DESCRIPTION

The present invention relates to an antenna adapted to receive and transmit an electromagnetic field, in particular a radio signal, according to the preamble of claim 1. Many antennas are known in the art which are designed to receive and transmit radio signals; most antennas known in the art are of the type known as Yagi-Uda, or are derived therefrom.

The antennas known in the art, in particular of the Yagi-Uda type, comprise a support element, which is typically a rod known as "cradle" or "boom".

Mounted on the support element of these known antennas there are a radiator (e.g. a λ/2 dipole or a bent dipole), adapted to generate the electromagnetic field, and linearly shaped directors (typically metal rods), adapted to receive a linearly polarized electric field.

The following parts are also installed on said support element:

a first reflector, in particular for the UHF band, having a structure which comprises two grids arranged on opposite sides of the support element or boom,

a second reflector, in particular for the VHF band, having a structure which comprises a pair of uprights adapted to support at least one horizontal element, said pair of uprights being arranged on opposite sides of the support element or boom.

In particular, both the grids of the first reflector and the uprights of the second reflector can be mounted on opposite sides of the support element or boom so as to correspond to the faces of a dihedral (i.e. at an angle) or so as to lie in a single plane orthogonal to the boom (i.e. flat).

However, the known antennas described above suffer from a few drawbacks, which are due in particular to the fact that the grids of the first reflector are associated with the support element through a first connecting element, whereas the uprights of the second reflector are associated with said support element through a second connecting element.

This inevitably implies that the antenna is more difficult to assemble, in particular when this is done by a user.

A further drawback of known antennas is that the system for associating the first and second reflectors with the support element or boom necessarily requires that the support element be long enough to house all the components of the antenna, thus increasing the overall dimensions of the latter. As a consequence, the larger dimensions of the antenna require the use of bigger packages as well.

In this frame, it is the main object of the present invention to provide an antenna adapted to overcome the above-described drawbacks.

In particular, it is one object of the present invention to provide an antenna which is so designed that it can be assembled quickly and easily, in particular by a user.

It is another object of the present invention to provide an antenna conceived in a manner such that its overall dimensions are adequately limited, while at the same time properly accommodating all the necessary components.

It is a further object of the present invention to provide an antenna which is designed in a manner such that it can be contained in packages of limited sizes.

Said objects are achieved by the present invention through an antenna incorporating the features set out in the appended claims, which are intended as an integral part of the present description.

Further objects, features and advantages of the present invention will become apparent from the following detailed description and from the annexed drawings, which are supplied by way of non-limiting example, wherein:

Figs, la and lb show a first and a second perspective views, respectively, of an antenna according to the present invention;

Figs. 2a and 2b show a first and a second perspective views, respectively, of a detail of the antenna according to the present invention;

Figs. 3a and 3b show a first and a second side views, respectively, of a detail of the antenna according to the present invention.

Said description and said drawings are to be considered as non-limiting examples.

Referring now to the drawings, in Figs, la and lb reference numeral 1 designates as a whole an antenna according to the present invention.

The antenna 1 is designed to receive and transmit an electromagnetic field, in particular a radio signal.

The antenna 1 comprises a support element 2, which in the example of Figs, la and lb is a rod (known in the art as "cradle" or "boom"); preferably, said support element 2 has a fitting 3 through which it can be mounted to a pole 4.

In addition, said antenna 1 comprises a first reflector 10, in particular for the UHF band, mounted on said support element 2 and having a structure which comprises at least one grid 11;

Preferably, said at least one grid 11 comprises two grids 11 arranged on opposite sides of the support element 2. In the example of Figs, la and lb, said two grids 11 of the first reflector 10 are arranged on opposite sides of the support element 2 in a manner such as to correspond to the faces of a dihedral, i.e. so that each grid 11 forms an acute angle with the support element 2. As an alternative, it is clear that the two grids 11 of the first reflector 10 may be arranged on opposite sides of the support element 2 in a manner such as to lie in a single plane orthogonal to the latter.

Preferably, the grids 11 are associated with the support element 2 through a connecting element 20 having suitable slots 21 adapted to accommodate the grids 11. In addition, in a preferred embodiment said grids 11 are metallic ones.

The antenna 1 comprises means adapted to receive and transmit said electromagnetic field, in particular at least one radiator R and/or a plurality of directors D.

As can also be seen in Figs. 2a and 2b, said grid 11 is made up of a plurality of bars 12 mounted substantially parallel to one another on a central upright 13; preferably, the grid 11 comprises a pair of side uprights 14, the central upright 13 and the side uprights 14 being made of a metallic or dielectric material.

The number, dimensions and spacing of said bars 12 may be varied from those shown in the annexed drawings in order to improve the directionality and gain of the antenna 1; furthermore, each grid 11 may be so designed as to keep said bars 12 more or less close to one another. For example, the grid 11 may be designed in a manner such that said bars 12 are closest to one another in that portion which, when installed, is nearest to the support element 2; this has the effect of improving the forward/backward ratio of the antenna 1. The antenna 1 according to the present invention also comprises a second reflector, in particular for the VHF band.

According to the present invention, said second reflector comprises at least one support 30 and at least one rod 31, said at least one support 30 being pivoted to said at least one grid 11 in a manner such that it can rotate from a closed position to an open position, and vice versa, relative to said at least one grid 11 of the first reflector 10.

In particular, in the closed position (shown in Figs, la, 2a and 3a) said at least one support 30 lies in a position substantially parallel to said grid 11, whereas in the open position (shown in Figs, lb, 2b and 3b) said at least one support 30 is in a raised position relative to said grid 11. In particular, in said open or raised position the support 30 is substantially perpendicular to said grid 11.

The fact that the antenna 1 according to the present invention includes a second reflector, in particular for the VHF band, which comprises at least one support 30 pivoted to the grid 11 and which is adapted to switch from a closed position to an open position and vice versa, allows to adequately limit the overall dimensions of the antenna 1 ; at the same time, such a design allows all the components of the antenna 1 to be properly accommodated without having to increase the length of the support element 2.

Additionally, the fact that the support 30 is pivoted to said grid 11 so that it can rotate from a closed position to an open position (and vice versa) allows the antenna 1 to be designed in a manner such as to allow for easy and comfortable packaging and installation thereof; in addition, such a design ensures a proper operation of the whole antenna 1 according to the present invention.

In a preferred embodiment, said second reflector comprises a first and a second pairs of supports 30 associated with each grid 11 of the antenna 1, each pair of supports 30 being associated with at least one rod 31.

Figs. 3a and 3b show a side view of a support 30 in said closed position and in said open position, respectively.

In these drawings, it can be observed that the support 30 according to the present invention substantially has an "L" shape and comprises a first portion 30 A and a second portion 30B joined together.

Besides, the support 30 is associated with a bar 12 of said grid 11 and comprises a seat 32 adapted to house the bar 12, so that it can rotate about said bar 12 and switch from said closed position to said open position relative to the grid 11. In particular, in Figs. 3a and 3b said seat 32 is represented as a circular hole and is located substantially halfway along the second portion 30B of the support 30; however, it is clear that the seat 32 may also be designed differently from the one shown in such drawings.

The support 30 also comprises a housing 33 adapted to house said at least one rod 31; in Figs. 3a and 3b said housing 33 is represented as a circular hole and is substantially located at the free end of the first portion 30A of the support 30. As regards the housing 33 as well, it is apparent that it may also be designed and positioned differently from the one shown in Figs. 3a and 3b. For example, the support 30 may be so designed as to comprise a plurality of housings 33 (not shown in the drawings), each housing 33 being adapted to house one rod 31; in particular, this may be useful when the second reflector comprises a plurality of rods 31.

The support 30 comprises a section 30C of the first portion 30A which is substantially in contact with at least one bar 12 when said support 30 is in said closed position; Fig. 3a shows the contact between three bars 12 and said section 30C. The support 30 also comprises a recess 34 adapted to accommodate a bar 12 when the support 30 is in said open position (as shown in Fig. 3b); preferably, said recess 34 is substantially located at the free end of the second portion 3 OB of the support 30.

In addition, at least one elastic element 35 is associated with said recess 34 for allowing the bar 12 to enter and snap into the recess 34.

The provision of the recess 34 and of said at least one elastic element 35 is particularly advantageous in that it allows the user to rapidly and easily assemble the second reflector and firmly secure it to the first reflector 10. As a matter of fact, in order to bring said second reflector into the open position it is sufficient to rotate the supports 30 and the respective rod 31 about the bar 12 until a further bar 12 snaps into the recess 34. In particular, said further bar 12 snapping into the recess 34 is the one contiguous to the bar 12 housed in the seat 32, about which the support 30 rotates.

The support 30 may then comprise a plurality of apertures 36 adapted to lighten the structure of said support 30.

The features and advantages of the antenna according to the present invention are apparent from the above description.

In particular, the fact that the support 30 is pivoted to the grids 11 of the first reflector 10, so that it can rotate from a closed position to an open position and vice versa, allows for easy and comfortable packaging and installation of the antenna 1, and even improves the operation of said antenna 1.

Another advantage is that the particular design of the antenna 1 according to the present invention allows to adequately limit the overall dimensions of said antenna 1 while at the same time properly accommodating all the components thereof.

It is however clear that many changes may be made to the antenna according to the present invention, and that in its practical implementation the various components may have different shapes and arrangements or be replaced with other technically equivalent elements without departing from the novelty spirit of the inventive idea.

It can therefore be easily understood that the present invention is not limited to the above- described antenna, but may be subject to many modifications, improvements or replacements of equivalent parts and elements without departing from the inventive idea, as clearly specified in the following claims.

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