EP1689022A1 - Basestation antenna - Google Patents

Abstract

The antenna has a reflector and a set of transmitters are arranged before the reflector. A radome surrounds the transmitters and the reflector and has front and back sides and side wall sections. Another reflector is arranged behind the former reflector. The latter reflector has a conducting surface structure that is introduced and/or arranged in a rear wall of the radome, where the structure is provided with non-conducting sections.

Description

The invention relates to a mobile radio antenna according to the preamble of claim 1.

Cellular antennas for base stations usually have a vertically extending conductive reflector, which may optionally be provided with extending in the longitudinal or vertical direction and offset from the center outwardly webs, edge boundaries, etc., which extend perpendicular to the reflector plane or at an angle thereto. In front of the reflector a plurality of vertically offset radiators, radiator elements or radiator groups are arranged, which can radiate and / or receive, for example, in a polarization or in two mutually perpendicular polarizations.

Frequently, the dual-polarized emitters are aligned at an angle of + 45 ° and -45 ° relative to the vertical (or horizontal), which is why we also speak of X-polarization emitters.

The radiators, radiator elements and radiator groups can be arranged side by side in one or more columns. However, such antenna arrays, which have several columns next to one another, generally also have a common reflector or a common reflector plate.

As radiator elements, all conceivable radiators come into consideration, for example, single-polarized or dual-polarized radiator, dipole radiator or dipole radiators, patch radiators, etc. With regard to the various radiator types used, reference is made, by way of example only, to the following prior publications, namely DE 197 22 742 A1, DE 196 27 015 A1, US 5,710,569, WO 00/39894 or DE 101 50 150 A1.

Such antenna arrangements are usually housed in a radome, which serves to protect the radiator from the weather. The radome itself is permeable to electromagnetic waves and usually consists of a glass fiber reinforced plastic.

Although cellular antennas may be constructed such that the casing-like radome is comprised of a cup-shaped front surface which is mountable to the antennas and to the bottom plate covering the reflector, a circumferentially closed radome is often used which is open at its opposite end faces and there can be closed by placing made of fiberglass reinforced plastic existing or, for example, metal end caps. At the bottom cap are still the corresponding electrical connections for the Supply lines and other measures, for example, to adjust the downtilt angle, etc. provided. These electrical connections can also be provided on the back of the radome (that is, at the rear of the radome). Finally, also appropriate holding and fixing devices are provided, about which the entire antenna is held and fixed, for example, on a mast. These holding and fixing devices are generally provided on the respective supporting parts of the construction, for example on the reflector, on the radome itself, etc.

It is known that mobile radio antennas are usually designed for radiation only in a specific sector, for example, for a sector of 120 °, ± 30 ° or 180 ° ± 30 ° etc. Therefore, a high return loss is often desired, the larger than 20 dB, often even greater than 25 dB or even greater than 30 dB.

In order to achieve a better return damping, the radome already accommodates a mobile radio antenna (with the entire antenna device including the reflector and the radiator, radiator elements or radiator groups built thereon in the radome enclosed in the circumferential direction) at a distance behind the rear side of the radome to attach additional metal sheet. As a result, a "double reflector" is formed as it were, whereby the rear damping is improved.

Finally, it has also been tried not to mount this second reflector at a distance behind the radome separately, but to install on the rear side of the radome itself or on the inside of the radome with.

An antenna subassembly basically using three reflectors arranged at a distance one behind the other, with respective lateral boundaries set up transversely to the reflector plane, has become known, for example, from DE 102 17 330 A1. This specific design is intended to improve the overall backward attenuation of the antenna.

The object of the present invention is to provide an improved mobile radio antenna, which is simple and efficient and has optimal electrical properties.

The object is achieved according to the features specified in claim 1. Advantageous embodiments of the invention are specified in the subclaims.

The mobile radio antenna according to the invention is characterized in that for the antenna in addition to a reflector and the front-mounted spotlights (regardless of whether it is a cover or a multi-band antenna, a simple or dual polarized antenna, etc.) to increase the rear damping double Reflector construction is used, wherein the distant from the emitters reflector remote (behind the first reflector) is not an independent construction but is provided as an integral part in the relevant wall portion of an antenna array protecting radome. In other words, during the manufacturing process, the radome is preferably incorporated into the material of the radome at the corresponding point as a flat line structure, which from the outside in the Usually not recognizable at all. The reflector itself is preferably visible from the outside only if the rear wall of the radome would be drilled out or external material layers of the radome would be removed. The radome can be made of any suitable material, which is preferably as well as possible for electromagnetic waves permeable. For example, a glass fiber reinforced plastic can be used.

Thus, such a second reflector does not need to be manufactured separately nor separately attached and mounted. He is integrated in the radome itself.

However, these large-area conductive structures can be incorporated not only on the rear wall, but also partially in the sidewall areas (which usually also vertically when installing the antenna with vertically aligned radome), whereby, for example, lateral outer webs or edge boundaries are formed they are also known from reflectors made of sheet metal separately.

The flat line structures can be made in many different ways. These sheet-like conductor structures may have, for example, a hole structure or lattice structure. They can consist of conductors extending in the longitudinal direction, but also of transverse conductor tracks, in particular if they are connected by non-conductive cable structures extending in the longitudinal direction. Restrictions on a particular structure or a specific material is not given according to the invention. When using grid or hole structures, only screen size, grid size or hole size should be used be suitably dimensioned so that it is suitable for the corresponding wavelength range of the mobile radio antenna. In other words, therefore, the hole size of such a hole or grid structure should be smaller than λ / 10, where λ represents the wavelength of the highest transmitted frequency.

In a particularly preferred form, the planar conductive structure to be incorporated can be made of metal, for example aluminum or an aluminum foil, which is already coated on both sides with paper or a material comprising paper. Such coated metal or in particular aluminum foils are available on the market and can be incorporated particularly well in the production in a radome, since the existing paper or paper outer layers of the metal foil are particularly well impregnated with resin and thus a particularly good connection such surface line structure in a plastic, in particular glass fiber reinforced plastic existing radome can be incorporated.

If a fabric structure for the second reflector is preferably used, it may be constructed from a metallically conductive woven fiber or else in the form of an absorbent conductive structure, for example using a carbon fiber. The reflector could also be referred to as "absorber".

Such a radome can also be used for omnidirectional radiators, which can be held, for example, via the end caps which are placed on the radome. As a result, by an omnidirectional a corresponding Directional radiators are generated, wherein the half-width of the antenna is determined by the size of the incorporated planar line structure in the radome and the reflector formed thereby.

Above all, however, such a radome is used to form a built-in second reflector to improve the return loss.

The radome according to the invention thus has many advantages. Compared to conventional solutions, the solution according to the invention with a built-in radome material reflector to the fact that the radome is lighter overall, the incorporated reflector is better protected and the entire radome assembly is thereby also denser (because an additional reflector, for example, not on the Inside or outside of the radome must be attached and mounted). In particular, if in the prior art such additional reflector devices were adhered to the wheel material, there was also the danger that these reflectors have been released from the wheel material again at high heat. Finally, the emergence of intermodulation products is avoided. Furthermore, the number of required components is reduced and simplifies and reduces the total assembly costs.

The radom in the further properties of the radome-changing structures are incorporated, is basically known. For example, according to US 4,467,330, it is proposed to incorporate into the radome a structure made of dielectric material. This dielectric material, which is additionally incorporated into the radome, consists of a multiplicity of annular elements which are intrinsic are closed. As a result, an inductive effect is generated, which ultimately makes it possible to produce the radome overall with a thinner material cross-section. A radome with a lenticular structure has also become known, for example, from US Pat. No. 5,103,241 A. Also, this radome is basically designed so that it is permeable to the electromagnetic radiation for the radiators sitting behind the radome. According to this prior publication, the specific characteristics of the radar antenna are to be improved by the specific lattice structure of the radome configured with a multiplicity of transmission slots.

In contrast, the present invention is concerned with providing a structure impermeable to electromagnetic radiation, and this behind an actual reflector in the sense of a second reflector integrated in the radome material.

Figur 1 :

eine perspektivische schematische Darstellung einer Mobilfunkantenne mit einem Radom, die an einem Mast befestigt ist;

Figur 2 :

eine schematische perspektivische Schnittdarstellung durch eine Antenne mit einem erfindungsgemäßen Radom mit einer in die rückwärtige Seite eingearbeiteten flächigen Leitungsstruktur;

Figur 3 :

eine entsprechende Darstellung zu Figur 2 mit einer eingearbeiteten gewebeartigen Metallfolie;

Figur 4 :

eine entsprechende Darstellung zu Figur 2 oder 3 mit einer eingearbeiteten flächigen Leitungsstruktur mit Lochraster;

Figur 5 :

eine entsprechende Darstellung mit einer eingearbeiteten flächigen Leitungsstruktur mit einem gitterförmigen Raster mit in Längs- und Querrichtung verlaufenden Gitterstäben;

Figur 6 :

eine entsprechende Darstellung mit einem in Längsrichtung verlaufenden Streifengitter als flächige Leitungsstruktur;

Figur 7 :

ein weiteres abgewandeltes Ausführungsbeispiel mit einer eher drahtgewebeförmigen Struktur mit unterschiedlichen Größen der Gitter- oder Lochöffnungen;

Figur 8 :

ein abgewandeltes Ausführungsbeispiel mit zwei in Längsrichtung verlaufenden und in Querrichtung beabstandeten separaten flächigen Leitungsstrukturen und der rückwärtigen Rand des Radoms;

Figur 9 :

ein weiteres Ausführungsbeispiel mit in Querrichtung verlaufenden flächigen Leitungsstruktur-Abschnitten, die in Längsrichtung zueinander beabstandet sind;

Figur 10 :

ein weiteres Ausführungsbeispiel, bei welchem die flächige Leitungsstruktur bis in den Seitenwandbereich unter Bildung von Seitenbegrenzungen oder Seitenstegen gebildet ist;

Figur 11 :

eine Darstellung einer Richtantenne, die aus einem Rundstrahler gebildet ist; und

Figur 12 :

eine entsprechende Darstellung einer in Vertikalrichtung polarisierten Antenne.

Further details, features and advantages of the invention will become apparent from the following with reference to drawings embodiments explained. In detail:

FIG. 1:

a perspective schematic representation of a mobile radio antenna with a radome, which is attached to a mast;

FIG. 2:

a schematic perspective sectional view through an antenna with a radome according to the invention with a machined in the rear side surface conduction structure;

FIG. 3:

a corresponding view to Figure 2 with an incorporated fabric-like metal foil;

FIG. 4:

a corresponding representation of Figure 2 or 3 with an incorporated flat line structure with breadboard;

FIG. 5:

a corresponding representation with an integrated planar line structure with a grid-shaped grid with running in the longitudinal and transverse direction bars;

FIG. 6:

a corresponding representation with a longitudinally extending strip grid as a planar line structure;

FIG. 7:

a further modified embodiment with a rather wire-mesh structure with different sizes of the grid or hole openings;

FIG. 8:

a modified embodiment with two longitudinally extending and transversely spaced separate planar line structures and the rear edge of the radome;

FIG. 9:

a further embodiment with transversely extending planar line structure sections, which are spaced apart in the longitudinal direction;

FIG. 10:

a further embodiment in which the planar line structure is formed into the side wall area to form side boundaries or side bars;

FIG. 11:

a representation of a directional antenna, which is formed from an omnidirectional; and

FIG. 12:

a corresponding representation of a vertically polarized antenna.

1 shows a schematic representation of a mobile radio antenna 1, which belongs for example to a base station. The mobile radio antenna 1 is held and adjusted via a mast 2. The mobile radio antenna 1 comprises inside a reflector 3, not yet visible in FIG. 1, in front of which, as a rule, a large number of radiators, for example dipole radiators, patch radiators, etc., are arranged offset to one another in the vertical direction.

The emitters may be any suitable emitters, emitter elements or emitter groups, as they are basically known, for example, from the prior publications DE 197 22 742 A1, DE 196 27 015 A1, US Pat. No. 5,710,569, WO 00/39894 or DE 101 50 150 A1 ,

The radiator, radiator elements or radiator groups are housed protected below a radome 5, wherein the radome 5 is usually made as a one-piece body which is closed in the circumferential direction and a rather bulbous curved front 7, side wall portions 10 and a generally rather flat back 9 includes. At the top of an upper cap 11 is placed and fastened and at the bottom of a corresponding lower end cap 13 (Figure 1). However, the lower end cap 13 often also consists of a metal flange on which the electrical connections for the radiators or other control devices located in the antenna are then provided, in order, for example, to adjust a downtilt angle differently. In Figure 1, cables 8 are shown leading to the terminals on the underside of the antenna cover. In this respect, reference is made to known solutions.

In Figure 2 is now a perspective excerpts sectional view can be seen that the mobile antenna comprises a circumferentially closed radome 5, within which a conductive reflector 3 is housed, which is usually made of metal. The reflector 3 further comprises two side wall sections or webs 3a, which also extend in the vertical direction and can be erected perpendicular thereto or at a different angle relative to the reflector plane.

Spaced in the vertical direction to each other then suitable radiators are arranged for the mobile radio range. FIG. 2 shows, in a partially perspective illustration, a dual-polarized emitter 15, which consists of a dipole square 15 'and is mounted on the reflector 3 via the associated balancing 17. The connection cables located on the back of the reflector are all not shown.

In the representation according to FIG. 2, on the inside of the rear wall 9 of the radome the upper layer 9 'is formed. has been partially omitted, so that in the rear wall or back 9 incorporated conductive structure 21 is visible, which is hereinafter also referred to partially as a planar line structure.

This planar conductor structure 21 can extend over the entire or only a part of the entire length or height of the radome in the back 9 and for example consist of a continuous closed metal layer, metal foil or a metal sheet, which incorporated in the wall of the radome in the manufacturing process of the radome is, so usually covered both on the inside of the radome and on the outside of the radome by a material layer 5 'of the radome and is not visible from the outside. In this way, a second reflector 32 is formed, which is incorporated in the rear Radomwand and spaced from the inside of the radome reflector 3 in parallel thereto, i. to be behind this.

In the embodiment shown in Figure 3, the line structure consists of a close-meshed fabric structure 21a, the lattice or fabric lines are aligned, for example, at + 45 ° or -45 ° angle with respect to the vertical and the horizontal. This fabric-like structure is conductive.

In the embodiment according to FIG. 4, a hole structure 21b is used as the line structure. It may be a metal foil or a metal sheet (as thin as possible), which is provided with a corresponding hole structure. The rows of holes do not have to run exactly in vertical or longitudinal direction, but can also be provided from one to the next row with transverse offset to the holes located in the adjacent row of holes, so that the rows of holes are aligned, for example, more angularly to the vertical or longitudinal direction of the radome, for example, in the + 45 ° or -45 ° angle the horizontal or vertical.

In the exemplary embodiment according to FIG. 5, a grid structure 21c is now used in which the grid bars extend in the horizontal or vertical direction, ie in the longitudinal or transverse direction of the radome. But here, too, the grid structure may be provided extending in another angular orientation.

In the exemplary embodiment according to FIG. 6, a line grid structure 21d is used, which may, for example, consist of a multiplicity of longitudinal wires extending parallel to one another. Furthermore, transverse connections can also be provided which extend transversely across the longitudinal wires and hold and stabilize them in their alignment during the production process. These cross-connections would then be non-conductive, for example.

In the exemplary embodiment according to FIG. 7, a wire-fabric-like planar line structure 21e is used, resulting in rows of holes having at least two hole diameters of different sizes.

Finally, it is shown with reference to FIG. 8 that the planar line structures do not have to pass through the entire width of the rear wall 9 of the radome 5, but that a plurality of planar structures 21 may also be provided which run, for example, in the longitudinal direction and with Side offset are arranged to each other.

In this case, FIG. 9 shows that the corresponding plurality of line structures can extend not only in the longitudinal direction but also, for example, in the transverse direction, and can be arranged with offset from each other in the longitudinal direction of the radome with the formation of distances 23. Thus, a second rear reflector 33 is also formed by these structures, in front of which the real reflector 3 located in the radome is arranged.

The embodiment according to FIG. 10 shows that the conductive structures can not only be incorporated in the rear wall 9 of the radome 5. In the exemplary embodiment according to FIG. 10, the conductive structure 21 is incorporated into the side wall region 10 of the radome 5 and extends there over one Partial height of the entire radome. As a result, an integrated reflector 33 is created, which is quasi likewise formed again with side wall boundaries or side wall webs 33a.

As not shown in detail in the drawings, however, for example, rectangular recesses in the conductive side wall structure which form the side wall webs 33a could also be provided in the side wall webs 33a. As a result, quasi "slots" or "windows" would be formed in the conductive side wall webs 33a serving as passive elements for beam shaping (as, for example, basically also described in the previously published EP 0 916 169 B1, the disclosure of which is fully incorporated by reference becomes). Likewise, in the side wall webs 33a but also decoupling structures or decoupling elements may be provided which are conductive. These may for example consist of peg-shaped elevations extending perpendicular to the reflector plane extending in the side wall portions 33a and thereby survive beyond the upper edge of the side wall webs over a certain extent. These decoupling elements or structures are therefore also part of the conductive structure 21. Reference is made in principle to the development of such decoupling elements to EP 1 194 982 B1, to the full extent of which disclosure is made.

In all the above-described embodiments, a second reflector has been created by the incorporation of an integrated reflector 33 in particular in the rear wall 9, possibly also up to the side wall portions 10 of the radome 5, which in addition to the arranged within the reflector, more conventional reflector 3 at a distance is provided for this purpose. This results in a double reflector structure, whereby the re-damping over conventional solutions can be significantly improved. Since the integrated reflector is incorporated into the rear wall of the radome, there is the advantage that this integrated reflector 33 is protected against environmental influences, is not visible and the entire arrangement is denser (because no separate reflector must be mounted on the rear wall, ie no further drilling, riveting, etc. are necessary). As a result, the insulating and protective effect of the radome is not adversely affected. Finally, despite the integrated reflector, only one uniformly manageable component in the form of the radome is provided.

Reference to the embodiments according to Figures 11 and 12th However, it is now also shown that, for example, an antenna arrangement in the form of an omnidirectional radiator (FIG. 11) or in the form of, for example, linearly polarized radiators (vertically polarized dipole radiators) according to FIG. 12 can be used, which interact only with a single reflector, and only the one integrated reflector 33 and no additional separately installed reflector 3 is used.

11, an omnidirectional radiator 15a has been used, for example, which penetrates the space within the radome at a distance in front of the rear wall in the longitudinal direction and is mechanically held, for example, by the upper cap 11 and the lower end cap 13 (see FIG. ,

In the embodiment according to FIG. 12, the simply polarized dipole radiators 15b used in the longitudinal or vertical direction are mounted on a hollow support and terminal strip 25, within which the connecting line to the radiators 15b can also be laid. This support bar 25 may be mounted on the inside of the rear wall 9 of the radome 5 or attached or held at a distance, for example, again on the upper cap 11 and the lower end cap 13 of the radome. Also in this embodiment, therefore, only the integrated reflector 33 and no separate reflector 3 is used.

In the embodiment of Figures 11 and 12, however, other emitters or emitter shapes are used accordingly.

The illustrated embodiments have been described for the case that the conductive structures are incorporated directly into the material of the radome. Preferably, however, a conductive structure can be used, which is coated or laminated on at least one side and preferably on both sides with paper. This offers advantages in the production of the radome because such a sheet-like line structure, which is coated on one side and preferably on both sides with paper, can be impregnated particularly well with resin. This achieves a particularly good connection to the material used for the radome.

The radome may also have a standard thickness or material thickness as in conventional radome designs. Typical wall thicknesses of the radome are for example 1.5 to 4 mm, often between 2 to 3 mm (in particular around 2.3 mm). Larger wall thicknesses at reinforcement points are common.

The material of the radome is, as mentioned, often made of fiber-reinforced plastic. Equally, however, it is also possible to use a plastic without fiber-reinforced plastic, for example unreinforced ABS.

In the illustrated embodiment, the radome is always closed in the circumferential direction (ie also on its rear side). However, if the antenna has a metallic reflector from home, the radome may need to be provided only on the front side, in other words covering the radiator elements in front of the reflector on the front side including the side areas. In such a case, electrically conductive parts may also be incorporated, ie electrically conductive planar structures, such as electrically conductive side wall portions 33a and / or other conductive structures at other locations of the radome or the Radommaterials, for example in the form of active or passive patching. Thus, an integrated on the front side of the radome above a radiator element in the material of the radome patch (ie, a corresponding conductive structure, as discussed for example with reference to the embodiments of an integrated reflector) are excited by an aperture coupling. Common here is a printed circuit that contains a feed network over a ground plane. In the ground surface is a slot (aperture), which is excited by the feed network. This slot then couples to the patch. In this type of patch supply, therefore, no galvanic connection to a patch formed as a planar conductive structure in the material of the radome patch is required.

As mentioned, simple emitters or, for example, dual-polarized emitter elements or emitter structures can be used as emitters. The antenna can be designed as a single-band, dual-band or multi-band antenna. There are no limits in any direction.

Claims (17)

Mobile radio antenna with a reflector (3), in front of which one or more radiators (15, 15 ') are arranged, and with a radome (5) surrounding the radiators (15, 15') and the reflector (3) with a front side (7 ), with side wall sections (10) and a rear side (9), and with a further reflector (33) arranged behind the reflector (3), characterized in that the further reflector (33) has a conductive surface structure (21) which in the rear wall (9) of the radome (5) is incorporated and / or is located in the rear wall (9) of the radome (5). Mobile radio antenna according to claim 1, characterized in that in addition to the rear wall (9) and on the at least two side wall portions (10) of the radome (5) a planar line structure (21) is provided or incorporated. Mobile radio antenna according to Claim 2, characterized in that the line structures or line structure sections (21) provided in the side wall section (10) form side wall sections (33a) belonging to the integrated reflector (33), which coincide with that in the rear side (7). the radome (5) incorporated reflector (33) are electrically connected and / or part of the Radom (5) integrated reflector (33) represent. Mobile radio antenna according to one of claims 1 to 3,
characterized in that the at least one planar line structure (21) is penetrated by non-conductive sections, preferably with a slot structure. Mobile radio antenna according to one of claims 1 to 4,
characterized in that the planar line structure (21) comprises branching sections and / or non-conductive sections, whereby passive beam-forming elements are formed. Mobile radio antenna according to one of claims 1 to 5,
characterized in that the at least one planar conductor structure (21) has a conductive tissue structure (21a),
in particular in the form of a wire mesh structure (21e) and / or a carbon fiber structure. Mobile radio antenna according to one of claims 1 to 6, characterized in that the at least one planar line structure (21) has a hole structure. Mobile radio antenna according to one of claims 1 to 7,
characterized in that the at least one planar line structure (21) has a grid structure. Mobile radio antenna according to one of claims 1 to 8,
characterized in that the at least one planar line structure (21) has a line grid structure. Mobile radio antenna according to one of claims 7 to 9,
characterized in that the planar line structure (21) is provided with rows of apertures extending in the longitudinal direction or in angular alignment with the longitudinal or vertical direction of the radome (5). Mobile radio antenna according to one of claims 1 to 10,
characterized in that the openings in the fabric structure (21a), the hole structure (21b), the grid structure (21c), the strip grid structure (21d) and / or the honeycomb structure (21e) is dimensioned so that the opening size or the distance between two conductive Elements is less than λ / 10, where λ is the wavelength of the largest frequency to be transmitted. Mobile radio antenna according to one of claims 1 to 11,
characterized in that the planar line structure consists of a metal foil which is laminated on at least one side and preferably on both sides with a layer consisting of paper or paper comprehensive. Mobile radio antenna according to one of claims 1 to 12,
characterized in that inside the radome (5) an omnidirectional is housed. Mobile radio antenna according to one of claims 1 to 13,
characterized in that inside the radome (5) linearly polarized radiator are housed. Mobile radio antenna according to one of claims 1 to 14,
characterized in that the radiators are held and mounted on a carrier strip (25) in the interior of the radome (5). Mobile radio antenna according to one of claims 1 to 15,
characterized in that the mobile radio antenna is a single-band, a dual-band or a multi-band antenna. Mobile radio antenna according to one of claims 1 to 16,
characterized in that the antenna is a single-polarized or dual-polarized antenna.

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