DE102009034429B4 - Flachantenne - Google Patents

Abstract

Flat antenna in the form of an antenna array with a plurality of in columns (2) and rows (4) arranged individual radiators (1), having the following features
The individual radiators (1) comprise tube radiators (9) and horn radiators (11),
The tube radiators (9) are made of dielectric material or essentially comprise dielectric material,
The dielectric constant of the tube radiators (9) is ≥ 2,
The horn radiators (11) consist of a groove horn (11 ') or comprise a groove horn (11'),
- The outer diameter of the dielectric tube radiator (9) is at least at the junction with the grooved horn (11 ') smaller than one or more grooves (13) and / or the grooves (13) surrounding webs (15), and
- The dielectric tube radiator (9) is inserted with its insertion end within the at least one groove (13) or the at least one web (15) on the Öffnungsq- or feed side (11b) of the horn (11 ') in this limited stop.

Description

The invention relates to a flat antenna, in particular as a satellite antenna for the preamble of claim 1.

Satellite dishes for receiving satellite signals are well known. Such parabolic antennas can be used, for example, to receive satellite signals in the frequency range from 10.7 to 12.75 GHz. With them, the reception of analog or digital television or radio broadcasts is possible, which are broadcast with vertical or horizontal polarization, for example in a so-called lower or upper frequency band.

It depends on the geostationary positioning of a satellite and its radiated power (EIRP) which diameter a parabolic antenna should have in order to receive a sufficiently strong antenna signal.

In addition, so-called flat antennas have become known, which also serve for the reception of satellite signals in the corresponding frequency range. Such flat antennas are often square in plan view (not round) designed and have a flat construction in side view.

An available on the market, widespread flat antenna, for example, the known under the name "Kathrein BAS 60" flat antenna. This flat antenna is constructed, for example, from 144 horns, which are arranged in an array with 12 rows and 12 columns. The single radiators are combined with a waveguide network.

Such a flat antenna without converter circuit (without LNB), for example, a dimension of 50 cm × 50 cm × 6.5 cm.

In principle, flat antennas have become known, which are constructed for example from an array with slotted waveguides. Such flat antennas are partly suitable only for reception in a polarization (corresponding to the slot alignment in the slotted waveguides). Therefore, such antennas must be rotated by 90 ° to receive the respective polarization perpendicular thereto. However, this is cumbersome for practical use.

In addition, flat antennas have become known which comprise an antenna array of printed dipole antennas. The printed dipoles can be constructed in stripline technology. The disadvantage of such planar antennas, however, is the higher loss absorption that occurs compared to a merging waveguide network. In other words, the overall efficiency of such an antenna is worse than with an antenna using a merge waveguide network.

In addition, flat antennas have become known that do not use a radiator array, but a so-called Displaced-Axis Dual Reflector antenna.

This type of antenna comprises a special sub-reflector, so that the overall antenna structure is particularly low. By a corresponding surrounding housing this antenna acts optically like a flat antenna, even if it is with approximately 14 cm (without associated converter "LNB") more than twice as thick as the above mentioned flat antenna "Kathrein BAS 60", which built up from 144 horn radiators is. The reflector of this Displaced-Axis Dual Reflector antenna generally has a diameter of about 60 cm, so that this antenna is built in total optically much larger than the aforementioned Kathrein antenna.

In addition, an antenna from the company Camos has become known, which consists internally of two arrays with slotted waveguides. The upper array is for receiving vertical polarization, whereas the lower array is for receiving horizontally polarized electromagnetic waves. A switch is used to connect the desired array to the built-in LNB (converter). This is to impractical turning of the antenna, d. H. the unwanted alignment of the antenna depending on the reception of the selected polarization omitted. However, this is done with the disadvantage that the effective area of the array - in relation to the total area of the antenna - is halved. Because it can be used to receive one or the other polarization currently only the horizontally extending slotted waveguide or vertically slotted waveguide, so that doubles the entire space thereby. Halving the effective area of the array - based on the total area - also reduces the antenna gain by 3 dB. In other words, such an antenna with a given total area requirement has a 3 dB lower antenna gain than, for example, the above-mentioned flat antenna "Kathrein BAS 60".

In order to reduce the size of the antenna with a comparatively good antenna reception in optical terms, it has also been proposed to form a planar antenna in array technology in plan view not square, but rectangular. That is, the vertical height of a such flat antenna is reduced, while the width in the horizontal direction is dimensioned so that the beam bundling is large enough to sufficiently suppress the signal reception of neighboring satellites can. However, this is only given when receiving a polarization, z. B. upon receipt of the horizontal polarized signals, since to receive the cross-polarized signals, z. B. when receiving vertically polarized signals such an antenna must be placed upright.

Against this background, it can be stated that the most varied flat antennas, as they are also available on the market, are either larger than the above mentioned. Kathrein antenna "BAS 60" or usually have a lower antenna gain, since the surface efficiency of o. G. Kathrein antenna is not exceeded. Due to the large system reserve when receiving DVB-S signals, this can be tolerated in favorable reception situations, since a trouble-free reception is possible already at a carrier-to-noise ratio of about 7 dB. However, the limits of the competing products show up at higher bad weather attenuation or in the peripheral areas of the footprints of the satellites. Even when receiving signals transmitted to the DVB-S2 standard (eg the HDTV signals), reception problems can occur, since here a minimum carrier signal to noise ratio of up to 11 dB - depending on the code rate and the modulation type of the signal - is necessary.

Individual features of the present invention are also known from the following prior art:
An antenna system with a single radiator is out of the US Pat. No. 6,094,175 A known. It comprises a corrugated horn whose webs are aligned in the radial direction, ie transversely to the longitudinal axis of the horn, so that it is not demoldable casting technology. In front of this horn then a cylinder is placed, which is provided on the opposite side to the horn with an inwardly concave projecting, ie cone-shaped reflector. The background of this design is that the electromagnetic radiation is to be reflected via the horn and the reflector so that an omnidirectional is formed. On the side opposite the horn, a radome is also placed on the cylindrical dielectric hollow body, which fulfills a purely protective function. In order to achieve a good antenna effect, it is intended to be formed on the horn and provided with the cone-shaped reflector cylinder with a dielectric wall so that it is as transparent as possible for the electromagnetic radiation, ie with a dielectric constant E of at least approximately air, ie by 1.

Supporting to such a dielectric constant by number 1, the wall thickness of the mentioned cylinder can also be made as thin as possible relative to the radiated wavelength.

An antenna array is also from the US 4 219 820 A known. It comprises a series of individual radiators, which are arranged parallel to one another, so that a total of plan view in the axial direction results in a square arrangement of in several rows and columns each provided with a horn 13 individual radiators. Each of these horn assemblies has on the input side at the horn on a substrate which is formed of a dielectric disc. From each of which a few conductive elements are provided.

In addition, the prior publications MUELLER, GE and TYRRELL, WA: "Polyrod Antennas", Bell Syst. Tech. J., 26, 1947, pp. 837-851, the DE 40 35 793 A1 as well as the DE 33 31 023 A1 it can be seen that so-called stem lamps or grooved horns can reduce the side lobes. Nevertheless, the overall structure is expansive. For example, at the DE 33 31 023 A1 further provided that the groove horn radiators used there are formed as a common structure having grooves on its transmitting and receiving side, which are surrounded by dielectric. In other words, the grooves sit inside the dielectric.

In the pre-publication DOMBEK, Karl-Peter: "Dielectric antennas of small transverse dimensions as exciters for mirror antennas" dielectric antennas are shown with small transverse dimensions as exciters for mirror antennas and described. Dielectric radiators in cylindrical form are described. This cylindrical tube radiator passes through a tubular waveguide, in which an annular gap for the adaptation of the dielectric radiator is incorporated. The dielectric tube radiators protrude in the axial direction of the waveguide both in the transmitting and in the receiving direction.

A so far identical training also describes the DE 25 49 363 A1 , Ultimately, this is not a real horn, for example in the form of a groove horn, but it is only for the dielectric radiator, a hollow line is provided, which has at least one discontinuity in cross-section before its radiant end to compensate for existing reflections as much as possible.

In contrast, it is an object of the present invention to provide a flat-building (ie no parabolic antenna) antenna, with the highest possible antenna gain is achievable and this total at not larger or preferably even smaller area size of the antenna.

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

It must be described as extremely surprising that in the context of the present invention, a flat antenna could be developed that builds much smaller in plan view than conventional, comparable antennas and thereby even about a 3dB-4dB higher antenna gain over the initially mentioned - already so far Optimum performing - Kathrein antenna "BAS 60" is achievable.

It is possible within the scope of the invention to increase the antenna gain even further by the longitudinal and transverse extension of the antenna is still slightly increased.

The advantages of the invention are made possible by using an antenna array with a plurality of individual radiators, which are each equipped with a so-called grooved horn. Grooved horns as such are known, but are generally used only for individual antennas and not for waveguide antennas with a variety of waveguides.

In addition, an improvement according to the invention is achieved in that hollow radiators or tube radiators are also used for the individual radiators, in the form of dielectric hollow radiators.

Although it has hitherto been known to use a single radiator in the form of a hollow radiator or a dielectric Stielstrahlers. An electric stalk radiator is a feed system using a dielectric taped rod, which is used, for example, for the Ka band in the center of a groove horn, ie in a frequency band of about 27 GHz to 40 GHz.

For example, from "Prof. Dipl.-Ing. Erich Pehl: Microwave Technology Volume 2: Antennas and Active Components, 2nd, revised and expanded edition, Dr. Ing. Alfred Hüthig Verlag Heidelberg, 1989, pages 71 to 74 ", the electric rod and tube emitters as known to remove. These single radiators are described as surface acoustic wave antennas. It is stated that, for example, trolitul having an epsilon value of 2.5 is suitable as the dielectric material. The rods or tubes may be provided with a round or rectangular cross-section. The excitation of the antenna can be done with a pin or dipole perpendicular to the rod axis with coaxial or waveguide power at the end of the rod. There should also be mounted a metallic reflector plate for suppressing the back radiation.

An antenna comparable in this respect is also known, for example, from US Pat DE 195 44 511 C2 known. Described is a dielectric rod antenna having a slightly tapered to the front end of the beam rod end, said dielectric rod is inserted into a dielectric sleeve.

Finally, reference is also made to the prior publication "FTZ, Telecommunications Technical Magazine, Volume 2, Issue 2, February 1949, page 33-40", from the investigation of a single waveguide with metal sheath, a dielectric tube radiator (= sheath conductor) and a dielectric Stem or rod radiator emerges. It is stated that in the case of a waveguide, a radiation pattern with a half-value width of 80 ° can be achieved, whereas in the case of a dielectric pedestal radiator, a width of 38 ° can be achieved and, using a dielectric tube radiator, a width of 28 ° can be achieved.

At the end of this publication, it is further noted that, for example, a plurality of conical stems can be combined into groups in order to achieve the sharpest possible bundling. Thus, it is stated that, for example, two stems can be arranged at a distance of 1.5 λ in order to achieve bundling in the main beam direction of 24 °, for example.

In addition, a group of four stems and a maximum of 64 stems has been examined. In the latter case, the half width was less than 0.5 °.

In the context of the invention, however, it has been shown that in the case of dielectric rod radiators, for example of polyethylene with and without tapering, the found dimensions of such radiators were very thin (for example 14 mm) and relatively long (for example 173 mm) and in connections with waveguides dimensioned for the ku band, a poor forward-to-back ratio as well as a lack of return loss resulted, why such antenna arrays proved to be unsuitable.

In contrast, it is surprising that the advantages described according to the invention can be achieved, above all, only if an antenna array with a plurality of individual radiators is used, the individual radiators each consisting of a combination of a dielectric tube radiator and a horn radiator, in particular a groove horn having at least one or more usually arranged centrally to the tube radiator Grooves. In other words, the use of mantle radiators is generally not sufficient to achieve the sufficient antenna gain. Therefore, within the scope of the invention, dielectric tube radiators are used.

The lengths of the tube radiators can be chosen quite differently. Lengths between 20 mm to 400 mm are possible. Lengths between 100 mm to 200 mm, in particular between 100 mm to 180 mm appear favorable. In particular, it has been shown that a length, for example, between 120 mm to 160 mm, in particular between 130 mm and 140 mm is particularly favorable.

Finally, in the context of the invention also proves to be an advantage (for example, compared to the described rod emitters) that can be achieved in an antenna array, which is constructed of tube radiators, a material and thus especially a weight saving. This is an advantage which is particularly evident in many individual emitters, for example in the antenna array with 64 individual emitters.

The dielectric constant of the dielectric tube radiators can be in different ranges. In the context of the invention, the value for the dielectric constant ≥ 2 should be selected. In particular, however, this value can also be above 2.5 or around 3 or higher. For example, tubular radiators made of inexpensive PVC with a corresponding dielectric constant can exist.

The invention will be explained in more detail with reference to drawings for an embodiment. In detail:

1 a schematic plan view of a flat antenna according to the invention;

2 a longitudinal axial view through a single radiator used in the invention and

3 : a spatial representation of a single radiator using a grooved horn.

In 1 For example, a plan view of a planar antenna according to the invention in the form of an antenna array using dielectric tube radiators can be seen. In the plan view according to 1 For example, 64 are single radiators 1 to see in axial plan view, in the embodiment shown in eight columns 2 and eight rows 4 are arranged. It thus results in a plan view of square overall structure. Here are in 1 in axial plan view only for the left column 2 and the top row 4 as well as the corresponding individual spotlights right below 1 located. The other individual emitters are each located at the crossing points of the lines in 1 illustrated columns and rows.

The single emitters 1 consist of dielectric tube or so-called Mantelstrahlern 9 and groove horns 11 ' ,

In 2 is in a schematic axial sectional view and in 3 in spatial reproduction a single emitter 1 represented, as mentioned, a dielectric tube radiator 9 includes, which with a horn 11 combined. In the illustrated embodiment, this horn radiator 11 from a known corn groove 11 ' , which in spatial representation according to 2 one with the mentioned grooves 13 equipped funnel-shaped extended receiving side 11b having. It can be seen that the pipe or shell section 9 ' of the dielectric tube radiator 9 on the receiving side 11b on the groove horn 11 ' is placed, ie in the funnel-shaped expanding receiving side 11b of the grooved horn 11 ' is used (limited stop is used). In the embodiment shown, the groove horn 11 with two concentric grooves 13 fitted. These concentric with each other, with the opening side towards increasingly larger radius arranged grooves 13 are part of the Horn Wall 11a where each groove 13 with larger diameter of the opening side 11b the horn radiator 11 closer. The height of the individual grooves can vary in certain areas, so be different.

In other words, so is the tube emitter 9 with its radiator end 9a on the funnel-shaped expanding entrance side of the horn 11 on or inserted, wherein the pipe or shell section 9 ' of the tube heater 9 at the funnel-shaped extended entrance side 11b the horn radiator 11 at a section 111 ends or attaches, within the grooves 13 lies. In other words, the grooves surround 13 with the intervening, the grooves 13 separating webs 15 the tube heater 9 , Through this overall structure with the mentioned dielectric tube radiator 9 and the groove horn 11 ' becomes the mentioned single radiator 1 formed in which the dielectric tube radiator 9 on the feed side of the preferred in the form of a grooved horn 11 ' formed horn radiator 11 is used.

The insertion depth of the emitter end 9a in the funnel-shaped opening-receiving side 11b of the grooved horn 11 ' can be different. It is possible, for example, that the dielectric tube radiator 9 with about 5% to 25% to a total length, in particular with 10% to 20% of its total axial length, in the funnel-shaped enlarged opening or reception area 11b of the grooved horn 11 dips.

The length of the cylindrical tube radiator 9 excluding the patch Groove horn, for example, between 30 mm to 400 mm, in particular between 40 mm to 200 mm or 50 mm to 180 mm vary. Overall lengths of 60 mm to 160 mm, 70 mm to 150 mm and in particular 80 mm to 140 mm are sufficient and inexpensive. An optimal range is between 90 mm and 135 mm.

The radial distance between the individual radiators 1 to each other ultimately results from the maximum diameter of the dielectric tube radiator 9 attached or integrally connected with these Rillenhörner 11 ' , The diameter of such a compact grooved horn which proves to be favorable may, for example, be 35 mm to 45 mm, in particular 39 mm to 41 mm, ie vary by 39.8 mm to 40.2 mm. A diameter value of 39.8 mm corresponds to an axial distance (from axial axis to axial axis) to the respective adjacent individual radiator, which at an adjacent place in the same row 4 or in the same column 2 of about 1.55 times the free space wavelength at a transmitter frequency of 11.7 GHz, for example, if this is the middle of the relevant transmission range (frequency band). Thus, this value is at the theoretical optimum of 1.5 times the mean free space wavelength of the associated operating frequency (ie the associated frequency band). But even larger distances of over 39.8 mm prove to be still cheap.

As a dielectric material for the tube radiator 9 For example, PVC is suitable. In general, materials are considered whose dielectric constant is greater than 2, in particular greater than 2.5 or greater than or equal to 3. The material wall thickness of the tube radiator 9 can vary, for example, between 1.4 mm and 1.6 mm, with a wall thickness of 1.5 mm has proved favorable when using PVC.

For example, a flat antenna constructed in this way gives a size in the longitudinal and in the width direction (ie, a size across all the columns and rows of the array) of 50 cm × 50 cm. The height can be only 20 cm. This height thus depends on the axial length of the tube radiator 9 including the attached grooved horns 11 ' from. Accordingly, the axial height of the planar antenna thus formed is larger or smaller. It can be between 6 cm and 45 cm, in particular between 7 cm and 25 cm, 8 cm and 23 cm, 9 cm and 21 cm, 10 cm and 20 cm, 11 cm and 19 cm and in particular 12 cm and 18.5 cm ,

With an antenna array comprising 64 individual radiators, it is possible, for example, to achieve a 3 dB to 4 dB higher antenna gain compared to the Kathrein antenna "BAS 60" which has already been shown to be at an optimum.

Within the scope of the invention, however, other array forms with more or fewer individual emitters would also be possible.

It would also be conceivable, for example, an antenna array using 49 individual emitters, which are arranged side by side sitting in 7 rows and 7 columns. This would, for example, result in a reduction of the edge length from 32 cm to 28 cm, which should result in an antenna gain of about 34 dB to 35 dBi. Would a corresponding antenna array, for example, 36 inventively constructed individual radiators 1 produced, for example, would give an edge length of 24 cm and an antenna gain of about 33 dB to 34 dBi. Ie. with an edge length halved compared to the Kathrein BAS-60 antenna or with only a quarter of the surface of the Kathrein BAS-60 antenna, this would result in an antenna gain comparable to the antenna gain of the Kathrein BAS-60 antenna.

Finally, additional information for implementing the invention will be given.

The grooved horn described 11 may for example consist of conductive material (metal), ie at least conductive metal according to the penetration depth of the microwaves. That is, the material for the grooved horn 11 ' may also be formed of plastic, which may be, for example, galvano-plastic coated with a conductive layer. In addition, the corrugated horn, for example, can also be milled from a metal block or manufactured in a die-casting process. Thus, in particular, a grooved horn, which is milled from aluminum. Likewise, it may be made, for example, in an aluminum or zinc die-casting process. In principle, however, another dielectric grooved horn could also be used. There are no compelling restrictions.

The described dielectric tube of the tube radiator 9 should have a suitable length. This length may for example be between 100 mm and 180 mm. Values between 110 mm and 170 mm, in particular 120 mm and 160 mm, for example by 135 mm are suitable. Also, the outer diameter may vary in the corresponding areas, for example between 20 mm to 40 mm, in particular between 25 mm to 32 mm, in particular between 26 mm to 30 mm. Values between 27 mm to 29 mm, in particular around 28 mm are suitable. A suitable wall thickness of the tube radiator can be, for example, between 1 mm to 2 mm, in particular between 1.4 mm to 1.6 mm, preferably around 1.5 mm.

The grooved horn used 11 ' may for example have a length of 30 mm to 50 mm, for example between 35 mm to 45 mm, in particular between 35 mm to 42 mm. For the following OMT (Orthomodemkoppler) comes, for example, a length between 25 mm to 50 mm, in particular between 30 mm to 35 mm into consideration. Taking into account the dielectric tube, the grooved horn and the OMT, an overall length of, for example, 160 mm to 230 mm, in particular between 190 mm to 200 mm, can result. Other intermediate values are just as conceivable. Regarding the groove horn 11 ' may be noted that the depth of the grooves of the grooved horn, for example, 4 mm to 10 mm, in particular 5 mm to 9 mm, especially 6 mm to 8 mm, ie in particular may be 7 mm. The width may, for example, vary between 1.4 mm to 2 mm, in particular 1.5 mm to 1.9 mm, in particular 1.6 mm to 1.8 mm, preferably by 1.7 mm. The webs between the grooves may, for example, be between 0.5 mm to 1.1 mm wide, that is, for example between 0.6 mm and 1.0 mm, in particular between 0.7 mm and 0.9 mm, in particular around 0, 98 mm.

A favorable outer diameter for the grooved horn may for example be between 35 mm to 45 mm, in particular between 37 mm and 43 mm, especially between 39 mm and 41 mm. By contrast, the inner diameter can be smaller, for example, by a value of 0.5 mm to 1.2 mm, that is to say in particular by 0.6 mm to 1.1 mm or in particular by 0.7 mm to 1.0 mm, in particular by 0 , 8 mm to 0.9 mm lower.

Claims (9)

Flat antenna in the form of an antenna array with a plurality of in columns ( 2 ) and rows ( 4 ) arranged individual radiators ( 1 ), with the following features - the individual emitters ( 1 ) comprise tube radiators ( 9 ) and horns ( 11 ), - the tube radiators ( 9 ) consist of dielectric material or essentially comprise dielectric material, - the dielectric constant of the tube radiators ( 9 ) is ≥ 2, - the horns ( 11 ) consist of a grooved horn ( 11 ' ) or include a grooved horn ( 11 ' ), - the outer diameter of the dielectric tube radiator ( 9 ) is at least at the junction with the grooved horn ( 11 ' ) smaller than one or more grooves ( 13 ) and / or the grooves ( 13 ) surrounding webs ( 15 ), and - the dielectric tube radiator ( 9 ) is with its insertion end within the at least one groove ( 13 ) or the at least one bridge ( 15 ) at the opening or infeed side ( 11b ) of the horn ( 11 ' ) used in this limited stop. Flat antenna according to claim 1, characterized in that the dielectric constant of the tube radiators ( 9 ) ≥ 2.5 and preferably ≥ 3. Flat antenna according to claim 1 or 2, characterized in that the tube radiators ( 9 ) consist of PVC or polyethylene or comprise such a material. Flat antenna according to one of claims 1 to 3, characterized in that the maximum diameter of the grooved horn varies between 3 cm to 5 cm, in particular between 3.5 cm to 4.5 cm, preferably between 3.8 cm to 4.2 cm, and preferably 4.0 cm. Flat antenna according to one of claims 1 to 4, characterized in that the length of the cylindrical tube radiator ( 9 ) between 30 mm to 400 mm, in particular between 40 mm to 200 mm, between 50 mm to 180 mm, between 60 mm and 160 mm, between 70 mm and 150 mm, between 80 mm and 140 mm and in particular between 90 mm and 135 mm is located. Flat antenna according to one of claims 1 to 5, characterized in that the axial length of the grooved horn is between 30 mm and 50 mm, between 35 mm and 45 mm and in particular between 35 mm to 42 mm. Flat antenna according to one of claims 1 to 6, characterized in that the axial length of the tube radiator ( 9 ) including the attached grooved horns ( 11 ' ) is between 6 cm and 45 cm, in particular between 7 cm and 25 cm, 8 cm and 23 cm, 9 cm and 21 cm, 10 cm and 20 cm, 11 cm and 19 cm and in particular 12 cm and 18.5 cm Flat antenna according to one of claims 1 to 7, characterized in that the wall or sheath thickness of the dielectric tube radiator ( 9 ) is between 1.4 mm to 1.6 mm, preferably 1.5 mm. Flat antenna according to one of claims 1 to 8, characterized in that the dielectric tube radiator ( 9 ) with 5% to 25%, in particular 10% to 20% of its total axial length on the funnel-shaped extended opening or receiving side ( 11b ) of the grooved horn ( 11 ' ) dives into this.

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