DE20220086U1 - Broadband crossed dipole antenna has bent sheet metal construction - Google Patents

Abstract

A broadband crossed dipole antenna (10) has three dimensional bent sheet metal outline cross radiator (11) and ground plane (13) with polarisation selecting feed lines (12.1,2).

Description

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Huber+Suhner AG, CH-9100 Herisau, Switzerland

H2406G-DE Germany

Broadband antenna with a 3-dimensional sheet metal part

[001] The present invention relates to antennas having a

Radiating element that can be arranged in front of a reflector surface.

[002] Crossed dipole antennas for generating linear or circular

Polarizations are known. A crossed dipole antenna is known from the article "A wide-band aerial system for circularly polarized waves, suitable for ionospheric research", GJ. Phillips, IEE Proc, Vol. 98 III, 1951, pp. 237 - 239. Turnstile antennas are described in various US patents. An example is shown in US patent US 2,086,976 from 1935. The antenna shown comprises a mast on which several crossed antennas are arranged. There are also numerous textbooks that deal with turnstile antennas.

[003] To improve the directivity, the antenna elements

often arranged in front of a metallic reflector surface. This approach is well known and is used in the following two antennas. A dual-polarized dipole antenna can be found in US patent US 6,313,809 (essentially corresponds to the German laid-open specification DE 198 60 121 Al) from the company Kathrein. This dipole antenna is characterized by the fact that it consists of a number of individual dipole elements that are arranged in front of a reflector

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The dipole elements are arranged as a dipole square in plan view and each dipole element is fed individually via a symmetrical line.

[004] A dual polarized multi-range dipole antenna is available from the US

Patent US 6,333,720 of the company Kathrein.

[005] The bandwidth of a dipole antenna can be improved by

thick dipoles or so-called bow-tie dipole structures are used. Such a broadband dipole antenna is known from the article "Broadband half-wave dipole", M.C. Bailey, IEEE Trans. Antennas Prop., Vol. 32, 1984, pp. 410 - 412. A broadband antenna with a thick dipole structure is mentioned in the Antenna Engineering Handbook, R.C. Johnson and H. Jasik, editors, 2nd edition, McGraw Hill, 1984, on pp. 28-11.

[006] It is a problem of the known antenna arrangements, which in

The problem with the use of antennas in the field of communication, and in particular mobile communications, is that the antennas are expensive and heavy. This leads to expensive and complicated array antennas.

[007] Based on the above-mentioned prior art,

The task was to create a broadband dipole antenna that is simple and cost-effective.

[008] It is a further object of the invention to provide a dipole antenna

which is suitable for installation in a group antenna.

[009] According to the invention, an antenna with a radiating element is provided

which is arranged in front of a conductive reflector and comprises a three-dimensional sheet metal part. The sheet metal part has at least two planes of symmetry, is conductive and has a closed circumferential structure with alternating constrictions and bulges. The circumferential structure preferably spans an imaginary surface which is intersected by the planes of symmetry of the sheet metal part.

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at least two fastening elements are present which extend essentially perpendicular to the surface of the conductive reflector and support the peripheral structure at two support points - which preferably but not necessarily lie on intersection lines of the planes of symmetry with the imaginary surface. The at least two fastening elements run essentially parallel to one another and lie in the cylinder surface of an imaginary cylinder, the cylinder's longitudinal axis is perpendicular to the surface of the conductive reflector. The said planes of symmetry intersect one another in a common intersection line which coincides with the cylinder's longitudinal axis.

[0010] Preferably, the fastening elements are arranged symmetrically in

With respect to the planes of symmetry, or in the limiting case in the planes of symmetry. At their (lower) ends, the fastening elements are connected to the conductive reflector, with at least one of the fastening elements serving to electrically excite the radiating element.

[0011] Further embodiments of the invention are described in

dependent protection claims 2 to 9.

[0012] According to the invention, a group antenna with several

Beam elements are provided as claimed in claim 10. Further embodiments according to the invention can be found in the dependent claims 11 and 12.

[0013] The invention is described below with reference to the drawings

illustrated embodiments are described in detail. Symmetry planes are indicated in the drawings by dashed lines and imaginary surfaces by dotted lines where this is necessary for a clearer representation of the invention. They show:

Fig. 1A shows an antenna according to the invention in a schematic view; Fig. 1B shows the antenna according to Fig. 1A in a second schematic view; Fig. 2A shows an antenna according to the invention in a perspective view;

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Fig. 2B shows the antenna according to Fig. 2A in a second perspective view;

Fig. 2C a component of the antenna according to Fig. 2A in a top view; Fig. 3A-3F various regular orbital structures according to the invention; Fig. 4A-4B various irregular orbital structures according to the invention; Fig. 5 a group antenna according to the invention in a schematic

Top view.

Detailed description:

[0014] In the following, terms are explained and defined which are used in the

Description and protection claims appear several times.

[0015] The following text refers to sheet metal parts. According to the invention

The term sheet metal part refers to molded parts that have been manufactured using an automatic, semi-automatic or manual bending process. Preferably, sheets or sheet-like materials are processed that can be processed and bent in a controlled manner.

[0016] According to the invention, various metal sheets (for

For example, brass or copper) can be used to produce a sheet metal part that, through appropriate bending/folding, produces the desired three-dimensional structure.

[0017] The sheet metal parts can be produced by punching, laser processing,

Plasma and water jet cutting or a combined punching and laser beam process.

[0018] Sheet metal parts can also be used which have one or more

contain metals.

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[0019] The three-dimensional sheet metal parts are characterized by the fact that

only a few production steps and little post-processing is required. In addition, the dimensions of the sheet metal parts are precise.

[0020] Reflectors can be used, which preferably have a

conductive surface. This conductive surface can be connected to ground. The reflector surface can be flat or curved.

[0021] A first antenna 10 according to the invention is shown in Figures IA and

IB. An antenna 10 according to the invention comprises a three-dimensional radiating element which is arranged in front of a conductive reflector 13. The radiating element is a sheet metal part. The sheet metal part is conductive. It can optionally be provided with a non-conductive layer which covers the sheet metal part completely or partially.

[0022] The sheet metal part comprises a closed circulation structure 11 with

alternating constrictions and bulges. In the example shown, the orbital structure 11 has the shape of a cross that spans an imaginary surface 14 that is intersected by at least two planes of symmetry. The planes of symmetry intersect the imaginary surface 14 and thus form intersection lines 15.1 and 15.3, as shown in Fig. IB using dashed lines. In addition to the two intersection lines 15.1 and 15.3, the actual orbital structure 11 also has two axes of symmetry, which are designated 15.2 and 15.4 in Fig. IB.

[0023] There are at least two fastening elements 12.1, 12.2

which extend essentially perpendicular to the surface of the conductive reflector 13. The fastening elements 12.1, 12.2 are connected to the circumferential structure 11 at two support points - which in the embodiment shown lie on the intersection line 15.1. The at least two fastening elements 12.1, 12.2 run essentially parallel to one another and lie in the cylinder surface of an imaginary cylinder 9, the cylinder longitudinal axis 8 of which is perpendicular to the surface of the conductive reflector 13.

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The mentioned symmetry planes 15.1 and 15.3 intersect each other in a common intersection line which coincides with the cylinder longitudinal axis 8.

[0024] As mentioned, the fastening elements 12.1, 12.2 are attached to two

Support points that lie on the intersection line 15.1 are connected to the rotating structure 11 and support the rotating structure 11. At their other ends 16, the fastening elements 12.1, 12.2 are connected to the reflector 13. In addition to the supporting function, at least one of the fastening elements 12.1, 12.2 serves to electrically excite the beam element.

[0025] Overall, the beam element has a mushroom-like shape, in which

the surface 14 spanned by the circumferential structure 11 forms the mushroom cap and the imaginary cylinder 9 forms the foot of the mushroom. The comparison of the beam element with a mushroom-like shape serves only to better illustrate the invention.

[0026] Particularly suitable are fastening elements that have a

columnar structure. Preferably, the fastening elements are an integral part of the circumferential structure 11.

[0027] A second antenna 20 according to the invention is shown in Figures 2A and

2B. An antenna 20 according to the invention comprises a three-dimensional beam element that can be arranged in front of a conductive reflector. The beam element is a sheet metal part. The sheet metal part is conductive. It is made from four identical components 21. Such a component 21 is shown in Fig. 2C. The components 21 are made from sheet metal, for example by means of punching. In a subsequent processing step, the components 21 are bent. In the embodiment shown, some of the elements of the component 21 are bent by 90 degrees. Other parts, however, are only bent by 45 degrees. The lines along which the bending takes place are shown as dashed lines. After assembly, a three-dimensional bleached part with a total of four planes of symmetry is obtained.

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[0028] The elements 22 each form one half of a

Fastening element. The two elements 22 of two adjacent components form a fastening element.

[0029] After bending the components 21, they are assembled

joined. In order to connect the components 21 to one another, they can be spot welded at the points marked in black, for example. However, the components 21 can also be connected to one another by soldering, gluing, screwing, riveting or using other joining techniques.

[0030] As can be seen from Figures 2A to 2C, the

Beam element in the assembled state made of a three-dimensional sheet metal part. The sheet metal part comprises a circumferential structure 23 and, in the example shown, four fastening elements 22.

[0031] In a preferred embodiment, the

Fastening elements at the bottom end have fastening means that allow the peripheral structure including the fastening elements to be attached to the reflector. For this purpose, the fastening elements can be provided with a snap mechanism or a plug connection, for example, which allows the fastening elements to be inserted into holes in the reflector and locked into place. Instead of a snap connection, screw, solder or other connections can also be provided. Connections that create an electrically conductive connection in addition to a mechanical connection are ideal.

[0032] Some of the antennas according to the invention are characterized in that

that the imaginary surface spanned by the orbiting structure extends essentially parallel to the reflector. The imaginary surface can be flat or curved.

[0033] The reflector may be slightly curved.

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[0034] Depending on the control of the beam element according to the invention

Different polarizations can be achieved, for example horizontal, vertical, circular or elliptical.

[0035] The control of the beam element can be done via a

supply circuit, for example (combination) networks and delay lines. The supply circuit can be designed in such a way that it generates up to four different control signals from one signal for controlling the radiating element.

[0036] According to the invention, the circulation structure can have any shape

which meets the following conditions:

- The circumferential structure is a closed circumferential structure with alternating constrictions and bulges. The circumferential structure spans an imaginary surface that is cut by at least two planes of symmetry of the sheet metal part. The planes of symmetry intersect in a common intersection line that runs approximately perpendicular to the reflector.

[0037] A particularly advantageous embodiment of the circulation structure has

four wing elements that are arranged symmetrically. If the furthest apart points (bulges) of the orbital structure are about half a wavelength apart, it acts like two crossed dipole elements. Preferably, the two planes of symmetry of the sheet metal part are perpendicular to each other.

[0038] Each dipole element of the crossed dipole antenna is preferably

fed symmetrically.

[0039] Various regular circulation structures are shown in Figures 3A

to 3D are schematically indicated, although it should be noted that there are numerous other shapes that are also suitable as orbital structures. These regular orbital structures have four planes of symmetry.

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[0040] Further circulation structures according to the invention, now with three

Planes of symmetry are shown in Fig. 3E and 3F. The orbital structure of Fig. 3E has three wing elements, each of which is rotated by 120° relative to one another. If signals of the same amplitude and with a phase shift of 0°, 120° and 240° are fed into the three constrictions, circularly polarized radiation is obtained to the right or left. Fig. 3F shows an orbital structure that is also suitable for generating circularly polarized radiation.

[0041] Various irregular orbital structures are shown in Figures

4A and 4B are indicated schematically. These irregular circular structures have at least two planes of symmetry. A further advantageous application of the circular structures in Figures 4A and 4B is the simplified generation of circular polarization by applying antiphase feed signals to two opposing constrictions.

[0042] Preferably, the circulation structure is designed so that

Wing elements are present which result in at least one resonance circuit which is loaded by the radiation.

[0043] The fastening elements are preferably designed so that

Transformers result from the excitation impedances to the resonator impedances.

[0044] According to the invention, the radiation characteristic is essentially

determined by the distance of the beam element from the reflector. The distance of the beam element from the reflector is preferably between 1/10 and 1/3 of the emitted wavelength in air.

[0045] According to the invention, a metallic shielding arrangement

which is completely, partially or not at all connected to the conductive reflector surface. The shield arrangement preferably has the same planes of symmetry as the radiating element it surrounds. It can be in one piece or, taking the planes of symmetry into account, can be constructed from a corresponding number of individual elements. A particularly

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An advantageous arrangement consists of a surrounding electrically conductive wall which, depending on the desired beam bundling, ends below or above the point of the beam element furthest away from the reflector surface. The shield arrangement can also be used to reduce the mutual coupling between adjacent beam elements in a group antenna.

[0046] A group antenna according to the invention is characterized in that

that several antennas are arranged in rows and columns. An example group antenna 70 is shown in Fig. 5. The group antenna 70 comprises two columns with three antennas 71 each. In the example shown, the beam elements of the antennas 71 are arranged rotated by 45 degrees. However, the beam elements can also have any other orientation. In addition, it may be necessary or useful to choose a different horizontal distance between the individual antennas than the vertical distance. A reflector surface 73 is arranged behind the steel elements. There is a supply matrix (not visible in Fig. 5) which allows the antennas to be grouped together in rows and/or columns. Each antenna 71 preferably comprises a beam element and an individual supply circuit. The supply matrix then establishes the necessary connections between the overall inputs of the group antenna and the feed inputs of the supply circuits. In the example shown, the supply matrix, the supply circuit and the feed signal are designed to result in a linear polarization in the vertical direction, as indicated by the ε-fields.

[0047] The antennas described and shown are particularly suitable

for operation in the gigahertz frequency range, with the feed inputs being fed with signals that have a center frequency greater than 1 GHz. The antennas are particularly suitable for mobile radio and other communication systems.

[0048] It is an advantage of the invention that the beam elements are relatively

are easy to manufacture, while maintaining good shape accuracy.

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The described embodiments of the sheet metal part forming the beam element enable the mirror symmetries necessary to achieve cross-polarization decoupling to be maintained, even though the beam element is composed of several (preferably identical) parts.

Claims (12)

1. Antenna ( 10 ; 20 ; 70 ) with a radiating element which is designed to be arranged in front of a conductive reflector ( 13 ; 73 ), characterized in that the radiating element comprises a three-dimensional sheet metal part, - which has at least two planes of symmetry ( 15.1 , 15.3 ), - which has a closed peripheral structure ( 11 ; 23 ; 71 ) with alternating constrictions and bulges, wherein the peripheral structure ( 11 ; 23 ; 71 ) spans an imaginary surface ( 14 ) which is intersected by the at least two planes of symmetry ( 15.1 , 15.3 ), and - which has at least two fastening elements ( 12.1 to 12.4 ) which extend substantially perpendicular to the imaginary surface ( 14 ) and support the circumferential structure ( 11 ; 23 ; 71 ) at points which lie on at least one of the planes of symmetry ( 15.1 , 15.3 ) and can be connected to the reflector ( 13 ) at the ends ( 16 ), wherein at least one of the two fastening elements ( 12.1 , 12.2 ) serves to electrically excite the beam element. 2. Antenna according to claim 1, characterized in that the reflector ( 13 ; 73 ) comprises a flat surface having a conductive side (17.2) facing the sheet metal part. 3. Antenna according to claim 1 or 2, characterized in that the imaginary surface ( 14 ) spanned by the circumferential structure ( 11 ; 23 ; 71 ) extends substantially parallel to the reflector ( 13 ; 73 ). 4. Antenna according to claim 1 or 2, characterized in that the imaginary surface ( 14 ) spanned by the circumferential structure ( 11 ; 23 ; 71 ) is flat or curved. 5. Antenna according to one of the preceding claims, characterized in that the sheet metal part was produced by punching, laser beam processing, plasma and water jet cutting or by a combined punching-laser beam process. 6. Antenna according to claim 5, characterized in that the sheet metal part was brought into the three-dimensional shape by bending. 7. Antenna according to one of claims 1 to 6, characterized in that the sheet metal part comprises aluminum or copper. 8. Antenna according to one of claims 1 to 6, characterized in that a supply circuit is provided which is designed such that, depending on the supply, the polarization of the signals emitted by the radiating element can be influenced. 9. Antenna according to one of the preceding claims, characterized in that the sheet metal part is surrounded by a shield arrangement, which is preferably metallized. 10. Group antenna with several antennas according to one of the preceding claims, characterized in that the antennas are arranged in rows and columns and preferably a supply matrix is present by which the antennas can be combined row by row and/or column. 11. Group antenna according to claim 10, characterized in that each of the antennas has a supply circuit with feed inputs. 12. Group antenna according to claim 11, characterized in that connections between total inputs of the group antenna and the feed inputs of the supply circuits can be established by the supply matrix.