EP2784874A2 - Broadband monopole antenna for vehicles for two frequency bands separated by a frequency gap in the decimeter wavelength - Google Patents

Abstract

The antenna (0) has an upper band monopole (1), a lower band monopole (2) and an electrically conductive structure i.e. electrically conducting foil, oriented above a conducting base surface (6). A triangular structure (4) is formed at a lower end of the antenna. A roof capacitor (10) designed as a rectangular structure (16) is arranged below an upper end of the antenna. The triangular structure and the rectangular structure are connected inductively with high impedance by a conductor strip (15) for separating radio signals in the upper band.

Description

The invention relates to a vertical broadband monopole antenna for two frequency bands separated by a frequency gap - the lower band for the lower frequencies and the upper band for the higher frequencies - both located in Dezimeterwellenbereich - for vehicles and for transmission and / or reception with terrestrial emitted vertically polarized radio signals over a substantially horizontal conductive base surface 6 as a vehicle ground with an antenna connection point 3 located in the monopole base, comprising an antenna connection point 5 and a ground connection 7.

Such broadband antennas are known in the art. These antennas are designed as multi-resonant rod antennas, wherein the coverage of a plurality of frequency bands separated by frequency gaps in frequency by means of multiple, applied to the elongated rod wire windings, which overlap partially. Such antennas are used for transmission and reception in the decimeter-wave range on vehicles, preferably in each case on the vehicle roof. Antennas of this type, on the one hand, have the disadvantage that they are only provided for relatively narrowband frequency bands separated from one another by frequency gaps, and that they are only of limited use for wide frequency bands. Especially for use on vehicles, the height, their aerodynamic shape and their wind resistance value are important. However, the special significance is due to the usual in vehicle large numbers of economic efficiency of the production of such an antenna. This shows that the application of different wire windings must be mechanically tight tolerated, so that the required frequency accuracy is achieved. Furthermore, the application of the windings on the rod, their attachment and the production of their long-term stability and the reproducibility of the performance of the antenna are relatively complicated and economically expensive.

The variety of modern mobile networks, such as those designed according to the LTE (Long Term Evolution) or still under development, requires antennas with extreme bandwidth. For example, a frequency range between 698 and 960 MHz is provided for the LTE mobile radio standard - hereinafter referred to as subband U - and above a frequency gap the frequency range between 1460 MHz and 2700 MHz, which is denoted here by upper band O, is provided, as in Fig. 1 shown. Frequently, in addition, a middle band M is provided in the frequency range between 1460 MHz and 1700 MHz, which is to be assigned to the upper band. With regard to the antenna function, the frequency gap between lower band U and upper band O is desired for protection against the radio services located there. For this application antennas are needed, which are suitable in addition to the electrical function for vehicles, with the economy of production is of particular importance.

The object of the invention is therefore to provide an antenna for two separated by a frequency gap frequency bands, which at low height and favorable aerodynamic properties has the necessary mechanical stability and can be produced economically, especially in a simple manufacturing process.

The solution of this object is achieved by the features of claim 1.

Advantageous embodiments of the invention are described in the subclaims and the description.

The antenna may comprise a vertical wideband monopole antenna for two frequency bands separated by a frequency gap - the lower band for the lower frequencies and the upper band for the higher frequencies - both located in the decimeter wave range, for vehicles and for transmission and / or reception with terrestrially emitted vertically polarized Radio signals over a substantially horizontal conductive base surface 6 as a vehicle mass with an antenna connection point 3 located in the monopole base, comprising an antenna connection point 5.

The broadband monopole antenna 0 can be formed from a top band monopole 1 and a subband monopole combined and is for example made of a mechanically stiff electrically conductive film 33 as a continuous, electrically conductive and, for example, planar structure over a conductive base 6 in a substantially vertical Designed to run to this oriented level. At the lower end of the broadband monopole antenna 0, an example flat triangular structure 4 may be present as a top band monopole 1 with a substantially horizontally oriented baseline in a top band monopole 8 above the conductive base 6 whose tip is connected to the antenna connection point 5 is.

Adjacent to the upper end of the broadband monopole antenna 0 located in the antenna height 9 above the conductive base area 6, a roof capacitance 10 designed substantially as a rectangular planar structure 16, in particular, is designed underneath.

The triangular structure 4 and the rectangular structure 16 as a roofing capacity 10 are provided by at least one conductor strip 15, in particular with a narrow stripline width 14 of, for example, less than or equal to 7 mm for the separation of radio signals in the upper band inductively connected high impedance, whereby the lower band monopole 2 is formed.

Disclosed is a vertical broadband monopole antenna for vehicles for two frequency bands separated frequency bands, namely a lower band U for lower frequencies and an upper band O for higher frequencies, both located in the Dezimeterwellenbereich, for transmission and / or reception with terrestrially emitted vertically polarized radio signals a substantially horizontal conductive base 6 as a vehicle ground with an antenna connection point 3 located in the monopole base comprising the following features: The broadband monopole antenna is formed of a self-supporting electrically conductive structure which is oriented over the base 6 substantially perpendicular to this. The electrically conductive structure comprises at the lower end of the broadband monopole antenna a truncated triangular structure 4 with a substantially horizontally oriented baseline, the tip of which forms an antenna connection point 5 of the antenna connection point 3. The electrically conductive structure comprises, adjacent to the upper end of the broadband monopole antenna 0 underneath, a roof capacitance 10 substantially configured as a rectangular structure 16. The triangular structure 4 and the rectangular structure 16 are inductive by at least one conductor strip 15, 15a, 15b for separating radio signals in the upper band connected with high resistance.

The electrically conductive structure may have at least two spaced conductor strips 15, whereby a frame structure 11, consisting of the triangular structure 4, the rectangular structure 16 and the conductor strip 15 is formed.

The conductor strip or strips 15, 15a, 15b may contain meander-shaped forms 24 for the frequency-selective separation.

The inner angle 12 at the top of the triangular structure 4 may be approximately between 30 and 90 degrees.

The triangular structure 4 may also be designed by strip-shaped lamellae 20 arranged in a fan-like manner and converging in the tip.

At least one annular satellite receiving antenna 25, 25a, 25b arranged concentrically with the antenna connection point 3 can be present above the conductive base area 6.

In order to improve the electromagnetic decoupling, the rectangular structure 16 may be formed substantially by vertical strip conductors 19, 19a, 19b which are separated from each other vertically but electrically, but which are connected at their upper end by a remaining strip 31.

The strip-like lamellae 30, 30a, 30b which converge in the tip can be bent out of the plane of the triangular structure (4) in such a way that they essentially run on the lateral surface of a tip-shaped cone with a circular or elliptical cross section.

The roof slats 19, 19a, 19b may be successively in the opposite direction in the way that they are arranged in the projection on a transverse to the strip 31 plane V-shaped.

The lamellae 20a, 20b which converge in the tip can be successively counteracted in the opposite direction in the plane of the triangular structure 4 in such a way that they are arranged in the projection on a plane transverse to the triangular structure 4 in a V-shaped manner.

The broadband monopole antenna 0 may be disposed under a cover 32 and the at least one conductor strip 15, 15a, 15b may be at least partially and in particular be guided as far as possible along the inner wall of the cover.

The electrically conductive structure may be made of electrically conductive sheet and only one, i. a single self-supporting conductor strip 15 may be present.

The electrically conductive structure may be provided by metallic coating 33 on a printed circuit board whose contour substantially follows the contours of the electrically conductive structure of the broadband monopole antenna 0.

The mirror image of the broadband monopole antenna 0 at the conductive base 6 can be replaced by their omission by a same to this other broadband monopole antenna in such a way that is given to the plane of the conductive base 6 symmetrical dipole and a symmetrical antenna junction of this dipole between the antenna connection point 5 of the broadband monopole antenna 0 and the - this accordingly - mirrored at the conductive base 6 antenna connection point 5 of the further broadband monopole antenna is formed.

There may be a connected at its upper end with the roof capacitance 10 coupling conductor 35, which is coupled at its lower end to the conductive base 6

Fig. 1:

Frequenzbereiche nach dem LTE- Mobilfunk Standard als Beispiel für zwei durch eine Frequenzlücke getrennte Frequenzbänder im Dezimeterwellenbereich mit einem Frequenzbereich zwischen 698 und 960 MHz als Unterband U und einem Frequenzbereich zwischen 1460 MHz und 2700 MHz als Oberband O oberhalb einer Frequenzlücke

Fig. 2:

Zweidimensionale Breitband-Monopolantenne 0 über der elektrisch leitenden Grundfläche 6 und der im Fußpunkt gebildeten Antennenanschlussstelle 3 mit auf der Spitze stehender flächiger Dreieckstruktur 4 als Oberband-Monopol 1 und der Dachkapazität 10, welche über zwei Leiterstreifen 15 mit mäanderförmiger Ausprägung 24 mit der Dreiecksstruktur 4 zur Bildung des Unterband-Monopols 2 verbunden sind. Die Struktur der Breitband-Monopolantenne 0 kann ganzheitlich beispielhaft aus Blech gestanzt oder geschnitten werden.

Fig. 3:

Breitband-Monopolantenne 0 wie in Fig. 2, kombiniert mit einer konzentrisch zur Spitze der flächigen Dreieckstruktur 4 konzentrisch gestalteten, ringförmigen Satellitenempfangsantenne 25. Zur weiteren Erhöhung der induktiven Wirkung der Leiterstreifen 15 sind beispielhaft weitere mäanderförmige Ausprägungen 24 ausgebildet.

Fig. 4:

Beispiel einer aus leitender Folie oder Blech durch Stanzen oder Schneiden herstellbaren Struktur mit dem Frequenzverhalten eines elektrischen Parallelschwingkreises 29 im Leiterstreifen 15 zur Gestaltung der frequenzselektiven Trennung des Unterband-Monopols 2 vom Oberband-Monopol 1. Der Parallelschwingkreis 29 ist durch Interdigitalstruktur 26 als Parallel kapazität 27 und die Leiterschleife als Parallelinduktivität 28 gebildet.

Fig. 5:

Zweidimensionale Breitband-Monopolantenne 0 wie in den Fig. 2 und 3, wobei die flächige Dreieckstruktur 4 des Oberband-Monopols 1 durch in der Dreiecksebene fächerartig angeordnete und an der unteren Dreiecksspitze zusammen laufende streifenförmige Lamellen 20 gestaltet ist. Die ausschließlich über die Dreiecksspitze miteinander leitend verbundenen Lamellen 20 bewirken die elektromagnetische Entkopplung des Oberband-Monopols 1 von der ringförmigen Satellitenempfangsantenne 25.

Fig. 6a:

Schwankung des Antennengewinns über dem Azimutwinkel Phi der Satellitenempfangsantenne 25 in dBi bei Vorhandensein der flächigen Dreiecksstruktur 4 als geschlossene elektrisch leitende Fläche.

Fig. 6b:

Wie in Fig. 6a jedoch mit durch fächerartig verlaufende, streifenförmige Lamellen 20 gestaltete Dreieckstruktur 4. Die azimutalen Schwankungen sind jeweils für die Zenitwinkel Theta (Winkel gegen die vertikale, d.h. z-Achse) 20°, 40° und 60° dargestellt.

Fig. 7:

Monopolantenne wie in Fig. 4 mit ringförmiger Satellitenempfangsantenne 25 wobei jedoch zur Verbesserung der elektromagnetischen Entkopplung zwischen dieser und dem Unterband-Monopol 2 die die Dachkapazität 10 bildende flächige Rechteckstruktur 16 durch vertikal voneinander getrennt verlaufende, jedoch an ihrem oberen Ende über einen verbleibenden Streifen 31 zusammenhängende streifenförmige Dachlamellen 19 gebildet ist.

Fig. 8:

Monopolantenne wie in Fig. 7, jedoch mit nur einem selbsttragenden Leiterstreifen 15 mit größerer Blechstärke zu Gunsten besonderer mechanischer Steifigkeit und zur Erreichung der notwendigen eigenen Induktivität des Leiterstreifens 15 mit entsprechend mehreren mäanderförmigen Ausprägungen 24.

Fig. 9:

Monopolantenne wie in Fig. 7, jedoch mit einem anstelle der flächigen Dreieckstruktur kegelförmig und auf der Spitze stehend ausgebildeten Oberband-Monopol 1 zur Vergrößerung der Bandbreite im Oberband. Der elektrisch leitende Kegelmantel ist punktiert angedeutet.

Fig. 10:

Oberband-Monopol 1wie in den Fig. 5, 7 und 8, wobei jedoch die in der unteren Dreiecksspitze fächerartig zusammenlaufenden streifenförmigen Lamellen 30 des Oberband-Monopols 1 in der Weise aus der Ebene der flächigen Dreiecksstruktur 4 ausgewinkelt sind, dass sie etwa wie die Mantellinien eines gemäß Fig. 8 auf der Spitze stehenden Kegels mit kreisrundem bzw. elliptischem Querschnitt verlaufen.

Fig. 11:

Draufsicht auf eine Antenne gemäß der in Fig. 10 angedeuteten Schnittlinie A-A' zur Klarstellung des Verlaufs der fächerartig verlaufenden streifenförmigen Lamellen 30, 30a, 30b. Die ringförmigen Satellitenempfangsantennen 25a und 25b sind durch unterbrochene Linien angedeutet.

Fig. 12:

Maximalwert der azimutalen Schwankung des Antennengewinns in dBi bei geschlossenem elektrisch leitendem Kegelmantel und bei einem aus streifenförmigen Lamellen 20 gebildetem Kegelmantel in Abhängigkeit vom Zenitwinkel (Winkel gegen die z-Achse).

Fig. 13:

Einbausituation einer Breitband-Monopolantenne unter einer Abdeckhaube 32 mit Blick auf die Antenne quer zur Fahrtrichtung (y-Richtung) zusammen mit einer ringförmigen Satellitenempfangsantenne 25. Die schwarz unterlegten und mit a) gekennzeichneten Leiterteile sind die Leiterstreifen 15a, die Dachlamellen 19a sowie die streifenförmigen Lamellen 20a sind aus der y-z-Ebene der flächigen Dreiecksstruktur 4 in Richtung der x-Achse ausgewinkelt und entsprechend die Leiterstreifen 15b, die Dachlamellen 19b sowie die streifenförmigen Lamellen 20b sind in Richtung der negativen x-Achse ausgewinkelt, so dass eine räumliche Antennenstruktur gebildet ist.

Fig. 14:

Einbausituation gemäß Fig. 13 jedoch mit Blick auf die Anordnung in Fahrtrichtung.

Fig. 15:

Einbausituation von zwei Breitband-Monopolantennen 0 und 0a gemäß Fig. 14 in Fahrtrichtung hintereinander unter einer gemeinsamen Abdeckhaube 32 bestehend aus Oberband-Monopol 1 bzw.1a und Unterband-Monopol 2 bzw.2a mit jeweils einer ringförmigen Satellitenempfangsantenne 25a bzw. 25b am Fußpunkt der Breitband-Monopolantenne 0 bzw.0a.

Fig. 16:

Breitband-Monopolantenne 0 wie in Fig. 2, wobei die elektrisch leitende Struktur 33 durch die metallische Beschichtung einer Leiterplatte gegeben ist und die Leiterplatte mit ihrer Beschichtung ungefähr gemäß den Umrissen der Breitband-Monopolantenne 0 , dargestellt durch die Schnittlinien der dielektrischen Platte 34, gestaltet ist.

Fig. 17:

Breitband-Monopolantenne 0 wie in Fig. 2, 3, 5, 7, 8, 9, 10, jedoch mit einem mit der Dachkapazität 10 verbundenen Koppelleiter 35 als Ergänzung des Unterband-Monopols 2 zur Verbesserung der Impedanz-Anpassung an der Antennenanschlussstelle 3 am unteren Frequenzende des Unterbandes der Breitband- Monopolantenne 0. Die Verkopplung des Koppelleiters 35 am seinem unteren Ende mit der leitenden Grundfläche 6 ist wahlweise durch galvanischen Anschluss bzw. über ein zweipoliges verlustarmes Koppelnetzwerk 36 gestaltet.

The invention will be explained in more detail below with reference to exemplary embodiments. The accompanying figures show in detail:

Fig. 1:

Frequency ranges according to the LTE mobile radio standard as an example for two frequency bands separated by a frequency gap in the decimeter wave range with a frequency range between 698 and 960 MHz as a subband U and a frequency range between 1460 MHz and 2700 MHz as the upper band O above a frequency gap

Fig. 2:

Two-dimensional broadband monopole antenna 0 over the electrically conductive base 6 and formed at the base antenna connection point 3 with standing on top flat triangular structure 4 as a top band monopoly 1 and the roof capacity 10, which two conductor strips 15 with meander-shaped expression 24 with the triangular structure 4 to Formation of the subband monopoly 2 are connected. The structure of the broadband monopole antenna 0 can be holistically punched or cut from sheet metal, for example.

3:

Broadband monopole antenna 0 as in Fig. 2 , combined with a concentric with the top of the flat triangular structure 4 concentrically shaped, annular satellite receiving antenna 25. To further increase the inductive effect of the conductor strip 15 further meandering shapes 24 are formed by way of example.

4:

Example of a conductive foil or sheet produced by punching or cutting structure with the frequency response of an electrical parallel resonant circuit 29 in the conductor strip 15 to design the frequency-selective separation of the sub-band monopole 2 from the upper band monopole 1. The parallel resonant circuit 29 is by interdigital structure 26 as a parallel capacitance 27th and the conductor loop is formed as a parallel inductor 28.

Fig. 5:

Two-dimensional broadband monopole antenna 0 as in Fig. 2 and 3 wherein the planar triangular structure 4 of the upper band monopole 1 is designed by strip-shaped lamellae 20 arranged in a fan-like manner in the triangular plane and running together at the lower triangular tip. The lamellae which are connected to one another exclusively via the triangle tip 20 cause the electromagnetic decoupling of the upper band monopole 1 from the annular satellite receiving antenna 25th

6a:

Fluctuation of the antenna gain over the azimuth angle Phi of the satellite receiving antenna 25 in dBi in the presence of the flat triangular structure 4 as a closed electrically conductive surface.

Fig. 6b:

As in Fig. 6a however, with triangular structure 4 formed by fan-shaped, strip-like lamellae 20. The azimuthal fluctuations are shown in each case for the zenith angle theta (angle with respect to the vertical, ie z-axis) 20 °, 40 ° and 60 °.

Fig. 7:

Monopole antenna as in Fig. 4 with annular satellite receiving antenna 25, however, to improve the electromagnetic decoupling between this and the lower band monopole 2, the roof capacity 10 forming flat rectangular structure 16 by vertically separated from each other, but at its upper end via a remaining strip 31 contiguous strip-shaped roof blades 19 is formed.

Fig. 8:

Monopole antenna as in Fig. 7 , but with only a self-supporting conductor strip 15 with greater sheet thickness in favor of special mechanical rigidity and to achieve the necessary own inductance of the conductor strip 15 with a corresponding plurality of meandering shapes 24th

Fig. 9:

Monopole antenna as in Fig. 7 , but formed with a cone-shaped and standing on top instead of the flat triangular structure Highband monopoly 1 for increasing the bandwidth in the upper band. The electrically conductive conical surface is indicated by dots.

Fig. 10:

Upper-band monopoly 1wie in the Fig. 5 . 7 and 8th However, wherein the converging fan-like in the lower triangular tip strip-like fins 30 of the upper band monopoly 1 are in the way out of the plane of the flat triangular structure 4 that they are approximately like the generatrices of a according to Fig. 8 on the top of standing cone with circular or elliptical cross section.

Fig. 11:

Top view of an antenna according to the in Fig. 10 indicated section line AA 'to clarify the course of the fan-like strip-shaped strips 30, 30a, 30b. The annular satellite receiving antennas 25a and 25b are indicated by broken lines.

Fig. 12:

Maximum value of the azimuthal fluctuation of the antenna gain in dBi with closed electrically conductive cone sheath and with a cone sheath formed from strip-shaped lamellae 20 as a function of the zenith angle (angle with respect to the z-axis).

Fig. 13:

Installation situation of a broadband monopole antenna under a cover 32 with a view to the antenna transverse to the direction of travel (y-direction) together with an annular satellite receiving antenna 25. The black highlighted and marked with a) ladder parts are the conductor strips 15a, the roof lamellae 19a and the strip-shaped lamellae 20a are selected from the yz plane of the flat triangular structure 4 in the direction of the x-axis, and accordingly the conductor strips 15b, the roof lamellae 19b and the strip-like lamellae 20b are in the direction of the negative x-axis, so that a spatial antenna structure is formed.

Fig. 14:

Installation situation according to Fig. 13 but with a view to the arrangement in the direction of travel.

Fig. 15:

Installation situation of two broadband monopole antennas 0 and 0a according to Fig. 14 in the direction of travel behind each other under a common cover 32 consisting of upper band monopole 1 bzw.1a and subband monopoly 2 bzw.2a each having an annular satellite receiving antenna 25a and 25b at the base of the broadband monopole antenna 0 bzw.0a.

Fig. 16:

Broadband monopole antenna 0 as in Fig. 2 wherein the electrically conductive structure 33 is given by the metallic coating of a printed circuit board and the printed circuit board is designed with its coating approximately according to the contours of the broadband monopole antenna 0, represented by the cut lines of the dielectric plate 34.

Fig. 17:

Broadband monopole antenna 0 as in Fig. 2 . 3 . 5 . 7 . 8th . 9 . 10 but with a coupling line 35 connected to the roofing capacitor 10 as a supplement to the subband monopole 2 for improving the impedance matching at the antenna connection point 3 at the lower frequency end of the subband of the broadband monopole antenna 0. The coupling of the coupling conductor 35 at its lower end with the conductive base 6 is designed either by galvanic connection or via a two-pole low-loss coupling network 36.

A particular advantage of a broadband monopole antenna 0 according to the invention is the property that the measurable at the antenna connection point 3 impedance broadband in the vicinity of prescribed for antenna systems for vehicles standard impedance of Z0 = 50 ohms can be made largely problem-free. From this results further the economic advantage that a matching network between the antenna connection point 3 in the base of the broadband monopole antenna and the secondary circuit usually accounts for or at least can be designed particularly low expenditure.

The following is an example of a broadband monopole antenna 0 according to the invention for the two separated by a frequency gap frequency ranges according to the in Fig. 1 illustrated sub-band U and the upper band O explained. The broadband monopole antenna in its flat designed basic version in Fig. 2 is essentially formed of a subband monopole 2 for covering the sub-band with a required antenna height 9 in combination with a top band monopole 1 with the top band monopole 8 with a common antenna connection point 3. To avoid an excessive effective antenna height 9 in the frequency range of the upper band of the lower band monopole 2 is designed in the frequency range of the upper band inductively high impedance conductor strips 15 with narrow stripline width 14 in conjunction with a roofing capacity 10. The latter is essentially embodied as a flat rectangular structure 16 and designed with a large horizontal extension 23 compared to the vertical extension 22.

In order to meet the demand for the simplest and most economical method of production, the monopole antenna according to the invention is made, for example, from an electrically conductive foil 33 (FIG. Fig. 16 ) designed as a contiguous, electrically conductive structure extending in a plane substantially perpendicular to the conductive base 6 level extending. In this case, it turns out to be a particularly advantageous embodiment of the invention for the self-supporting, electrically conductive structure, which is in particular integrally formed to use electrically conductive sheet or a self-supporting electrically conductive foil, resulting in the entire broadband monopole antenna 0 produce a mechanically self-supporting structure leaves. This structure can be exemplified by a punching operation or by a controlled cutting operation, for example produced by controlled laser cutting. In this case, the production of a punching tool will prove to be economically advantageous in particularly large numbers, because the monopole antenna can be multiplied by automated punching operations extremely cost. On the other hand, with smaller quantities the computer-controlled laser cutting can be more economical. Fabrication of the broadband monopole antenna 0 of sheet metal offers the particular advantage of metallic rigidity, which is of particular importance for use as a vehicle antenna. A particular advantage of this flat design structure is their negligible wind resistance to call, if it is designed to extend in an advantageous manner in a plane whose normal is oriented perpendicular to the direction of travel of the vehicle.

Furthermore, in an advantageous embodiment of the invention, the electrically conductive structure can be selected by the metallic coating of a dielectric plate, that is to say a printed circuit board. It should be noted, however, that a coming into consideration for economic reasons material for the circuit board in the decimeter wave range is lossy, so that according to the invention can be provided to print the structure of the broadband monopole antenna 0 on the circuit board in a known per se, but these for example, according to the contours of the broadband monopole antenna 0 with slight protrusion to keep the course of electric field lines in the lossy dielectric plate as small as possible. The trimming of the dielectric plate along the dot-dashed lines 34 is shown in FIG Fig. 16 shown. This form of representation is particularly advantageous in complicated geometric structure of the broadband monopole antenna 0, because the cutting lines 34 can be made less finely following the geometric structure and therefore require a less expensive punching tool.

In a broadband monopole antenna 0 of this kind is for example for the adaptation of antenna systems to the prescribed for vehicles standardized Impedance of Z0 = 50 ohms in the above-mentioned sub-band VSWR (voltage standing wave ratio) required <3. This value can in principle be achieved in an antenna according to the invention in its complete embodiment at the antenna connection point 3 with an antenna height 9 of 6 cm. The properties of the sub-band monopole 2 are essentially determined by its antenna height 9 and the size of the flat roof capacity 10, the horizontal extent 23 with about 6cm much larger, that is designed at least three times larger than the vertical extent 22. A much larger Although the vertical extent 22 increases the capacitance value of the roof capacitance 10, it reduces the effective height of the subband monopole 2, which, in contrast to the capacitance value, squares into the formation of the frequency bandwidth of the subband monopole 2.

The formation of the upper band monopole 1 is essentially given by the flat triangular structure 4, provided that the inductive effect of the conductor strips 15 with narrow stripline width 14 for the separation of radio signals in the upper band of the roof capacity 10 is sufficiently large. This is usually given with a stripline width of less than or equal to 7 mm. To increase this separating effect can be inventively provided to provide the conductor strips 15 with meandering shapes 24. Of course, the functional division of the wideband monopole antenna 0 into the subband monopole 2 and the top band monopole 1 is not strictly seen. Rather, the transition between the effects is fluent and the subdivision is to be understood as a description of the main effects in the two frequency ranges. The mode of action of the upper band monopole 1 located above the conductive base surface 6 is essentially given by the design of the flat triangular structure 4. In the interest of a particularly broadband behavior, an apex triangular structure 4 with a triangular opening angle 12 is provided in this embodiment, the tip of which is connected to the antenna connection point 5. Through this is together with the ground connection point 7 on the conductive base 6, the antenna connection point 3 for the broadband monopole antenna 0 is formed. The height of the baseline of the flat triangular structure 4 above the conductive base 6 essentially forms the effective upper band monopole height 8, by which the frequency response of the upper band monopole 1 is substantially determined. For reasons of the vertical radiation pattern for communication with terrestrial transmitting and receiving stations, the upper band monopole height 8 at the upper frequency limit of the upper band should not be greater than about 1/3 of the free space wavelength at this frequency. As a triangle opening angle 12, values between 30 and 90 degrees have proved favorable. For example, the resulting wideband triangular structure allows it to meet the often-demanded impedance matching requirement at the VSWR <2.5 in the upper band frequency range.

According to the task with regard to the required mechanical stability for holding the roofing capacity 10 by narrow conductor strips 15, it is inventively provided to perform this mechanically sufficiently stiff. In a particularly advantageous embodiment of a broadband monopole antenna 0 according to the invention made of stamped or cut sheet metal, a frame structure 11 is designed to achieve a particular rigidity. In this case, the frame structure 11, as in the Fig. 2 and 3 illustrated, formed from two spaced apart 13 spaced narrow conductor strips 15, the baseline of the flat triangular structure 4 and the flat rectangular structure 16 of the roof capacity 10.

In a further advantageous embodiment of the invention, the electrically conductive structure consists of a material of particular rigidity, for example, thin sheet metal. Using such materials, the broadband monopole antenna 0 can be used with only one conductor strip 15, as in FIG Fig. 8 represented, designed. In the interest of mechanical stability for this, however, then to provide a larger stripline width 14. In order to design a sufficiently large inductive effect of the conductor strip 15, a plurality of meander-shaped expression 24 is generally necessary.

To fine-tune the interaction between the lower band monopole 2 and the upper band monopoly 1, it is provided in an advantageous embodiment of the invention to introduce a switching element with the operation of a parallel resonant circuit 28 in the conductor strips 15. This parallel resonant circuit is used to support the frequency-selective separation of the sub-band monopole 2 of signals in the upper band. According to the invention, the parallel resonant circuit 28, as in FIG Fig. 4 In each case, a parallel capacitance 27 designed as an interdigital structure 26 and a parallel inductance 28 embodied as a strip conductor can also be included. This switching element can also be punched or cut from sheet metal into the design of the mechanically self-supporting broadband monopole antenna 0 via the conductor strips 15.

To further improve the frequency bandwidth of the upper band monopole 1 is provided in an advantageous embodiment of the invention for this a three-dimensional structure, which is formed from the two-dimensional structure in such a way that instead of the flat triangular structure 4, an approximately conical structure is sought. The form of such a monopoly is in Fig. 9 indicated by the conical monopole 18 with electrically conductive lateral surfaces. In this case, the economically advantageous manufacturability of punched or cut sheet should be maintained. According to the invention, it is therefore provided, the flat triangular structure 4 by in the lower triangular tip fan-like running together strip-shaped fins 20, as in Fig. 5 shown to execute. By diffusing the slats 20 so that they lie on the lateral surface of a cone standing on the top, these become conical slats 30 and the conical monopole 18 in Fig. 9 is modeled in terms of its effect as a high band monopoly 1. This is in Fig. 10 detailed represented and also according to the section AA 'in Fig. 11 seen as a plan view. In Fig. 11 is the in Fig. 10 indicated cone cross section elliptical and thus the cone opening angle 17a ( Figure 10 ) in the x direction due to the requirements with respect to the aerodynamic properties of the antenna chosen smaller than the cone opening angle 17 in the direction of travel of the vehicle (y-direction).

Due to the limited space available in vehicle antennas is the essential requirement for smallness and in particular to minimize the floor plan of the antenna. In particular for satellite radio services and antennas for other radio services in a confined space, the deformation of the directional diagram of the satellite antenna due to the radiation coupling between the antennas is problematic. This problem exists even if - as in the Fig. 3 . 5 . 7 . 8th . 10 . 11 and 15 - At least one concentric with the antenna connection point 3 of a broadband monopole antenna 0 arranged annular satellite receiving antenna 25, 25a, 25b is present. For this exists z. For example, according to the standard of satellite broadcasting SDARS in the zenith angle range (angle to the z-axis), for example, between 0 and 60 degrees the strict demand for an antenna gain, which depending on the operator for circular polarization of constant eg 2 dBi or eg 3 dBi at a azimuthal fluctuation of less than 0.5 dB. In Fig. 3 a ring-shaped satellite receiving antenna 25 is disposed concentrically with the antenna junction 3 of a broadband monopole antenna 0. In the formation of the upper band monopoly 1 as a closed planar structure, the result in Fig. 6a illustrated azimuthal variations in the antenna gain of the satellite receiving antenna 25 at about 2.3 GHz. At a zenith angle theta of 40 degrees, the gain variation of 0.6 dBi is already above the tolerance value and can not be tolerated at 60 degrees with 1.2 dBi. In this context, the design of the triangular structure 4 is made up of lamellae 20 that converge at the top in a fan-like manner, as in FIG Fig. 5 , more favorable than a closed flat triangular structure 4 according to Fig. 3 , This advantage of slight influence on the radiation properties of the satellite receiving antenna 25 is particularly pronounced in the design of the upper band monopoly 1 of cone blades 30. This is an example of the in Fig. 6b under different zenith angles shown azimuthal fluctuations of the antenna gain, which even at a zenith angle of 60 degrees has an experimentally barely detectable variation of 0.07dB. The difference between the influences of the upper band monopole 1 in the form of a closed electrically conductive cone shell and a cone of cone blades 30 on the azimuthal fluctuation of the antenna gain of the satellite receiving antenna 25 as a function of the zenith angle in degrees continues to be impressive Fig. 12 out. This shows the azimuthal gain variation in dB for a closed conductive cone sheath (upper graph) and a conical shroud of lamellae (lower graph). By avoiding ring currents, which are caused by the currents on the satellite antenna 25 on a conductive cone sheath by radiation coupling of the two antennas, this is without influence on the radiation properties of the satellite receiving antenna 25 in the design of the cone sheath of cone blades 30 of the upper band monopoly.

In order to perfect also the electromagnetic decoupling between the satellite receiving antenna 2 and the roofing capacity 10 forming rectangular structure 16 of the sub-band monopoly 2, this according to the invention substantially vertically vertically separated from each other running, but at its upper end over a remaining strip 31 related strip-shaped roof blades 19, as in the Fig. 7 . 8th and 9 shown, executed. In this case, the strip width 21 should not be greater than 1/8 of the free space wavelength of the highest frequency in the upper band.

Often it is intended to accommodate a broadband monopole antenna 0 under a cover 32 made of plastic material, as shown in FIG Fig. 13 with view across the direction of travel (x-direction) and in Fig. 14 with view in direction of travel (y-direction) is shown. Hereby, the in Fig. 14 visible extension of the cover 32 transversely to the direction of travel the possibility of further spatial design of the originally areal manufactured broadband monopole antenna 0 with the advantages of increasing the bandwidths of both monopolies 1 and 2. This is expressed by a better configurability of the antenna impedance with respect to the VSWR Value at the antenna connection point 3 off. This gives the possibility to be able to largely do without a matching network.

In order to design the spatiality of the sub-band monopole 2, according to the invention, the strip-shaped roof louvers 19 of the roofing capacity 10, which are connected at their upper end over a remaining strip, can be selected in such a way that they are arranged in the projection on a plane lying transversely to the direction of travel , These are alternately the in Fig. 13 black-filled marked roof slats 19a in the x direction and the white filled filled roof slats 19b deflected in the opposite direction in the negative x-direction, so that in the projection in Fig. 13 visible V-shaped structure is given. Due to the lateral deflection transversely to the direction of travel or to the plane of the triangular structure or the strip 31, the capacity value of the roofing capacity 10 is greater. This leads to an increase in the bandwidth of the subband monopole 2 and facilitates compliance with the impedance matching condition at the VSWR value to be maintained.

In analogy to the design of a cone with an elliptical cross section through corresponding deflection of the slats 20, 20a, 20b of the upper band monopole 1 in FIG Fig. 11 can in a further advantageous embodiment of the invention, the lamellae 20, 20a, 20b about the inner boundary of the cover 32 following be ausgeknelt following. That is, the strip-shaped fins 20, 20a, 20b of the upper band monopole 1 converging in the lower triangular tip become successively out of the plane of the triangular flat structure 4 in the manner bent, that they are arranged in the projection on a plane transverse to the direction of travel about V-shaped. As described above for the roof slats 19, 19a, 19b, the slats 20 are in such a way dignified that the in Fig. 13 fills 20 a marked in black in the x direction and the lamellae 20 b marked filled in white are deflected in opposite directions in the negative x direction, so that the fins projected in the projection in FIG Fig. 14 visible V-shaped structure is given. Again, this measure serves to increase the frequency bandwidth of the upper band monopole 1 with the associated advantage in the realization of the impedance matching in the antenna base. In the realization of antennas, as in the Fig. 13 . 14 and 15 are shown, it has proved to be advantageous, the at least two conductor strips 15, 15 a, 15 b in the manner spatially execute that they are z. B. by waving at half antenna height 9 by about 45 °, or -45 ° with respect to the y-axis, the available horizontal expansion transverse to the direction within the cover 32 fill. The conductor strips can thus be shaped so that they extend as far as possible along the inner wall of the cover 32.

In general, it can be observed that the spatial design according to the invention, starting from the described two-dimensional design of the monopole antenna 0 according to the invention, is additionally advantageous with respect to the problem of impedance matching over large frequency ranges. Thus, the special advantage associated with the present invention is that this spatially designed antenna can be punched or cut from a sheet-like electrically conductive structure (sheet or foil) and designed by simple subsequent bending as described above.

It is also possible, two broadband monopole antennas 0 and 0a according to the invention under a cover 32 in the direction of travel behind each other, as in Fig. 15 to install. It has been found that the annular satellite antennas 25 at the base of a broadband monopole antenna 0 by the presence of other broadband monopole antenna 0a undergoes no disturbing influence on their radiation properties. Conversely, this also applies with regard to the effect of the broadband monopole antenna 0 on the satellite antennas 25a at the base of the broadband monopole antenna 0a.

In a further advantageous application of a broadband monopole antenna 0 according to the invention, this is supplemented by a further, same to this same broadband monopole antenna in a known per se to a dipole. In this case, the mirror image of the broadband monopole antenna 0 is replaced at the conductive base 6 with their omission by this further broadband monopole antenna in such a way that a symmetrical to the plane of the conductive surface 6 dipole is given. In this case, the symmetrical antenna connection point of this dipole is formed between the antenna connection point 5 of the broadband monopole antenna 0 and the antenna connection point 5 which is mirrored to the conductive base 6.

In a further advantageous application of a broadband monopole antenna 0 according to the invention is in support of the impedance matching at the lower frequency end of the lower band connected at its upper end with the roof capacity 10 and the conductive base 6 extending towards coupling ladder 35 is present, which at its lower end with the conductive base 6 is coupled. This coupling conductor 35 is in Fig. 17 illustrates and supplements the subband monopole 2 in such a way that it is possible to improve the impedance matching at the antenna connection point 3, at the lower frequency end of the subband. By designing the coupling conductor width 37 or by partially meandering expression 24 of the coupling conductor 35, its inductive effect can be suitably adjusted to the requirements for the impedance matching (eg VSWR <3). With sufficient inductively high-impedance design of the Koppleiters 35 this is ineffective in the frequency range of the upper band monopoly 1 in such a way that its radiation properties are not affected.

It is often advantageous to produce the coupling of the coupling conductor 35 with the conductive base 6 at its lower end galvanically or capacitively. In particular, with a particularly small antenna height 9, the impedance matching can be further improved in that this coupling of the coupling conductor 35 with the conductive base 6 via a two-pole coupling network 36, consisting of reactive elements occurs. In a special case, it may also be advantageous to make the coupling network 36 slightly lossy in order to maintain a specific VSWR value at the lower frequency end of the lower band while accepting the smallest possible radiation losses.

List of terms

• Broadband monopole antenna 0.0a
• High-band monopoly 1, 1 a
• Subband monopole 2, 2a
• Antenna connection point 3
• Triangular structure 4
• Antenna connection point 5
• conductive base 6
• Ground connection point 7
• Upper Band Monopoly Height 8
• Antenna height 9
• Roof capacity 10
• Frame structure 11
• Triangle opening angle 12
• Distance 13
• Stripline width 14
• Conductor strips 15, 15a, 15b
• Rectangular structure 16
• Cone opening angle in y-direction 17
• Cone opening angle in the x direction 17a
• conical monopole 18
• Roof lamella 19, 19a, 19b
• strip-shaped slats 20
• Strip width 21
• Vertical extension 22
• Horizontal expansion 23
• meandering form 24
• annular satellite receiving antenna 25, 25a, 25b
• Interdigital structure 26
• Parallel capacity 27
• Parallel inductance 28
• Parallel resonant circuit 29
• Cone blade 30, 30a, 30b
• remaining strip 31
• Cover 32
• electrically conductive foil 33
• Cutting lines of the dielectric plate 34th
• Coupling conductor 35
• Coupling network 36
• Coupling conductor width 37

Claims (15)

Vertical broadband monopole antenna for vehicles for two frequency bands separated frequency bands, namely a lower band (U) for lower frequencies and an upper band (O) for higher frequencies, both located in the Dezimeterwellenbereich, for transmission and / or reception with terrestrial emitted vertically polarized radio signals over a substantially horizontal conductive base (6) as a vehicle mass with an antenna connection point (3) located in the monopole base, comprising the following features: - The broadband monopole antenna (0) is made of a self-supporting electrically conductive structure which is oriented over the base (6) substantially perpendicular to this; - The electrically conductive structure comprises at the lower end of the broadband monopole antenna (0) a truncated triangle structure (4) with a substantially horizontally oriented baseline, the tip of which forms an antenna connection point (5) of the antenna connection point (3); - The electrically conductive structure comprises adjacent to the upper end of the broadband monopole antenna (0) including a substantially rectangular structure (16) running roof capacity (10); - The triangular structure (4) and the rectangular structure (16) are connected by at least one conductor strip (15, 15a, 15b) for the separation of radio signals in the upper band inductively high impedance. Broadband monopole antenna (0) according to claim 1,
characterized in that
the electrically conductive structure has at least two spaced conductor strips (15), whereby a frame structure (11) consisting of the triangular structure (4), the rectangular structure (16) and the conductor strip (15) is formed. Broadband monopole antenna (0) according to claim 1 or 2,
characterized in that
the conductor strip or strips (15, 15a, 15b) contain meander-shaped forms (24) for the frequency-selective separation. Broadband monopole antenna (0) according to at least one of claims 1 to 3,
characterized in that
the inner angle (12) at the top of the triangular structure (4) is approximately between 30 and 90 degrees. Broadband monopole antenna (0) according to at least one of claims 1 to 4,
characterized in that
the triangular structure (4) is formed by strip-shaped lamellae (20) arranged in a fan-like manner in the triangular plane and converging in the tip. Broadband monopole antenna (0) according to claim 5,
characterized in that
over the conductive base (6) at least one concentric with the antenna connection point (3) arranged annular satellite receiving antenna (25, 25a, 25b) is present. Broadband monopole antenna (0) according to at least one of claims 1 to 6,
characterized in that
in order to improve the electromagnetic decoupling, the rectangular structure (16) is formed essentially by vertical electrically conductive mutually separated, but at its upper end over a remaining strip (31) contiguous strip-shaped roof blades (19, 19a, 19b) is formed. Broadband monopole antenna (0) according to at least one of claims 5 to 7,
characterized in that
the strip-like lamellae (30, 30a, 30b) converging in the tip are bent out of the plane of the triangular structure (4) in such a way that they essentially run on the lateral surface of a tip-shaped cone with a circular or elliptical cross-section. Broadband monopole antenna (0) according to claim 7,
characterized in that
the roof lamellae (19, 19a, 19b) are sequentially in opposite directions in the manner that they are arranged in the projection on a to the strip (31) transversely extending plane V-shaped. Broadband monopole antenna (0) according to at least one of claims 5 to 9,
characterized in that
the lamellae (20a, 20b) converging in the tip are successively counteracted in the opposite direction from the plane of the triangular structure (4) in such a way that they are arranged in the projection on a plane V-shaped transversely to the triangular structure (4). Broadband monopole antenna (0) according to at least one of claims 1 to 10,
characterized in that
the broadband monopole antenna (0) is arranged under a covering hood (32) and that the at least one conductor strip (15, 15a, 15b) is guided at least partially and in particular as far as possible along the inner wall of the covering hood. Broadband monopole antenna (0) according to one of claims 1 to 11,
characterized in that
the electrically conductive structure consists of electrically conductive sheet metal and only a self-supporting conductor strip (15) is present whose stripline width (14) is in particular less than or equal to 7 mm. Broadband monopole antenna (0) according to at least one of claims 1-7 and 12,
characterized in that
the electrically conductive structure is given by metallic coating (33) on a printed circuit board whose contour substantially follows the contours of the electrically conductive structure of the broadband monopole antenna (0). Broadband monopole antenna (0) according to at least one of claims 1 to 13,
characterized in that
the mirror image of the broadband monopole antenna (0) at the conductive base (6) is replaced with its omission by another same broadband monopole antenna in such a way that to the plane of the conductive base (6) symmetrical dipole is given and a symmetrical antenna connection point of this dipole between the antenna connection point (5) of the broadband monopole antenna (0) and - this accordingly - at the conductive base (6) mirrored antenna connection point (5) of the further broadband monopole antenna is formed. Broadband monopole antenna (0) according to at least one of claims 1 to 14,
characterized in that
a coupling conductor (35) connected at its upper end to the roofing capacitance (10) is present, which is coupled at its lower end to the conductive base (6)

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