EP3900111B1 - Antenna device - Google Patents

Description

Embodiments of the present invention relate to an antenna device and a GNSS antenna. Preferred embodiments relate to a broadband antenna device with limited dimensions.

Global satellite navigation systems (GNSS), such as the American GPS, the Russian GLONASS, the Chinese BeiDou or the European Galileo, have become an elementary part of navigation applications, which constantly increasing demands on an accurate, reliable and always available position, speed and and have time information.

However, the greater the dependency on GNSS, the greater the risk of interference and deception. In order to enable GNSS operation that is as tamper-proof as possible, various security mechanisms have been and are being developed for authorized users.

In the case of GPS, in addition to the civilian C/A code (Coarse/Acquisition) in the L1 band (see 1 ) the not publicly known (military) P/Y code (Precisiontencrypted) is used in the bands L1 and L2. Military GPS receivers and antennas are therefore mostly designed for these two frequency bands.

The Galileo system offers the Public Regulated Service (PRS) for sovereign purposes. The bandwidth of the encrypted PRS signals E1 and E6 is specified with at least 40 MHz (slightly larger than in 1 shown). It is planned to equip military and BOS vehicles (authorities and organizations with security tasks) of the participating EU member states with PRS receiver modules in the near future.

There are already a number of approaches in the prior art as to how one or more bands of the L band explained above can be received based on limited space.

The basis for robust position determination is the highest possible signal-to-noise power density ratio (C/N0), which is proportional to the passive antenna gain.

One of the most commonly used military GPS antennas is the in 2 illustrated S67-1575-86 from Sensor Systems. 3 shows a compatible antenna from AntCom. In order to prevent static charging and to ensure the best possible interference suppression in the HF and VHF range, the antenna elements are galvanically connected to ground (DC grounded). Like most compact L1/L2 antennas, these are very resonant, allowing relatively high gain values only within the L1 and L2 bands.

Ceramic antennas with two planar antenna elements (resonators) arranged one above the other are characterized by such behavior (cf. 4 ).

One possibility, known from the literature, of achieving high efficiency with an electrically small antenna size is the use of planar antenna structures with a cross slot (cf. figure 5 ).

Each of the four metallic radiator parts is fed at one of the outer corners and is galvanically connected to the ground plane at the outer edge. The relative impedance bandwidth (measuring: standing wave ratio VSWR≤2:1) of the antennas shown here is approx. 20%. The axial ratio bandwidth (axial ratio AR≤3 dB or cross-polarization suppression XPD≥15.5 dB) is limited to approx. 10% by the narrow-band concept of the serial feed network.

A larger bandwidth (approx. 30%) with regard to all antenna parameters can be achieved using a parallel four-point feed network. In 6 Figure 1 illustrates the structure and miniaturization of the four-point parallel feed network of a circularly polarized antenna. Each feed point of the miniaturized variant is broadband adjusted with the help of a line transformer and an open-circuit stub line.

None of the prior art variants explained above offers a sufficient broadband antenna gain with equally small dimensions. In this respect, there is a need for an improved approach for a broadband antenna solution, especially with similar form factors as commercially available L1/L2 solutions (diameter < 90 mm, height < 30 mm), which enables a robust reception of all GNSS signals in the L-Band. It is therefore the object of the present invention to create an antenna concept that creates an improved compromise between the required installation space, antenna gain and broadband capability.

The object is solved by the independent patent claims.

Embodiments of the present invention create an antenna device with a radiator arrangement and a feed network. The radiator arrangement is arranged in an upper level in the emission direction, while the feed network is arranged in a corresponding lower level. For example, the feed network can be provided on a single-layer or multi-layer carrier. The radiator array comprises at least four elements (four radiating elements) spaced (isolated) from each other by gaps in the upper plane. The arrangement is such that four quadrants are formed. Each of the four elements is connected in a central angular range via a respective feed point to a corresponding feed point of the feed network. For this purpose, each element has a foot element (e.g. a folded header or attached via) extending from the upper level in the direction of the lower level.

According to embodiments, each of the four elements is defined by a circular arc segment, e.g. B. formed a 90 ° arc segment. The four circular arc segments in the quadrature arrangement thus form a kind of full circle, with the elements each being spaced apart from the next element by a gap. As a result of this quadrature arrangement, the columns form a kind of cross slot. This shape advantageously allows a maximum area to be occupied, particularly given the boundary condition of a limited diameter (e.g. 100 or 90 mm). Advantageously, the above design can also be used to achieve a flat shape (e.g. <30mm), which enables flush installation with the vehicle.

Exemplary embodiments of the present invention are based on the finding that the layered arrangement of feed network and antenna emitter allows optimal use of space in a housing to be achieved, with good radiation characteristics being achieved by the quadrature arrangement or cross slot arrangement. By having each of the four elements have a single feed connected to the sub-feed network directly below, the beam assembly can be operated very efficiently. This promotes the resulting antenna gain. The fact that each radiating element is excited centrally (i.e. in the middle sector or middle angular sector) or centrally via the base element, which is connected to the feed point, results in symmetrical excitation, which is important for broadband operation and in particular dual-circular operation (RHCP + LHCP) is particularly important.

As a result, the arrangement outlined above achieves an antenna device with a high bandwidth and good antenna gain over the entire bandwidth, with boundary conditions such as the small installation space being achieved.

According to further exemplary embodiments, a dielectric element, such as e.g. B. provided a Teflon body. On the one hand, this enables a sufficient distance to be formed between the feed network and the radiating elements, with this distance being filled in order to achieve increased mechanical stability (step protection).

According to exemplary embodiments, the four elements are identical or essentially identical and can include, for example, circle elements, 90° circle segments, triangles or polygons. Particularly in the case of the structure with 90° circle segments, it becomes clear that the arrangement is at least two mirror-symmetrical and also point-symmetrical in some areas.

With regard to the central coupling, it should be noted that, according to exemplary embodiments, this is realized in that the coupling takes place in a middle partial circle segment (generally partial segment). This middle pitch circle segment (sub-segment) is achieved if the individual circular arc segment (segment) is subdivided into three pitch circle segments of equal size (e.g. 30° pitch circle segments) or generally angular segments and the coupling is carried out here in the middle segment (element) ( if possible far outside or in the outer third). The angle for the angular segments of one or all elements of the radiator arrangement extends out, for example, from the middle or the middle region of the radiator arrangement. According to further exemplary embodiments, an optimal coupling is achieved when the coupling point is present exactly along the center line in relation to the angle of the circle segment. In the case of a 90° circle segment, that would then be a 45° angle, with a coupling here again being as far outside as possible, i. H. in the area of the outer third would be desirable.

According to embodiments, the antenna device has an array of radiator arrangements on. Each of these radiator arrays includes four elements. Preferably (but not necessarily) the multiple radiator arrangements in the array are symmetrical. According to one exemplary embodiment, four antenna element arrangements can be provided, which are arranged point-symmetrically, for example, around the center point of the entire antenna element arrangement or antenna device. In this respect, these four radiator arrangements are located in four quadrants of the antenna device. According to a further embodiment, an additional radiator arrangement can be arranged in the middle of the antenna device, which also comprises four elements, whereby this does not necessarily have to behave similarly or identically to the four elements of the other radiator arrangement.

With regard to the production, it should be noted that each of the elements of the radiating elements can be formed by sheets or foils, because the foil is applied to the dielectric body as a carrier, for example. Even if any conductive elements are suitable, the base element with the feed point can be realized at the same time by an unfolded nose (generally base point element) during the production of sheets and foils. This nose extends, for example, at the outer edge from the main plane in the direction of the feed network (for example, at an angle of 35° to 80° out of the plane and/or along an angle in the range of 35 to 55° or 10° to 80°) . The nose can also be tapered so that in the upper plane it has a connection from 10° (or 20° or x°) to 80° (70° or -x°), while the attachment point to the lower plane is at 45° (or in the range between 40° and 50°).

• Speisenetzwerkslage dazwischenliegende Masselage oder dazwischenliegende Doppelmasselage
• RF-Frontend-Lage.

With regard to the feed network, as already noted above, it should be pointed out that this is arranged on a single-layer or multi-layer carrier. If you start from a multi-layer carrier, this can be realized as follows according to exemplary embodiments:

• feed network layer intermediate ground layer or intermediate double ground layer
• RF frontend location.

According to exemplary embodiments, each feed network has a section for the individual ones of the at least four elements of the radiator arrangement. According to the invention, a stub line or a stub line short-circuited to ground is provided for each feed point (for each radiating element) for broadband matching. Accordingly According to exemplary embodiments, the feed network can also include at least one of the following elements: line transformer, Wilkinson coupler and/or delay line.

Another embodiment provides a GNSS antenna with a housing and a corresponding antenna device. According to exemplary embodiments, this GNSS antenna is round and has a maximum diameter of 90 mm.

Fig. 1

eine schematische Darstellung der GNSS-Signale im L-Band;

Fig. 2 und 3

schematische Darstellungen von Stand der Technik-Sensoren;

Fig. 4

schematische Darstellung eines typischen Antennenelements für dualbandige GPS-Antennen in Form einer zirkularpolarisierten Stacked Patch-Antenne (vgl. [4]);

Fig. 5a und 5b

eine quadratische und eine runde zirkularpolarisierte Patch-Antenne (vgl. [5], [6] und [7]) mit Kreuzschlitz und seriellem Speisenetzwerk;

Fig. 6a bis 6c

schematische Darstellungen einer typischen Topologie eines Speisenetzwerks einer breitbandigen zirkularpolarisierten Antenne (vgl. [8]) zur Illustration der Miniaturisierbarkeit gemäß Ausführungsbeispielen;

Fig. 7a

eine schematische Darstellung einer Antennenvorrichtung gemäß einem Basisausführungsbeispiel;

Fig. 7b

eine schematische Darstellung einer Antennenvorrichtung gemäß erweiterten Ausführungsbeispielen;

Fig. 7c und 7d

eine schematische Darstellung einer Antennenvorrichtung in einem Gehäuse (GNSS-Antenne) in der Seitenansicht und in einer Schnittdarstellung gemäß erweiterten Ausführungsbeispielen;

Fig. 7e und 7f

schematische Darstellungen zur Illustration des Speisenetzwerks zur Illustration von optionalen Aspekten gemäß Ausführungsbeispielen;

Fig. 7g

eine schematische Darstellung einer weiteren Antennenvorrichtung gemäß einem weiteren Ausführungsbeispiel;

Fig. 8A und 8b

schematische Diagramme zur Illustration des passiven Antennengewinns in dBic für einen ersten Frequenzbereich in Fig. 8a und einen zweiten Frequenzbereich in Fig. 8b zur Illustration der Effizienz der GNSS-Antenne aus Fig. 7c,d; und

Fig. 9a und 9b

zeigen eine weitere Implementierung der Antennenvorrichtung mit einem Array an Strahleranordnungen gemäß weiteren Ausführungsbeispielen.

Further developments are defined in the dependent claims. Exemplary embodiments of the present invention are explained with reference to the accompanying drawings. Show it:

1

a schematic representation of the GNSS signals in the L-band;

Figures 2 and 3

schematic representations of prior art sensors;

4

Schematic representation of a typical antenna element for dual-band GPS antennas in the form of a circularly polarized stacked patch antenna (cf. [4]);

Figures 5a and 5b

a square and a round circularly polarized patch antenna (cf. [5], [6] and [7]) with a cross slot and a serial feed network;

Figures 6a to 6c

schematic representations of a typical topology of a feed network of a broadband circularly polarized antenna (cf. [8]) to illustrate the miniaturization according to exemplary embodiments;

Figure 7a

a schematic representation of an antenna device according to a basic embodiment;

Figure 7b

a schematic representation of an antenna device according to extended embodiments;

Figures 7c and 7d

a schematic representation of an antenna device in a housing (GNSS antenna) in the side view and in a sectional view according to extended embodiments;

Figures 7e and 7f

schematic representations to illustrate the feed network to illustrate optional aspects according to embodiments;

Fig. 7g

a schematic representation of a further antenna device according to a further embodiment;

Figures 8A and 8b

schematic diagrams to illustrate the passive antenna gain in dBic for a first frequency range in Figure 8a and a second frequency range in Figure 8b to illustrate the efficiency of the GNSS antenna Figure 7c ,d; and

Figures 9a and 9b

show a further implementation of the antenna device with an array of radiator arrangements according to further exemplary embodiments.

Before exemplary embodiments of the present invention are explained below with reference to the attached drawing, it should be noted that elements and structures that have the same effect are provided with the same reference symbols, so that the description of them can be applied to one another or are interchangeable.

In the following discussion, the basic embodiment is based on Figure 7a explained, while optional aspects related to the Figure 7b , 7c and 7d to be discussed. Figures 7e and 7f 12 show optional aspects of the feed network according to extended embodiments.

Referring to Figure 7a it should be noted that all basic elements are shown here, although additional elements can also be included in the figure representation, but for the Antenna device are not absolutely necessary. Referring to Figures 8a and 8b the efficiency is then explained using diagrams to illustrate the radiation characteristics. After these diagrams have been discussed, possible variations for the individual features, in particular the features of the basic exemplary embodiment, are then discussed.

Figure 7a shows an antenna device 10 with the two basic features radiator arrangement 12 and feed network 14. The feed network is applied, for example, to a single-layer or multi-layer circuit board and is located in a lower level, e.g. B. at the bottom of the antenna device, while the radiator assembly is in an upper level. Both planes can be essentially parallel to one another, with the feed network 14 and the radiator arrangement optionally being aligned with one another. According to an optional aspect, as shown here, they are spaced apart from one another in the emission direction 12r. The emission direction 12r of the antenna device 10 is marked with an arrow.

In this exemplary embodiment, the radiator arrangement 12 comprises four individual elements 12a to 12d (whereby 12d is covered by an optional component). The four elements 12a to 12c are each, for example, semicircular elements arranged in a quadrant. In this exemplary embodiment, the individual elements 12a to 12d are formed by segments of a circle of 90°, so that a two-fold mirror-symmetrical and one-dimensional point-symmetrical structure is established. All elements 12a to 12d are arranged in a common plane, namely the upper plane. All of the radiator elements 12a to 12d arranged in the four quadrants are separated by gaps 12s. Starting from the 90° circle segments, these can have a constant thickness of 1 to 3 mm, but of course any other shape with a variable cross section would also be conceivable.

Each radiating element 12a to 12c is connected to the associated feed point of the feed network 14 via its own feed point. The feed points belonging to the radiators 12a to 12d are identified by the reference symbols 12as, 12bs, 12cs and 12ds. In this embodiment, these feeding points 12as to 12ds are formed by lugs arranged on the circle line. These tabs are folded down (i.e. extend out of the upper level towards the lower level and thus enable connection to the associated feed points 14as to 14ds. Regarding the feed points, it is important to mention that this is a so-called central feed is involved, which means that when you look at the respective circle segment, it acts in the middle with respect to the angle .In general, the respective nose 12as to 14ds is arranged in a middle angle range.

This middle angular range is identified here with the reference symbol β and essentially corresponds to the middle pitch circle segment if the individual circle segment is subdivided into three circle segments of equal size. The feed point can be arranged anywhere within this range. At this point, however, it should also be pointed out that a preferred attachment should be as central as possible, i. H. should be provided on the bisector of the 90° circle segment (or a circle segment with a different angle), while an arrangement as close as possible to the edge line (cf. circle line) would also be preferable. According to the invention, the feed point is arranged on an axis of symmetry, it being possible for the axis of symmetry to run along an angle bisector or diagonal (depending on the shape of the segment). This has the advantageous technical effect that a symmetrical feed takes place.

Figure 7b shows another antenna device 10'. The device 10′ essentially corresponds to the antenna device 10, the space between the radiator arrangement 12 comprising the four radiating quadrants 12a, 12b and 12c and the feed network 14 being filled with a material, here a dielectric body 16. The dielectric support may be formed from a bulk plastic or a polyimide film, for example. This foil can be coated with an additional metallization (flexible printed circuit board), which then forms the radiating elements 12. If one starts from a round body 16, the four circular segments are applied to the surface with a type of cross slot shape in order to form the four radiator elements 12a to 12d. According to exemplary embodiments, a recess can be provided both centrally at the cross slot and at the end of the slots 12s, in order to create the necessary installation space for screws or other fastening means, for example. Furthermore, the body 16 can also have a recess in the area of the lugs 12as to 12ds, so that these can be bent towards the feed network 14 corresponding to the printed circuit board.

In the variant shown here Figure 7b Also, the antenna device 10 is embedded in a case composed of the base plate 18g and the lid 18d. The bottom has a receptacle for the single or multi-layer printed circuit board that houses the feed network. The dielectric body 16 with the radiating elements 12a to 12d is then applied to the feed network before the housing is then closed from above with the cover 18d. A seal can optionally be provided between the housing base 18g and the housing cover 18d. The individual components can be connected to one another using the screws. It is thus possible, for example, for the dielectric block with the radiating elements to be fastened together with the circuit board 14 on the base plate 18g with the central central screw, while the cover 18d and thus the housing can be closed with the four decentralized screws. The entire antenna is also open via these screws another component, such as B. a vehicle applicable. The locked position is in Figure 7c shown while Figure 7d represents the decentralized bores (cf. reference numeral 18s) in the sectional view.

A further optional feature, namely electrical connection for the entire antenna device, is also provided in these figures. This is provided with the reference number 20 and protrudes on the underside of the floor 18g. The plug 20 protrudes through the base 18g and makes contact with the printed circuit board, which houses the feed network 14, from below. Because the plug 20 protrudes on the underside, the antenna device can be contacted from below and at the same time the cable can be lowered when the antenna device is attached. The connector shown here can be, for example, an F-connector or a similar connector.

It should also be noted at this point that the thickness of the base plate 18g allows components such as B. filters or the like can be provided on the circuit board.

The embedding of the printed circuit board that houses the feed network 14 is in Figures 7e and 7f shown. Both figures show the embedding of the printed circuit board 14l in the housing base 18g, the bores 18s being visible here again. Optionally, the printed circuit board 14l can be recessed in the area of these bores.

The printed circuit board 14l with the switching network 14 is round and can be divided roughly into four sectors/circle segments, as shown by the dashed lines. Each sector includes a portion of the feed network associated with one of the four elements. Consequently, a feed point 14as to 14ad is provided in each sector. How based on Fig. 7f As shown, each nose 12as to 12ds is connected to the respective feed point 14as to 14ds, e.g. B. by a pure clamping force or by a mechanical-electrical connection such. B. based on a solder. A corresponding feed network section is arranged around each feed point and serves to feed the individual element. According to the invention, each section comprises a short-circuited stub 15sd, the short-circuit point being identified by the reference numeral 15sdk. This short-circuit point is implemented, for example, by a via that connects the stub line to a ground layer arranged in a lower level. Of course, there can also be another possibility of forming a short circuit. According to further embodiments, a Line transformer be provided for each feed point. This line transformer is provided with the reference number 15lt. The individual feed points 14as to 14ds are connected to one another by so-called delay lines 15vl (e.g. two pairs each with a 90° (quarter wavelength) difference in length at the center frequency), which then together make it possible to operate the antenna as an RHCP antenna.

According to exemplary embodiments, the feed network 14, in particular in the central section 14z, also includes other components which are implemented here in the feed network layer, such as a 180° hybrid, one or more Wilkinson couplers and/or line transformers.

The feed network 14 shown here can be used as a conventional feed network (cf. Figure 6a ) or as a miniaturized feed network, e.g. based on meander shapes (cf. Figures 6b and 6c ) has to be implemented, the basic idea of which is based on the fact that loops make it possible to miniaturize a topology (cf. [8]).

In addition, a free area is provided in a further central area 14n, in which the location of the feed network can be connected to the antenna connection. This antenna connector is, as in Figures 7c and 7d visible, provided from the back for contacting.

According to exemplary embodiments, the feed network 14 shown here is designed on a multi-layer circuit board, the z. B. accommodates the feed network in a top layer (layer facing the radiating elements 12), while the RF front end is implemented with filters, LNAs or other electronic components in a lower layer. As already explained above, the use of this lowest layer is advantageous because these components can be accommodated in the housing base 18g and thus shielded. According to additional exemplary embodiments, an additional ground layer is provided between this RF front-end layer and the feed network layer, with respect to which, for example, the short circuit of the stub 15sd (cf. 15sdk) can be connected. According to an additional exemplary embodiment, two ground layers can also be provided, which are easy to implement in terms of production technology, if one starts from two stacked printed circuit boards. In addition, this double ground layer between the RF front end layer and the feed network layer also offers shielding advantages.

In the exemplary embodiments, it was assumed that the feed point for each radiator element is arranged centrally, e.g. B. at the outer end of the circle segment. It would of course also be a central arrangement, e.g. B. in the pitch circle segment β possible, which can be realized in terms of production technology by an attached via or a different type of soldered leg.

Figures 8a and 8b illustrate the antenna gain for two different bands. Here shows Figure 8a antenna gain in dBic for 1.16 to 1.30 GHz, while Figure 8b shows antenna gain in dBic in the 1.52 to 1.61 GHz range. The RHCP component is illustrated in solid lines, while the LHCP component is illustrated in dashed lines. Good antenna efficiency is achieved when, among other things, there is sufficient spacing between the RHCP and LHCP components.

A symmetrical reception gain develops in both relevant bands or areas of the L-band, which is generally 0 to +5 dBiC, depending on the angle, or at least -60 to +60°. In detail, the antenna gain in free space (without ground plane) in the lower frequency range is -3.5 dBic at 10° elevation and +2.5 dBic at the zenith; in the upper frequency range the values are between -3.5 and +5 dBic. Cross-polarization rejection is better than 15.5 dB (AR≤3 dB) over the entire frequency range.

The relationship is also shown again in the following table: example StdT: Sensor Systems S67-575-86 StdT: AntCom G5Ant-3A4T1-SS Dimensions (without TNC socket), mm Ø89, H25 Ø89, H18 Ø89, H22 Passive antenna gain in dBic @ elevation 10 ... 90° L5 & E5 ≥-3.5 k. A ≥-9.0 L2 ≥-3.5 ≥-2.5 ≥-3.5 E6 ≥-3.5 (50MHz BB) k. A ≥-6.5 (20MHz BB) L1 & E1 ≥-3.5 (50MHz ≥-2.5 (20MHz ≥-2.7 (20MHz BB) BB) BB)

As can be seen from the table above, such antennas are limited in particular with regard to their diameter (<100 or <90 mm).

Fig. 7g shows an implementation of the referring to Figure 7a illustrated antenna device 10". Here, the radiating elements 12a"-12d" are formed by printed circuit boards. Each radiating element 12a"-12d" has a substantially triangular shape or a triangular shape with flattened corners, so that through the radiator array 12" a Square or octagon is formed. The foot elements 12af"-12df" are attached vertically (generally: angled) along the hypotenuses. These foot elements 12af"-12df" extend over the entire side and are triangular, so that in the central angular area (here at 45° between the two legs) the feeding point is formed by the tip of the dirt / triangular foot element 12af"-12df", which is then connected to the feed point of the feed network 14".

Even if it was assumed in the above exemplary embodiments that the antenna arrangement essentially forms a circular segment with four 90° segments, it should be noted at this point that the segments can also be < (e.g. 75°) or generally in the range from 30 to 90 ° can be, in which case either additional elements are provided or the columns 12s are larger in size. It should also be noted that, according to exemplary embodiments, it is also not necessary for each element to describe a semicircle, so that the circular line can also be formed by a simple straight boundary line, so that each of the four elements is therefore formed by a triangle. An angular boundary line in the sense of a polygon would also be conceivable. In general, it should be noted that any free form would be possible.

With regard to the three-dimensional design, it should be noted that, as shown in particular on the basis of Figure 7d As can be seen, each individual element can be bent at the edge area, so that the antenna arrangement as a whole forms a mushroom-shaped structure, for example. On the one hand, this has the purpose that good reception properties can also be made possible towards the sides and, on the other hand, it is also due to the fact that the desired housing shape requires such a bending of the radiating elements. It should therefore be noted at this point that, according to exemplary embodiments, the elements of the radiator arrangement can be shaped/bent as desired.

Figure 9a shows another antenna device 10‴. Both antenna devices 10‴ and 10″″ include at least four radiator arrangements 12‴ which are constructed as explained above. For example, the radiator arrangements are implemented with four identical elements, here 90-degree circle segments (cf. FIGS. 12a-12d). The feed points are marked with reference numerals 12as-12ds. As can be seen, the feed points 12as-12ds for each element are in turn arranged in a middle angular segment, middle pitch circle segment, here along the axis of symmetry through the respective element 12a-12d, for example as far as possible on the outer edge, so that the feed points, e.g. B. 12as and 12cs are as far apart as possible.

According to further exemplary embodiments, the antenna device 10‴ and 10″″ can also have a further radiator arrangement 13‴ which is arranged centrally in relation to the antenna device 10‴ and 10″″. This radiator arrangement 13‴ in turn comprises four elements which are numbered 13a‴ to 13d". The elements 13a‴ to 13b‴ are similar or identical to one another and have a polygonal shape. In detail, each extends from the center of the radiator arrangement 13‴ element to the outside and is symmetrical in itself. The feeding point 13as‴ to 13ds‴ is located along the axis of symmetry and, seen from the center point, is as far outside as possible, i.e. in the outer third, so that the distances between the feeding points, e.g 13as" and 13cs are as far apart as possible. The four elements 13a" to 13d" are separated from one another by gaps. The outer contour of the elements 13a" to 13b" can be adapted to the outer contour of the radiator elements 12'' according to exemplary embodiments.

Now that the two exemplary embodiments Figure 9a and 9b were explained in their commonality, it should be pointed out that the differences between the two antenna devices 10‴ and 10‴ʺ lies in particular in the dimensioning of the gaps between the individual radiator arrangements 12‴ and 13‴ and between the individual elements of the radiator arrangements 12‴ and 13′ ". The geometry of the individual elements changes due to the wider or narrower dimensioning.

Now that the structure of the other exemplary embodiments 10‴ and 10″″ has been explained, the mode of operation will be discussed below. The antenna arrays 10‴ and 10″″ form null-steering GNSS antennas (Controlled Radiation Pattern Antenna, CRPA) in two different sizes, 90 and 150 mm. Operation is intended for the L1 and E1 band as well as the L2 and E6 band. in contrast to the prior art, the antenna elements shown are microstrip line antennas (patch antennas) and not dielectric resonator antennas. The CRPA arrangement shown enables higher C/N0 values (approx. 3 dB for the 150 mm variant) thanks to the four-point feed and the star-shaped shape of the middle element 13‴. The construction is simpler and can be reduced and compared to the prior art it is more cost-effective and mechanically more stable.

It should be noted at this point that the number can also vary in an antenna device with an array of radiator arrangements. The star-shaped radiator element 13‴ is optional. According to further exemplary embodiments, it would also be possible to implement an antenna device with only one star-shaped radiating element 13‴. This would be an alternative variant to the in Figure 7a shown antenna device.

As already explained above, the feed network 14 can be implemented on a single-layer or multi-layer printed circuit board or a discrete structure (cf. Figure 6a ) exhibit.

Even if it was assumed in the above examples that the dielectric body 16k is present as an element to which the radiating elements 12a to 12d are applied as films, for example, it should be noted at this point that this can of course also be formed by a plastic cage or the like to achieve the desired dielectric properties. A perforation of the body would also be conceivable. Alternatively, the entire housing could be potted when sealed so that the body is formed later. Possible materials for this carrier are ceramics, PTFE or other non-conductive polymers or generally non-conductive elements.

With regard to the materials for the radiating elements, it should be noted that any metal sheets, such as e.g. B. tinplate (preferably solderable) or metal foils are suitable.

The antenna devices explained above are suitable for possible use in military and BOS vehicles (possibly slightly modified), which are to be equipped with PRS modules in the near future.

In addition, the technical field of application of the invention includes positioning and surveying in agriculture and forestry, cadastral surveying, vehicle and machine controls in construction and agriculture, GNSS surveillance systems, aerospace applications.

Further aspects are explained below. The invention relates to an antenna device with a centrally placed radiator which, according to a further exemplary embodiment, is mounted on a dielectric carrier, such as e.g. B. a polyimide film can be applied. According to the invention, its metallization is divided into four equal elements, e.g. B. through a cruciform prism. In addition, each metallization has its own feeding point, which is broadband-adapted with the aid of a line transformer and, according to the invention, at least one short-circuited stub line. In particular, the short-circuited stub provides integrated protection against static charging. According to further exemplary embodiments, a line transformer and at least the running stub line with at least one parallel inductance can be provided in addition to this short-circuited stub line, which also enables integrated protection. Furthermore, these short-circuited stubs enable high interference suppression in the HF and VHF range (also in a significantly lower frequency range). Due to the short-circuits via the stub lines, the resulting signal is not negative either

As already explained above, the dielectric carrier is optional, with precisely this dielectric filling between the radiator and a printed circuit board arranged under the radiator being used for increased mechanical stability (impact protection). According to one aspect, the printed circuit board has a multilayer design, with a feed network being able to be provided on the upper side and an RF front end (e.g. comprising filters, LNAs, etc.) being provided on the underside, for example. One or more inner layers can be provided between these two layers, which form mass.

These features advantageously allow a broadband GNSS antenna to be implemented starting from the limited space, for example 89×25 mm or generally <90 mm in diameter and <30 mm in height.

A GNSS antenna with the above antenna device and a corresponding housing is thus created according to exemplary embodiments.

referenced documents

1. [1] K. Fletcher (ed.), "GNSS Data Processing, Vol. I: Fundamentals and Algorithms", ESA Communications, ESA TM-23/1, May 2013
2. [2]Sensor Systems: Data sheet S67-1575-86
3. [3]AntCom: Data sheet G5Ant-3A4T1-SS
4. [4] B. Rama Rao et al "Compact Co-Planar Dual-Band Microstrip Patch Antennas for Modernized GPS", https://www.mitre.org/publications/technical-papers/compact-coplanardualband-microstrip-patch-antennas-for- modernized-gps
5. [5] Xi Chen et al "High-Efficiency Compact Circularly Polarized Microstrip Antenna With Wide Beamwidth for Airborne Communication", IEEE Antennas and Wireless Propag. Letters, vol. 15, 2016
6. [6] Xi Chen et al "Low-cost 3D Printed Compact Circularly Polarized Antenna with High Efficiency and Wide Beamwidth", In Proceedings of the International Conference on Electromagnetics in Advanced Applications (ICEAA) 2016
7. [7] CN 105811099A (EN: Small satellite navigation antenna and anti-multipath interference cavity thereof)
8. [8th] A. Popugaev "Miniaturized microstrip line circuits consisting of assembled quadrant rings" PhD thesis, N&H Verlag, Erlangen, 2014

Claims (15)

1. Antenna device (10, 10', 10"), comprising

   a radiator arrangement (12, 12") in an upper plane in the radiating/receiving direction (12r); and

   a feed network (14, 14") arranged in a lower plane in the radiating/receiving direction (12r);

   wherein the radiator arrangement (12, 12") includes at least four elements (12a, 12b, 12c, 12d) spaced apart by columns (12s) in the upper plane to be arranged in a quadrant structure, wherein each of the four elements (12a, 12b, 12c, 12d) includes, along an axis of symmetry, a base element extending from the upper plane towards the lower plane, forming a feed point (12as, 12bs, 12cs, 12ds) via which each element is connected to a corresponding feed point of the feed network (14as, 14bs, 14cs, 14ds);

   characterized in that the feed network (14, 14") includes, for each feed point (12as, 12bs, 12cs, 12ds), a stub (15sd) short circuited with respect to ground and configured to protect against static charge and to suppress interference in HF and VHF ranges.
2. Antenna device (10, 10', 10") according to any one of the preceding claims, wherein the radiator arrangement (12, 12") and the feed network (14, 14") are arranged flush with each other and/or wherein the radiator arrangement (12, 12") and the feed network (14, 14") have a circular shape.
3. Antenna device (10, 10', 10") according to any one of the preceding claims, wherein the at least four elements (12a, 12b, 12c, 12d) are identical elements.
4. Antenna device (10, 10', 10") according to any one of the preceding claims, wherein at least four elements (12a, 12b, 12c, 12d) include circle segments, 90° circle segments, triangles and/or polygons; and/or

   wherein the radiator arrangement (12, 12") is symmetrical, rotationally symmetrical, point symmetrical, single or double-mirror symmetrical; or

   wherein the at least four elements (12a, 12b, 12c, 12d) of the radiator arrangement (12, 12") are symmetrical, rotationally symmetrical, point symmetrical or mirror symmetrical.
5. Antenna device (10, 10', 10") according to any one of the preceding claims,

   wherein the at least four elements (12a, 12b, 12c, 12d) are formed by angular segments, each of which is divisible into three equally sized sub-angular segments, the central one of the three sub-angular segments including the central angular region (β); or

   wherein the at least four elements (12a, 12b, 12c, 12d) are formed by circle segments, each of which is divisible into three equally sized sub-circle segments, the central one of the three sub-circle segments including the central angular region (β); or

   wherein each of the at least four elements (12a, 12b, 12c, 12d) is formed by circle segments and the base element and/or the feed point (12as, 12bs, 12cs, 12ds) is arranged along the half angle of the circle segment.
6. Antenna device (10, 10', 10") according to claim 5, wherein the angular segments and sub-angular segments extend from a common point or center of the radiator arrangement (12, 12"); or
   wherein the circle segments and sub-circle segments extend from a common point or center of the radiator arrangement (12, 12").
7. Antenna device (10, 10', 10") according to any one of the preceding claims, wherein a dielectric carrier (16) is arranged between the plane of the radiator arrangement (12, 12") and the plane of the feed network (14, 14").
8. Antenna device (10, 10', 10") according to any one of the preceding claims, wherein the at least four elements (12a, 12b, 12c, 12d) are each formed by a foil, in particular a foil on a carrier, or a metalized dielectric foil or a metalized foil; and/or
   wherein the at least four elements (12a, 12b, 12c, 12d) are each formed by sheet metals, printed circuit boards, bent sheet metals, or a combination thereof.
9. Antenna device (10, 10', 10") according to claim 9, wherein each of the at least four base elements is formed by a lug (12as, 12bs, 12cs, 12ds) or ungrooved lug on an outer side of the respective element or circular arch line of the respective element, the lug or ungrooved lug forming the respective feed point (12as, 12bs, 12cs, 12ds) connected to the corresponding feed point of the feed network (14as, 14bs, 14cs, 14ds).
10. Antenna device according to any one of the preceding claims, wherein the feed network (14, 14") is formed on a single layer or multilayer printed circuit board arrangement; or wherein the feed network (14, 14") is formed on a single layer or multilayer printed circuit board arrangement; wherein the multilayer printed circuit board arrangement includes a feed network layer and an RF front end layer having a ground layer therebetween, or
    wherein the multilayer arrangement includes a feed network layer and an RF front end layer having a dual ground layer therebetween.
11. Antenna device (10, 10', 10") according to any one of the preceding claims, wherein the feed network (14, 14") includes at least one of the elements from the group comprising a line transformer (15lt), a Wilkinson coupler, and a delay line, or
    wherein the feed network (14, 14") includes at least one of the elements from the group comprising a line transformer (15lt), a Wilkinson coupler and a delay line for each feed point (12as, 12bs, 12cs, 12ds).
12. Antenna device (10, 10', 10") according to any one of the preceding claims, comprising at least two radiator arrangements (12, 12"); or

    comprising at least two radiator arrangements (12, 12") and wherein the radiator arrangements (12, 12") are arranged symmetrically, point symmetrically or axis symmetrically with respect to the antenna device; and/or

    the one further radiator arrangement is arranged between the radiator arrangements (12, 12').
13. GNSS antenna, comprising:

    a housing (18g, 18d); and

    an antenna device (10, 10', 10") according to any one of the preceding claims embedded in the housing.
14. GNSS antenna according to claim 13, wherein the GNSS antenna is circular and/or wherein the GNSS antenna has a maximum diameter of 100 mm.
15. Antenna device (10, 10', 10") according to any one of claims 1 to 12, wherein the axis of symmetry runs along a diagonal or an angle bisector.

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