CN114824751A

CN114824751A - Directional antenna and vehicle comprising such a directional antenna

Info

Publication number: CN114824751A
Application number: CN202210059910.1A
Authority: CN
Inventors: M·塞里特里; A·诺塔里; P·法基尼; S·伦齐尼
Original assignee: Ask Industries SpA
Current assignee: Ask Industries SpA
Priority date: 2021-01-19
Filing date: 2022-01-19
Publication date: 2022-07-29
Also published as: EP4040598A1; IT202100000887A1

Abstract

The present disclosure relates to a directional antenna and a vehicle including such a directional antenna. The directional antenna includes: a first radiating element and a second radiating element arranged to be spaced apart from each other by a predetermined first distance; a supply circuit connected to the first and second radiating elements and adapted to supply the first and second radiating elements with a feed signal to be radiated, wherein the supply circuit comprises at least one conductive element having a first end connected to the first radiating element and a second end connected to the second radiating element, the at least one conductive element having a predetermined electrical length, measured between the first end and the second end, comprised between one fifth of a wave and three quarters of a wave, measured with respect to a nominal operating frequency of the antenna, the supply circuit being configured such that the signal fed into the input of the first radiating element is temporally phase-shifted with respect to the signal fed into the input of the second radiating element by a first value comprised between 30 and 120 sexagesimal degrees.

Description

Directional antenna and vehicle comprising such a directional antenna

Technical Field

The present invention relates generally to a directional antenna, in particular for a vehicle, and to a vehicle comprising such a directional antenna.

The directional antenna according to the invention is particularly suitable for use in vehicles, in particular for enabling V2X (vehicle-to-all) communications preferably operating at frequencies around 5.9Ghz, and will be described below with reference to such an application, without intending to limit in any way the possible field of application.

Background

As is well known, in recent years, an increasing commercialization of connected vehicles has been seen, which integrate many services ranging from entertainment (e.g. radio and/or television) to driver assistance (typically via satellite navigation systems).

Disclosure of Invention

In this regard, in the field of telecommunications, with respect to vehicles, communication between vehicles is indicated with V2V (vehicle to vehicle), communication between vehicle and infrastructure is indicated with V2I (vehicle to infrastructure), and communication between vehicle and pedestrian is indicated with V2P (vehicle to pedestrian), and communication between vehicle and everything that may be relevant is indicated with the acronym V2X.

For this type of V2X communication, which can be performed according to different standards (ieee802.11p or CV2X), an international frequency band around 5.9GHz has been allocated with small differences depending on the standardization bodies.

Therefore, modern vehicles must be equipped with antennas capable of operating at this frequency.

Furthermore, given that V2X communication may be possible for applications that are also related to safety, it is generally desirable for the antenna on the vehicle to have as wide and sufficient coverage as possible.

Such coverage may be obtained with a single antenna or by placing several antennas at different locations of the vehicle. In fact, since the vehicle itself is mainly constituted by a metal part which, by its very nature, interacts with the electromagnetic waves emitted by the antenna, the radiation pattern may be deformed differently, depending on the position of the antenna.

For example, depending on the curvature of the roof, an antenna positioned towards the rear of the car may not be able to radiate electromagnetic power towards the front of the car itself, and in order to compensate for this effect it is often necessary to mount a second antenna on the front of the car, for example at the rear view mirror.

In order to make the antennas located at different points of the vehicle more efficient, the radiation pattern of the antennas can be manipulated to avoid dispersing the electromagnetic power in directions that are not of interest, or in case the antennas are mounted inside the car in a position such as a rear view mirror, it can be ensured that the electromagnetic field is correctly transmitted towards the outside of the vehicle (forwards and sideways) where there is more likely to be a device with which to exchange communication than towards its passengers (behind).

In this respect, there are antennas on the market which, in order to obtain the desired deformation of the radiation pattern, use a single radiating element combined with a guiding effect of a barrier of conductive material placed at a controlled distance from the radiating element itself.

The solutions known at present, although obtaining considerable results, allow further improvements.

For example, the use of several antennas installed at different locations of a vehicle negatively impacts the cost of production and installation.

On the other hand, antennas coupled to the shield exhibit a control of the radiation pattern that is not completely optimal, in particular with respect to the coverage of the intermediate angle transverse to the ideal axis connecting the direction of maximum radiation to the direction of minimum.

It is therefore a main object of the present invention to provide a directional antenna, in particular for communication of the V2X type, which enables improved control of the radiation pattern and is easy to implement compared to known solutions.

Within this main object, another scope of the invention is to provide a directional antenna which allows ensuring greater bandwidths with respect to the known solutions, in particular greater bandwidths than those using a shielded antenna.

Yet another scope of the invention is to provide a solution for a directional antenna that is easy to implement and relatively inexpensive and that can be easily installed in most different types of vehicles, both road types such as cars, buses, various types of commercial vehicles and railway types such as trams, trains, etc.

This main object, together with the aforesaid additional scope and others that will emerge more fully from the following description, are achieved by a directional antenna, the characteristics of which are defined in claim 1.

This main object and the aforementioned additional scope are also achieved by a vehicle according to claim 10.

Particular embodiments are subject matter of the dependent claims, the content of which is intended to form an integral part of the present description.

Drawings

Further characteristics and advantages of the invention will emerge from the following detailed description, given purely by way of non-limiting example, with reference to the accompanying drawings, in which:

fig. 1 schematically illustrates a possible embodiment of a directional antenna according to the present invention;

fig. 2 schematically illustrates another possible embodiment of the antenna of fig. 1;

fig. 3 and 4 schematically illustrate another possible embodiment of a directional antenna according to the present invention;

fig. 5 schematically illustrates a further embodiment of a directional antenna according to the present invention;

fig. 6 shows the horizontal radiation pattern obtained using the antennas of fig. 3 and 4;

fig. 7 shows the vertical radiation pattern obtained using the antenna of fig. 3 and 4;

figure 8 shows the reflection coefficients obtained using the antennas of figures 3 and 4;

fig. 9 illustrates a possible horizontal radiation angle θ obtainable using a directional antenna according to the invention positioned at the front of a vehicle;

FIG. 10 illustrates the use of a position at the front of the vehiclePossible vertical radiation angles achievable with directional antennas according to the invention

Detailed Description

It should be noted that in the following detailed description, identical or similar components have the same reference numerals from a structural and/or functional point of view, whether or not shown in different embodiments of the present disclosure.

It should also be noted that in order to clearly and concisely describe the present invention, the drawings may not necessarily be to scale and certain features described may be shown in somewhat schematic form.

Furthermore, when the terms "adapted" or "arranged" or "configured" or "shaped" or similar terms are used herein, although referring to any component as a whole, or to any part of a component, or to a combination of components, it must be understood that it means and accordingly encompasses structures and/or configurations and/or forms and/or locations.

Further, when the terms "substantially" or "substantially" are used herein, it must be understood to encompass actual variations of plus or minus 5% relative to the indicated reference value or position, and when the terms transverse or transverse are used herein, they must be understood to encompass directions that are not parallel to the direction/axis(s) to which they refer or the reference component(s), and perpendicular must be considered a particular instance of a transverse direction.

Finally, in the following description and claims, the numerical ordinals first, second, etc. are used for descriptive purposes only and in no way should they be construed as limiting for any reason; in particular, an indication of, for example, "first value …" or "first distance" does not necessarily imply that there is or is strictly required an additional "second distance" or "second value," and vice versa, unless such presence is evident for proper functioning of the described embodiments, nor does it imply that the order should be exactly that which is described with reference to the illustrated exemplary embodiments.

Fig. 1-5 schematically illustrate a possible embodiment of a directional antenna according to the present invention, which is designated in its entirety by reference numeral 100.

The antenna 100 according to the present invention comprises a plurality of radiating elements, i.e. at least two, and a supply circuit connected to the radiating elements and adapted to feed them appropriately with a feed signal to be radiated.

In particular, according to an implementation embodiment, which will be derived in greater detail from the following description, said first and second radiating elements and said supply circuit are configured and operatively connected therebetween so as to generate a combined irradiation pattern exhibiting, in a horizontal plane, a decrease in signal in a selected direction substantially equal to one quarter of the circumference angle and an increase distributed in a substantially uniform manner in the remaining three quarters of the circumference angle.

In fact, the antenna 100 according to the invention allows widening the irradiation beam towards the middle direction as much as possible, once the direction of the maximum and minimum of the desired irradiation signal is selected, for example forwards and respectively backwards with respect to the vehicle on which the antenna 100 is mounted.

In more detail, as illustrated for example in the embodiments of fig. 1, 3, 4 and 5, the antenna 100 comprises at least:

a first radiating element 1 and a second radiating element 2 arranged spaced apart from each other by a predetermined first distance D1; and

a supply circuit or network 5 connected to said first and second

radiating elements

1, 2 and adapted to supply the first and second

radiating elements

1, 2 with a feed signal S to be radiated _i 。

In particular, the supply circuit 5 is configured such that the signal to be radiated fed into the input of the first radiating element 1 is offset in time by a first predetermined value Δ Φ with respect to the same signal to be radiated fed into the input of the second radiating element 2.

In a possible embodiment of the directional antenna 100 according to the invention, the supply circuit 5 is configured so that the phase difference in time of the signal fed into the input of the first radiating element 1 with respect to the signal fed into the input of the second radiating element 2 is a first value comprised between 30 and 120 decimal degrees (sexagesimal degree).

In particular, according to a possible embodiment, the supply circuit 5 is conveniently configured so that the phase difference in time of the signal fed into the input of the first radiating element 1 with respect to the signal fed into the input of the second radiating element 2 is a first value comprised between 50 and 70 sexagesimal degrees, preferably equal to 60 sexagesimal degrees.

Usefully, according to a possible embodiment shown in the figures, the supply circuit 5 comprises at least one conductive element 5a having a first end 5b connected to the first radiating element 1 and a second end 5c connected to the second radiating element 2, said at least one conductive element 5a having a predetermined electrical length "d" measured between said first end 5b and said second end 5c, with respect to the nominal operating frequency of the antenna 100.

In practice, the supply circuit 5 carries electromagnetic waves in input at the connection 6, for example from/in output at the connection 6, for example to an electronic device of a vehicle on which the antenna 100 is mounted, which vehicle is indicated by reference numeral 200 in fig. 9 and 10. In particular, in the case of waves coming from the input connection 6 of the antenna 100 and travelling through the supply network 5, due to the combination of the appropriately sized physical distance D1 between the two

radiating elements

1 and 2 and the configuration of the supply circuit 5, and in particular the portion 5a of the supply circuit 5 comprised between the two

radiating elements

1 and 2, the transmitted waves will reach first the closest radiating element, i.e. the first radiating element 1, and then the farthest radiating element, i.e. the second radiating element 2, with the phase difference defined by the following equation:

wherein the content of the first and second substances,

is fed to the first radiating elementThe phase difference between the signal of the transmitted wave in the input of the piece 1 and the signal of the same wave fed into the input of the second radiating element 2, "d" being the electrical length of the part of the supply network or circuit 5 comprised between the two ends connected respectively to the first radiating element 1 and the second radiating element 2, and λ _lt Is the wavelength of the electromagnetic wave within the supply circuit 5.

In a possible embodiment, the predetermined electrical length "d" is included in the signal S carried by the circuit 5 _i Between one fifth of the wave and three quarters of the wave.

More particularly, according to a possible embodiment, the predetermined electrical length "d" is comprised between two fifths of the wave and three fifths of the wave, more preferably equal to one half of the wave.

In the embodiments illustrated in fig. 3-4 and 5, the conductor element 5a is formed by a meander line having three substantially straight portions forming a generally U-shaped or C-shaped path, wherein the electrical distance is substantially formed by the electrical length d of the three straight portions ₁ 、d ₂ 、d ₃ The sum is given.

In practice, by applying different phases to the

radiating elements

1 and 2, the desired deformation of the radiation pattern is obtained, as illustrated for example in fig. 7 and 8, which can be suitably calibrated as required.

It is clear that the supply circuit 5, and in particular the portion 5a of the supply circuit 5 interconnecting the two

radiating elements

1 and 2, can be configured differently in order to similarly obtain the same technical result in terms of the modification of the radiation pattern of the antenna 100.

For example, in a possible embodiment, the supply circuit 5 comprises at least one conductive element 5a having a first end 5b connected to the first radiating element 1, a second end 5c connected to the second radiating element 2, and a support element, for example a strip made of dielectric material, which is at least mechanically connected to said conductive element 5a and acts as a mechanical support for the same, also contributing to obtain the desired phase shift Δ Φ.

The support element may be shaped, for example, to duplicate the shape of the supply circuit 5 or only the portion 5a thereof and follow the physical path of the supply circuit 5 or only the portion 5a thereof, or even have a different shape, as long as it is suitable to support the circuit 5 itself and in particular the portion 5a thereof and to contribute to achieving the desired phase shift Δ Φ.

For example, if the signal supply circuit 5 is realized by a microstrip, the support element may be realized by a body made of dielectric material, which at least partially reproduces the path of the microstrip, in particular at least with respect to its portion 5 a. If instead the signal supply circuit 5 and in particular at least its part 5a is made of a coaxial cable, for example, the cable can also be mechanically released from the support holding the radiating element, with the

ends

5b and 5c as its only contact points.

In yet another possible embodiment of the directional antenna 100 according to the present invention, the supply circuit 5 comprises at least one lumped constant component (alternatively defined as a component having a lumped constant) arranged between said first and

second radiating elements

1, 2. Such components (schematically illustrated by dashed box 30 in fig. 2) may be constituted by e.g. capacitors or inductors.

In particular, according to this embodiment, the supply circuit 5, or at least the portion thereof interposed between the two radiating

elements

1 and 2 and interconnecting the two radiating

elements

1 and 2, may comprise or consist of a combined "T" or "pi" (pi greek) network of inductors or capacitors, which achieves the desired phase shift without having to resort to a constrained physical spacing between the input ports of the radiating

elements

1 and 2. In this way, there is a greater degree of freedom regarding the spacing between the

same radiating elements

1 and 2, and it is thus possible to select this spacing to a degree that is less dependent on the physical architecture of the supply network 5 itself.

In a possible embodiment, and as illustrated in the examples of fig. 1-5, the directional antenna 100 further comprises a support element 3 on which said first and

second radiating elements

1, 2 and the supply circuit 5 are at least partially arranged or connected.

In the illustrated example, the support element 3 has a substantially planar development, and the radiating

elements

1 and 2 and the supply circuit 5 may be arranged on opposite sides of the planar element 3, as in the exemplary embodiment illustrated in fig. 3 and 4, or on the same face as illustrated in the exemplary embodiments of fig. 1, 2 and 5.

In a possible embodiment, said power supply circuit 5 and one or more of the first and

second radiating elements

1, 2, preferably each of them, comprise a respective metal conductor connected to a grounding element fixed to the support element 3 or formed by the support element 3 itself.

In particular, such a grounding element may then be formed, depending on the application, by the same support element 3, which in this case is substantially made of an electrically conductive material.

Alternatively, the support member 3 may be made of a dielectric material and the grounding element comprises at least one conductive surface at least partially covering one face of the support member 3 (see fig. 5), or arranged on both faces of the support member 3 so as to at least partially cover them (see fig. 3 and 4).

In the illustrated embodiment, each grounding element comprises a conductive foil made of copper, having a substantially planar development and indicated by reference numeral 4 in fig. 3-5.

The ground element 4 is dimensioned with a surface suitably larger than the radiating element in order to modify (typically for lowering or for raising) the height of the maximum of the radiated signal illustrated in fig. 7.

In particular, in the exemplary embodiment of fig. 3 and 4, the radiating

elements

1 and 2 are realized using PCB (from british printed circuit board) technology and are formed, for example, by copper tracks deposited on the dielectric support 7.

The shape and dimensions of the copper traces forming the two radiating

elements

1 and 2 are selected to obtain a resonance of the antenna 100 around the operating frequency (e.g., about 5.9 GHz). Furthermore, in order to improve the adaptability of the antenna, in this exemplary embodiment, a

corresponding branch

8 and 9 is provided for each radiating

element

1 and 2, respectively, the two

branches

8 and 9 being connected to the common ground element 4.

In this example, the supply circuit 5 is again realized on the face of the support element 3 opposite to the face where the radiating

elements

1 and 2 are present, and can also be realized using PCB technology. For example, the circuit 5 may comprise a waveguide called microstrip. Such a waveguide is formed from a ground element and a copper trace separated by a dielectric thickness. The width of the copper tracks is suitably dimensioned, for example, so that the characteristic impedance of the microstrip is equal to 50 Ω. The narrowed or widened portion 11 of the microstrip may be made to improve the overall adaptability of the antenna 100. In order to fix the

radiating elements

1 and 2 to the support element 3, a hole 10 can be drilled, inside which the PCB of the radiating

elements

1 and 2 is inserted to be subsequently connected to the supply circuit 5 by soldering.

In the example illustrated in fig. 5, the radiating

elements

1 and 2 are made of folded sheets. Such a solution allows, for example, to utilize the available space more efficiently by developing the radiating element three-dimensionally, and in many cases to optimize (i.e. reduce) the production costs of the radiating element itself, compared to PCB technology. In this case the supply circuit 5 is always implemented on the same side of the radiating

elements

1 and 2 using, for example, microstrips. To obtain a better adaptability of the antenna 100, two connection points to the ground plane 4 have been added to the

radiating elements

1 and 2, indicated by

reference numerals

12 and 13, respectively.

In a further embodiment, similar to the embodiment of fig. 3 and 4 (and not illustrated in detail in the figures), the dielectric support 7 is positioned directly above the grounding element 4, i.e. it is formed by a substantially planar area of one single dielectric or by two separate planar areas located within the grounding element 4; in this embodiment, the radiating

elements

1 and 2 with their respective metallic connectors or connecting

branches

8 and 9 are shaped similarly to that in fig. 3 and are positioned over the dielectric areas (or over the respective dielectric areas) and connected to the supply circuit 5 placed on the opposite face of the support 3, as shown in fig. 4.

It is clear that in the antenna 100 according to the invention, different configurations of radiating elements and a larger number of radiating elements may be used, depending on the application.

For example, as schematically illustrated in the exemplary embodiment of fig. 2, it is foreseen to use at least a third radiating element 20, which third radiating element 20 is spaced from the first radiating element 1 by a predetermined second distance D2 and from the second radiating element 2 by a predetermined third distance D3. The third radiating element 20 may be suitably arranged to achieve a triangular configuration, as illustrated for example in fig. 2, or may be arranged to align with the two radiating

elements

1 and 2 to form a linear configuration.

The supply circuit 5 is in turn connected to the third radiating element 20 and is adapted to supply the third radiating element 20 also with a feed signal S to be radiated _i . In particular, the supply circuit 5 is configured such that the signal S to be radiated, fed at the input of the third radiating element 20 _i Time-shifted by a second predetermined value with respect to the signal fed at the input of the first radiating element 1 and by a third predetermined value with respect to the signal fed at the input of the second radiating element 2.

What has been described above in relation to the embodiment with only two radiating

elements

1 and 2 is equally applicable to the presence of the third radiating element 20, as well as any other radiating element.

In particular, the values indicated for the electrical distance "d" and the phase shift between the first and

second radiating elements

1 and 2 are applicable to each pair of radiating elements, and thus in the case of the third radiating element 20, to the pairs of first-

third radiating elements

1 and 20, and to the pairs of second-

third radiating elements

2 and 20, respectively.

Further, in the illustrated example, each of the physical distances D1, D2, and D3 between pairs of elements measured between two nearest surfaces facing each other is illustrated; alternatively, each distance may be defined in another way, for example by calculating it as the distance between the respective symmetry axes in case of symmetrically shaped radiating elements, or in another way still suitable for determining the size of the antenna according to the invention.

In yet another possible embodiment, the antenna 100 comprises a housing, for example made of a dielectric material, only schematically illustrated in fig. 2 by reference numeral 50. Such a housing 50 allows further and in a controlled manner deforming the overall radiation pattern.

In practice, it has been determined that the directional antenna 100 according to the invention allows to achieve the intended aim, since it allows to obtain a significantly improved control of the radiation pattern compared to known solutions and, in particular, allows to extend to a maximum the azimuth angle of the coverage which, with known solutions, does not reach three quarters of the angular circle, thus obtaining a greater coverage of the intermediate angle transversal to the ideal axis connecting the direction of maximum radiation to the direction of minimum.

To this end, fig. 6, 7 and 8 illustrate examples in which the results shown are obtained by the embodiments of the antenna 100 illustrated in fig. 3 and 4. In particular, these results are obtained by applying a phase shift of 60 ° and a physical distance D1 of about 12.7mm, thus determining the length of the supply circuit 5 according to the equation indicated previously. In particular, fig. 6 and 7 refer to irradiation patterns on a horizontal plane and a vertical plane, respectively; wherein the definition of horizontal and vertical planes means, for example, those illustrated in fig. 9 and 10, wherein the sector in which most of the radiated power is highlighted, the angle theta is for the horizontal, and the angle theta is for the most part

For vertical. Fig. 8 also shows the reflection coefficient obtained for the antenna 100 as an example.

The antenna 100 envisaged also allows, thanks to the particular feeding technique, to guarantee a greater bandwidth, allowing, if necessary, the use of the same antenna also for transmissions in a frequency band close to the one allocated to V2X communication, such as the WiFi band.

To achieve this, as previously mentioned, an assembly is used that is easy to construct and assemble and is low-cost, which allows to properly calibrate the operation of the antenna itself, in particular to properly act on the mutual distance between the radiating elements and the electrical length of the portion of the supply circuit or network that interconnects the radiating elements and feeds them with the signal to be radiated.

A further advantage is that the antenna 100 according to the invention can in principle be used in any type of vehicle, both road and railway, and can easily be installed both in new vehicles and, if required, in vehicles already in use. Another object of the invention therefore relates to a vehicle characterized by the fact that: it comprises at least one directional antenna 100, the directional antenna 100 being in accordance with the above, and more particularly, as defined in the appended claims.

Naturally, without prejudice to the principle of the invention, the embodiments and the implementation details may vary widely with respect to what has been described and illustrated by way of preferred but non-limiting example, without thereby departing from the scope of protection of the present invention, as defined in particular by the annexed claims. For example, the previously described embodiments may be combined, even partially, by selecting for this purpose one or more of the features described with reference to the possible embodiments, and using each feature selected in one of the other described embodiments where useful or possible.

For example, the device 30 or the housing 50 may be used in all or only some of the disclosed embodiments. The shapes of the components or portions thereof may be appropriately modified so long as they are compatible with the purposes and functions of these components conceived within the scope of the present invention. For example, the radiating

elements

1, 2 and 20 and/or the supply circuit 5 or parts thereof may be made by metallization on a dielectric material, such as plastic; such radiating elements may be shaped differently with respect to what is illustrated in the examples, and may be arranged in positions other than the substantially vertical position shown in the figures; the supply circuit 5 may at least partially have a curved or mixed path; there may be a single ground element 4 for all radiating elements, or one ground element may be used for each radiating element used, and the ground elements may or may not be electrically connected to each other; each grounding element may be constituted by an element not necessarily having a planar development; the housing 50 of dielectric material can be replaced by a bulky mechanical assembly, i.e. having dimensions comparable to or larger than those of the radiating element; and so on.

Claims

1. A directional antenna (100), characterized in that the directional antenna (100) comprises at least:

-a first radiating element (1) and a second radiating element (2), the first radiating element (1) and the second radiating element (2) being arranged spaced apart from each other by a predetermined first distance (D1);

-a supply circuit (5), said supply circuit (5) being connected to said first and second radiating elements (1, 2) and being adapted to supply said first and second radiating elements (1, 2) with a feed signal to be radiated, wherein said supply circuit (5) comprises at least one conductive element (5a) having a first end (5b) connected to said first radiating element (1) and a second end (5c) connected to said second radiating element (2), said at least one conductive element (5a) having a predetermined electrical length (d) measured between said first end (5b) and said second end (5c) with respect to a nominal operating frequency of said antenna (100), said predetermined electrical length (d) being comprised between one fifth of a wave and three quarters of a wave, said supply circuit (5) being configured such that it feeds into an input of said first radiating element (1) The phase difference in time of the signals with respect to the signals fed into the input of said second radiating element (2) is a first value comprised between 30 and 120 sexagesimal degrees.

2. The directional antenna (100) according to claim 1, wherein the first and second radiating elements (1, 2) and the supply circuit (5) are configured and operatively connected therebetween so as to generate a combined irradiation pattern exhibiting, on a horizontal plane, a signal decrease in a selected direction substantially equal to one quarter of a circumference angle and an increase distributed in a substantially uniform manner in the remaining three quarters of the circumference angle.

3. The directional antenna (100) according to claim 1 or 2, wherein the supply circuit (5) comprises a support element at least mechanically connected to the conductive element (5 a).

4. The directional antenna (100) according to any one of the preceding claims, wherein the supply circuit (5) comprises at least one lumped constant component (30) arranged between the first and second radiating elements (1, 2).

5. The directional antenna (100) according to any one of the preceding claims, wherein the predetermined electrical length (d) is comprised between two fifths of a wave and three fifths of a wave.

6. The directional antenna (100) according to any one of the preceding claims, wherein the supply circuit (5) is configured such that the signal fed into the input of the first radiating element (1) is temporally phase-shifted by a first value with respect to the signal fed into the input of the second radiating element (2), the first value being comprised between 50 and 70 sixty-ary degrees.

7. The directional antenna (100) according to any one of the preceding claims, further comprising at least one support element (3), the first and second radiating elements (1, 2) and the supply circuit (5) being at least partially arranged or connected to the at least one support element (3).

8. The directional antenna (100) according to claim 7, wherein one or more of the supply circuit (5), the first radiating element (1) and the second radiating element (2) comprise a metal conductor connected to a grounding element (4), the grounding element (4) being fixed to the support element (3) or being constituted by the support element (3) itself.

9. The directional antenna (100) according to any one of the preceding claims, comprising at least a third radiating element (20), the third radiating element (20) being arranged spaced apart from the first radiating element (1) by a predetermined second distance (D2) and from the second radiating element (2) by a predetermined third distance (D3), and wherein the supply circuit (5) is connected to the third radiating element (20) and adapted to supply the feed signal to be radiated to the third radiating element (20), wherein the supply circuit (5) is configured in such a way that: the phase difference in time of the signal to be radiated fed into the input of the third radiating element (20) with respect to the signal fed into the input of the first radiating element (1) is a second predetermined value and the phase difference in time with respect to the signal fed into the input of the second radiating element (2) is a third predetermined value.

10. A vehicle (200), characterized in that the vehicle (200) comprises at least one directional antenna (100) according to any one of claims 1 to 9.