Electromagnetic system with angular deviation of the main dispersion lobe of an antenna.

Field of the invention

0001The present invention relates to the field of antennas. More specifically, it relates to the control of the radiation pattern, and in particular of the angular direction of the main antenna radiation lobe.

Previous state of the art

0002In an airborne and/or naval system, electromagnetic communication is the dominant mode of communication due to its accuracy, ease of control, and wide range of functionality. An antenna is an essential part of a wireless system. For communications purposes, an antenna is ideally a broadband and circularly polarized or dual linearly polarized antenna.

0003Due to the space constraint on the carriers, an antenna system must be as compact as possible. To this end, one of the possible solutions consists in placing the antenna in a compact cavity. The cavity makes the radiation unidirectional and provides the antenna with electromagnetic shielding vis-à-vis the surrounding electronic systems.

0004However, a compact cavity can deteriorate the natural radiation mechanism of the antenna, leading to poor matching, poor polarization, ripples in the radiated gain, etc. A possible structure consists of placing a spiral antenna on a filled cavity of an electromagnetic absorber. Such an antenna has a unidirectional radiation pattern, in the direction of the line of sight, that is to say along the radioelectric axis of the antenna.

0005When an antenna placed under a flying aircraft is pointed towards the ground, the main beam or lobe of radiation from the antenna should be aimed slightly forward (for example) rather than directly towards the ground, i.e. i.e. it should face forward at an angle to the perpendicular to the ground.

0006Another objective of this angular deviation is to avoid interference between the various antennas of the aircraft, including between an antenna in transmission and an antenna in reception. Indeed, antennas with a wide frequency band usually have fairly wide radiation lobes, which can lead to undesirable interactions between nearby antennas.

0007In the context of a spiral antenna system loaded with an electromagnetic absorber placed in the antenna cavity (the antenna cavity representing the part between the lower part of the substrate of the radiating circuit and the lower reflective plane (or ground plane)), the antenna is physically tilted to meet this requirement. This physical tilt, however, may not be possible in the design of the aircraft on which the antenna is to be placed. The use of an antenna array is another possible solution but it is not suitable in an environment where space is a strong constraint.

0008Another solution consists in applying an angular deviation to the beam. The electronic deviation consists in inducing a deviation of the main beam with respect to the radioelectric axis of the antenna. In order to be able to operate over a wide band of frequencies, such an electronic deflection must be coherent over a wide frequency range, maintaining good matching, polarization purity and no degradation of radiated gain in the desired direction, so that the antenna can be qualified as a wide frequency band antenna.

0009The problem of the deflection of the beam of an antenna has been partially addressed by the prior art.

0010The American patent application published under the number<patcit id="pcit0001" dnum="US6947010B"><text>US 6,947,010</text></patcit> discloses an antenna having an eccentric spiral structure. The design principle of this antenna is similar to that of an Archimedean spiral antenna except that on one side the spaces between the strands are larger than those on the other side. This device makes it possible to orient the beam of the antenna, but has the drawback of being bulky and of not being able to ensure a uniform deviation over a wide band of frequencies.

0011The paper<nplcit id="ncit0001" npl-type="s"><text>P. Deo, A. Mehta, D. Mirshekar-Syahkal and H. Nakano, "An HIS-Based Spiral Antenna for Pattern Reconfigurable Applications," in IEEE Antennas and Wireless Propagation Letters, vol. 8, p. 196-199, 2009</text></nplcit>. discloses a single strand spiral antenna with four open circuit switches placed on a high impedance structure to achieve a 360° sweep angle. The four switches are toggled on and off to achieve beam orientation in different directions. However, this system only works for a monofilament antenna, at a single frequency. In addition, the desired angular deviation is not always well respected as a function of the combinations of switches and desired angles. This solution also has the disadvantage of requiring active elements to drive the switches.

0012The documents<nplcit id="ncit0002" npl-type="b"><text>H. Nakano, T. Abe and J. Yamauchi, "A Metaspiral Antenna for Azimuthal Beam Steering," 2019 International Symposium on Antennas and Propagation (ISAP), Xi'an, China, 2019, pp. 1-3</text></nplcit>, And<nplcit id="ncit0003" npl-type="s"><text> Tomoki Abe, Junji Yamauchi, Hisamatsu Nakano, Steering of the Circularly Polarized Beam from a Spiral Antenna, IEICE Communications Express, Article ID 2019SPL0014, [Advance publication] Released February 20, 2020, Online ISSN 2187-0136</text></nplcit> also disclose solutions for angular deflection of an antenna beam. In the first of the documents, a rectangular metamaterial spiral antenna is used while in the second a conventional cavity spiral antenna is used to demonstrate the steering performance. However, these solutions are inherently narrowband. Certain combinations of input amplitudes and phases indeed produce different angles of deflection at different frequencies.

0013However, none of the prior art systems is capable of applying beam deflection, nor of modifying the main lobe of the radiation pattern of a wired broadband antenna over a wide band of frequencies.

0014There is therefore a need for an antenna system capable of generating an angular deviation of the antenna beam over a wide frequency band. There is also a need for an antenna system capable of generating a deflection of the beam of the antenna while limiting its size.

Summary of the invention

0015To this end, the subject of the invention is an antenna system comprising: a ground plane with a cavity covered with a dielectric, magnetic or magneto-dielectric substrate, the cavity comprising an opening and walls; an antenna disposed on the dielectric, magnetic or magneto-dielectric substrate; an absorbent peripheral ring placed between the antenna and the walls; an absorbing half-lens having a shape of an angular sector (or angular segment), comprising a base element substantially covering a first part of the opening of the cavity, a second part of the opening of the cavity being not covered by said basic element.

0016Advantageously, the absorbent half-lens comprises an annular element forming an extension of the absorbent peripheral ring on the second part of the opening.

0017Advantageously, in which the first part of the opening of the cavity corresponds to half of the opening of the cavity

0018Advantageously, the absorbing half-lens comprises at least one circular sector element whose thickness varies according to the distance from the center of the half-lens.

0019Advantageously, the absorbing half-lens comprises a plurality of circular sector elements whose thickness is defined by an increasing function of an angular distance from the edges of the lens.

0020Advantageously, each circular sector element is defined by a function of increasing then decreasing thickness as a function of a distance from the center of the half-lens.

0021Advantageously, at least one element among the absorbent peripheral ring and the half-lens is made of a partially absorbent dielectric material.

0022Advantageously, the dielectric material partially comprises carbon.

0023Advantageously, the antenna is a spiral antenna, a sinusoidal antenna or a periodic antenna.

0024Advantageously, the antenna is one defined by an Archimedean spiral.

0025Advantageously, the antenna is a broadband antenna, making it possible to obtain a substantially constant deviation angle over the entire operating frequency band of the antenna.

0026Advantageously, the antenna system comprises: a first device comprising the ground plane, the antenna and the peripheral absorbing ring; a second device comprising the absorbing half-lens.

0027Other characteristics, details and advantages of the invention will become apparent on reading the description given with reference to the appended drawings given by way of example and which represent, respectively:<ul id="ul0001" list-style="none"><li>[<figref idref="f0001">Fig.1a</figref>] a first exemplary antenna system in one set of embodiments of the invention;</li><li>[<figref idref="f0001">Fig.1b</figref>], a second exemplary antenna system in one set of embodiments of the invention;</li><li>[<figref idref="f0001">Fig.2</figref>], an example of a spiral antenna in a set of embodiments of the invention;</li><li>[<figref idref="f0002">Fig.3</figref>], an example of a so-called reference section of an antenna system in a set of embodiments of the invention;</li><li>[<figref idref="f0002">Fig.4</figref>], an example of a metal cavity in one set of embodiments of the invention;</li><li>[<figref idref="f0002">Fig.5</figref>], an example of an absorbent peripheral ring in one set of embodiments of the invention;</li><li>[<figref idref="f0003">Fig.6</figref>], an example of a basic element of an absorbent half-lens in a set of embodiments of the invention;</li><li>[<figref idref="f0003">Fig.7</figref>], an example of an annular element in a set of embodiments of the invention.</li><li>[<figref idref="f0003">Fig.8</figref>], an example of a set of circular sector elements of an absorbing half-lens in a set of embodiments of the invention;</li><li>[<figref idref="f0004">Fig.9</figref>], an example of a side view of a set of circular sector elements of an absorbing half-lens in a set of embodiments of the invention;</li><li>[<figref idref="f0004">Fig.10</figref>], an exemplary overview of an antenna system comprising a set of circular sector elements of an absorber half-lens in a set of embodiments of the invention.</li><li>[<figref idref="f0005">Fig.11a</figref>], an example of radiation patterns of an antenna of the state of the art according to different frequencies, without deflection of the beam of the antenna;</li><li>[<figref idref="f0006">Fig.11b</figref>], an example of radiation patterns of an antenna according to different frequencies, with deflection of the beam of the antenna by an antenna system in a set of embodiments of the invention;</li><li>[<figref idref="f0007">Fig.12</figref>], two sections of a 3D representation of the main lobe of the radiation pattern of an antenna deflected by an antenna system in one set of embodiments of the invention;</li><li>[<figref idref="f0007">Fig.13</figref>], an example of a deviation angle obtained by an antenna system as a function of frequency in a set of embodiments of the invention;</li><li>[<figref idref="f0008">Fig.14</figref>], an example of an angular deviation angle obtained by an antenna system as a function of frequency in a set of embodiments of the invention;</li><li>[<figref idref="f0008">Fig.15</figref>], an example of antenna gain obtained by an antenna system as a function of frequency in one set of embodiments of the invention;</li><li>[<figref idref="f0009">Fig.16</figref>], an example of an axial ratio obtained by an antenna system as a function of frequency in a set of embodiments of the invention;</li><li>[<figref idref="f0009">Fig.17</figref>], an example of -3dB lobe width obtained by an antenna system as a function of frequency in a set of embodiments of the invention;</li><li>[<figref idref="f0010">Fig.18</figref>], an example of impedance matching achieved by an antenna system as a function of frequency in one set of embodiments of the invention.</li></ul>

0028There<figref idref="f0001">picture 1a</figref> depicts a first exemplary antenna system in one set of embodiments of the invention.

0029The antenna system Sys1a comprises a ground plane with a cylindrical cavity Cav filled with a dielectric, magnetic or magneto-dielectric substrate. The cavity includes an opening and walls. The antenna system Sys1a also comprises an antenna Ant arranged on the dielectric, magnetic or magneto-dielectric substrate.

0030The invention will be described through examples where the antenna is a planar antenna, but the invention is not restricted to these examples, and 3D antennas could be used.

0031In one set of embodiments of the invention, the substrate is a so-called low-loss dielectric substrate, for example a substrate whose dielectric loss angle tangent (tanδ) is less than 10^-2. This substrate can also be either magnetic or magneto-dielectric.

0032The cavity may also be filled with electromagnetic absorber and/or a partial resistive film may be placed therein.

0033The Ant antenna can be of different types, for example a planar antenna. For example, the planar antenna Ant can be a spiral antenna, a sinuous antenna or a planar periodic antenna. It can for example be formed of different current rings corresponding to different frequencies, the perimeter of a given ring being equal to the wavelength of the corresponding frequency. The outer rings therefore correspond to low frequencies, and the inner rings to high frequencies.

0034This type of spiral therefore makes it possible to operate the antenna over a wide band of frequencies, within which the different rings contribute to the radiation for different frequencies according to their diameter (for a wavelength λ, it is a ring-shaped zone of circumference λ which will contribute to the radiation).

0035The Ant antenna can be a transmit or receive antenna.

0036There<figref idref="f0001">picture 2</figref> shows an example of a spiral antenna in one set of embodiments of the invention.

0037In one set of embodiments of the invention, the antenna has for example the shape of an Archimedean spiral defined by the equation<i>r</i>(<i>ϕ</i>) = <i>e^aϕ</i>, Or<i>r</i>(ϕ) is the radius of the spiral at a location<i>ϕ</i>, And<i>To</i> is a constant.

0038There<figref idref="f0001">picture 2</figref> shows an example of such a spiral antenna comprising two strands Brin1 and Brin2, said antenna being printed on the dielectric substrate Subs of thickness h1 and diameter d1.

0039The X, Y and Z axes represent three axes of an orthogonal frame, where Z is the axis of the antenna. The X and Y axes correspond to the plane of the antenna, and can be defined for example by the geometry of the points of excitation of the spiral. By convention, these same three axes X, Y and Z will be represented in several figures. To facilitate the intelligibility of the description, it will be considered that the “top” of the system will correspond to high values ​​on the z axis, and the “bottom” to low values. Thus, an element will be considered "on" or "above" another if its position is higher on the z axis, and on the contrary "under" or "below" another if its position is weaker on the z axis.

0040There<figref idref="f0002">picture 3</figref> shows an example of a so-called reference section of an antenna system in one set of embodiments of the invention.

0041The so-called reference section comprises a metallic cavity Cav, on which is arranged the dielectric substrate Subs in which the planar antenna Ant is printed. As indicated above, the antenna can operate at different frequencies, and, at a given frequency, it is a specific zone of the antenna which will participate in the radiation. For example, in a spiral antenna, for a wavelength λ, it is a zone in the form of a ring of circumference λ which will contribute to the radiation.

0042The Sys1a antenna system also includes an absorbing peripheral ring, not visible on the<figref idref="f0002">picture 3</figref>, arranged between the antenna and the walls of the cavity.

0043The absorbing peripheral crown makes it possible to trap the effects of ends of strands, that is to say to limit the effect of open circuit. Indeed, these effects, by recombining locally with the rest of the circuit radiating towards the center of the antenna, can in particular cause mismatching and a loss of radiation efficiency depending on the frequency.

0044Returning to the<figref idref="f0001">picture 1a</figref>, The antenna system Sys1a also comprises an absorber half-lens Lent1a having the shape of an angular sector and comprising a base element substantially covering a first part of the opening of the cavity, a second part of the opening of the cavity not being covered by said base element.

0045In some embodiments, the first portion of the cavity opening is half of the cavity opening.

0046For example, the half absorbing lens can cover:<ul id="ul0002" list-style="dash"><li>Between 45% and 55% of the surface of the cavity;</li><li>And, more preferably, between 48% and 52% of the surface of the cavity;</li><li>And, more preferentially, between 49% and 51% of the surface of the cavity;</li><li>And, more preferably, between 49.5% and 50.5% of the surface of the cavity;</li><li>And, more preferentially, between 49.9% and 50.1% of the surface of the cavity;</li><li>And, more preferably, half of the surface of the cavity.</li></ul>

0047Thus, the electromagnetic waves emitted by the antenna will be affected, in the half of the cavity covered by the half-lens, by a phase shift, whereas they will not be modified in the half not covered by the half-lens. .

0048This creates a phase and amplitude imbalance between the two halves of the cavity opening, thus generating a deviation from the axis of the antenna.

0049This therefore makes it possible to obtain a deflection of the antenna beam, while maintaining a compact and passive system.

0050The peripheral absorbent crown and the absorbent half-lens can be integral, and form a single absorbent element, or be formed from two distinct elements.

0051The peripheral absorbent crown, and the absorbent half-lens can be made of a partially absorbent dielectric material.

0052For example, an absorbent material comprising carbon can be used. This type of material has the advantage of having absorbent properties while being compatible with 3D printing, which makes the antenna system more flexible to reproduce and modify.

0053More generally, the half-lens can be secured to the cavity Cav and to the antenna Ant, in which case the system Sys1a is formed from a single device.

0054In one set of embodiments of the invention, the half-lens can on the contrary be located in a device independent of that of the antenna.

0055For example, the half-lens can be arranged slightly above the antenna. This makes it possible to integrate the half-lens into already existing antenna devices. For example, the half-lens can be integrated into a radome which is added above a pre-existing antenna.

0056There<figref idref="f0002">figure 4</figref> shows an example of a metal cavity in one set of embodiments of the invention.

0057In one set of embodiments of the invention, the cavity Cav is cylindrical in shape, with a diameter d1 and a height h2. The metallic cavity has a bottom 410 and metallic walls 420.

0058However, this shape is given by way of non-limiting example only, and other cavity shapes can be envisaged. For example, the cavity may be square. The ground plane of the cavity may or may not be flat. In the latter case, the depth of the cavity may be lower towards the center thereof. For example, the cavity may be conical in shape.

0059There<figref idref="f0002">figure 5</figref> shows an example of an absorbent peripheral crown in one set of embodiments of the invention.

0060In one set of embodiments of the invention, the peripheral absorbent crown Cour is in the form of a hollow cylinder.

0061In the example of the<figref idref="f0002">figure 5</figref>, the hollow cylinder has a height h2, and an external diameter d1 respectively identical to the height and external diameter of the metal cavity Cav represented in<figref idref="f0002">figure 4</figref>, and a thickness w1, corresponding to an inside diameter d1 - w1.

0062The peripheral absorbent crown shown in<figref idref="f0002">figure 5</figref> can therefore be placed in the metal cavity shown in<figref idref="f0002">figure 4</figref>, and absorb the electromagnetic waves between the antenna and the side 420 of the metal cavity.

0063There<figref idref="f0003">figure 6</figref> shows an example of a basic element of an absorbent half-lens in a set of embodiments of the invention.

0064The bottom base element of the absorbing half-lens appears here as a half-cylinder of thickness h4 and diameter d2 > d1. The base element can therefore block off half of the metal cavity.

0065The base element thus contributes to the deflection of the beam.

0066The base element can, in certain embodiments, serve as a support for other elements of the lens such as those represented in<figref idref="f0003">figure 8</figref>

0067In other embodiments of the invention, the base element is the only element of the half-lens closing off the metal cavity. In these embodiments, the height of the base element can be set according to the desired deflection of the beam. In particular, certain heights can favor the deflection of the beam in certain frequency bands; the height h4 can therefore be defined as a function of a frequency band to be deflected preferentially.

0068The design of the basic element presented in<figref idref="f0003">figure 6</figref> is provided as an example only, and other designs are possible. For example, the base element can be formed of a semi-cylinder of diameter d1 entering slightly into the metal cavity, or the annular element represented in<figref idref="f0003">figure 7</figref>, and a semi-cylinder of diameter d2 as shown in<figref idref="f0003">figure 6</figref>. In general, the design of the basic element can obey the following considerations:<ul id="ul0003" list-style="dash"><li>the base element must close off half of the metal cavity, or half of the hollow part of the annular peripheral crown;</li><li>the base element may have a constant height, for the part closing off the metal cavity, or half of the hollow part of the annular peripheral crown.</li></ul>

0069There<figref idref="f0003">figure 7</figref> shows an example of an annular element in a set of embodiments of the invention.

0070In all embodiments of the invention, the absorbent half-lens is arranged on an annular element forming an extension of the absorbent peripheral ring out of the cavity as far as the base element. According to the embodiments of the invention, the absorbing half-lens and the annular element can be integral and form a single element, or be two distinct juxtaposed elements.

0071In the example of the<figref idref="f0003">figure 7</figref>, the annular element Ann is presented as a hollow cylinder of external diameter d1, of thickness w1 and of height h3. It is therefore a hollow half-cylinder of the same external diameter and thickness as the hollow half-cylinder of the peripheral ring shown in<figref idref="f0002">figure 5</figref>, which extends it out of the metal cavity, up to the bottom base element, and therefore form a support for the bottom base element.

0072This annular element therefore absorbs the reflections of the antenna, while fixing the other elements of the lens and maintaining a fixed distance between the antenna and the base element of the half-lens.

0073When the half-lens and the annular element are joined, this also makes it possible to produce the half-lens without requiring a mechanical interface between its lower face and the upper face of the radiating circuit. In other words, the one-piece combination of the half-lens and the annular element, these two elements (for example by 3D printing) makes it possible to reduce the assembly interfaces along the axis perpendicular to the radiating circuit, while making it possible to choose precisely the air gap between the upper face of the radiating circuit and the lower face of the half-lens: there is for example no need for a film of glue-foam-film of glue between the radiating circuit and the half-lens .

0074There<figref idref="f0003">figure 8</figref> shows an example of a set of circular sector elements of an absorber half-lens in a set of embodiments of the invention.

0075In one set of embodiments of the invention, the absorbing half-lens comprises at least one circular sector element whose thickness varies according to the distance from the center of the half-lens.

0076As indicated above, the antenna can process, whether it is a transmitting or receiving antenna, frequencies depending on the distance to the center of the antenna, and therefore to the center of the half-lens . For example a spiral, sinuous or log-periodic antenna, for which the active zone at a given wavelength has the shape of a ring whose diameter corresponds to the given wavelength, the lower rings therefore corresponding to low frequencies, and the inner rings at high frequencies. In parallel, the thickness of the lens makes it possible to deflect the beam more or less according to the frequencies of the electromagnetic waves.

0077Adapting the thickness of the half-lens as a function of the distance from the center therefore makes it possible to locally adapt the deviation of the beam to the frequency of the waves emitted at a given distance from the center of the antenna. This makes it possible to obtain a deflection of the beam which is coherent over a wide frequency band.

0078In one set of embodiments of the invention, the half-lens comprises a plurality of circular sector elements whose thickness is defined by an increasing function of an angular distance from the edges of the lens.

0079In the example of the<figref idref="f0003">figure 8</figref>, the half-lens comprises 9 circular sector elements, arranged symmetrically, with, from the edges of the half-lens:<ul id="ul0004" list-style="dash"><li>two 8th circular sector elements;</li><li>two 8d circular sector elements;</li><li>two circular sector elements 8c;</li><li>two circular sector elements 8b;</li><li>a circular sector element 8a.</li></ul>

0080Each circular sector element is defined by a thickness profile depending on the distance to the center of the half-lens, and the thickness is defined by an increasing function of an angular distance from the edges of the lens (the angular distance being by example represented by the angle<i>α</i> starting from the right edge of the half-lens), i.e., in the example of the<figref idref="f0003">figure 8</figref>, at a given distance from the center, the thickness of the element 8a will be greater than the thicknesses of the elements 8b, themselves greater than the thicknesses of the elements 8c, themselves greater than the thicknesses of the elements 8d, themselves greater than the thicknesses 8th elements.

0081The use of a plurality of circular sector elements whose thickness is defined by an increasing function of an angular distance from the edges of the lens makes it possible to limit the frequency dependence of the angular deviation of the main radiation lobe. This also makes it possible to restrict the discontinuities along the strands of the spiral, and therefore to avoid impedance mismatches.

0082There<figref idref="f0004">figure 9</figref> shows an example of a side view of a set of circular sector elements of an absorbing half-lens in a set of embodiments of the invention.

0083There<figref idref="f0004">figure 9</figref> more precisely represents a profile view of the circular sector elements (or sectors) 8a, 8b, 8c, 8d and 8e represented in<figref idref="f0003">figure 8</figref>. For each of the profiles, the<figref idref="f0004">figure 9</figref> represents the thickness of the profile as a function of the distance from the center of the half-lens, the distance being represented increasing from left to right.

0084As in<figref idref="f0003">figure 8</figref>, it can be noted that, at a given distance from the center, the thickness is respectively less and less important for the sectors 8a, 8b, 8c, 8d and 8e. Indeed, all sectors follow a similar profile pattern, in which:<ul id="ul0005" list-style="dash"><li>the thicknesses for sector 8a are defined by a function parameterized by four thicknesses s1, s2, s3 and s4; And</li><li>the thicknesses for the sectors 8b are defined by the same function, parameterized with the thicknesses 0.8*s1, 0.8*s2, 0.8*s3 and 0.8*s4;</li><li>the thicknesses for the sectors 8c are defined by the same function, parameterized with the thicknesses 0.6*s1, 0.6*s2, 0.6*s3 and 0.6*s4;</li><li>the thicknesses for the 8d sectors are defined by the same function, parameterized with the thicknesses 0.4*s1, 0.4*s2, 0.4*s3 and 0.4*s4;</li><li>the thicknesses for the 8d sectors are defined by the same function, parameterized with the thicknesses 0.2*s1, 0.2*s2, 0.2*s3 and 0.2*s4.</li></ul>

0085In one set of embodiments of the invention, each circular sector element is defined by a function of increasing then decreasing thickness as a function of a distance from the center of the half-lens.

0086This is for example the case of the circular sector elements represented in<figref idref="f0004">figure 9</figref>, for which the thickness increases first, from the center of the lens (on the left on the<figref idref="f0004">figure 9</figref>) up to a distance ds3, then decreases between the distance ds3 and a distance ds4 representing the radius of the circular sector elements.

0087The distance ds3 can for example correspond substantially to the radius of the antenna. This makes it possible to obtain a thickness of the half-lens which increases with the distance from the center of the antenna, and therefore with the wavelength of the waves used locally by the antenna. This makes it possible to have a significant thickness for the low frequencies, and weaker for the high frequencies. This makes it possible to obtain a homogeneous beam deflection over a wide frequency band.

0088There<figref idref="f0004">figure 10</figref> depicts an exemplary overview of an antenna system comprising a set of circular sector elements of an absorber half lens in one set of embodiments of the invention.

0089There<figref idref="f0004">figure 10</figref> shows an overview of a Sys10 antenna system including a number of the elements discussed above. The Sys10 antenna system includes:<ul id="ul0006" list-style="dash"><li>a metal cavity Cav;</li><li>an Ant antenna in the metal cavity;</li><li>a half-lens comprising:<ul id="ul0007" list-style="none"><li>∘ an annular element Ann;</li><li>∘ a plurality of circular sector elements Sect.</li></ul></li></ul>

0090Some elements of the Sys10 antenna system are not visible on the<figref idref="f0004">figure 10</figref>. For example, the base element of the half-lens is located either the plurality of circular sector elements Sect, and the absorbing peripheral ring inside the walls of the metal cavity.

0091There<figref idref="f0005">picture 11a</figref> represents an example of radiation patterns of an antenna of the state of the art according to different frequencies, without deflection of the beam of the antenna.

0092There<figref idref="f0006">figure 11b</figref> shows an example of radiation patterns of an antenna according to different frequencies, with deflection of the beam of the antenna by an antenna system in a set of embodiments of the invention.

0093In general, the<figref idref="f0005 f0006 f0007 f0008 f0009 f0010">figures 11a to 18</figref> correspond to 3D electromagnetic simulations performed on an antenna system model according to the invention. They are given by way of illustrative and non-limiting example only of the results obtained by an antenna system according to the invention, different results being able to be obtained in other embodiments of the invention (for example, with a other type of antenna, or other dimensions).

0094Each of the 6 diagrams represented on the<figref idref="f0005">figure 11a</figref> And<figref idref="f0006">11b</figref> corresponds to a given frequency, from left to right and from top to bottom, 3.5 GHz, 4.5 GHz, 5.5 GHz, 6.5 GHz, 7.5 GHz, and 8.5 GHz.

0095For each of the frequencies the<figref idref="f0005">picture 11a</figref> represents the diagram without deviation, and the<figref idref="f0006">figure 11b</figref> the diagram with deviation. The deviation is represented by the angle of roll ϕ and elevation θ.

0096There<figref idref="f0006">figure 11b</figref> shows that the system according to the invention indeed allows a deviation of the radiation pattern of the antenna, and that this deviation is fairly homogeneous over a wide band of frequencies, in this example from 3.5 GHz to 8.5 GHz.

0097There<figref idref="f0007">figure 12</figref> shows two sections of a 3D representation of the main lobe of the radiation pattern of an antenna deflected by an antenna system in one set of embodiments of the invention.

0098The two cuts correspond to cuts according to the planes defined by the axes X and Y, and the axes X and Z respectively.

0099This example shows that the system according to the invention makes it possible to deflect the antenna beam, both according to the roll angle ϕ and the elevation angle θ.

0100There<figref idref="f0007">figure 13</figref> shows an example of a deflection angle obtained by an antenna system as a function of frequency in one set of embodiments of the invention.

0101There<figref idref="f0007">figure 13</figref>, as well as<figref idref="f0008 f0009 f0010">figures 14 to 18</figref>, relate to the same example as the<figref idref="f0005 f0006 f0007">figures 11a to 12</figref>. We observe on the<figref idref="f0007">figure 13</figref> that the deviation angle of the main lobe of the antenna's radiation pattern is between 11° and 22°. The invention therefore makes it possible to obtain a relatively constant angle of deviation over a wide band of frequencies.

0102There<figref idref="f0008">figure 14</figref> shows an example of an angular deviation angle obtained by an antenna system as a function of frequency in one set of embodiments of the invention.

0103The angle of angular deviation is between 340° and 25°, and can therefore be limited over the entire frequency band.

0104There<figref idref="f0008">figure 15</figref> shows an example of antenna gain achieved by an antenna system as a function of frequency in one set of embodiments of the invention.

0105Antenna gain is plotted on the vertical axis, in dB, as a function of frequency, on the horizontal axis, in GHz.

0106It is observed that the radiated gain typically greater than 2 dB, which shows that the half-lens makes it possible to obtain the angular deviation shown<figref idref="f0007">Figure 13</figref>, without significant degradation of the radiated gain level. We also observe that there is no gain dip depending on the frequency: this shows that the addition of the half-lens does not create any additional destructive interference phenomenon with the lower ground plane of the cavity. antenna

0107There<figref idref="f0009">figure 16</figref> shows an example of an axial ratio obtained by an antenna system as a function of frequency in one set of embodiments of the invention.

0108The axial ratio is represented on the vertical axis, in dB, as a function of frequency, on the horizontal axis, in GHz.

0109It is observed that the axial ratio is well below -3dB, which represents good purity of the polarization, over a wide band of frequencies, in this case all the frequencies tested between 3.5 and 8.5 GHz.

0110There<figref idref="f0009">figure 17</figref> shows an example of -3dB lobewidth obtained by an antenna system as a function of frequency in one set of embodiments of the invention.

0111Lobewidth is plotted on the vertical axis, in dB, as a function of frequency, on the horizontal axis, in GHz.

0112We observe that the lobe width at -3 dB, in the presence of the half-lens, remains consistent with that expected for this type of antenna: the half-lens therefore creates an angular deviation of the main radiation lobe but does not alter not the half-power angular aperture domain in the studied radiation planes, with a rather frequency-stable angular aperture.<ul id="ul0008" list-style="none"><li>There<figref idref="f0010">figure 18</figref> shows an example of impedance matching obtained by an antenna system as a function of frequency in a set of embodiments of the invention;</li><li>The matching is represented on the vertical axis, in dB, as a function of frequency, on the horizontal axis, in GHz.</li></ul>

0113It is observed that the addition of the absorbing dielectric half-lens does not induce mismatching of the antenna.

0114The examples above demonstrate the ability of the invention to generate a deflection of the beam of an antenna in a homogeneous manner over a wide frequency band, while limiting the size of the antenna system and preserving the performance of the 'antenna. However, they are only given by way of example and in no way limit the scope of the invention, defined in the claims below.