EP2226895B1 - Antenna for receiving satellite radio signals emitted circularly in a polarisation direction - Google Patents

Description

The invention relates to an antenna for receiving circularly in a direction of rotation of the polarization of radiated satellite radio signals

US 5 751 252 A discloses an antenna for receiving radio signals radiated circularly in a direction of rotation of the polarization, at least two emitters connected to an antenna connection, each linearly polarized in a spatial direction and connected via a matching and phase shifter network. One of the radiators is formed as a loop antenna of a conductor loop, which has at least one bridged by a capacity interruption for their electrically effective shortening. In cooperation with the interruption of the conductor loop, a loop antenna connection point for feeding in a ring current is formed on the loop antenna. The other of the two radiators with its radiator junction and the loop antenna junction of the loop antenna are connected via the matching and phase shifter network, which is designed so that in reciprocal operation of the antenna, the radiation fields of the loop antenna and the other radiator in the far field of the antenna with different phases are superimposed. Here, the further radiator has a polarization oriented essentially perpendicular to the polarization of the loop antenna and a substantially orthogonal phase in the far field.

In particular, in satellite broadcasting systems, the economics of both the transmitted power emitted by the satellite and the efficiency of the receiving antenna are particularly important. Satellite radio signals are transmitted due to polarization rotations in the transmission path usually with circularly polarized electromagnetic waves. In many cases, program contents are transmitted, for example, in frequency bands closely adjacent to each other separated frequency bands, as in FIG. 1 is shown. This is done in the example of SDARS satellite broadcasting at a frequency of about 2.33 GHz in two adjacent frequency bands each with a bandwidth of 4 MHz with a spacing of the center frequencies of 8 MHz. The signals are emitted by different satellites with a circularly polarized in one direction electromagnetic wave. As a result, circularly polarized antennas are used to receive in the corresponding direction of rotation. Such antennas are for example off DE-A-4008505 and DE-A-10163793 known. This satellite broadcasting system is additionally supported by the regional emission of terrestrial signals in another, arranged between the two satellite signals frequency band of the same bandwidth. Similar satellite broadcasting systems are currently being planned.

The from the DE-A-4008505 known antenna is constructed on a substantially horizontally oriented conductive base and consists of crossed horizontal dipoles with V-shaped downwardly inclined, consisting of linear ladder parts Dipolhälften which are mechanically fixed at an azimuthal angle of 90 degrees to each other and at the top of a on the conductive base surface mounted linear vertical conductor are mounted. The from the DE-A-10163793 known antenna is also constructed on a generally horizontally oriented conductive base and consists of crossed azimuthally mounted at 90 ° to each other frame structures. In both antennas, the mutually spatially offset by 90 ° antenna parts in the electrical phase are interconnected shifted by 90 ° to each other to generate the circular polarization.

Both types of antennas are particularly suitable for the reception of satellite signals emitted by high-flying satellites - so-called HEOS. However, the signals of geostationary satellites - known as GEOS - are incident at lower elevation angles in regions remote from the equatorial zones. The reception of such signals is possible with the two antenna types mentioned only with comparatively small antenna gain and therefore problematic due to the - due to economic reasons - weak transmitter power of the satellites. Added to this is the difficulty of designing antennas with a smaller height, which is imperative especially for mobile applications. As further antennas of this type are known in the prior art patch antennas, which are also less efficient in terms of the reception at a low elevation angle.

The object of the invention is therefore to provide an antenna with low height, which is particularly suitable for the high-power reception of low elevation angles incident circularly polarized in one direction emitted satellite signals and with which the signal-noise ratio can be optimally designed during one.

This object is solved by the features of the independent claims.

Furthermore, an antenna of this type is advantageously combined in a common space with antenna structures, which also receive a circularly polarized field and which together with these antenna structures in an antenna diversity system or a system for digital beam shaping Azimuthal beam swing can be used. This combination is particularly interesting for receiving systems in which signals from GEO satellites and HEO satellites in closely adjacent frequency bands are to be received equally. The antenna combination is characterized by a particularly low mutual coupling of the antennas with each other.

For the production of antennas, which from the DE-A-4008505 and the DE-A-10163793 Problems arise from the fact that the individual antenna parts are placed on crossed at a right angle planes and these levels in addition to the conductive ground plane stand vertically. Such antennas can not be produced sufficiently economically, as desired, for example, for use in the automotive industry. This applies in particular to the frequencies of several gigahertz common in satellite antennas, for which a particularly high mechanical accuracy is necessary in the interest of polarization R unit, the impedance matching and the reproducibility of the directional diagram in the series production of the antennas. The required in antennas according to the present invention manufacturing tolerances can be maintained in an advantageous manner much easier. Another very important advantage of the present invention results from the property that in addition to the horizontally polarized loop antenna 14 at least one further radiator 7 is present, which has a polarization oriented perpendicular to the polarization of the loop antenna 14. In the presence of terrestrially vertically polarized signals, this emitter can advantageously also be used to receive these signals.

The distribution of the currents on an antenna in receive mode depends on the terminator at the antenna junction. In contrast, in the transmission mode, the distribution of the currents on the antenna conductors relative to the supply current at the antenna connection point is independent of the source resistance of the supplying signal source and is thus clearly linked to the directional diagram and the polarization of the antenna. Because of this uniqueness in connection with the law of reciprocity, according to which the radiation properties - such as directional diagram and polarization - are identical in the transmission mode as in the receiving mode, the object of the invention with respect to polarization and radiation patterns on the basis of the design of the antenna structure for generating corresponding currents in the transmission mode of Antenna solved. Thus, the object of the invention for the receiving operation is solved. All considerations made below about currents on the antenna structure and their phases or their phase reference point thus refer to the reciprocal operation of the receiving antenna as a transmitting antenna, unless the receiving mode is specifically addressed.

• Fig. 1: Frequenzbänder zweier Satelliten-Rundfunksignale mit in derselben Drehrichtung zirkular polarisierter Ausstrahlung in dichter Frequenznachbarschaft;
• Fig. 2: Antenne mit der Schleifenantenne 14 über leitender Grundfläche 6 mit horizontaler Polarisation und mit einem als Stabantenne ausgebildeten Monopol 7a als weiteren Strahler 7 im Zentrum Z der horizontalen Schleifenantenne 14 für den Empfang vertikal polarisierter Felder mit Anpassnetzwerk 25 und Phasenschieber-Netzwerk 23 zur phasenunterschiedlichen Überlagerung des Empfangs der horizontal und vertikal polarisierten Feldanteile im Summations-Netzwerk 53.
• Fig. 3: Antenne wie in Figur 2, jedoch mit einem aus mehreren rotationssymmetrisch zum Zentrum Z angeordneten Monopolen 7a - deren Empfangssignale im gemeinsamen Phasenbezugspunkt B zusammengefasst sind - als weiterer Strahler 7.
• Fig. 4: Antenne wie in Figur 2, jedoch mit einer Schleifenantenne 14 mit zwei aus Symmetriegründen einander gegenüberliegend gebildeten Antennenanschlussstellen 3a, 3b mit einem im Zentrum Z angeordneten Monopol 7b mit einer aus horizontalen Leiterelementen rotationssymmetrisch zum Zentrum Z gebildeten Dachkapazität als weiteren Strahler 7.
• Fig. 5: Antenne wie in Figur 4, wobei jedoch Leiterteile 14a der Schleifenantenne 14 zur Bildung der rotationssymmetrischen Dachkapazität 12 herangezogen sind.
• Fig. 6: Antenne nach dem Funktionsprinzip der Antenne in Fig. 2, jedoch mit einer vertikalen Zuleitung 26 zur Speisung der Schleifenantenne 14, wobei die Zuleitung 26 zusätzlich einen vertikalen Monopol 7a und die Schleifenantenne 14 eine Dachkapazität 12 des Monopols 7a bildet.
• Fig. 7: Antenne nach dem Funktionsprinzip der Antenne in Fig. 6, jedoch mit einer als Quadrat mit dem Zentrum Z gestalteten Schleifenantenne 14.
• Fig. 8: nicht beanspruchte Antennenanordnung mit phasenunterschiedlicher Überlagerung der Empfangsspannungen aus den horizontalen und den vertikalen elektrischen Feldanteilen einer Schleifenantenne 14 und einer durch die vertikale Zweidrahtleitung 26 gebildeten Monopolantenne 7.
• Fig. 9 : Antenne wie in Fig. 2, wobei anstelle diskreter Kapazitäten die Kapazität 16, die jeweils aus einer Schaltung aus mehreren Blindelementen gebildet ist, derart, dass bei unterschiedlichen Frequenzen unterschiedliche Kapazitätswerte wirksam sind.
• Fig. 10: kombinierte Antennenanordnung für getrennte Verfügbarkeit von LHCP- beziehungsweise RHCP-Signalen unterschiedlicher Satellitensignale an unterschiedlichen Antennenanschlussstellen 28a, 28b mit einem als Stabantenne ausgebildeten, vertikal polarisierten Monopol 7, einer horizontal polarisierten Schleifenantenne 14 und einem 90°-Hybridkoppler 45.
• Fig. 11: Antennenanordnung wie in Figur 10, jedoch mit einer Realisierung des Monopols 7 gemäß der Antennenanordnung in Figur 6 durch die Kombination der Wirkungen der Schleifenantenne 14 als Dachkapazität und der Zweidrahtleitung 26;
• Fig. 12: Antenne zur alternativen Auskopplung von RHCPbeziehungsweise LHCP-Signalen für Diversity-Technologien angesteuert durch einen in einem Radioempfängermodul 52 befindlichen Umschalter.
• Fig. 13: Antenne für Diversity-Technologien mit LHCP/RHCP-Umschalter 55 wie in Fig. 12, jedoch, ähnlich wie bei der Antenne in Fig. 8 ohne gesonderten Monopol 7. Der Empfang bei vertikaler Polarisation ist durch die Zweidrahteitung 26 bewirkt. Der für die Überlagerung der Empfangssignale der Schleifenantenne und des Monopols geforderte Phasenunterschied ist durch das Netzwerk 61 bewirkt.
• Fig. 14: Antenne wie in Fig. 5, jedoch mit einer gemeinsamen Strahleranschlussstelle 2 für die gemeinsame Speisung der Schleifenantenne 14 und des vertikalen Monopols mit Dachkapazität 7b.
• Fig. 15: Vertikale Richtcharakteristik des LHCP-polarisierten elektromagnetischen Feldes
  1. a) einer Antenne wie in Fig. 2 mit zirkularer Polarisation bei niedrigen Elevationswinkeln und mit azimutaler Unabhängigkeit der Phase der Strahlung.
  2. b) eines gekreuzten Strahlers 7d nach dem Stand der Technik bzw. eines Ringleitungsstrahlers 7c wie in Fig. 19 mit zirkularer Polarisation bei hohen Elevationswinkeln; wobei sich die Phase der zirkularen Polarisation mit dem azimutalen Winkel des Ausbreitungsvektors dreht
• Fig. 16:
  1. a) Vertikale Richtcharakteristik des LHCP-polarisierten elektromagnetischen Feldes einer Antenne für 2,3 GHz nach der Erfindung entsprechend Figur 18, bestehend aus einer Schleifenantenne 14 mit vertikalem Monopol 7a in Kombination mit einem Ringleitungsstrahler 7c bei Abmessungen von 3,4cm x 3,4 cm x 1,3 cm der Gesamtstruktur, wobei sich die Charakteristik aus der gleichphasigen Überlagerung der Strahlung gemäß Fig. 15a und Figur 15b für den Azimutwinkel 0° (rechts) und 180° (links) ergibt.
  2. b) Horizontale Richtcharakteristik des LHCP-polarisierten elektromagnetischen Feldes unter einem Elevationswinkel von etwa 30° mit minimaler Strahlung für den Azimutwinkel von 180°.
• Fig. 17: Antenne nach der Erfindung bestehend aus der Schleifenantenne 14 mit zwei symmetrisch angeordneten Schleifenantennen-Anschlussstellen 3a, 3b und Monopol 7b mit im Zentrum Z gekennzeichnetem Bauraum für einen gekreuzten Strahler 42 mit zirkularer Polarisation nach dem Stand der Technik und Anschlussstelle 56 zur phaseneinstellbaren Überlagerung von dessen Strahlung im Summations-Netzwerk 53 mit Hilfe des steuerbaren Phasendrehglieds 39
• Fig. 18: Antenne wie in Figur 17, jedoch anstelle eines zentral angebrachten gekreuzten Strahles 42 mit einem erfindungsgemäß neuartigen Ringleitungsstrahler 7c zur Erzeugung eines zirkular polarisierten Feldes mit azimutal abhängiger Phase mit einer durch Einspeisung an A/4 voneinander entfernten Ringleitungs-Einspeisestellen 20a, 20b von um 90° in der Phase unterschiedlichen Signalen zur Erzeugung einer umlaufenden Welle von einer Wellenlänge über den Umfang der Leitung.
• Fig. 19: Ringleitungsstrahler 7c jedoch über vier jeweils um λ/4 längs der Ringleitung versetzte Einspeisestellen 22 von in der Phase jeweils um 90° versetzten Signalen gespeist. Die Speisequellen können auf an sich bekannte Weise durch Leistungsteilung und 90°-Hybridkoppler 45 gewonnen werden.
• Fig. 20: Antenne nach der Erfindung wie in Figur 18, jedoch zur Erzeugung der fortlaufenden Leitungswelle mit einem in günstigem Abstand - bezüglich des Leitungs-Wellenwiderstands - parallel zum Ringleitungsstrahler 7c geführten λ /4-Koppelleiter 43
• Fig. 21: Antenne wie in Figur 20, jedoch mit λ/4-Richtkoppler 44. Zu einem Mikrostreifenleiter 30 ist ein λ/4-Koppelleiter 43 parallel geführt, welcher zusammen mit dem an den Ringleitungsstrahler 7c angekoppelten λ/4-Koppelleiter 43 den λ/4-Richtkoppler 44 bildet.
• Fig. 22: Antenne nach der Erfindung mit quadratisch ausgeführter Schleifenantenne 14 und einem als geschlossenen quadratischen Leitungsring mit der Kantenlänge von λ/4 gestalteten Ringleitungsstrahler 7c. Die Ankopplung an den Ringleitungsstrahler 7c erfolgt berührungslos über den rampenförmig gestalteten λ/4-Koppelleiter 57 mit der Ringleitungs-Anschlussstelle 19
• Fig. 23: Antenne nach der Erfindung mit quadratischem Ringleitungsstrahler 7c wie in Figur 22 mit einem Leistungs-Verteilnetzwerk bestehend aus in Kette geschalteten λ/4-langen Mikrostreifenleitern 30 (15a,15b,15c) zur Einspeisung an den Ecken des quadratischen Ringleitungsstrahlers 7c.
• Fig. 24: Antenne nach der Erfindung mit Schleifenantenne 14, Monopol 7a, Ringleitungsstrahler 7c und dem zusätzlichen äußeren Ringleitungsstrahler 7d, auf dem eine fortlaufende Leitungswelle von zwei Wellenlängen erzeugt ist zur Anhebung des Strahlungsgewinns durch Anhebung der Strahlungsbündelung
• Fig. 25: Kreisgruppenstrahler nach der Erfindung mit n gleichen rotationssymmetrisch um das Zentrum Z angeordneten horizontal polarisierten Strahlerelementen 59, deren Speisung jeweils im Drehsinn benachbarter Strahlerelemente sich in der Phase um jeweils 360°/n unterscheidet. Fig. 25 oben: n =4. Fig. 25 unten: n =5.
• Fig. 26: Kreisgruppenstrahler 7f gemäß einer Anordnung wie in Fig. 25 mit an den Eckpunkten eines Quadrats mit Zentrum Z angeordneten horizontal polarisierten Strahlerelementen 59 mit Zuleitungen 18 und Leistungsteiler- und Phasenschiebernetzwerk aus λ/4-langen Mikrostreifenleitern 30 mit den Teilstücken 15a, 15b, 15c.

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

• Fig. 1 : Frequency bands of two satellite broadcast signals with circularly polarized radiation in the same direction of rotation in dense frequency neighborhood;
• Fig. 2 Antenna with the loop antenna 14 over conductive base 6 with horizontal polarization and with a designed as a rod antenna monopoly 7a as a further radiator 7 in the center Z of the horizontal loop antenna 14 for receiving vertically polarized fields with matching network 25 and phase shifter network 23 for phase difference superposition of Receiving the horizontally and vertically polarized field components in the summation network 53.
• Fig. 3 : Antenna as in FIG. 2 , However, with one of a plurality of rotationally symmetrical to the center Z arranged monopolies 7a - whose received signals are combined in the common phase reference point B - as a further radiator. 7
• Fig. 4 : Antenna as in FIG. 2 , but with a loop antenna 14 with two antenna connection points 3a, 3b arranged opposite one another for reasons of symmetry, with a monopole 7b arranged in the center Z with a roof capacitance formed from horizontal conductor elements rotationally symmetrical to the center Z as another radiator 7.
• Fig. 5 : Antenna as in FIG. 4 However, wherein conductor parts 14a of the loop antenna 14 are used to form the rotationally symmetrical roof capacity 12.
• Fig. 6 : Antenna according to the principle of operation of the antenna in Fig. 2 but with a vertical feed line 26 for feeding the loop antenna 14, the feed line 26 additionally forming a vertical monopole 7a and the loop antenna 14 forming a roofing capacity 12 of the monopole 7a.
• Fig. 7 : Antenna according to the principle of operation of the antenna in Fig. 6 but with a loop antenna 14 designed as a square with the center Z.
• Fig. 8 : Unclaimed antenna arrangement with phase-different superimposition of the received voltages from the horizontal and vertical electric field components of a loop antenna 14 and a monopole antenna 7 formed by the vertical two-wire line 26.
• Fig. 9 : Antenna as in Fig. 2 in which, instead of discrete capacitances, the capacitance 16, which is formed in each case from a circuit of a plurality of dummy elements, is such that different capacitance values are effective at different frequencies.
• Fig. 10 Combined antenna arrangement for separate availability of LHCP or RHCP signals of different satellite signals at different antenna connection points 28a, 28b with a vertically polarized monopole 7 formed as a rod antenna, a horizontally polarized loop antenna 14 and a 90 ° hybrid coupler 45.
• Fig. 11 : Antenna arrangement as in FIG. 10 , but with a realization of the monopole 7 according to the antenna arrangement in FIG FIG. 6 by combining the effects of the loop antenna 14 as the roof capacitance and the two-wire line 26;
• Fig. 12 : Antenna for alternative coupling of RHCP and LHCP signals for diversity technologies driven by a switch located in a radio receiver module 52.
• Fig. 13 : Antenna for diversity technologies with LHCP / RHCP 55 switch as in Fig. 12 , however, similar to the antenna in Fig. 8 without a separate monopole 7. Reception in the case of vertical polarization is effected by the two-wire line 26. The for the superposition of the received signals of the Loop antenna and the monopole required phase difference is effected by the network 61.
• Fig. 14 : Antenna as in Fig. 5 but with a common radiator junction 2 for the common feed of the loop antenna 14 and the vertical monopole with roofing capacity 7b.
• Fig. 15 : Vertical directivity of the LHCP polarized electromagnetic field
  1. a) an antenna as in Fig. 2 with circular polarization at low elevation angles and with azimuthal independence of the phase of the radiation.
  2. b) a crossed radiator 7d according to the prior art or a ring line radiator 7c as in Fig. 19 with circular polarization at high elevation angles; wherein the phase of the circular polarization rotates with the azimuthal angle of the propagation vector
• Fig. 16 :
  1. a) Corresponding vertical directional characteristic of the LHCP polarized electromagnetic field of a 2.3 GHz antenna according to the invention FIG. 18 consisting of a loop antenna 14 with vertical monopole 7a in combination with a ring line radiator 7c with dimensions of 3.4 cm x 3.4 cm x 1.3 cm of the overall structure, wherein the characteristic of the in-phase superposition of the radiation according to Fig. 15a and Figure 15b for the azimuth angle 0 ° (right) and 180 ° (left).
  2. b) Horizontal directional characteristic of the LHCP polarized electromagnetic field at an elevation angle of about 30 ° with minimum radiation for the azimuth angle of 180 °.
• Fig. 17 Antenna according to the invention consisting of the loop antenna 14 with two symmetrically arranged loop antenna connection points 3a, 3b and monopole 7b with a space marked in the center Z for a crossed Radiator 42 with circular polarization according to the prior art and connection point 56 for the phase-adjustable superposition of its radiation in the summation network 53 by means of the controllable phase shifter 39th
• Fig. 18 : Antenna as in FIG. 17 However, instead of a centrally mounted crossed beam 42 with a novel ring line radiator 7c according to the invention for generating a circularly polarized field with azimuthally dependent phase with a by A / 4 remote ring line feed points 20a, 20b of 90 ° in phase different signals for generating a circumferential wave of one wavelength over the circumference of the line.
• Fig. 19 : Ring line radiator 7c, however, fed via four in each case by λ / 4 along the ring line offset feed points 22 of the phase in each case offset by 90 ° signals. The feed sources can be obtained in a manner known per se by power sharing and 90 ° hybrid coupler 45.
• Fig. 20 : Antenna according to the invention as in FIG. 18 , However, for generating the continuous line wave with a at a favorable distance - with respect to the line characteristic impedance - parallel to the ring line radiator 7c guided λ / 4-coupling conductor 43rd
• Fig. 21 : Antenna as in FIG. 20 , but with λ / 4-directional coupler 44. To a microstrip conductor 30, a λ / 4 coupling conductor 43 is guided in parallel, which forms the λ / 4 directional coupler 44 together with the coupled to the ring line radiator 7c λ / 4-coupler 43.
• Fig. 22 : Antenna according to the invention with square executed loop antenna 14 and designed as a closed square line ring with the edge length of λ / 4 ring line radiator 7c. The coupling to the ring line radiator 7c takes place contactlessly via the ramp-shaped λ / 4 coupling conductor 57 with the ring line connection point 19
• Fig. 23 : Antenna according to the invention with square loop emitter 7c as in FIG. 22 comprising a power distribution network consisting of λ / 4-long microstrip conductors 30 (15a, 15b, 15c) connected in a chain for feeding in at the corners of the square ring-shaped radiator 7c.
• Fig. 24 Antenna according to the invention with loop antenna 14, monopole 7a, ring line radiator 7c and the additional outer ring radiator 7d, on which a continuous line wave of two wavelengths is generated to increase the radiation gain by increasing the beamforming
• Fig. 25 : Circular array according to the invention with n the same rotationally symmetrical about the center Z arranged horizontally polarized radiator elements 59, the feed respectively in the direction of rotation of adjacent radiator elements differs in phase by 360 ° / n. Fig. 25 above: n = 4. Fig. 25 below: n = 5.
• Fig. 26 Circular array radiator 7f according to an arrangement as in Fig. 25 with at the vertices of a square center Z arranged horizontally polarized radiator elements 59 with leads 18 and power divider and phase shifter network of λ / 4-long microstrip conductors 30 with the sections 15a, 15b, 15c.

Although the object of the invention is directed to a receiving antenna, the properties of the antenna are described below for better traceability for the reciprocal operation of the antenna as a transmitting antenna, the transmission case but applies due to the naturally valid reciprocity relationship for the directional diagrams of the receiving case.

In the following, the principles for the design of antennas are explained, which are based on the antenna according to the invention.

The particular advantage of an antenna according to the invention, as for example in FIG. 2 is shown, the property is that according to the reciprocity law when operating the antenna as a transmitting antenna in the far field generated electric field strength vector even at relatively low elevation angles of the radiation describes a purely circular circular polarization with azimuthal omnidirectional in the technical sense.

This is achieved by phase-locked combination of the horizontally polarized loop antenna 14 with the at least one vertical emitter 7 and is done by superposition of the distant radiation fields of the two emitters by 90 ° by correspondingly different phase supply and corresponding amplitude supply of the two antennas. Thus, in the distant radiation field in a plane perpendicular to the direction of propagation two mutually perpendicular and by 90 ° in phase differing field strength vectors are generated, which represent the desired circularly polarized field. For the generation of the omnidirectional characteristic, it is necessary for the phase reference points B - or else the phase centroids - of the two antennas to coincide, which is achieved by rotationally symmetrical arrangement about the common center Z of the antennas.

This is achieved on the one hand by the circular or polygonal loop antenna 14 arranged horizontally in a plane with a constant spacing 4 as the height h above the base surface 6. This acts essentially similar to a loop antenna over a conductive surface. Assuming an azimuthally constant current allocation on the loop antenna 14, the elevation angle of the main beam direction can be adjusted by selecting the height h and the horizontal extent-that is, the radius in a circular design of the loop antenna 14. In this case, a zero point in the vertical direction and in the horizontal direction can be achieved. The achievement of a desired vertical directional pattern, however, requires a horizontal extension of the loop antenna such that its total orbital length is no longer small compared to the free-space electrical wavelength λ ₀ . According to the invention, the loop antenna into n equal portions of the cable length .DELTA.s is therefore λ _0/8 divided by break points 5 ', which are connected to each other by inserting a capacitor. The capacitances are preferably selected such that resonances occur at the operating frequency fm together with the properties of the line sections. Such an antenna can advantageously for an azimuthally pure Rundcharakteristik be designed. In conjunction with the at least one vertical radiator 7, which in the example of the Fig.2 is present in the center Z of the loop antenna 14 and whose azimuthal radiation pattern is also omnidirectional, resulting for the antenna according to the invention, the desired circularly polarized radiation field with pure omnidirectional. Thus, the antenna according to the invention is advantageously suitable in particular for satellite radio reception in vehicles, where antennas with azimuthal omnidirectional characteristics are mounted on the electrically conductive vehicle outer skin.

Fig. 2 shows a circular loop antenna 14 with radius R, which may also be designed polygonal. At its center in the center Z is its phase reference point B. The structure is subdivided into "n" line sections, each with the length Δs. The total orbital length is S. The antenna acts as a loop antenna with dimensions in the range of the wavelength, wherein nevertheless a homogeneous current distribution is achieved by dividing the structure and inserting capacitances 16 according to the invention. As a result, the length of the antenna is electrically shortened and creates a homogeneous, horizontally polarized electromagnetic field all around. The loop antenna 14 is arranged at a constant height h above the conductive base 6. The main vertical beam direction can be adjusted by selecting the height h and the radius of the loop antenna 14. It can be achieved a zero point in the vertical direction and in the horizontal direction.

The annular circumferential conductor length S is divided into n equal pieces of length Δs = S / n. The conductor impedance of the circulating line over the conductive base 6 is Zw. The capacitive reactance ΔX per line section Δs and thus the capacitance value C = 1 / (ω * ΔX) to be inserted into this conductor section is defined assuming an elongated length Δs and for an approximately annular line with a large radius R of the annular loop antenna 14 with respect to the conductor height h by $$\mathrm{.DELTA.X}\mathrm{/}\mathrm{tw}\mathrm{=}\tan \left(\mathrm{2}\mathrm{\pi \; \Delta s}\mathrm{/}{\mathrm{<figure-callout\; id="0"\; label="\lambda "\; filenames="imgf0015.png"\; state="\{\{state\}\}">\lambda </figure-callout>}}_{\mathrm{0}}\right)\mathrm{,}$$

This results in a good approximation for the capacitance value C to be inserted into the line section Δs: $$\mathrm{C}\mathrm{=}\mathrm{1}\mathrm{/}\left(\mathrm{\omega }\mathrm{•}\mathrm{<figure-callout\; id="2"\; label="Twan"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">Twan</figure-callout>}\left(\mathrm{2}\mathrm{\pi \Delta s}\mathrm{/}{\mathrm{<figure-callout\; id="0"\; label="\lambda "\; filenames="imgf0015.png"\; state="\{\{state\}\}">\lambda </figure-callout>}}_{\mathrm{0}}\right)\right)$$

Angular frequency of the satellite signals = ω; Free space wavelength of the satellite signals = λ ₀

With this dimensioning of the capacitance values C, resonance can be set for the loop antenna 14, so that the antenna impedance occurring at the loop antenna connection point 3 can be made substantially real.

In order to obtain a round diagram to a good approximation, the line of length S is to be divided into a sufficient number of sections by insertion of capacitances 16. For a meaningful subdivision: Δs / λ ₀ <1/8. Are the portions .DELTA.s = S / n made sufficiently small, so the equality is .DELTA.s all sections not necessarily required, as long as a capacitor 16 is inserted only after each section whose value-described upward criterion of the relative length Δ s / λ ₀ of the relevant part.

As a further radiator 7 is in the example of Fig. 2 in the center Z of the loop antenna 14, an electrically short, vertically oriented monopole 7a attached. The deviation of the positioning of the monopole 7a from the center Z should not exceed in the interest of circularity of the radiation pattern of λ ₀ / 20th At an interruption point of the loop antenna 14 whose loop antenna connection point 3 is formed, to which a matching network 25 with Umsymmetrierglied 29 and a switched after phase shifter network 23 are connected via a two-wire line 26. The radiator junction 2 of the monopole 7a is followed by the matching network 25 for impedance matching and the signals of the monopole 7a and the loop antenna are superimposed in the summing network 53; this in turn is connected to the antenna connection point 28. To generate the circularly polarized radiation, the phase of the phase shifter network 23 and all the networks are adjusted in their interaction such that the radiation fields of the loop antenna 14 and the monopole 7a in the far field of the antenna with a phase difference of 90 ° and with equal intensity are superimposed.

To avoid asymmetries of the azimuthal directional pattern of the monopole 7a, caused by the substantially vertically extending Two-wire line 26, the latter is designed according to the invention in such a way that it acts inductively high impedance with respect to the current flowing in the common mode longitudinal current, which is superimposed on the current in the push-pull current pair on the two conductors. It is thereby achieved that the two-wire line 26 does not influence the radiation field of the monopole 7a. For the design of such a two-wire line 26 there are a number of possibilities. In practice, for example, it can be advantageously produced by a printed on a support two-wire line, which is designed to increase the inductance as a meander. Additionally, by choosing its length, a desired phase relationship can be established.

By different weighting in the superposition of the two antenna signals, the vertical radiation pattern can be filled to low elevation angles for these signals. The trained as a rod antenna monopole 7a has in its vertical directional characteristic a similar main beam direction as the horizontally polarized loop antenna 14, but provides for low elevation angle a larger contribution than this. With the help of the networks 25, 23, 53 both the weighting of the properties of the two antenna signals can be set differently and additionally the necessary phase condition can be maintained.

The influence of a symmetrical vertical feed line not in the center Z in the form of the symmetrical two-wire line 26 does not diminish the polarization purity of the loop antenna 14 itself. The connection of one terminal on the unbalanced side of the matching and Umsymmetrierglieds 25, 29 for further switching of the antenna assembly is advantageously carried out using a guided over the conductive base 6 microstrip line 30. The other terminal on the unbalanced side of Umsymmetrierglieds 29 is electrically connected to the conductive base 6 connected. Due to the symmetry properties of the two-wire line 26, the effects of the currents flowing toward one another in the opposite direction compensate each other sufficiently on the conductors of the two-wire line 26, so that these also do not influence the radiation properties of the loop antenna 14. As explained below, are However, with respect to the azimuthal radiation pattern of the monopole 7a, depending on the radius R of the loop antennas 14, a residual imbalance may occur.

It is in accordance with the spirit of the present invention that by adjusting the matching networks 25 and the phase shifter network 23, both the axial ratio and the spatial orientation of the ellipse for elliptical polarization can be adjusted. This adjustability can according to the invention in a very advantageous manner, for. As in antenna diversity technologies, are used to continuously optimize the receive power by current adjustment of the ellipticity of the polarization in the distorted by multipath propagation reception field.

As an example for the design of the reception in the range of an elevation angle between 25 ° and 65 ° (typical angular range for GEO stationary satellite reception) with azimuthal omnidirectional characteristic, a horizontally arranged loop antenna 14 is placed at a distance of about 1/10 of the wavelength above the conductive base 6. The diameter of the loop antenna 14 is advantageously not chosen substantially smaller than 1/4 of the wavelength. Along the conductor guide in each case one with a capacity 16 with a reactance of about -200 ohms connected interruption point 5 is introduced at intervals of about 1/8 of the wavelength. By virtue of the capacitances 16 according to the invention, it is possible on the loop antenna 14 to achieve an azimuthally constant current distribution necessary for the round radiation, although the stretched length of the loop antennas 14 is not short in comparison to the wavelength λ. On the other hand, this length is again necessary to effect a practical impedance of the loop antenna 14. In Figure 15 (a) For example, the vertical diagram of such an antenna according to the invention is shown. For the example of a square shaped loop antenna 14 with central short vertical monopole in the frequency range around 2.3 GHz, the loop antenna 14 has an edge length of about 3 cm and a height h of 13 mm for the realization of both of the vertical directional diagram Fig. 15 (a) as well as a matching conductor characteristic impedance Zw proved to be favorable.

Another compared to the known from the prior art antennas, such as those from the DE-A-4008505 and the DE-A-10163793 As well as patch antennas, the characteristic to be emphasized is the azimuthal phase independence of the circularly polarized radiation of an antenna according to the present invention. In contrast, in the prior art antennas mentioned above, the phase changes with the azimuthal angle of the propagation vector, ie with a complete azimuthal orbit around the angle 2π. The inventive meaning of these properties with respect to a combination of antennas according to the cited prior art with an antenna according to the present invention will be explained below.

In the event that the satellite broadcasting system is additionally supported by the regionally radiating vertically polarized terrestrial signals in another frequency band closely adjacent to the frequency band of similar bandwidth, it is desirable to use the vertical radiation pattern for the vertical component of the electric field strength at low elevation angles fill. The connection according to the invention of the loop antenna 14 and of the further polarized further radiator 7 - mostly realized as a vertical monopole - allows this aspect to be considered in a particularly advantageous manner.

In Fig. 3 an antenna according to the invention is shown, wherein the further radiator 7, which is oriented perpendicular to the plane of the loop antenna 14, is formed from a group of monopoles 7a. These are arranged rotationally symmetrical to the center Z and within the loop antenna 14. The monopolies are connected to each other at their lower end via lines in the center Z and form there the radiator junction 2. In the not too large diameter of the annulus on which the monopoles 7a are arranged around the center Z and 7a is not too small number of monopolies the azimuthal directional diagram of the thus designed radiator 7 sufficiently omnidirectional.

Fig. 4 shows an advantageous embodiment of an antenna according to the invention similar to in FIG. 2 , wherein the loop antenna 14 for reducing the residual asymmetry of the arrangement with respect to the azimuthal directional diagram of the monopole 7 has two antenna connection points 3a, 3b opposite each other in the plane of symmetry SE, to which balancing and matching networks 25, 29 arranged in the loop plane are connected, their outputs via same phase shifter networks 23 are connected in parallel and connected to the two-wire line 26. The arranged in the center Z further radiator 7 is designed as a monopoly 7b with horizontal, rotationally symmetrical to the center Z arranged ladder parts as roof capacity. These ladder parts are symmetrical to the plane of symmetry SE executed.

In Fig. 5 a further advantageous embodiment of the invention is similar to that shown in Figure four, but with conductor parts of the loop antenna 14 are used to form the rotationally symmetrical roof capacity 12. In a perfectly symmetrical design of the roof capacity 12 both in terms of rotational symmetry and similar to that in FIG. 4 illustrated symmetry plane SE, the function of the loop antenna 14 is not affected by the connection of the roof capacitance 12 of the monopoly.

In Fig. 14 is the antenna according to the invention as in Fig. 5 illustrated, but with a common radiator junction 2 for the common feed of the loop antenna 14 and the vertical monopoly with roof capacity 7b. The circularly polarized field is formed by splitting the waves incident on the vertical monopole antenna and the horizontal arms of the roof capacitance 12 on the loop antenna 14 right and left, the distance to the next capacitance 16 on the loop antenna being to the right is selected differently than the distance to the next capacitance 16 on the loop antenna towards the left side. The loop antenna is thus so to rotate around the z-axis against the Dachkapaziät that arise on the left and right sides different angular distances α and β between the horizontal arms of the roof capacity and the next capacity. In this way, in the interaction of the feeding horizontal arms of Roof capacitor 12 and the respective interruptions of the conductor loop a loop antenna connection point for feeding the ring current on the loop antenna 14 is formed. The horizontal arms of the roof capacitance 12 are fed via the radiator junction 2 not only for their effect as roof capacity but also for generating the ring current on the loop antenna 14, so that the feeding of the loop antenna 14 and the monopoly 7b with roof capacity in an economically very advantageous manner According to the invention can take place via the common radiator junction 2 of the monopoly 7b.

FIG. 6 shows a further advantageous embodiment of the invention according to the principle of operation of the antenna in Fig. 2 but with a vertical feed line 26 arranged in the center Z for supplying the loop antenna 14, the feed line 26 forming a vertical monopole 7a and the loop antenna 14 forming a roofing capacity 12 of the monopole 7. The loop antenna 14 is formed with two antenna connection points 3a, 3b arranged symmetrically to each other and one matching network 25 in the loop plane as well as with a central connection to the vertical feed line to the matching network 33, which is designed as a two-wire line 26. In this case, the effects of the currents of the loop antenna 14 flowing in push-pull mode in the opposite direction compensate each other on the conductors of the two-wire line 26. The reception voltage of the monopole 7a becomes at its radiator junction 2 as a common mode of the two-wire line 26 at one output and the receiving voltage of the loop antenna 14th is supplied as a push-pull mode of the two-wire line 26 at the other output of the matching network 33 to the power divider and phase shifter network 31 for amplitude-matched and phase-different superposition of the signals at the antenna terminal 28.

Fig. 7 shows a further advantageous embodiment of the antenna according to the principle of operation of the antenna in Fig. 6 , but with a designed as a square with the center Z loop antenna 14, which by four arranged in a square, horizontally disposed and connected at their ends via capacitances 16 dipoles 21 with a connected via leads 18, centrally in the Phase reference point B arranged distribution network 10 is formed. The dipole system acts as a roofing capacity of the vertical monopole formed in this manner, similar to FIG FIG. 5 explained. The reception of horizontal or vertical electric field components is effected via the summation 34 or the difference formation 35 and the phase-different superimposition of the signals via the phase shifter network 23 and the summation network 53.

In a further advantageous embodiment is in Fig. 8 an antenna arrangement shown with phase-different superposition of the received voltages from the horizontal and the vertical electric field components of a loop antenna 14 and a monopole antenna 7a formed by the vertical two-wire line 26. Similar to in Fig. 4 Here again, in order to improve the symmetry of the arrangement, two antenna connection points 3a, 3b with matching networks 25 in the plane of the loop antenna 14 are present in the plane of symmetry SE. With the aid of a two-pole network 61 introduced into one of the conductors of the two-wire line 26, the adjustment of the common mode to normal ratio on the vertical two-wire line 26 takes place, whereby the ratio of the portion of the vertically polarized low elevation field of the main beam direction to the portion of the horizontally polarized field Field with higher elevation of the main beam direction is set. In addition, the adjustment of the phases necessary for the generation of the circular polarization takes place with the aid of this summing network 53. According to the invention, the axial ratio and the spatial orientation of the ellipse for elliptical polarization can be set by selecting the above-mentioned common-mode-to-differential ratio and the phase adjustment ,

In a further advantageous embodiment in Fig. 9 is the antenna - for example similar to the embodiment as in FIG. 2 - But designed as a multi-frequency area antenna. For this purpose, instead of discrete capacitances in the loop antenna 14, the capacitances 16 are each formed in each case from identical bipolar networks, preferably each consisting of a circuit comprising a plurality of dummy elements. So that's different Operating frequencies different capacitance values effective, which allow the resonance for the design of the real antenna impedance at these different operating frequencies.

In FIG. 1 is the situation shown that two satellite radio frequency bands with small bandwidth Bu or Bo closely adjacent at a high frequency in the L-band or in the S-band, at least at a frequency of fm> 1 GHz with the same directions, ie z , B. left-rotating circular polarization (LHCP) are radiated. With a bandwidth Bu or Bo of a few megahertz (typically about 4 -25 MHz), the relative frequency spacing between the center frequencies fmu and fmo is so small that a frequency-selective design of the antenna is not possible and is not necessary given a suitable frequency bandwidth of the antenna. Both signals can therefore be received at the same antenna pad 28 due to the equality of the polarization directions of rotation. In the event that another satellite broadcasting signal would be present in close frequency proximity with the other circular polarization, this can be done by designing two separate antenna pads 28a and 28b in a combined antenna according to the invention. Fig. 10 shows an antenna arrangement with a vertically polarized monopole 7 formed as a rod antenna and a horizontally polarized loop antenna 14 according to the invention with respect to the transmission case common phase reference point B, but with separate supply of signals to the terminal for vertical polarization 49 and for connection for horizontal polarization 48th Der At these terminals, connected hybrid couplers 45 with 90 ° positive and negative phase difference with respect to the LHCP terminal 28a and the RHCP terminal 28b enables the separate availability of LHCP or RHCP signals of different circular polarization directions of rotation. The monopole 7 embodied as a rod antenna 32 has an interruption point 5 connected to a dummy element 8 in order to design its vertical diagram.

In particular for the reception of geostationary satellites whose signals occur in northern latitudes with comparatively low elevation, it is provided that the one substantially perpendicular monopole 7 contains at least one interruption point 5 which connects or bridges with the design of the vertical diagram with at least one dummy element 8 is. In this way, the vertical diagram can be advantageously adapted to the requirements. The antenna connection point 2 is formed at the base of the monopole 7 at the connection to the matching network 33.

A similar antenna arrangement is in Fig. 11 however, the realization of the monopole 7 is similar to the antenna arrangement in FIG FIG. 10 by the combination of acting as a roof capacitance loop antenna 14 and the two-wire line 26 takes place. By means of a combined matching circuit 50, both the adaptation of the loop antenna 14 and the adjustment of the monopole 7 as well as the setting of a common phase reference point B are created.

In a further advantageous antenna arrangement for the alternative decoupling of RHCP or LHCP signals, as in FIG. 12 shown, a loop antenna 14 - as in FIG. 6 - Provided with two opposing antenna connection points 3a, 3b and connected thereto and located in the loop level matching networks 25, which are implemented, for example, as λ / 4 transformation lines. The outputs of the matching networks 25 are connected in parallel in addition. The received signal is fed via the two-wire line 26 to a matching network 25 located on the base area 6, the output of which is in turn connected to one of the two inputs of a signal combination circuit designed in particular as a 90 ° hybrid coupler 45. At the antenna connection point 2 at the base of the located in the center Z of the arrangement, designed as a rod antenna monopoly 7a also a matching network 25 is connected, the output of the other inputs of the 90 ° hybrid coupler 45 feeds. An LHCP / RHCP change-over switch 55 connected to the outputs of the 90 ° hybrid coupler 45 provides at the connection point 28 - controlled by a switching control located in a radio receiver module 52 - Satellite receive signals of the two directions of polarization alternatively available. When driven by a diversity control module 38 located in an LHCP / RHCP radio module 52, the antenna arrangement can also advantageously be used for polarization diversity by switching between reception for LHCP and RHCP waves.

In a further particularly economical embodiment of such an antenna with circularly polarized field with reversible direction of rotation is in FIG. 13 - similar to the antenna in FIG. 12 - The separate monopoly 7 saved. For the reception with vertical polarization is also the two-wire line 26 - similar to FIG. 8 - exploited. By inserting a suitably designed two-terminal network 61 into one of the strands of the vertical two-wire line 26, the difference of 90 ° between the phases of the horizontal field component picked up by the vertical two-wire line 26 with the loop antenna 14 as the roof capacitance 12 and that picked up by the loop antenna 14 is set their combination with this phase difference is present at the microstrip conductor 30 to the matching network 54 and thus also at the junction 28. Thus, the antenna receives a circularly polarized field. A circuit combining the receive signals of the loop antenna 14 at the output of the matching networks 25 from the horizontally polarized electric field and the receiving signals of the vertical two-wire line 26 from the vertically polarized electric field comprises an LHCP / RHCP switch 55 for reversing the polarity of the receiving voltage of the loop antenna 14. The latter can be added in this way with different signs of the received voltage from the vertically polarized electric field, so that between the reception of the LHCP field and the RHCP field by switching the LHCP / RHCP switch 55 can be switched. Triggered by a switchover control between LHCP and RHCP received signals located in the receiver, signals of differently polarized polarization of the satellite signals are available alternately on different transmission paths.

As already related to the antenna in FIG. 8 explained - can also be a corresponding network 61 of reactances in the ground connected strand of the vertical two-wire line 26 are switched. With the aid of the network 61, the adjustment of the common mode to differential ratio on the vertical two-wire line 26 can be set. The received voltages from the horizontal and the vertical electric field components are superimposed phase-differently according to the circular polarization. By adjusting the common-mode to differential ratio on the vertical two-wire line 26, the ratio of the low-polarization vertically-polarized field of the main beam direction to the proportion of the higher polarization horizontally-polarized field of the main beam direction can be adjusted.

According to the invention, in the above embodiments, the antenna is combined with another azimuth circular radiator whose polarization is circular and the phase of circular polarization rotates at the azimuthal angle of the propagation vector - ie, at a complete azimuthal orbit of 2π. As mentioned above, meet from the DE-A-4008505 and the DE-A-10163793 , respectively. EP 1 239 543 B1 known antennas of the prior art, as well as other known antenna forms this condition. The mode of operation of these antennas is essentially based on the fact that the individual antenna parts are placed on planes crossed at right angles and perpendicular to the ground plane and the antenna parts of the different planes are interconnected by 90 ° in phase in order to produce the circular polarization. Even the effect of patch antennas can be represented in a similar way. Radiators 7d with an azimuthal circular diagram whose polarization is circular and whose phase of circular polarization rotates with the azimuthal angle of the propagation vector and which are composed of two crossed radiators are referred to below as "crossed radiators" for easy distinction.

When combining such a crossed emitter 7d in such a way that its phase reference point B coincides with that of the previously described inventive antenna and the signals of the two antennas via a controllable phase shifter 39 and a summation network are summarized in accordance with the amplitude, formed in an advantageous manner in the azimuth directional diagram of the combined antenna arrangement, a main direction of the radiation, which is dependent on the setting of the phase rotation member 39.

The mode of operation of the superimposition of the signals is based on the FIGS. 15 and 16 explained. In FIG. 15a is the vertical directional characteristic of the LHCP polarized electromagnetic field of a previously described inventive antenna shown. The phase of this field is independent of the azimuthal angle and thus the phase for the azimuthal angles 0 ° and 180 ° are each marked with the same angle - in the example 0 °. By comparison, the elevation directional diagram of a further radiator 7d in FIG FIG. 15b of a type generated by a crossed emitter 7d as described above, with different phase values for the azimuthal angles 0 ° and 180 ° by 180 °, which in the example are denoted by 0 ° and 180 °. Thus, with in-phase superimposition of both signals, the antenna gain of the combined antenna arrangement can increase 0 ° for the azimuthal angle and weaken 180 ° for the azimuthal angle and even adjust a zero point of the directional diagram with a suitable adjustment of the amplitudes at a desired elevation angle, as in Fig. 16 is shown. If the two signals are superimposed on one another by the adjustable phase angle .phi., The azimuthal directional diagram, while maintaining the elevation directional diagram, results from the same angle .phi., In .sup.-, due to the phase change of the circular polarization of the crossed emitter (7d) with the azimuthal angle of the propagation vector turned one way or the other. In this way, the directional diagram of the combined antenna arrangement in mobile use advantageously z. B. be tracked with his main direction pointing to the satellite or, for example, a disturber by directional assignment of the zero point of the directional diagram are selectively hidden. In particular, when satellite reception on vehicles can hereby be in the context of a dynamically tracked setting of the directional diagram, the signal-noise ratio while driving optimally designed.

In Fig. 17 the combined antenna arrangement according to the invention is shown with a crossed emitter 7b indicated by the construction space 42, as it is described, for example, in US Pat EP 1 239 543 B1 , there in Fig. 10a, is shown. Here, the vertical antenna conductor 20 indicated there is here in FIG Fig. 17 is executed as an equivalent vertical monopole 7a in the center Z and is decoupled from the junction 56 of the crossed radiator 49 due to symmetry conditions. The latter is connected via the controllable phase shifter 39 to the summing network 53, in which the signals of the loop antenna 14, the vertical monopole 7a and the crossed emitter 49 are combined with the respectively suitable weighting to the received signal of the combined antenna arrangement. Equivalently, an antenna of the type shown in FIG DE-A-4008505 or a patch antenna with the vertical monopole 7a in the center Z, as well as an arrangement over the ground plane of parallel crossed dipoles are combined. All arrangements of n equal horizontal radiating elements 59 can be used for this, if they are arranged so that their centers give the corners of an equilateral polygon, and if the rotation of the arrangement about the z-axis by an angle of 360 ° / n, the structure in depicts itself and if the feed in each case in the direction of rotation of adjacent radiator elements differs in phase by 360 ° / n. In Fig. 25 Such arrangements are shown respectively for the example of four and five radiator elements.

In a particularly advantageous further development of the invention, instead of a radiator of the "crossed radiator" type described, a novel radiator 7c with circular polarization and azimuthal omnidirectional diagram, the phase of which rotates with the azimuthal angle of the propagation vector, is hereinafter referred to as ring line radiator 7c designated used. In FIG. 15 (b) For example, the vertical diagram of such an antenna according to the invention is shown.

According to the invention, the ring line radiator 7c is arranged as a polygonal or circular, arranged rotationally symmetrically about the center Z Ring line in a horizontal plane with the height h1 extending over the conductive base 6, designed.

According to the invention, the ring line can be fed in such a way that it adjusts the current distribution of a current line wave whose phase difference over a cycle is just 2π, thus the elongated length of the ring line corresponds to the wavelength λ, which adjusts itself to the ring line. The radiation contributions of the horizontally polarized individual conductor sections are superimposed in the far field in such a way that the desired radiation with circular polarization and the required phase dependence adjusts itself to the azimuthal propagation direction and the substantially omnidirectional azimuthal directional characteristic. With a circular design of the loop, its horizontal extent is thus D = λ / π. For a loop as in FIG. 18 is shown, the wavelength λ on the loop is equal to the free space wavelength λ ₀ . In order to reduce the diameter D, the wavelength λ on the loop can be made by increasing the line inductance and / or the line capacitance to the conductive base 6. This can be done in a known per se, for example, preferably by introducing concentrated inductive elements in the line structure or, for example by meandering design of the ring conductor.

Fig. 18 shows such a combined antenna arrangement, consisting of the loop antenna 14 and the combined with a phase difference monopole 7a for generating the circularly polarized radiation field with azimuthal independent phase position and a concentric with center Z arranged circular ring radiator 7c with loop connection point 19 for superimposing its circular polarized radiation field, however, with azimuthally dependent phase position and to control the azimuthal main direction via the controllable phase shifter 39. The phase center of the ring line radiator 7c is due to the described phase distribution on the rotationally symmetric loop structure in the center Z of the antenna array and thus falls with the described phase reference point B of the loop antenna 14th and that of the monopole 7a together - regardless of the position of the controllable phase shifter 39. The generation of the continuous line shaft au for that Ring line radiator 7c takes place starting from the ring line connection point 19 via the power divider and phase shifter network 31, at whose outputs are shifted by 90 ° to each other in phase signals, which in each case via a matching network 25 via the leads 18 to λ / 4 apart ring line Supply points 22a and 22b are connected along the loop structure. With a ring line radiator 7c of this type has the particular advantage that it is concentric with the loop antenna 14 and designed in comparison to this with a larger diameter. A transverse dimension which is customary for the loop antenna 14 can be designed within wide limits, but is generally smaller than λ / 4 and can therefore be designed within the ring line radiator 7c with a diameter λ / π. This allows the advantageous permissive configurability of located in the center Z vertical monopole 7b, or monopole system, such as in the Figures 3 . 4 and 5 , Due to the geometrically induced radiation decoupling between the loop antenna 14 and the surrounding loop emitter 7c, the diameters of the two emitters can be designed within wide limits independently of each other in the interest of designing their vertical directional patterns and the resulting vertical directional pattern of the antenna array at the antenna port 28. Likewise, the distance h of the plane of the loop antenna 14 from the conductive base 6 from the distance h1 between the plane of the loop emitter 7c and the conductive base 6 can be chosen to be different, although it is particularly economical to manufacture if both emitters are in printed form, for example printed on the same sheet carrier. In Figure 16 (a) is an example of the vertical diagram and in Fig. 16 (b) the horizontal diagram of such an antenna according to the invention is shown. For the example of a square shaped loop antenna 14 with central short vertical monopole in combination with an equally square shaped ring radiation conductor in the frequency range around 2.3 GHz, the loop antenna 14 has an edge length of about 3 cm and a height h of 13 mm and for the square shaped loop emitter has an edge length of about 3.4 cm, which corresponds to about ¼ of the wavelength, and a height h of 10 mm for the realization of both the directional diagram according to Fig. 16 proved favorable.

The loop antenna 14 is connected via the common-mode high-resistance two-wire line 26 via a matching network 25 and the monopole 7a is connected via a matching network 25 and via the phase shifter network 23 to the summing network 53 to form the circular polarized radiation with azimuthal phase independence. Similarly, the ring line connection point 19 is connected via the controllable phase shifter 39 to the summation network 53 and the signals are superimposed there with the appropriate weight for generating the desired vertical directional diagram of the antenna arrangement with adjustable azimuthal main direction at the antenna port 28 the other signals.

To perfect the azimuthal symmetry of the ring line radiator 7c is advantageous in FIG. 19 Advantageously fed via four in each case by λ / 4 along the ring line offset feed points of each phase offset by 90 ° signals. The feed sources can be obtained in a manner known per se by power sharing and 90 ° hybrid coupler 45.

In an advantageous embodiment of the invention, the generation of the continuous line shaft on the ring line radiator 7c takes place in accordance with FIG. 18 but through the λ / 4 coupling conductor 43 in FIG FIG. 20 , This is performed in a respect to the line impedance characteristic distance over a straight length of λ / 4 parallel to the ring line radiator 7c. For the production of the λ / 4 coupling conductor 43 can be economically applied to the same carrier as the ring line radiator 7c and optionally the loop antenna 14 printed.

In a further advantageous embodiment of the invention, the generation of the continuous line shaft takes place on the ring line radiator 7c in accordance with FIG. 20 however, by λ / 4 directional coupler 44 in FIG FIG. 21 , To a microstrip conductor 30, a λ / 4-coupling conductor 43 is guided in parallel, which forms the λ / 4-directional coupler 44 together with the coupled to the ring line radiator 7c λ / 4-coupler 43.

In FIG. 22 the ring line radiator 7c is similar to an antenna as in FIG FIG. 18 , but formed as a closed square line ring over the conductive base 6 with the edge length of λ / 4 in a plane at a distance h1 above the conductive base 6. Likewise, the loop antenna 14 is arranged with its capacitances 6 as a square conductor structure within the ring line radiator 7c with the same center Z. The remaining antennas are not shown for reasons of clarity. As a particularly advantageous form of non-contact coupling to the ring line radiator 7c is in FIG. 22 the ramped λ / 4 coupling conductor 43 to emphasize. Starting from the ring line connection point 19 located on the conductive base area 6, a vertical feed line 18 leads to a coupling spacing 58 at one of the corners, from where it essentially meets the base area 6 according to a ramp function below an adjacent corner in order to electrically connect with the latter to be connected. This form of coupling is particularly advantageous for economic production because, due to the square design of the ring line radiator 7c, the ramped λ / 4 coupling conductor 43 can be designed on a planar support. By adjusting a suitable coupling spacing 58, impedance matching at the ring line connection point 19 can also be brought about in an advantageous manner.

In FIG. 23 the ring line radiator 7c is designed as square as in FIG. 22 , However, is fed at its corners in each case via a feed line 18, which runs in each case over an equal length as a microstrip conductor 30 on the conductive base surface 6 and which each contains an equally long vertical conductor. The remaining antennas are not shown for reasons of clarity. The supply lines 18 are - starting from the ring line connection point 19 - connected to a power distribution network, which consists of connected in chain λ / 4-long microstrip conductors 30 (15a, 15b, 15c). The characteristic impedances of the microstrip conductors 30 are - starting from a low characteristic impedance at the ring line connection point 19 - to which one of the supply lines 18 is directly connected - stepped up in such a way that the signals fed in at the corners into the ring line radiator 7c have the same powers and in each case by 90 ° in the phase continuously lagging differ. The remaining antenna parts are also not shown for reasons of clarity.

In an advantageous extension of the invention is in the antenna in FIG. 24 another radiator in the form of an outer ring channel radiator 7e present. In contrast to the ring line radiator 7c, whose circumference corresponds to exactly one wavelength λ-ie one full period-the circumference of the outer ring channel radiator 7e is selected to be two wavelengths λ, so that upon excitation with signals shifted in phase by 90 ° to one another at λ / 4 spaced loop feeders 22 along the outer loop structure adjusts a continuous line wave on the loop emitter 7d. This feed takes place in the example in FIG. 24 in both loops in a similar manner via the matching networks 25 and the power divider and phase shifter network 31. The junction 21 of the outer loop radiator 7e is also connected to the summing network 53, so that the effects of the radiation of the outer outer ring radiator 7e depending on the weight Antenna connector 28 occur. The signals at the loop antenna monopole connection point 27, at the ring line connection point 19 and at the connection point 21 of the outer loop emitter 7e are weighted together via controllable phase shifters 39 in the summation network 53, so that at the antenna connection 28 in the set azimuthal main direction increased antenna gain is achieved. Due to the larger diameter of the outer ring line radiator 7e, its contribution is more sharply focused than that of the circularly polarized ring line 7c. Although the polarization is no longer purely circular by connecting the outer loop emitter 7e, the radiation gain for certain situations can be increased by this measure due to the overall sharper focusing.

In an advantageous development of the invention is in FIG. 26 instead of the ring line radiator 7c in FIG. 22 a circle group radiator 7f from the in FIG. 25 described type shown. This consists of several in a parallel to the conductive base 6 and at a distance to this arranged plane and around the center Z azimuth rotationally symmetrical on a circle K. arranged horizontally polarized radiator elements 59. Via leads 18 with phase shifter network a common circular array radiator junction 60 is provided. With reciprocal operation of the antenna, the excitation of the circular array 7f is effected in such a way that each radiating element 59 is energized with a current of equal amplitude but phase-wise such that the magnitude of the current phase equals the azimuth angle φ originating from an azimuthal reference line the azimuthal position of the radiator element 59 is selected so that the current phase increases or decreases with increasing azimuth angle Φ. For this purpose, the horizontally polarized radiator elements 59 are arranged at the vertices of a square with center Z and oriented in each case perpendicular to the connecting lines between the relevant vertex and the center Z. The horizontally polarized radiator elements 59 are each connected via an equally long lead 18 to the terminals of a power divider and phase shifter network. The latter is made of chain-connected formed on the conductive base 6 λ / 4-long microstrip conductors 30 with the sections 15a, 15b, 15c, whose characteristic impedance - starting from a low characteristic impedance at the circular array radiator junction 60 - to which one of the leads 18 is directly connected - are staggered in such a way that the signals fed at the corners in the radiating elements 59 have the same powers and each lag 90 ° in the phase continuously lag.

List of terms

• Antenna 1
• Spotlight connection 2
• Loop Antenna Junction 3
• Loop antenna pads 3a, 3b, 3c, 3d
• Distance of height h, h1 4, 4a
• Interruption, point of interruption 5
• Base area 6
• Spotlight 7
• Vertical monopoly 7a
• Vertical monopoly m. Roof capacity 7b
• Ring line radiator 7c
• Crossed spotlight 7d
• Outer ring line radiator 7e
• Circle group radiator 7f,
• Blind element 8
• Circular antenna connection point (9)
• Distribution network 10
• Horizontal extension 11
• Roof capacity 12
• Spotlight 13
• Loop antenna 14
• Conductor parts of the loop antennas 14a
• Power distribution network 15a, 15b, 15c
• Capacity 16
• Horizontal dipoles 17
• Supply line 18
• Ring line connection point 19
• Ring line feed point 20a, 20b
• External loop connection 21
• Ring line feed point 22
• Phase shifter network 23
• Antenna of another radio service 24
• Matching network 25
• Two-wire line 26
• Loop Antenna Monopole Junction 27
• Antenna connector 28
• Antenna connection for LHCP 28a
• Antenna connector for RHCP 28b
• Balancing element 29
• Microstrip conductor 30
• Power divider and phase shifter network 31
• Rod antenna 32
• Matching network 33
• Summation 34
• Difference 35
• Outer ring line 36
• Diversity switch 37
• Diversity control module 38
• Controllable phase-shifting member 39
• Distance 40
• Reactance 41
• crossed spotlight 42
• Directional coupler 43
• second directional coupling conductor 44
• 90 "hybrid coupler 45
• LHCP connection 46
• RHCP port 47
• Terminal horizontal polarization 48
• Connection vertical polarization 49
• combined matching circuit 50
• Circuit of a plurality of dummy elements 51
• LHCP / RHCP radio module 52
• Summation network 53

Claims (24)

1. Antenna for reception of satellite radio signals emitted circularly in a rotational direction of the polarization, comprising at least two emitters (7, 7a, 14) connected to an antenna terminal (28), each linearly polarized in a spatial direction and connected via a matching and phase shifting network (25, 23; 33, 31; 45; 54, 61), having the following features:

   - one of the at least two emitters is formed as loop antenna (14), formed of a conductor loop arranged in a substantially horizontal plane parallel above a substantially horizontally oriented conductive base (6),

   - the conductor loop comprises at least one break point bridged by a capacitance (16) for its electrically effective shortening,

   - in cooperation with the at least one break point of the conductor loop, a loop antenna connection point (3, 3a, 3b, 3c, 3d) of the loop antenna (14) is formed on the loop antenna (14) for feeding a ring current,

   - the second of the at least two emitters (7, 7a) with its emitter connection point (2) and the loop antenna connection point (3, 3a, 3b, 3c, 3d) of the loop antenna (14) are connected via the matching and phase shifting network (25, 23; 33, 31; 45; 54, 61), which is adapted such that at reciprocal operation of the antenna the radiation fields of the loop antenna (14) and of the second emitter (7, 7a) are superposed in the far field of the antenna with different phases,

   - the second emitter (7, 7a) comprises a polarization oriented substantially perpendicular to the polarization of the loop antenna (14) and a substantially orthogonal phase in the far field,

   - a third emitter (7c, 7f, 14, 42) is provided having a circular polarization and an azimuthally dependent phase, provided in the center (Z) of the antenna or provided in rotational symmetry about the center (Z), whose reception signals are fed from its emitter connection point (19, 56) via a controllable phase rotation element (39) to a summation network (53) and thereat added in a weighted manner to the other reception signals for forming a main direction in the azimuthal directional diagram such that the azimuthal main direction establishes variably by variably setting the phase rotation element (39).
2. Antenna according to claim 1,
   characterized in that a plurality of break points are provided bridged by a capacitance (16) wherein the number and each capacitance value of the capacitances (16) distributed about the circumference of the loop antenna (14) are selected such that both an azimuthally constant current distribution on the loop antenna (14) and a resonance of the capacitances (16) together with the effects of the electrical conductors of the loop antenna are provided.
3. Antenna according to claim 1 to 2,
   characterized in that at reciprocal operation of the antenna, the radiation fields of the loop antenna (14) and of the second emitter (7, 7a) are superposed in the far field of the antenna for generation of radiation with circular polarization having substantially similar amplitude in the angular range of the elevation between 30° and 60° and a phase difference of 90°.
4. Antenna according to one of the claims 1 to 3,
   characterized in that the loop antenna connection point (3, 3a, 3b, 3c, 3d) of the loop antenna (14) is formed by the at least one break point of the conductor loop, and the loop antenna (14) is formed in rotational symmetry about a center Z in a plane, and the second emitter (7) is arranged as short vertical monopole (7a) above the conductive base (6) running through the center of the loop antenna (14), and that the emitter connection point (2) of the monopole (7a) and the loop antenna connection point (3, 3a, 3b, 3c, 3d) of the loop antenna (14) are connected to said antenna terminal (28) via the matching and phase shifting network (25, 23).
5. Antenna according to claim 4,
   characterized in that the plane of the loop antenna (14) is arranged at a distance (4) of height h of the electrically conductive base (6) and the electrically short vertical monopole (7a) is arranged above the electrically conductive base (6) of the loop antenna (14) and the elevation angle of the main emitting direction is set by the choice of the distance (4) of height h and the horizontal extent of the loop antenna (14) and by the ratio between the amplitudes of the loop antenna (14) and of the monopole (7a).
6. Antenna according to one of the claims 1 to 5,
   characterized in that the loop antenna connection point (3, 3a, 3b, 3c, 3d) of the loop antenna (14) is connected through a two-wire line (26), provided between the plane of the conductor loop and the electrically conductive base (6) and having a matching network (25) with a resymmetrization element (29), with the phase shifting network (23) and summation network (53), provided on the conductive base (6), and with said antenna terminal (28) such that the desired phase relationship establishes by the choice of the length of the two-wire line (26) and the phase shifting network (23).
7. Antenna according to one of the claims 1 to 3 or 6,
   characterized in that the second emitter (7), oriented perpendicular to the plane of the loop antenna (14), is formed of a group of monopoles (7a) arranged in rotational symmetry to a center Z of the antenna and within the loop antenna (14) and the monopoles are connected with one another at their lower end via lines in the center Z and thereat form the emitter connection point (2) of the second emitter (7).
8. Antenna according to claim 6,
   characterized in that in the loop antenna (14) for reducing the residual unbalance of the arrangement, two antenna connection points (3a, 3b), opposite of each other in the symmetry plane SE, or a plurality of connection points are arranged at equal distances from one another and connected to resymmetrization and matching networks (25, 29), whose outputs are connected in parallel via similar phase shifting networks (23) and connected to the two-wire line (26).
9. Antenna according to one of the claims 1 to 6 or 8,
   characterized in that the second emitter (7) is arranged in a center Z of the antenna and is configured as monopole (7b) with horizontal conductor parts arranged in rotational symmetry to the center Z as top-loading capacitor, and also symmetrical to the symmetry plane SE.
10. Antenna according to claim 9,
    characterized in that conductor parts of the loop antenna (14) are connected in a electrically conductive manner to conductor parts of the monopole (7b) to form the top-loading capacitor (12) in rotational symmetry, and the top-loading capacitor (12) is configured both in terms of compliance with the rotational symmetry and the symmetry with respect to the symmetry plane SE.
11. Antenna according to claim 1,
    characterized in that a two-wire line (26) is arranged in a center Z of the antenna for feeding the loop antenna (14) and the two-wire line (26) forms a vertical monopole (7a) as second emitter and the loop antenna (14) forms a top-loading capacitor (12) of the monopole (7a) and the loop antenna (14) includes one, two or more symmetrically arranged antenna connection points (3a, 3b, ...) each having a matching network (25) in the loop plane, and the reception voltage of the monopole (7a) is fed at its emitter connection point (2) as common mode of the two-wire line (26) at an output and the reception voltage of the loop antennas (14) is fed as push-pull mode of the two-wire line (26) at the other output of the matching network (33) to the phase shifting network (31) for an amplitude-suitable and phase different superposition of the signals at the antenna terminal (28), wherein the phase shifting network (31) is also configured as power divider network.
12. Antenna according to claim 1,
    characterized in that a two-wire line (26) is arranged in a center Z of the antenna for feeding the loop antenna (14) and the two-wire line (26) forms a vertical monopole (7a) as second emitter and the loop antenna (14) forms a top-loading capacitor (12) of the monopole (7a) and the loop antenna (14) includes one, two or more symmetrically arranged antenna connection points (3a, 3b, ...) each having a matching network (25) in the loop plane, and one of the two conductors of the two-wire line (26) is conductively connected to the conductive base (6) at a ground connection point (62) for weighting the reception of the horizontally polarized and the vertically polarized electrical field via a two-pole network (61) for adjusting the common-mode-to-push-pull relationship of the vertical two-wire line (26), and the other of the two conductors is connected to said antenna output terminal (28) via the matching network (54), and the setting of the phases necessary for the generation of the circular polarization is given by using said two-pole network (61).
13. Antenna according to one of the claims 1 to 12,
    characterized in that the antenna is provided as a multi-frequency band antenna, and, instead of at least one discrete capacitance (16), two-pole networks (51), consisting of a circuit of several reactance elements, are inserted into the break points of the loop antennas (14), and the two-pole networks (51) have different reactance values at different operating frequencies.
14. Antenna according to one of the claims 1 to 11,
    characterized in that the reception signals of the loop antenna (14) and of the second emitter configured as monopole (7a) are fed to the two inputs of a signal combination circuit formed as 90° hybrid coupler (45) and a LHCP/RHCP switch (55) at the antenna connection point (28) is connected to the outputs of the 90° hybrid coupler - controlled by a switching control located in a radio receiver module (52), so that the satellite reception signals of the two directions of rotation of the polarization are alternatively available for polarization diversity.
15. Antenna according to one of the claims 1 to 13,
    characterized in that the third emitter is a crossed emitter (42) provided in a center Z of the antenna.
16. Antenna according to one of the claims 1 to 13,
    characterized in that the third emitter is provided as patch antenna for circular polarization.
17. Antenna according to one of the claims 1 to 13,
    characterized in that the third emitter is a ring line emitter (7c) with circular polarization and azimuthally dependent phase, which is provided as polygonal or circular closed ring line arranged in rotational symmetry about the center Z of the antenna and extending in a horizontal plane with height h1 above the conductive base (6), and which is electrically excited such that the current distribution of a travelling line wave establishes on the ring line, whose phase difference across one cycle is 2π, and thus the extended length of the ring line corresponds to the line wavelength λ.
18. Antenna according to claim 17,
    characterized in that the ring line emitter (7c) is configured in a circular shape with its center at the center Z and two ring line feed points (22) are provided with a distance from each other of λ/4 along the ring line structure for generation of a travelling line wave on the ring line emitter (7c), to which signals of equal size are fed via feed lines (18) connected to the closed ring line, which are shifted 90° in phase to one another.
19. Antenna according to claim 18,
    characterized in that a power divider and phase shifting network (31) is provided, which is connected on one side with a ring line connection point (19), that on the other side the two signals of the same size, shifted 90° in phase to one another, are available to be fed into the ring line, and in that the ring line connection point (19) is connected via the controllable phase shifting element (39) to the summation network (53).
20. Antenna according to claim 18 or 19,
    characterized in that for generation of a travelling line wave on the ring line emitter (7c), instead of the ring line feed points (22), a directional coupling conductor (43) is provided, which is guided parallel to the ring line emitter (7c) over an extended length of λ/4 in a favorable coupling distance in relation to the line wave impedance, and the directional coupling conductor (43) is connected on the one side via a feed line (18) and a matching network (25) to the ring line connection point (19) and on the other side via a feed line (18) to the conductive base (6).
21. Antenna according to claim 20,
    characterized in that the loop antenna (14) is implemented as square loop having a loop antenna connection point (3) and the ring line emitter (7c) is implemented as closed square line ring, with the length of the edge of λ/4 above the conductive base (6) at a distance h1 above the conductive base (6), and a ramp-shaped directional coupling conductor (57) with an advantageous length of λ/4 is provided for generation of a travelling line wave on the ring line emitter (7c) and for non-contact coupling to the ring line emitter (7c), which, starting from the ring line connection point (19) on the conductive base (6), leads via a vertical feed line (18) to one of the corners except for a coupling distance (58), to meet from there substantially in accordance with a ramp function below an adjacent corner with the base (6) and is conductively connected with the latter via the ground terminal (62).
22. Antenna according to claim 1,
    characterized in that the third emitter is a ring line emitter (7c) with circular polarization and azimuthally dependent phase, which is provided as polygonal or circular closed ring line arranged in rotational symmetry about the center Z of the antenna and extending in a horizontal plane with height h1 above the conductive base (6), and that a fourth emitter is provided in the form of an outer ring line emitter (7e), whose circumference corresponds to two wavelengths λ, so that a travelling line wave establishes when excited with signals shifted 90° in phase to one another at ring line feed points (22) having a distance to each other of λ/4 along the outer ring line structure, and that the generation of said signals is provided, starting from the connection point (21) of the outer ring line, in a similar manner as for feeding of the third emitter configured as ring line emitter (7c), and the signals are summarized in a weighted manner at the loop antenna monopole connection point (27) at the ring line connection point (19) and at the connection point (21) of the outer ring line (7e) via several controllable phase shifting elements (39) in the summation network (53), so that an increased antenna gain is achieved in the established azimuthal main direction at the antenna terminal (28).
23. Antenna according to one of the claims 1 to 13,
    characterized in that the third emitter is a circular assembly emitter (7f), consisting of a plurality of horizontally polarized emitting elements (59) arranged in a plane parallel to the conductive base (6) and at a distance therefrom and arranged in azimuthally rotational symmetry about the center Z on a circle (K), having a common circular assembly emitter connection point (60) connected via feed lines (18) with power divider and phase shifting network (31), wherein at reciprocal operation of the antenna the excitation of the circular assembly emitter (7f) is effected such that each emitting element (59) is excited with current of the same amplitude but with a phase according to the manner that the amount of the current phase is selected equally to the azimuth angle (φ), starting from an azimuthal reference line, of the azimuthal position of the emitting element (59), so that the current phase increases or decreases with increasing azimuth angle (φ).
24. Antenna for reception of satellite radio signals emitted circularly in a rotational direction of the polarization, comprising two emitters (7b, 14) connected to an antenna terminal (28), each linearly polarized in a spatial direction, having the following features:

    - one of the two emitters is formed as loop antenna (14), formed of a conductor loop arranged in a substantially horizontal plane parallel above a substantially horizontally oriented conductive base (6),

    - the conductor loop comprises a plurality of break points bridged by a capacitance (16) for its electrically effective shortening,

    - the second (7b) of the two emitters is configured as monopole (7b) with top-loading capacitor (12) and horizontal arms through which the feeding of the loop antenna (14) is effected, wherein the loop antenna (14) and the monopole (7b) are commonly fed by a common emitter connection point (2) via a matching network (25),

    - wherein conductor parts of the loop antenna (14) are connected in an electrically conductive manner with conductor parts of the monopole (7b) for forming the top-loading capacitor (12),

    - wherein the loop antenna (14) is azimuthally rotated in relation to the top-loading capacitor (12) about the axis of the center Z such that in the leftward rotational direction and the rightward rotational direction different respective azimuthal angular distances α and β result between the horizontal arms of the top-loading capacitor (12) and the respective next break point (5) with the inserted capacitance (16) at the loop antenna (14),

    - the monopole (7b) comprises a polarization oriented substantially perpendicular to the polarization of the loop antenna (14) and a substantially orthogonal phase in the far field,

    - a third emitter (7c, 7f, 14, 42) is provided having a circular polarization and an azimuthally dependent phase, provided in the center (Z) of the antenna or provided in rotational symmetry about the center (Z), whose reception signals are fed from its emitter connection point (19, 56) via a controllable phase rotation element (39) to a summation network (53) and thereat added in a weighted manner to the other reception signals for forming a main direction in the azimuthal directional diagram such that the azimuthal main direction establishes variably by variably setting the phase rotation element (39).

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