EP3625847B1

EP3625847B1 - Antenna device

Info

Publication number: EP3625847B1
Application number: EP19727735.3A
Authority: EP
Inventors: Massimo Calearo Ciman; Marco De Gregorio; Matteo FRANZAN; Roberto Mestriner; Luigi CORRA'; Oscar DINON; Reiko OKUYAMA
Original assignee: Calearo Antenne SpA
Current assignee: Calearo Antenne SpA
Priority date: 2018-06-15
Filing date: 2019-04-30
Publication date: 2021-05-26
Anticipated expiration: 2039-04-30
Also published as: EP3625847A1; WO2019239230A1

Description

TECHNICAL FIELD

The present invention relates to an antenna device.
Preferably, the present invention relates to an antenna device installable on a vehicle, conveniently a motorized vehicle, such as, for example, a motor-vehicle or any similar vehicle, to which the ensuing description will make explicit reference, without any loss of generality.

BACKGROUND ART

Antenna devices are known that have a "shark-fin" shape and are structured to be stably fixed to the roof of a motor-vehicle.
An antenna device of the aforementioned type is described, for example, in patent EP 3 093 920 A1 and comprises a lower support base, a printed circuit board mounted on the base, a half-shell or inner casing coupled to the base and defining, with the latter, an internal space that contains the printed circuit board, and a half-shell or outer casing coupled to the inner half-shell.
The antenna device also comprises an umbrella-like element, which is arranged on the outer surface of the top part of the inner half-shell beneath the outer half-shell, and is connected to the printed circuit board via a coil arranged in the internal space delimited by the inner half-shell above the printed circuit board. The coil is a cylindrical wire coil that develops along a vertical axis arranged on the centre-line plane of the antenna device and orthogonal to the printed circuit board, and is electrically connected to the umbrella-like element via a watertight connection element.
The watertight connection element is formed by a vertical tubular support appendage that extends in a cantilever fashion from the internal surface of the inner half-shell beneath the umbrella-like element, and a cylindrical conductive element that is stably engaged in the support appendage and has an inner cylindrical chamber divided by a central portion. A threaded blind hole is provided on the top end of the conductive element, which receives a screw from above that passes through a hole made in the umbrella-like element. Respective threaded blind holes are made at the two, upper and lower, ends of the conductive element that house two screws. An upper screw passes through a hole made in a recess of the umbrella-like element and connects the latter to the upper portion of the conductive element, and a lower screw passes through a hole made in an end of a spring coupled to the coil and is adapted to connect the latter to the lower portion of the conductive element.
A technical problem of the above-described antenna device is that the central arrangement of the cylindrical wire coil significantly reduces the degree of freedom in adding other antennas to perform the communication functions required in latest-generation vehicles, such as, for example, V2V, V2X, Bluetooth, Wi-Fi, GNSS, SDARS and LTE, in view of the fact that constraints exist on the maximum external size of the antenna device, set by type approval regulations, which impose a maximum height of 70 mm on the antenna device that cannot be exceeded.
A second technical problem of the above-described antenna device is that the central position of the cylindrical wire coil increases the complexity of manufacturing and mounting of the conductive element.
An antenna device is also described in patent applications WO 2017/141635 A1 , WO 2018/105235 A1 , CN 205 609 730 U and US 2016/315378 A .

DISCLOSURE OF INVENTION

The applicant has therefore carried out an in-depth study on antenna devices, with the object of identifying a simple and inexpensive solution that enables increasing the internal space available in the container/casing of the antenna device.
The subject of the present invention is therefore that of providing a solution that enables achieving the aforesaid object.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings, which illustrate a non-limitative embodiment thereof, in which:

Figure 1 is an exploded view of an antenna device, with parts on an enlarged scale, made according to the principles of the present invention;
Figure 2 is a perspective side view of some components of the antenna device shown in Figure 1;
Figure 3 is an exploded view of the components shown in Figure 2;
Figures 4 and 5 are two perspective side views from opposite sides of an antenna element on the antenna device shown in Figure 1;
Figures 6 and 7 show two perspective views from opposite sides of the inner casing coupled to the base of the antenna device shown in Figure 1;
Figure 8 is a sectional view on plane VIII-VIII of the antenna device shown in Figure 6;
Figure 9 is internal, longitudinal, partially sectional view, with parts removed for the sake of clarity, of the connector and the antenna element in the antenna device shown in Figure 1;
Figure 10 is a vertical sectional view of the antenna device according to a first embodiment;
Figure 11 is a vertical sectional view of the antenna device in a second embodiment;
Figure 12 is a schematic view, with parts in section and parts removed for the sake of clarity, of a variant of the antenna device made according to an embodiment;
Figure 13 is an internal perspective view from below, with parts removed for the sake of clarity, of the inner casing and the antenna element, according to an embodiment of the antenna device; and
Figure 14 is a perspective side view of an antenna element in the antenna device made according to one embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will now be described in detail, with reference to the accompanying figures, to allow an expert in the field to embody it and use it. Various modifications to the described embodiments will be immediately obvious to experts in the field, and the generic principles described herein can be applied to other embodiments and applications without thereby departing from the scope of the present invention, as defined in the appended claims. Therefore, the present invention should not be considered as limited to the embodiments set forth herein, but is to be accorded the widest scope consistent with the principles and features described and claimed herein.
Referring to Figure 1 and to the remaining accompanying figures, reference numeral 1 indicates, as a whole, an antenna device made according to the present invention. The antenna device 1 is structured so that it can be mounted on a motorized vehicle (not shown), preferably a motor-vehicle or similar, preferably on the roof of the vehicle's passenger compartment.
As shown in Figure 1, the antenna device 1 has a longitudinal axis A and comprises a cover or inner casing 2 having a three-dimensional shape, and a plate-shaped antenna base 3 that has the bottom surface designed to be coupled to the vehicle, for example, to the roof. The antenna base 3 is stably connected to the inner casing 2 at the bottom opening of the latter, so as to create an antenna container, for example, a closed antenna container, delimiting an internal housing space for electrical antenna components, described in detail below. Preferably, the closed antenna container is watertight to protect the internal electronic antenna components.
The support base 3 comprises a plate-shaped body, at least partially made of an electrically insulating material, for example, a polymeric material or similar, which lies on a preferably horizontal plane, having two larger, approximately flat, opposite surfaces, and can centrally house a lower mechanical connection member 10, structured to fasten the antenna device 1 to the vehicle.
The antenna device 1 also comprises an outer cover or casing 4 structured to be fitted on the inner casing 2 so as to cover it on the outside. The inner casing 2 and/or outer casing 4 can be made of a material through which radio waves can pass, for example, based on polymeric materials or similar materials, such as synthetic resins, adapted for the aforementioned purpose. The inner casing 2 and/or outer casing 4 can be conveniently shaped more or less like a shark fin. Nevertheless, it is understood that the present invention is not limited to an inner casing 2 and/or outer casing 4 shaped like a shark fin, but can also be extended/applied to antenna devices 1 provided with casings of any shape, preferably, but not necessarily, shapes with aerodynamic profiles adapted for motor-vehicles.
The antenna device 1 also comprises an electronic processing circuit 5, which is arranged in the internal housing space of the inner casing 2 and is configured so as to at least receive/provide an antenna signal.
According to a preferred embodiment shown in Figure 1, the electronic processing circuit 5 can comprise at least one printed circuit board (PCB) arranged resting on the upper surface of the base 3 and that, preferably, can be fixed to the latter by fastening means, for example, screws or similar systems. According to a preferred embodiment shown in Figures 1, 2 and 3, the printed circuit board (PCB) of the electronic circuit 5 can have a substantially rectangular shape and is formed by a series of circuits, preferably associated with respective, mutually different transmission/reception frequency bands. It is understood that the printed circuit board could be single or formed by a combination of printed circuit boards.
In the example shown, the front portion 5a of the printed circuit board of the electronic circuit 5 (with respect to axis A) can be associated with a first frequency band, while the rear portion 5b of the printed circuit board can be associated with a second frequency band. Preferably, the first frequency band can comprise the DAB band, while the second frequency band can comprise the FM/AM band.
The electronic processing circuit 5 can be configured to perform analogue and/or digital processing of the antenna signal. To this end, the electronic circuit 5 can comprise at least one amplifier circuit adapted to amplify the antenna signal. However, the printed circuit board of the electronic circuit 5 could additionally or alternatively comprise other antenna signal processing and treatment circuits, such as, for example, a filter circuit and/or an equalizer circuit and/or a modulation and demodulation circuit. The analogue/digital processing procedures performed on an antenna signal through the electronic circuits are known and, not being the main object of the present invention, will not be described any further.
Referring to Figures 1, 6 and 7, the antenna device 1 also comprises at least one antenna element 6 defining at least one capacitive antenna component, which is arranged on the upper portion of the outer surface of the inner casing 2 and is shaped so as to be facing/adjacent to the inner surface of the outer casing 4. It is understood that the antenna element 6 can be integrated with or fixed to the outer surface of the inner casing 2 or the inner surface of the outer casing 4.
In the example shown in the accompanying figures, the antenna element 6 can comprise a plate-shaped element shaped/folded so as to be conveniently arranged/fitted on the upper portion of the inner casing 2. The plate-shaped element can conveniently comprise a film or sheet or thin plate made of a metal material folded/shaped so as approximately form a curved half-shell, i.e. having a substantially upside-down U-shaped vertical cross-section transversal to axis A.
According to a preferred embodiment shown in Figure 1, the antenna element 6 is conveniently fitted on the upper portion of the inner casing 2 inside a seat 7 that preferably has a shape and depth approximately corresponding to the shape and thickness of the antenna element 6.
According to a preferred embodiment shown in Figure 1, the antenna device 1 can further comprise an antenna element 8, also defining a circuit/capacitive antenna component, arranged on the upper portion of the inner casing 2 in a preferably front position, axially adjacent to the other, rear antenna element 6. Antenna element 8 is shaped so as be adjacent to/facing the inner surface of the outer casing 4. Antenna element 8 comprises a plate-shaped element folded so as to be conveniently fitted on the upper portion of the inner casing 2. The plate-shaped element of antenna element 8 can conveniently comprise a film or sheet or thin plate made of a metal material folded so as to have an upside-down U-shape.
According to a preferred embodiment shown in Figure 1, the antenna element 8 is conveniently fitted on a seat 9 made in the upper portion of the (preferably) front part of the inner casing 2, longitudinally adjacent to the rear seat 7. Seat 9 can preferably have a shape and depth approximately corresponding to the shape and thickness of the antenna element 8.
Seats 7 and 9 conveniently have a self-centring capability on the inner casing 2 of the respective antenna elements 6 and 8, which is found to be advantageous during assembly operations. Preferably, antenna elements 8 and 6 can be associated with the first and second frequency bands, respectively.
According to a preferred embodiment shown in Figures 1, 6 and 7, antenna elements 6 and 8 can be conveniently provided with retaining tongues 10 that extend in a cantilever fashion from the associated lower perimeter edges and engage in respective locking slots 11 made in the inner casing 2. The retaining tongues 10 centre and stably lock antenna elements 6 and 8 to the inner casing 2 and conveniently prevent movement of antenna elements 6 and 8, which would cause accidental detuning in the event of vibrations.
According to a preferred embodiment shown in the accompanying figures, the antenna device 1 also comprises an antenna element 12 and, preferably, an antenna element 13, which are arranged in the internal housing space of the inner casing 2 and each defining at least one inductive antenna component.
According to a preferred embodiment shown in Figure 1, antenna elements 12 and 13 electrically connect the electronic circuit 5 with antenna elements 6 and 8, respectively, to receive/provide corresponding antenna signals from/to them. Preferably, antenna elements 13 and 12 could be associated with the first and second frequency bands, respectively.
According to a preferred embodiment shown in the accompanying figures, antenna elements 12 and 13 are arranged approximately beneath antenna elements 6 and 8, respectively. Conveniently, antenna element 12 is arranged at the rear end of the antenna device 1, while antenna element 13 is arranged approximately in the intermediate-front part of the antenna device 1. Conveniently, antenna elements 12 and 13 can be arranged on parallel vertical planes set apart from the vertical centre-line plane passing through axis A of the inner casing 2. Conveniently, antenna elements 12 and 13 are arranged on mutually opposite sides with respect to the vertical centre-line plane of the inner casing 2 so as to be approximately facing the opposite parallel side walls of the inner casing 2.
According to a preferred embodiment shown in Figures 1-5, antenna elements 12 and 13 each comprise: a plate-shaped body 14 made of an electrically insulating material, having for example a rectangular shape, and provided with at least one larger flat vertical surface, and a spiral element 15 made of an electrically conductive material, arranged on the larger surface of the plate-shaped body 14. The spiral element 15 comprises a plurality of turns that are laid concentrically about a common axis B approximately orthogonal to the larger surface and are coplanar with one another on the larger surface. The turns extend on the larger surface so as to occupy a progressively increasing area. The turns of the spiral element 15 extend over the larger surface so as to progressively move away from axis B. it is understood that the width and thickness of the turns depends at least on the frequency band associated with antenna elements 12 and 13. Preferably, the turns of the spiral element 15 are circular.
It should be specified that the spiral element of each antenna element 12 and 13 and the respective plate-shaped element of antenna elements 6 and 8 are sized/shaped so as to form, through their connection in series, an inductive-capacitive circuit that operates in a condition of resonance.
In other words, the spiral element of antenna elements 12 or 13 constitutes an inductor specifically sized to form a resonant circuit with capacitive antenna element 6 or 8.
In this case, the resonance frequency of the inductive-capacitive-series-circuit formed by an antenna element 12 or 13 and the respective plate-shaped element of antenna elements 6 or 8 is approximately proportional to the frequency determined according to the following equation: $f_{0} = \frac{ω_{0}}{2 π} = \frac{1}{2 π \sqrt{LC}} .$
where:

L is the inductance value, which in this case depends on: the length of the filament forming the spiral element, the distance between the turns, the section of the filament, and the internal and external radii of the spiral, and
C is the capacitance of the plate-shaped element, which substantially depends on the area subtended by the plate-shaped element and the distance of the latter from the underlying ground plane (generally constituted by the roof of the motor-vehicle).

According to a preferred embodiment shown in the accompanying figures, the spiral element 15 of each inductive antenna element 12 and 13 and the plate-shaped element of each corresponding antenna element 6 and 8 are sized/shaped so as to form a resonant antenna circuit in a given frequency band.
According to a preferred embodiment shown in the accompanying figures, the spiral element 15 of antenna element 13 and the plate-shaped element of antenna element 8 are electrically connected in series with each other and are sized so as to form a resonant antenna circuit in the first frequency band, preferably the DAB band.
According to a preferred embodiment shown in the accompanying figures, the spiral element 15 of antenna element 12 and the plate-shaped element of antenna element 6 are electrically connected in series with each other and are sized so as to form a resonant antenna circuit in the second frequency band, preferably the FM/AM band.
The applicant has found that the use of vertical antenna elements 12 and 13 arranged off-centre, i.e. in asymmetric positions with respect to the vertical centre-line plane, and positioned at opposite longitudinal ends of the antenna device 1 as described and illustrated above, enables reducing the space they occupy inside the inner casing 2. Furthermore, the use of the spiral element 15 enables further reducing this bulk, without however compromising the transmission and reception of the antenna device 1.
According to a preferred embodiment shown in Figures 1-5, the plate-shaped body 14 can comprise a plate or board, for example quadrangular/rectangular, made of an electrically insulating material, for example, based on Vetronite and/or composite materials formed, for example, from glass fibre and epoxy resins (FR4), or similar. The spiral element 15 can comprise a spiral track of planar extension made, for example by moulding, on the larger surface of the plate-shaped body 14. The use of the vertical board with a moulded spiral track enables reducing the manufacturing costs of the antenna device.
In the preferred embodiment shown in Figures 1-3, the plate-shaped body 14 is stably fixed to the upper surface of the electronic circuit 5, preferably on an outer peripheral edge of the printed circuit board of the electronic circuit 5, preferably approximately parallel to axis A. The plate-shaped body 14 can have an electrical terminal 16, preferably arranged approximately on the lower side thereof, to electrically connect the spiral element 15 to the electronic circuit 5. The applicant has found that the fastening of the plate-shaped body 14 to the electronic circuit 5 enables advantageously pre-assembling antenna elements 12 and 13 and the electronic components, and reduces the overall assembly time of the antenna device 1.
Preferably, the electrical terminal 16 can comprise at least one contact pad made of an electrically conductive material connected by solder to a corresponding contact pad 5c of the electronic circuit 5 (Figure 2).
As shown in Figures 4 and 5, the electrical terminal 16 can be connected to a terminal end 15a of the spiral element 15, preferably the central end, via a conductive track 15b that preferably extends vertically on the larger surface of the plate-shaped body 14, preferably on the other side to the larger surface that houses the spiral element 15. To this end, it is possible to make a central through hole 14a in the plate-shaped body 14 (Figure 5), approximately parallel to axis B and approximately at end 15a, to electrically connect the latter with the upper terminal end 15c of the conductive track 15b, for example, by means of a transversal conductive pin engaged in the through hole 14a.
It is understood that the present invention is not limited to this arrangement and fastening of the plate-shaped body 14 on the electronic circuit 5, but could provide for other embodiments. For example, according to the embodiment shown in Figures 13 and 14, the antenna device 12 or 13 has the plate-shaped body 14 stably fixed to the inner casing 2 instead of to the electronic circuit 5 and is provided with a lower, U-shaped, male electrical connector 18, which is stably coupled (engaged) to (in) a female electrical connector (not shown) of the electronic circuit 5. The fastening of the plate-shaped body 14 to the inner casing 2 can be implemented via mechanical fastening means, for example screws. For example, as shown in Figures 13 and 14, the plate-shaped body 14 can be provided with two opposite vertical ends of two side and horizontal fastening lugs 19 with central holes that are arranged resting on the free ends of respective vertical hubs 20 inside the inner casing 2, to which they are fixed by screws 21 or alternative fastening means. The applicant has found that the pre-assembly of the plate-shaped body 14 on the inner casing 2 enables reducing the assembly times of the antenna device 1.
Referring to Figures 6-8, the antenna elements 12 and 13 are electrically connected to antenna elements 6 and 8, respectively, by associated watertight connectors 22A and 22B, each of which is arranged in the intermediate portion of a side wall of the inner casing 2, between the upper portion of the inner casing 2 that supports the antenna elements 6 and 8 and the lower portion connected to the base 3.
According to a preferred embodiment shown in Figure 6, each electrical connector 22A is approximately horizontal and comprises an insert 23 made of a conductive material that is stably embedded/integrated in said intermediate portion of a side wall, and fastening devices 24 that mechanically couple the insert 23 to the associated antenna element 6 to create an electrical connection between the latter and the insert 23.
According to a preferred embodiment shown in Figure 7, connector 22B is arranged on the wall opposite to connector 22A and is substantially identical to the latter.
The applicant has found that by making the electrical connection between the inductive elements 12 and 13 and capacitive elements 6 and 8 via the electrical connectors 22A and 22B, each positioned on the intermediate portion of a side wall, instead of on the top of the upper portion of the inner casing 2, it is possible to arrange the internal antenna elements 12 and 13 close to the opposite side walls of the inner casing 2, thus conveniently freeing the central space of the internal printed circuit board and consequently allowing the housing therein of other electronic antenna components associated with, for example, other frequency bands.
Referring to Figures 4-8, each antenna element 6 and 8 comprises elastic contact means 26 made of an electrically conductive material, which extend in a cantilever fashion from the larger surface of the vertical plate-shaped body 14 so as to be arranged in contact with one end of the associated electrical connector 22A and 22B inside the inner casing 2.
According to a preferred embodiment shown in Figure 8, the insert 23 can comprise a cup-shaped body that has a longitudinal axis C approximately orthogonal to the centre-line plane of the inner casing 2, and is embedded in a side rectangular portion 2a of the inner casing 2. The cup-shaped body has the bottom wall at least partially protruding inside the inner casing 2 and an internally threaded cavity with the opening towards the outer casing 4.
According to a preferred embodiment shown in Figures 6-8, the antenna elements 6 and 8 each have a tongue 25 with a side hole that extends in a cantilever fashion from an edge of the half-shell of the antenna element 6 or 8, so as to have the associated hole approximately aligned with the opening of the insert 23.
As shown in Figures 4-8, the fastening devices 24 can comprise a screw made of an electrically conductive metal material, which has a head arranged abutting on the outer surface of the tongue 25, with the thread passing through the hole of the tongue 25 and is screwed into the insert 23, to tighten the head against the insert 23 and the tongue 25 in abutment against the outer vertical surface portion of the rectangular portion 2a.
Preferably, the insert 23 can be incorporated in the inner casing 2 during the moulding procedure of the latter (co-moulding). The applicant has found that the embedding of the insert 23 in the body of the inner casing 2 enables ensuring the watertightness of the antenna container. Preferably, the insert 23 can have an outer side surface with an approximately hexagonal section so as counter any torsion forces generated by the screw and transmitted to the inner casing 2.
According to a preferred embodiment shown in Figures 1, 2, 4, 5 and 8, the elastic contact means 26 could comprise a strip made of a metal material and folded in a C-shape that extends on a plane parallel to the plate-shaped body 14. As shown in Figure 4, the strip folded in a C-shape can have a bottom end, preferably horizontal, stably connected to the plate-shaped body 14 via a support bracket 27 and the other upper end free, elastically arranged in abutment against the side surface of the uncovered inner end of the insert 23 that protrudes from the rectangular portion 2a in the inner casing 2 (Figures 8 and 9). The support bracket 27 can be fixed on the larger surface of the plate-shaped body 14, preferably on the top, alongside the spiral element 15 and be electrically connected to the upper terminal end 15c thereof.
It is understood that the present invention is not limited to the use of elastic contact means 26 provided with a strip folded in a C-shape, and that variants thereof could be envisaged. For example, as shown in Figure 14, the elastic contact means 26 could comprise a rectangular elastic tongue 31, which extends in a cantilever fashion from the support bracket 27 and is folded upwards so as to be arranged parallel to the larger surface of the plate-shaped body 14 and has the outer surface of the top end elastically in abutment against the distal end of the insert 23 inside the inner casing 2.
Referring to Figures 4, 5 and 9, the plate-shaped body 14 may have a projection 14b along the upper side, preferably rectangular, extending in a cantilever fashion from the vertical side along an approximately horizontal direction and is engaged between two vertical prongs of an upturned fork, obtained on the bottom of a protruding internal tongue 32, which extends on a plane approximately orthogonal to the inner surface of the inner casing 2. The two lower prongs of the internal tongue 32 hold the plate-shaped body 14 from the top so as to keep it in a vertical position.
It is also understood that the present invention is not limited to an insert 23 provided with a cup-shaped body or fastening devices 24 provided with a screw, and that different embodiments thereof could be envisaged.
For example, according to a first embodiment shown in Figure 10, the insert 23 could comprise a tubular body made of an electrically conductive material, and the fastening devices 24 can comprise a rivet made of a metal material, the stem of which is engaged in the tubular body, while the head is pressed against the tongue 25 with the interposition of a washer 28.
In a second embodiment shown in Figure 11, the insert 23 could comprise a pin that is embedded in the side wall of the inner casing 2 and partially protrudes from portion 2a with a threaded portion, on which a fastening device 24 constituted by lock nut is screwed, which pushes the tongue 25 against the surface of portion 2a.
Referring to Figure 3, the antenna device also comprises a ring or frame 33 made of an electrically conductive material that is interposed between the lower surface of the said printed circuit board of the electronic circuit 5 and the upper surface of the base 3, and is structured to electrically connect a plurality of terminals (not shown), preferably ground terminals of the electronic circuit 5, to a common reference potential, preferably the ground potential. In the example shown, the frame 33 is shaped so as to have geometry more or less corresponding to the outer rectangular peripheral edge of the printed circuit board and can be interposed/trapped between the latter and the base 3. The frame 33 can be provided with through holes that house screws fixing the frame 33 to the base 3. The frame 33 can also have a central transversal portion 33a that can be electrically coupled to the connector 10 so as to be, in use, electrically connected to the roof of the vehicle, i.e. the ground potential. To this end, holes that receive the vertical connection pins on the connector 10 are bore in the central transversal portion 33a.
To pre-assemble the antenna device on the vehicle prior to the fixing operations, an upper plate 34 (Figure 1) provided with lower anchorage clips that snap-fit into openings made in the base 3 can be used. The frame 33 forms a ground plane that allows positioning the ground contacts/terminals on the printed circuit board in an optimal and not geometrically binding manner.
It is also understood that the present invention is not limited to antenna elements provided with a single plate-shaped body 14 for supporting a single spiral element 15, and that alternative variants could be envisaged. For example, referring to Figure 12, the antenna device 1 could be provided with antenna elements provided with a single plate-shaped body 14 that supports at least two spiral elements 15, preferably arranged side-by-side on the same larger surface of the plate-shaped body 14. Preferably, the two spiral elements 15 can be part of an electric circuit that connects them to a single capacitive antenna element, for example a common antenna element 6 (Figure 12). The electric circuit can be provided with an electronic component for filtering the antenna signals, for example a filter 35 that connects the two spiral elements 15.
The electric circuit can be configured so as operate, based on the antenna signal frequencies, between a first operating configuration in which it selectively connects, via the filter 35, a single spiral element 15 between the antenna element 6 and the electronic circuit 5, excluding the other spiral element so as to operate in one band, for example in the AM/FM band, and a second operating configuration in which the electric circuit connects, via the filter 35, the two spiral elements 15 in parallel between the antenna element 6 and the electronic circuit 5 so as to operate in a second band, for example in the DAB band. This configuration is highly advantageous as it enables obtaining a dual resonance, for example, FM/DAB using a single plate-shaped support body 14 for both spiral elements 15. This configuration also enables further reducing the internal dimensions of the inductive antenna elements as it concentrates two spiral-shaped elements on a single plate-shaped body.
It is understood that, according to a variant that is not shown, the two spiral elements 15 can be arranged on two opposite larger faces of the plate-shaped support body 14. It is also understood that, according to a variant that is not shown, one or more spiral elements 15 could be integrated/comprised on a same number of parallel internal layers of the plate-shaped support body 14, so as to be parallel with each other.
Referring to Figure 1, the antenna device can also comprise at least one anti-vibration body 40 that is interposed between the inner surface of the outer casing 4 and the antenna elements 6 and/or 8 to dampen any vibrations to which the latter may be subjected. The anti-vibration body 40 can comprise, for example, a plate folded in a U-shape, sized in terms of thickness according to the width of the internal space between the inner surface of the outer casing 4 and the antenna elements 6 and/or 8.
The above-described antenna device is advantageous as in addition to being inexpensive to manufacture, it enables optimizing the internal spaces such that other antenna modules that require a minimum height to function can be inserted in the central are, were the useful height is greater. The antenna device offers the possibility of replacing the spiral elements, and therefore the band tuning, leaving all the other components of the antenna unchanged.
Finally, it is clear that modifications and variants can be made regarding the antenna device set forth herein without thereby departing from the scope of the present invention defined by the appended claims.

Claims

An antenna device (1) designed to be installed on a portion of a vehicle body, comprising:
a support base (3) defining a horizontal plane and designed to be arranged resting on said portion of the vehicle body,

an inner casing (2) having a three-dimensional shape that is coupled to said support base (3) to delimit an internal housing space,

an outer casing (4) structured to cover said inner casing (2), electronic signal processing means (5), that are arranged inside said inner casing (2) and are designed to receive/provide an antenna signal,

a first antenna element (6)(8) that defines at least one capacitive antenna element and comprises a plate-shaped element arranged on the upper portion of the outer surface of said inner casing (2), and

a second antenna element (12)(13) defining at least one inductive antenna element, that is arranged in said internal housing space of the inner casing (2) and is structured to electrically connect said first antenna element (6)(8) to said electronic signal processing means (5) so as to receive/provide said antenna signal,

said second antenna element (12)(13) comprising:
a plate-shaped support body (14) made of electrically insulating material, which is arranged on a vertical plane approximately orthogonal to said support base (3) and off-centre with respect to the vertical centre-line plane of said inner casing (2), and

at least one spiral element (15) that is arranged on a vertical surface of said plate-shaped support body (14) and comprises a plurality of turns made of electrically conductive material, which lie concentrically about a first common axis (B) approximately orthogonal to said vertical surface of said plate-shaped support body (14) coplanar with one another on the same surface.
The antenna device according to claim 1, wherein said plate-shaped support body (14) comprises a printed circuit board, PCB, and said spiral element (15) comprises a planar spiral conductive track made on the vertical surface of said PCB.
The antenna device according to claim 1 or 2, comprising a watertight electrical connector (22A) (22B) that is stably arranged in an intermediate portion of a side wall of said inner casing (2) positioned at a given distance from said upper portion of the same and is structured to electrically connect, in a watertight manner, the first antenna element (6)(8) to the second antenna element (12)(13).
The antenna device according to claim 3, wherein said electrical connector (22A) (22B) comprises an insert (23) made of electrically conductive material, which is embedded in said intermediate portion (2a) of said side wall of said inner casing (2) such that the electrical connector is arranged in an about horizontal direction, and fastening means (24) designed to be mechanically coupled to said insert (23) and to said first antenna element (6)(8) so as to electrically connect said first antenna element (6)(8) to said insert (23).
The antenna device according to claim 4, wherein said first antenna element (6) (8) comprises a perforated tongue which extends in a cantilever fashion from the plate-shaped element towards the support base (3) in order to be facing said insert (23) .
The antenna device according to claim 4 or 5, wherein said second antenna element (12)(13) comprises elastic contact means (26) made of electrically conductive material that extend in a cantilever fashion from a surface of said plate-shaped support body (14) so as to be arranged in contact with an inner end of said electrical connector (22A) (22B) in said housing space.
The antenna device according to any one of the preceding claims, wherein said plate-shaped support body (14) is stably fixed to said inner casing (2) so as to be adjacent to the inner surface of the side wall of the same.
The antenna device according to any one of the preceding claims, wherein said second antenna element (12)(13) comprises at least one pair of spiral elements (15) arranged side-by-side on a flat surface of the same plate-shaped support body (14), and configured to connect said first antenna element (6) to said electronic signal processing means (5).
The antenna device according to any one of claims 1 to 7, wherein said second antenna element (12)(13) comprises at least one pair of spiral elements (15) that are arranged on the opposite surfaces of a same plate-shaped support body (14) .
The antenna device according to claim 8, wherein said first antenna element (6) is selectively connectable to said electronic means (5) via one of the spiral elements (15) such that the device is configured to operate in a first frequency band, or alternatively via both the spiral elements (15) such that the device is configured to operate in a second frequency band, different from said first frequency band.
The antenna device according to any one of the preceding claims, comprising a mechanical connection connector (10) for the connection to the vehicle associated with said support base (3), and a frame (33) made of electrically conductive material that is interposed between an electronic circuit board of said electronic signal processing means (5) and said support base (3) for electrically connecting one or more ground terminals of said electronic signal processing means (5) to said mechanical connection connector (10).
The antenna device according to any one of the preceding claims, wherein the spiral element (15) of the second antenna element (12)(13) and the plate-shaped element of the corresponding first antenna element (6)(8) are sized/shaped so as to form, through connection in series, a resonant antenna circuit in a given frequency band.
The antenna device according to any of the preceding claims 1 to 7, comprising a pair of second antenna elements (12)(13) that are arranged in the internal housing space of the inner casing (2) and form respective inductive components adapted to resonate with the respective capacitive components of the first antenna elements (6) (8) in a first and a second frequency band, respectively, wherein the first frequency band comprises the DAB band and the second frequency band comprises the FM/AM band.
The antenna device according to claim 13, wherein said second antenna elements (12)(13) are arranged on mutually opposite sides with respect to the vertical centre-line plane of the inner casing (2) so as to be approximately facing the opposite parallel side walls of the inner casing (2).
The antenna device according to claim 14, wherein a second antenna element (12) is arranged at the rear end of the antenna device (1) and the other second antenna element (13) is arranged approximately at the intermediate-front part of the antenna device (1).