Antenna system for vehicles

Abstract

The present disclosure refers to an antenna system vehicles, preferably for Vehicle-to-Everything (V2X) communications, comprising a planar reflector and a radiating element placed over the reflector, wherein the radiating element comprises segments, preferably straight segments, arranged to configure two connected quadrilateral frame antenna elements. Each quadrilateral frame antenna element having an inner pair of segments and an outer pair of segments, wherein the segments of the inner pairs are substantially parallel to the reflector, and the segments of the outer pairs are inclined with respect to the segments of the inner pairs. The segments of the outer pairs have one end connected with the reflector.

Claims

1. An antenna system for vehicles, comprising: a first planar reflector; a radiating element placed over the reflector and including segments arranged to configure two connected quadrilateral frame antenna elements, each quadrilateral frame antenna element having an inner pair of segments and an outer pair of segments, wherein the segments of the inner pairs are substantially parallel to the reflector, and the segments of the outer pairs are inclined with respect to the segments of the inner pairs, and wherein the segments of the outer pairs have one end connected with the reflector; and a feeding line connected with the segments of the inner pairs and connected with the reflector.

2. The antenna system according to claim 1, wherein at least a major part of each segment is straight, and wherein the segments of the same pair of segments have the same length, and wherein the segment of the outer pairs are longer than the segments of the inner pairs.

3. The antenna system according to claim 2, wherein the segments of the outer pairs define together respectively two vertices that are aligned with respect to an axis, and wherein the segments of the inner pair and the segments of the outer pair of the same frame antenna elements, define respectively two vertices that are aligned with respect to axis (y1,y2) that are orthogonal to the axis, and wherein the reflector is rectangular and the width of the reflector is shorter than the distance between any the two vertices aligned with respect to the axis (y1,y2).

4. The antenna system according to claim 3, wherein each of the segments of one of the inner pairs is connected with a segment of the other inner pair, and wherein there is a gap between a first pair of connected segments and a second pair of connected segments, and wherein the feeding line has a positive pole connected with one of the pairs of connected segments, and a negative pole connected with the other pair of connected segments and with the first reflector.

5. The antenna system according to claim 4, wherein the first reflector has a lower surface and an upper surface, wherein the upper surface is closer to the radiating element than the lower surface, and wherein the feeding line runs longitudinally on the lower surface of the reflector, passes transversally through the reflector and extends below the pairs of inner segments.

6. The antenna system according to claim 5, wherein the width of the reflector is substantially equal to the distance between the vertices defined by the segments of the outer pairs.

7. The antenna system according to claim 6, wherein the distance between the vertices is within a range of 0.9 (λ)+/−0.2 (λ), or within a range of 0.9 (λ)+/−0.1 (λ) or substantially 0.9 (λ) of the wavelength at the operating frequency.

8. The antenna system according to claim 1, further comprising a second reflector connected with one of the short sides of the first reflector, and placed transversally with respect to the first reflector.

9. The antenna system according to claim 8, wherein the first pair of connected segments define a ninety degree angle, and second pair of connected segments define a ninety degree angle.

10. The antenna system according to claim 9, wherein each of the segments of the outer pair of segments, define a thirty-five degree angle with the first reflector.

11. The antenna system according to claim 10, wherein the height of the first reflector is within a range of ⅕ (λ)+/−0.06 (λ), or within a range of ⅕ (λ)+/−0.03 (λ) or is substantially ⅕ (λ) of the wavelength (λ) at the operating frequency.

12. The antenna system according to claim 11, wherein the distance between the segments of the inner pairs and the first reflector is within a range of 1/10 (λ)+/−0.04 (λ), or within a range of 1/10 (λ)+/−0.02 (λ), or is substantially 1/10 of the wavelength (λ) at the operating frequency.

13. The antenna system according to claim 12, adapted to operate in accordance with a Dedicated Short Range Communications (DSRC) protocol.

14. The antenna system according to claim 13, further comprising a casing configured to be attached externally to a vehicle, and wherein the radiating element, reflector and a part of the feeding line are enclosed within the casing.

15. The antenna system according to claim 14, wherein the casing configuration and the arrangement of the radiating element and first reflector within the casing, are selected such as, when the casing is attached to an external surface of a vehicle, the first reflector is transversally arranged to ground.

16. The antenna system according to claim 1, wherein the segments of the outer pairs define together respectively two vertices that are aligned with respect to an axis, and wherein the segments of the inner pair and the segments of the outer pair of the same frame antenna elements, define respectively two vertices that are aligned with respect to axis (y1,y2) that are orthogonal to the axis, and wherein the reflector is rectangular and the width of the reflector is shorter than the distance between any the two vertices aligned with respect to the axis (y1,y2).

17. The antenna system according to claim 1, wherein each of the segments of one of the inner pairs is connected with a segment of the other inner pair, and wherein there is a gap between a first pair of connected segments and a second pair of connected segments, and wherein the feeding line has a positive pole connected with one of the pairs of connected segments, and a negative pole connected with the other pair of connected segments and with the first reflector.

18. The antenna system according to claim 1, wherein the first reflector has a lower surface and an upper surface, wherein the upper surface is closer to the radiating element than the lower surface, and wherein the feeding line runs longitudinally on the lower surface of the reflector, passes transversally through the reflector and extends below the pairs of inner segments.

19. The antenna system according to claim 1, wherein the width of the reflector is substantially equal to the distance between the vertices defined by the segments of the outer pairs.

20. The antenna system according to claim 19, wherein the distance between the vertices is within a range of 0.9 (λ)+/−0.2 (λ), or within a range of 0.9 (λ)+/−0.1 (λ) or substantially 0.9 (λ) of the wavelength at the operating frequency.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the present disclosure are henceforth described with reference to the accompanying drawings, wherein:

(2) FIG. 1A shows one perspective view of an antenna system including a radiating element and a reflector;

(3) FIG. 1B shows another perspective view of the radiating element and the reflector;

(4) FIG. 1C shows a top plan view of the radiating element and the reflector;

(5) FIG. 1D shows a front elevational view of the radiating element and the reflector;

(6) FIG. 1E shows a side elevational view of the radiating element and the reflector;

(7) FIG. 1F shows another perspective view of the radiating element and the reflector;

(8) FIG. 2A shows a front elevational view of an arrangement of the antenna system including a feeding line with the radiating element and the reflector;

(9) FIG. 2B shows a perspective view of the arrangement;

(10) FIG. 2C shows an enlarged, partial, perspective view of the arrangement;

(11) FIG. 3 shows a perspective view of another embodiment of the antenna system including a lateral reflector;

(12) FIG. 4A shows a perspective view of a casing integrating the antenna system, and with portions removed to show internal detail;

(13) FIG. 4B shows an exemplary location of the casing in a truck;

(14) FIG. 5A is a schematic, top plane, view of a long truck incorporating two antenna systems attached to a cabin covering respective right and left sectors of the truck;

(15) FIG. 5B is a graph of antenna system radiation patterns for the right antenna system of FIG. 5A; and

(16) FIG. 5C is a graph of antenna system radiation patterns for the left antenna system of FIG. 5A.

DETAILED DESCRIPTION

(17) FIG. 1 shows an antenna system 1 comprising a first planar reflector 3 and a radiating element 2 placed over the reflector 3. The radiating element 2 is formed by a set of straight segments, eight segments in particular, arranged and connected to configure two connected quadrilateral frame antenna elements 4, 5. Each quadrilateral frame antenna element 4, 5 has an inner pair of segments 4a, 4b, 5a, 5b and an outer pair of segments 4c, 4d, 5c, 5d. The inner segments are closer to the center of the radiating element and closer to the feeding connection, than the outer segments.

(18) The first planar reflector 3 is a metallic plate that can be supported by a substrate (not shown), for example the reflector can be embodied as a conducting surface of a Printed Circuit Board (PCB). The first reflector 3 has a lower surface and an upper surface, wherein the upper surface is closer to the radiating element than the lower surface. The first reflector 3 is rectangular in this preferred embodiment, having a width (W) and a height (H).

(19) Unlike prior art BiQuad antennas, the radiating element 2 is a three-dimensional structure as illustrated in FIGS. 1D, 1E. The segments 4a, 4b, 5a, 5b of the inner pairs are substantially parallel to the reflector 3, and the segments 4c, 4d, 5c, 5d of the outer pairs are inclined, that is, define an angle (α) with respect to the respective segments 4a, 4b, 5a, 5b of the inner pairs to which they are connected. Preferably the angle (α) in the front view of FIG. 1D is about 155°. The angle between any of the segments 4c, 4d, 5c, 5d and the reflector 3 is about thirty-five degrees (35°).

(20) As an example, for a Dedicated Short Range Communications (DSRC) protocol with an operating frequency of about 5.9 GHz, and taking into account that c0=3e8 m/s then wavelength for that operating frequency is lambda (λ)=c0/Freq then lambda=3e+8/5.9 GHz is about fifty-one millimeters (51 mm).

(21) The length of the segments 4a, 4b, 5a, 5b is preferably within a range of ⅕(λ)+/−0.06 (λ), and more preferably within a range of ⅕+/−0.03 (λ), at the operating frequency, that is, with an operating frequency of 5.9 GHz, the length of these segments is about eleven and a half millimeters (11.5 mm).

(22) The length of the segments 4c, 4d, 5c, 5d is preferably within a range of ⅓ (λ)+/−0.06 (λ), and more preferably within a range of ⅓ (λ)+/−0.03 (λ), at the operating frequency, that is, with an operating frequency of 5.9 GHz, the length of these segments is about seventeen and a half millimeters (17.5 mm).

(23) The antenna system 1 features a thin profile since the distance or thickness (T) between the segments 4c, 4d, 5c, 5d of the inner pairs and the reflector 3, is preferably within a range of 1/10 (λ)+/−0.04 (λ), more preferably within a range of 1/10 (λ)+/−0.02 (λ), and preferably about 1/10 of the wavelength (λ) at the operating frequency, that is, with an operating frequency of 5.9 GHz, the total more preferably thickness of the antenna system is about five and a half millimeters (5.5 mm).

(24) The total electric length of each connected quadrilateral frame antenna elements 4, 5, that is, the sum of the length of all four segments of each quadrilateral frame antenna elements 4, 5, is preferably within a range of 1.1 (λ)+/−0.2 (λ), of more preferably within a range of 1.1 (λ)+/−0.1 (λ), and preferably 1.1 (λ) of the wavelength (λ) at the operating frequency, that is, with an operating frequency of 5.9 GHz, the total more preferably electric length of each connected quadrilateral frame antenna elements 4, 5 is about fifty-eight millimeters (58 mm).

(25) Additionally, the segments 4c, 4d, 5c, 5d of the outer pairs are connected together at their ends configuring vertices 11, 11′ of the quadrilateral frame antenna elements 4, 5, and connected with the reflector 3. In this way, the radiating element 2 is grounded and it is reinforced mechanically. Furthermore, that arrangement, reduce side nulls up to −5 dBi, maximizing the antenna's directivity in front and rear directions.

(26) As shown more clearly in FIG. 1D, the width (W) of the reflector is equal to the distance between the vertices 11, 11′ defined by the segments 4c, 4d and 5c, 5d of the outer pairs of segments. Preferably, this width (W) is preferably within a range of 0.9 (λ)+/−0.2 (λ), of more preferably within a range of 0.9 (λ)+/−0.1 (λ), and preferably 0.9 (λ) of the wavelength (λ) at the operating frequency, that is, with an operating frequency of 5.9 GHz, the total more preferably width (W) of the reflector 3 is about forty-five millimeters (45 mm).

(27) In the preferred embodiment of FIG. 1, the segments of the same pair have the same length, that is, the segments of the inner pairs 4a, 4b, 5a, 5b have substantially the same length, and the segments 4c, 4d, 5c, 5d of the outer pairs have substantially the same length. In order to match the antenna to a 50 Ohms impedance, one of the sets of segments of the same length, are longer than the segments of the other set. In this preferred embodiment, the segment 4c, 4d, 5c, 5d of the outer pairs, are longer than the segments 4a, 4b, 5a, 5b of the inner pairs.

(28) The segments 4a, 5a define a ninety degree (90°) angle, and the segments 4b, 5b define a ninety degree (90°) angle. In the top plan view of FIG. 1C, the radiating element 2 configures a double rhomboid or double diamond configuration shape.

(29) As shown more clearly in FIG. 1C, the vertices 11, 11′ defined by the segments 4c, 4d, 5c, 5d of the outer pairs, are aligned with respect to an axis (x), and the segments of the inner pair and the segments of the outer pair of the same frame antenna elements, define in a top plan view, respectively vertices 12, 12′, 13, 13′ that are aligned with respect to axis (y1, y2) that are orthogonal to the axis (x).

(30) It can be noted in FIGS. 1C, 1E that the height (H) of the reflector 3 is smaller than the distance between any of the pair of vertices 12, 12′, 13, 13′. Preferably, for proper matching of the antenna, the reflector height (H) is preferably within a range of ⅕ (λ)+/−0.06 (λ), of more preferably within a range of ⅕ (λ)+/−0.03 (λ), and preferably ⅕ (λ) of the wavelength (λ) at the operating frequency, that is, with an operating frequency of 5.9 GHz, the total more preferably height (H) of the reflector 3 is about ten millimeters (10 mm).

(31) The total height of the antenna system 1 is the distance between the pair of vertices 12, 12′, 13, 13′. Preferably, for proper matching of the antenna, the total height of the antenna is preferably within a range of ⅓ (λ)+/−0.06 (λ), of more preferably within a range of ⅓ (λ)+/−0.03 (λ), and preferably ⅓ (λ) of the wavelength (λ) at the operating frequency, that is, with an operating frequency of 5.9 GHz, the total more preferably height (H) of the reflector (3) is about sixteen millimeters (16 mm).

(32) The segments 4c, 4a, 5a, 5c are consecutive and connected at their ends as to form a first branch of the radiating element 2, and similarly the segments 4d, 4b, 5b, 5d are consecutive and connected at their ends as to form a second branch of the radiating element 2, such a gap 7 is formed between the connected segments 4a, 5a of the first branch and the connected segments 4b, 5b of the second branch.

(33) As shown in FIG. 2A, the antenna system is fed at the center of the radiating element 2 by means of a feeding line 6, for example a coaxial cable 8, which has one pole connected with the connected segments 4a, 5a for example the negative or ground pole 8b, and the positive pole 8a connected with the connected segments 4b, 5b.

(34) The coaxial cable 8 is placed on the lower surface of the reflector 3 extending longitudinally in the direction of axis (x), it is bent, in this case ninety degrees (90°), and passes through an opening 10 (at the geometric center of the same) in the reflector 3 extending transversally to the reflector reaching the segments of the inner pairs. The ground pole 8b of the coaxial cable 8 is also connected with the reflector 3 as shown in FIGS. 2A, 2C.

(35) As shown in FIG. 2B, the coaxial cable 8 extends beyond the reflector and it is provided with a connector 9 at its free end for its connection to an external circuit (not shown).

(36) In the preferred embodiment of FIG. 3, the antenna system 1 comprises a second planar reflector 14 connected with one of the short sides of the first reflector 3, and placed orthogonally with respect to the first reflector. This second reflector 14 reduces nulls at the opposite side of the reflector, in the side direction, such as the side direction of the radiation pattern is increased.

(37) In the preferred embodiment of FIGS. 4A and 4B, the antenna system 1 comprises a casing 15 in the form of an elongated arm, which has at one free end a housing 16 wherein the radiating element 2, reflector 3 are enclosed and fitted, and a base 17 configured for its attachment to an external surface 19 of a vehicle. The casing 15 has a channel running internally wherein the feeding line 8 is located being the feeding line accessible from outside the casing 15 for its connection with a communication system of a vehicle.

(38) As shown in FIG. 4A, the casing 15 is configured, and the radiating element 2 and first reflector 3 are arranged, within the casing 15, such as, when the casing 15 is attached to an external surface 19 of a vehicle 18, the first reflector 3 is transversally arranged (in any angle) with respect to ground 20. Additionally, the casing 15 is configured and the reflector 3 is arranged within the casing 2, such as, when the casing 15 is attached to an external surface 19 of a vehicle 18, the longer edges of the reflector 3 are parallel to ground 20. This position of the radiation element 2 and the reflector 3 relative to the vehicle, generates a radiation pattern suitable for V2X communications.

(39) In a preferred embodiment, the casing 15 is the casing or any arm of an external rearview mirror 21 for a vehicle. Similarly, in this case, radiating element 2 and first reflector 3 are arranged within the casing an external rearview mirror for a vehicle, such as, when the casing is attached to an external surface 19 of a vehicle 18, the first reflector 3 is transversally arranged with respect to the ground 20. Additionally, the casing 2 of an external rearview mirror is configured and the reflector 3 is arranged within the casing 2, such as, when the casing 15 is attached to an external surface 19 of a vehicle 18, the longer edges of the reflector 3 are parallel to ground 20, and the reflector is transversally arranged to the longitudinal axis of the vehicle.

(40) In a practical application as the one shown in FIGS. 4B and 5A, the antenna system is used for truck platooning, such as, two antenna systems 1 as the one previously described are used, one attached at the right side of the truck cabin 18, and another one attached to the left side.

(41) The present disclosure also refers to a vehicle 18 having two antenna systems 1 as the one described above, respectively attached externally to left and right sides of the vehicle, and wherein the antenna systems 1 are configured such as the reflectors 3 are generally transversally arranged with respect to ground 20. Described in another way, the axis (y1,y2) are generally vertical to ground.

(42) While the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted for elements thereof without departing from its scope. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed but will include all embodiments falling within the scope thereof.