type, characterised in that each one of said radiating elements comprises a shaped aperture, and in that said at least one BFN network is made through wave guides directly obtained from the bulk of the antenna, so that each one of the shaped apertures is an input and/or output horn of a wave guide of the BFN network.
• the antenna may comprise one BFN network for each wave polarization which the antenna is capable of receiving and/or transmitting.
• the antenna may comprise at least one input and/or output wave guide connection, arranged either sideways and/or onto the surface opposite to that of the shaped apertures.
• at least one shaped aperture may have square or rectangular or circular or exagonal or octagonal shape.
• at least one shaped aperture may be tapered.
• said at least one shaped aperture may have a truncated pyramid or truncated cone shape.
• the antenna may be capable of simultaneously receiving and/or transmitting dual polarization waves.
• the shaped apertures may be arranged in a square array, each one of the shaped apertures having truncated square based pyramid shape and being fed by an output of a corresponding square wave guide of said at least one BFN network the cross section of which is tilted by 45 degrees in respect to the square base of the truncated pyramid of the shaped aperture.
• each one of the shaped apertures may have a truncated square based pyramid shape and may be fed by an output of a corresponding square wave guide of said at least one BFN network the cross section of which corresponds to a square base of the truncated pyramid of the shaped aperture, the set of the shaped apertures being arranged in an array having a substantially rhombus-like configuration, wherein the number of shaped apertures in the vertical columns of the array decreases from the centre of the antenna towards the sides of it.
• the antenna may further comprise micro wave active components.
• the antenna may be capable of operating in C band and/or in Ku band and/or in Ka band and/or in Q/V band and/or in W band.
• the antenna may be made in metallic material and/or in plastic material, the surfaces of the wave guides and of the shaped apertures being metallised.
• the antenna to manufacture is may be made in metallic material, and the step of manufacturing said at least two layers may be a step of mechanical and/or electrical micromachining.
• the step of integrally coupling said at least two layers may be a step of welding.
• the antenna to manufacture may be made in plastic material, and the process may further comprise the following step:
• the step of manufacturing said at least two layers may be a step of moulding. Still according to the invention, the step of integrally coupling said at least two layers may be a step of welding.
• Figure 1 shows a perspective view of a first embodiment of the antenna according to the invention, exploded into the forming layers;
• Figure 2 shows a particular of the antenna of Figure 1 ;
• Figure 3 shows a perspective view of a first section of the antenna of Figure 1 ;
• Figure 4 shows a perspective view of a second section of the antenna of Figure 1 ;
• Figures 5a and 5b respectively show an arrangement of the antenna of Figure 1 and the related amplitude distribution over the aperture in the horizontal plane;
• Figure 6 show a second embodiment of the antenna according to the invention.
• the preferred embodiment of the array antenna 1 comprises a set of shaped apertures 2 tapered as a truncated square 0703
• each one of which constitutes an array radiating element each one of which constitutes an array radiating element.
• the square shape of the shaped apertures 2 of the antenna of Figures 1-4 is shown by way of example and not by way of limitation, other embodiments being able to adopt different shapes of the base of the truncated pyramid of the apertures 2, such as for instance rectangular, circular, exagonal, octagonal shapes, depending on the electromagnetic characteristics which are desired to obtain for the specific applications of the antenna.
• the truncated pyramid shape of the apertures 2 is shown by way of example and not by way of limitation.
• the apertures 2 are fed by means of a BFN network of parallel type for a fine control of the characteristics of the antenna 1 in terms of operative bandwidth, gain, minimum movement of the beam within the band, purity of polarization.
• the BFN network is based on the use of wave guides 3 directly obtained from the bulk of the antenna 1 , underneath the radiating elements 2 of the antenna 1.
• outputs 4 of the square wave guides of the BFN network are arranged with the cross section tilted by 45 degrees in respect to the bases of the truncated pyramid of the apertures 2.
• the antenna also comprises a wave guide input (or an output) (not shown), having square section, that is preferably arranged either sideways to the antenna 1 or backwards, onto the surface opposite to that of the radiating apertures 2.
• the size and the shape of the wave guides 3, as well as the BFN network configuration depends on the electromagnetic characteristics which are desired to obtain for the specific applications of the antenna, such as for instance on the frequency band wherein the antenna is used.
• the antenna 1 comprises a lower layer 5, an intermediate layer 6, and an upper layer 7 (that corresponds to the radiating elements 2), each one of which is obtained from the machining of the material(s) used for manufacturing the antenna 1.
• Such machining of the three layers 5, 6, and 7 makes a portion of the wave guides 3 of the BFN network.
• the three layers 5, 6, and 7 are integrally coupled to each other so as to make the respective portions of the BFN network wave guides 3 and the apertures 2 correspond to each other (by way of example and not by way of limitation, through the aid of shaped pins of a layer 3
• the material may be either metallic or low-cost material, such as for instance plastic that is subsequently metallised.
• the machining of each one of the three layers is a micromachining, for instance a mechanical and/or electrical one, and the integral coupling of the three layers 5, 6, and 7 may be obtained through standard techniques (by way of example and not by way of limitation, through laser welding).
• the machining of each one of the three layers may be simply a moulding, and the integral coupling of the three layers 5, 6, and 7 may be obtained through standard techniques (by way of example and not by way of limitation, through welding).
• the surfaces of the wave guides 3 and horns constituiting the shaped apertures 2 are metallised.
• the antenna 1 of Figures 1-4 comprises apertures 2 and two BFN networks capable to operate with two orthogonal polarizations, linear and/or circular ones.
• the antenna of Figure 1 thus allows to obtain 2 largely insulated simultaneous polarizations.
• Other embodiments of the antenna according to the invention may comprise radiating apertures and one single BFN network capable to provide a single polarization.
• the characteristics of the two operating polarizations, corresponding to two separated inputs (or outputs) of the antenna 1 , are very similar over the whole operating band.
• the antenna according to the invention may be used both in passive configuration, (such as that shown in Figures 1-4) since it is characterised by extremely reduced ohmic losses of the BFN network, and in "active antenna" configuration, i.e. provided (always within the antenna body) with a LNA amplifier and/or a SSPA amplifier and/or a Tx/Rx module and/or a phase shifter.
• the different embodiments of the antenna according to the invention may comprise a number of machined layers different from three, depending on the complexity of the BFN network that is to be made, and on the possible active components of an "active antenna" configuration.
• the antenna according to the invention may operate with any type of polarization, for instance single linear, dual linear, single circular, dual circular, with a separation of the orthogonal components better than 30 dB.
• the circular polarization may be obtained either at BFN network level, or through the insertion of suitable dielectric "slabs" into the radiating apertures, or through the use of an external polariser.
• the antenna according to the invention has an aperture efficiency substantially equal to the theoretical value, with a whole antenna efficiency better than 85%.
• the technology of the antenna causes it to be preferably used at high frequencies, up to the order of 100 GHz.
• the antenna according to the invention may be used in great many applications, as for instance: TV satellite reception in Ku band; multimedia satellite link in Ku band; multimedia satellite link in Ka band; high definition TV satellite reception in Ka band; connection between radio links from Ku band upwards; use as mobile terminal on transport means, such as trains, cars, airplanes, and shifts, in C, Ka, Ku, QA/, and W bands; use as fixed terminal; and use for terrestrial remote sensing applications (repeater/calibrator) in C band and in X band.
• TV satellite reception in Ku band multimedia satellite link in Ku band
• multimedia satellite link in Ka band high definition TV satellite reception in Ka band
• connection between radio links from Ku band upwards use as mobile terminal on transport means, such as trains, cars, airplanes, and shifts, in C, Ka, Ku, QA/, and W bands
• use as fixed terminal and use for terrestrial remote sensing applications (repeater/calibrator) in C band and in X band.
• the antenna according to the invention may need a spatial discrimination among contiguous satellites.
• this is easily obtainable by positioning the antenna 1 at 45 degrees (in case of square antenna as that of Figures 1-4) and exploiting the natural taper of amplitude illumination (amplitude taper) towards the edge of the same antenna 1 in the horizontal plane, resulting in very low side lobes of the radiation pattern.
• this shape of amplitude distribution corresponds to an antenna far field radiation pattern characterised by extremely low side lobes, capable of discriminating the reception of the desired signal from that of interfering signals coming from other satellites located close to that of interest.
• the antenna 1 of Figures 1-4 provides for linear polarizations which are parallel (horizontal) and perpendicular (vertical) in respect to the aforesaid horizontal plane (that is the reason because the output square wave guide horns 4 of the BFN network are placed with the cross section tilted by 45 degrees in respect to the bases of the truncated pyramid of the apertures 2).
• an antenna 1' according to the invention comprises a set of square radiating apertures 2 arranged in an array having a substantially rhombus-like configuration, wherein the number of radiating apertures 2 in the vertical columns decreases from the centre of the antenna towards the sides of it.

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Cited By (131)

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Citations (7)

• 2004
  • 2004-12-10 IT IT000605A patent/ITRM20040605A1/it unknown
• 2005
  • 2005-11-29 WO PCT/IT2005/000703 patent/WO2006061865A1/en active Application Filing
  • 2005-11-29 EP EP05823808.0A patent/EP1842265B1/en not_active Not-in-force
  • 2005-11-29 ES ES05823808.0T patent/ES2657869T3/es active Active

Patent Citations (7)

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