EP2296227B1 - Antenna for receiving circular polarised satellite radio signals - Google Patents

Description

The invention relates to an antenna for receiving circularly polarized satellite radio signals according to the preamble of claim 1 (see. US 5,977,921 A ).

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 spaced separate frequency bands. 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 satellites of the Global Positioning System (GPS) also radiate circularly polarized waves in one direction at the frequency of approximately 1575 MHz, so that the antenna forms mentioned can basically be designed for this service.

The from the DE-A-4008505 known antenna is constructed on a substantially horizontally oriented conductive base and It consists of crossed horizontal dipoles with V-shaped downwardly inclined dipole halves made of linear ladder sections mechanically fixed at an azimuthal angle of 90 degrees to each other and attached to the upper end of a linear vertical conductor fixed to the conductive base. 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.

Although both antenna types are suitable for the reception of satellite signals, which are emitted by high-flying satellites - so-called HEOS. However, by increasing the cross-polarization suppression in the largest possible elevation angle range, the reception of temperature noise can be significantly reduced compared to the reception of the satellite signals.

Added to this is the difficulty of designing antennas with a smaller volume, which is imperative especially for mobile applications. As other antennas of this type are known in the prior art patch antennas, which are also less efficient with respect to the reception at low elevation angle and due to the use of dielectric materials have losses that significantly affect the signal-to-noise ratio.

For the reception of all mentioned radio services, however, the economy in the production of essential because of the manufactured in mass production antennas of crucial importance.

From the US 2003/0063038 A and from the US 2003/0174098 A in each case an antenna with a loop emitter is known in the above four vertical emitters is coupled via a phase shifter network.

From the EP 1 986 269 A For example, there is known a circularly polarized antenna comprising a loop emitter powered by four vertical emitters which may be L-shaped, T-shaped or inverted triangle-shaped.

From the GB 1 105 354 various embodiments of antennas are known in which an open loop is provided to which a coaxial cable or a plug-in connection is coupled.

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 planes crossed at a right angle and these planes are also perpendicular to the conductive ground plane. 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 that are customary in satellite antennas, for which a particularly high mechanical accuracy is necessary in the interest of polarization purity, impedance matching and the reproducibility of the directional diagram in mass production of the antennas. Likewise, the production of patch antennas is usually relatively complicated due to the tightly tolerated dielectric.

The object of the invention is therefore to provide an antenna with low volume, which depending on their design for both a particularly powerful reception of high elevation angles incident circularly polarized in one direction radiated satellite signals with high gain in the vertical direction and for the high-performance reception of At low elevation angles incident circularly polarized in one direction of rotation emitted satellite signals with high cross polarization suppression over a large elevation angle range is suitable, in particular, the possibility should be given to an economical production.

This object is achieved in an antenna according to the preamble of the main claim by the characterizing features of the main claim.

With an antenna according to the invention, the advantage is associated with allowing the reception of linearly polarized waves received at low elevation with azimuthally nearly homogeneous directional diagram. Another advantage of an antenna according to the invention is its particularly simple manufacturability, which allows the realization by simple curved sheet metal structures.

Advantageous embodiments are described in the description and the dependent claims.

According to the invention, the antenna for receiving circularly polarized satellite radio signals comprises at least one substantially horizontally oriented conductor loop arranged above a conductive base surface 6, with an arrangement for electromagnetic excitation 3 of the conductor loop connected to an antenna connection 5. The conductor loop is designed as a ring line emitter 2 by a polygonal or circular closed loop in a horizontal plane with the height h over the conductive base 6 extending. The ring line emitter 2 forms a resonant structure and is electrically excitable by the electromagnetic excitation 3 in such a way that adjusts the current distribution of a current line wave in a circumferential direction, the phase difference over a revolution is just 2π on the loop. To support the vertically oriented portions of the electromagnetic field, there are at least two further radiators 4, which are vertical on the ring line radiator 2 and extend to the conductive base surface, which radiators are electromagnetically coupled to both the ring line radiator 2 and the electrically conductive base surface 6. To generate a pure line wave, the height h is preferably less than 1/5 of the free space wavelength λ to choose.

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 at a ring line coupling point 7, a further radiator 4 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.

• Fig. 1:
  1. a) Antenne mit einem als Resonanzstruktur gestalteten kreisförmigen Ringleitungsstrahler 2 zur Erzeugung eines zirkular polarisierten Feldes mit azimutal abhängiger Phase mit einer elektromagnetischen Erregung 3, welche durch Einspeisung an λ/4 voneinander entfernten Ringleitungs-koppelpunkten 7 von um 90° in der Phase unterschiedlichen Signalen zur Erzeugung einer umlaufenden Welle von einer Wellenlänge über den Umfang der Leitung gegeben ist. Die Unterstützung vertikaler Komponenten des elektrischen Strahlungsfeldes erfolgt durch die vertikalen Strahler 4.
  2. b) wie in a) jedoch mit zusätzlichen vertikalen Strahlern 4, welche jeweils an einer Unterbrechungsstelle 23 mit einer verlustarmen Blindwiderstandsschaltung 13 der Reaktanz X beschaltet sind.
• Fig. 2:
  1. a) Antenne wie in Figur 1, jedoch zur Erzeugung der fortlaufenden Leitungswelle mit einem in günstigem Abstand - bezüglich des Leitungs-Wellenwiderstands - parallel zum Ringleitungsstrahler 7c geführten λ/4-Richtkoppelleiters 8.
  2. b) Antenne wie in Figur a) mit jedoch zwei im Wesentlichen vertikalen Strahlern 4, welche in einem bezüglich der ¼-Leitungs-Wellenlänge kleinen Abstand 37 parallel geführt sind.
• Fig. 3: Ringleitungsstrahler 2 jedoch mit einer elektromagnetischen Erregung 3 an vier jeweils um λ/4 längs der Ringleitung versetzten Ringleitungs-Koppelpunkten 7 durch in der Phase jeweils um 90° versetzten Signalen der Speisequellen. Die Speisequellen der Erregung 3 können auf an sich bekannte Weise durch Leistungsteilung und 90°-Hybridkoppler gewonnen werden.
• Fig. 4: Antenne wie in Figur 2, jedoch mit einer einen zweiten Richtkoppelleiter 21 beinhaltenden Erregung 3. Der zweite λ/4-Richtkoppelleiter 8 ist parallel zu einem Mikrostreifenleiter 30 geführt und bildet zusammen mit dem an den Ringleitungsstrahler 2 angekoppelten λ/4-Richtkoppelleiter 8 den zweiten λ/4-Richtkoppler.
• Fig. 5: Antenne mit einem als geschlossenen quadratischen Leitungsring mit der Kantenlänge von λ/4 gestalteten Ringleitungsstrahler 2. Die Erregung 3 ist als berührungslose Ankopplung an den Ringleitungsstrahler 2 über die rampenförmige λ/4-richtwirkende Koppelstruktur 18 mit dem Antennenanschluss 5 gestaltet. Die Koppelstruktur 18 beinhaltet den vertikalen Strahler 4
• Fig. 6: Antenne mit λ/4 voneinander entfernten Ringleitungs-Koppelpunkten 7, wobei die elektromagnetische Erregung 3 über gleich lange vertikale Strahler 4 über den Anschluss an einen Leistungs-Verteilnetzwerk - bestehend aus in Kette geschalteten, auf der leitenden Grundfläche 6 gebildeten λ/4-langen Mikrostreifenleitern 30a, 30b, 30c unterschiedlicher Wellenwiderstände - gegeben ist.
• Fig. 7: Antenne, beispielhaft mit kreisförmigem Ringleitungsstrahler 2 mit allgemein angedeuteter Erregung 3 und mit am Umfang äquidistant angeordneten Ringleitungs-Koppelpunkten 7 mit daran angekoppelten vertikalen Strahlern 4, in welche an Unterbrechungsstellen verlustarme Blindwiderstandsschaltungen 13 mit den für die Erzeugung einer umlaufenden Stromwelle auf dem Ringleitungsstrahler 2 notwendigen unterschiedlichen Reaktanzen X eingeschaltet sind.
• Fig. 8: Antenne wie in Figur 7, jedoch mit horizontalen Zusatzelementen zur weiteren Formung des Richtdiagramms.
• Fig. 9: Antenne mit einer besonders vorteilhaften Ausführungsform des Ringleitungsstrahlers 2 in quadratischer Form mit vier an den Ecken befindlichen vertikalen Strahlern 4. Die auf unterschiedliche Weise gestaltete Erregung 3 ist nicht gezeichnet.
• Fig. 10: Antenne wie in Figur 9, wobei jedoch jeder Abschnitt zwischen benachbarten Ringleitungs-Koppelpunkten 7 des Ringleitungsstrahlers 2 zur Verkleinerung der Resonanzstruktur eine für alle Abschnitte gleiche mäanderförmige Ausformung 17 enthält.
• Fig. 11: Antenne wie in Figur 9, mit elektromagnetischer Erregung 3 in Form einer gerichtet induktiv und kapazitiv angekoppelten Leiterschleife als Richtkoppler 18 in getaperter Form und einem Netzwerk 25 zur Leistungsanpassung.
• Fig. 12:
  1. a) Antenne nach der Erfindung wie in Figur 9 mit elektromagnetischer Erregung 3 durch Einspeisung am unteren Ende an einem der vertikalen Strahler 4 über die als Kapazität 15 gestaltete Blindwiderstandsschaltung 13. Zur Unterstützung der Unidirektionalität der Wellenausbreitung auf dem Ringleitungsstrahler 2 ist durch Gestaltung des Wellenwiderstands des Teilstücks des Ringleitungsstrahlers 2 zum benachbarten Ringleitungs-Koppelpunkt 7b in Abweichung von dem Wellenwiderstand der übrigen Teilstücke des Ringleitungsstrahlers 2 gestaltet.
  2. b) wie in Figur a) jedoch mit zwei einander gegenüberliegenden Teilstücken des Ringleitungsstrahlers 2, deren Wellenwiderstand von dem der beiden übrigen Teilstücke abweichen.
• Fig. 13: Antenne nach der Erfindung wie in Figur 9. Die unidirektionale Wirkung der elektromagnetischen Erregung 3 ist durch Teilankopplung eines über einen Teil des Ringleitungsstrahlers 2 parallel zu diesem geführten Koppelleiter 23 an einen der vertikalen Strahler 4 gegeben. Das andere Ende des Koppelleiters 23 ist über einen vertikalen Strahler 4 mit daran angeschlossenem Anpassnetzwerk 25 mit dem Antennenanschluss 5 verbunden.
• Fig. 14: Antenne nach der Erfindung wie in Figur 13, wobei das Anpassnetzwerk 25 in Form einer parallel zur elektrisch leitenden Grundfläche 6 gelegten hochohmigen Übertragungsleitung über etwa ¼ der Wellenlänge ausgeführt ist.
• Fig. 15: Antenne nach der Erfindung wie in Figuren 12a und 12b. Die Kapazitäten 15 sind in der Weise gebildet, dass die vertikalen Strahler 4 an ihrem unteren Ende zu individuell gestalteten flächigen Kapazitätselektroden 32a, 32b, 32c, 32d ausgeformt sind. Durch Zwischenlage zwischen diesen und der als elektrisch leitend beschichteten Leiterplatte ausgeführten elektrisch leitenden Grundfläche 6 befindlichen dielektrischen Platte 33 sind die Kapazitäten 15 zur Ankopplung von drei vertikalen Strahlern 4a, 4b, 4c an die elektrisch leitende Grundfläche 6 gestaltet. Zur kapazitiven Ankopplung des vierten vertikalen Strahlers 4d, an den Antennenanschluss 5 ist dieser als eine von der leitenden Schicht isolierte, flächige Gegenelektrode 34 gestaltet.
• Fig. 16: Antenne nach der Erfindung wie in Figuren 12a und 12b. Zwischen den unteren Enden der vertikalen Strahler 4a, 4b, 4c, 4d und die als leitend beschichtete Leiterplatte ausgeführte elektrisch leitende Grundfläche 6 ist eine weitere leitend beschichtete dielektrische Leiterplatte eingefügt. Die unteren Enden der vertikalen Strahler 4a, 4b, 4c, 4d sind galvanisch mit auf der Oberseite der dielektrischen Leiterplatte gedruckten flächigen Kapazitätselektroden 32a, 32b, 32c, 32d zur Bildung der Kapazitäten 15 für die kapazitive Ankopplung von drei der vertikalen Strahler 4 an die elektrisch leitende Grundfläche 6 verbunden. Für die kapazitive Ankopplung des vierten vertikalen Strahlers 4d an den Antennenanschluss 5 ist dieser als eine von der leitenden Schicht isolierte, flächige Gegenelektrode 34 gestaltet.
• Fig. 17: Antenne nach der Erfindung wie in Figuren 15 und 16, wobei die leitende Struktur, bestehend aus dem Ringleiter 2 und den damit verbundenen vertikalen Strahlern 4 durch eine dielektrische Stützstruktur 36 so fixiert ist, dass die dielektrische Platte 33 in Form eines Luftspaltes realisiert ist.
• Fig. 18: Profilansicht eines Ringleitungsstrahlers 2 in einer sich nach oben öffnenden Kavität 38, welche z. B. zum Zwecke der Integration in eine Fahrzeugkarosserie durch Ausformung der leitenden Grundebene 6 gestaltet ist. Die Höhe h1 bezeichnet die Tiefe der Kavität und die Höhe h den Abstand des Ringleitungsstrahlers 2 über der Kavitäts-Basisfläche 39. Ein zu geringer Abstand 41 zwischen dem Ringleitungs-strahler 2 und den Kavitäts-Seitenflächen 40 hat eine die Frequenzbandbreite der Antenne 1 einengende Wirkung.
  1. a) h > h1: teilweise Integration
  2. b) h = h1: vollständige Integration
• Fig. 19: Ringleitungsstrahler 2 nach der Erfindung kombiniert mit einem weiteren Ringleitungsstrahler 2a mit gleichem Zentrum Z und einem Phasenunterschied der auf der Ringleitung 2a in einer einzigen Umlaufrichtung sich ausbreitenden Leitungswelle über einen Umlauf von gerade N*2π mit (N>2) zur Bildung einer Richtantenne mit einem Richtdiagramm mit azimutaler Hauptrichtung am Richtantennen-Anschluss 43.
• Fig. 20: Richtantenne wie in Figur 19 mit kreisförmigem Ringleitungsstrahler 2 und weiterem Ringleitungsstrahler 2a mit N=2. Die vertikalen Strahler 13a-d und 45a-h sind auf beiden Ringleitungsstrahlern äquidistant und entsprechend einer Phasen-Differenz der laufenden Welle von jeweils π/2 angeordnet. Die Empfangssignale am Antennenanschluss 5 und an der Strahler-Anschlussstelle 46 werden über ein steuerbares Phasendrehglied 42 im Summations- und Auswahl-Netzwerk 44 zur Bildung des Richtdiagramms mit steuerbarer azimutaler Hauptrichtung überlagert.
• Fig. 21: Richtantenne wie in Figur 20 jedoch mit quadratisch geformtem Ringleitungsstrahler 2 (Phasendifferenz der laufenden Welle von 2π verteilt über dem Umfang) und mit achteckig geformtem weiterem Ringleitungsstrahler 2a (Phasendifferenz der laufenden Welle von 4π verteilt über dem Umfang).
• Fig. 22: Räumliches Richtdiagramm der Richtantenne in Figur 21 mit ausgeprägter azimutaler Hauptrichtung (Pfeil) und Nullstelle.

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

• Fig. 1 :
  1. a) antenna having a designed as a resonant structure circular ring radiator 2 for generating a circularly polarized field with azimuthally dependent phase with an electromagnetic excitation 3, which by feeding at λ / 4 remote loop coupling points of 7 by 90 ° in the phase different signals to Generation of a rotating wave of a wavelength over the circumference of the line is given. The support of vertical components of the electric radiation field is carried out by the vertical radiator. 4
  2. b) as in a) but with additional vertical radiators 4, which are each connected at an interruption point 23 with a low-loss reactance circuit 13 of the reactance X.
• Fig. 2 :
  1. a) Antenna as in FIG. 1 , 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 out guided λ / 4 Richtkoppelleiters. 8
  2. b) Antenna as in Figure a) but with two substantially vertical radiators 4, which are guided in parallel with respect to the ¼-line wavelength distance 37.
• Fig. 3 : Ring line emitter 2, however, with an electromagnetic excitation 3 to four each by λ / 4 along the ring line offset loop line crosspoints 7 by in each case by 90 ° offset signals of the supply sources. The feed sources of the excitation 3 can be obtained in a manner known per se by power sharing and 90 ° hybrid coupler.
• Fig. 4 : Antenna as in FIG. 2 , but with a second directional coupler 21 containing excitation 3. The second λ / 4 Richtkoppelleiter 8 is guided parallel to a microstrip conductor 30 and forms together with the coupled to the ring line emitter λ / 4 Richtkoppelleiter 8 the second λ / 4-directional coupler ,
• Fig. 5 Antenna with a ring line radiator 2 designed as a closed square line ring with the edge length of λ / 4. The excitation 3 is designed as a non-contact coupling to the ring line radiator 2 via the ramp-shaped λ / 4-directional coupling structure 18 with the antenna connection 5. The coupling structure 18 includes the vertical radiator 4
• Fig. 6 : Antenna with λ / 4 distant ring line crosspoints 7, wherein the electromagnetic excitation 3 via equally long vertical radiator 4 via the connection to a power distribution network - consisting of connected in chain, formed on the conductive base 6 λ / 4-long Microstrip conductors 30a, 30b, 30c of different characteristic impedance - is given.
• Fig. 7 : Antenna, by way of example with circular ring line emitter 2 with generally indicated excitation 3 and with circumferentially equidistantly arranged ring line crosspoints 7 with vertical emitters 4 coupled thereto, into which at interruption points low-impedance reactance circuits 13 with those necessary for the generation of a circulating current wave on the ring line emitter 2 different reactances X are turned on.
• Fig. 8 : Antenna as in FIG. 7 , but with horizontal additional elements for further shaping of the directional diagram.
• Fig. 9 : Antenna with a particularly advantageous embodiment of the ring line radiator 2 in square shape with four vertical radiators located at the corners 4. The excitation 3 designed in different ways is not drawn.
• Fig. 10 : Antenna as in FIG. 9 , wherein, however, each section between adjacent ring line coupling points 7 of the ring line radiator 2 for reducing the resonance structure contains a meander-shaped formation 17 which is the same for all sections.
• Fig. 11 : Antenna as in FIG. 9 , with electromagnetic excitation 3 in the form of a directionally inductively and capacitively coupled conductor loop as a directional coupler 18 in capped form and a network 25 for power adjustment.
• Fig. 12 :
  1. a) Antenna according to the invention as in FIG. 9 with electromagnetic excitation 3 by feeding the lower end of one of the vertical radiator 4 via the designed as a capacitance 15 reactance circuit 13. To support the unidirectional wave propagation on the ring line radiator 2 is by shaping the characteristic impedance of the section of the ring line radiator 2 to the adjacent loop cross-coupling point 7b designed in deviation from the characteristic impedance of the remaining sections of the ring line radiator 2.
  2. b) as in Figure a) but with two opposing sections of the ring line radiator 2, whose characteristic impedance differ from that of the other two sections.
• Fig. 13 : Antenna according to the invention as in FIG. 9 , The unidirectional effect of the electromagnetic excitation 3 is given by partial coupling of a part of the ring line emitter 2 parallel to this guided coupling conductor 23 to one of the vertical radiator 4. The other end of the coupling conductor 23 is connected to the antenna connection 5 via a vertical radiator 4 with a matching network 25 connected thereto.
• Fig. 14 : Antenna according to the invention as in FIG. 13 , wherein the matching network 25 in the form of a parallel to the electrically conductive base surface 6 high-impedance transmission line is performed over about ¼ of the wavelength.
• Fig. 15 : Antenna according to the invention as in FIGS. 12a and 12b , The capacitances 15 are formed in such a way that the vertical radiators 4 are formed at their lower end to form individualized area capacitance electrodes 32a, 32b, 32c, 32d. By Interposed between these and the electrically conductive base plate running as electrically conductive base plate 6 located dielectric plate 33 are the capacitances 15 for coupling three vertical radiators 4a, 4b, 4c to the electrically conductive base 6 designed. For the capacitive coupling of the fourth vertical radiator 4d, to the antenna connection 5, this is designed as a flat counterelectrode 34 isolated from the conductive layer.
• Fig. 16 : Antenna according to the invention as in FIGS. 12a and 12b , Between the lower ends of the vertical radiators 4a, 4b, 4c, 4d and designed as a conductive coated circuit board electrically conductive base 6, a further conductive coated dielectric circuit board is inserted. The lower ends of the vertical radiators 4a, 4b, 4c, 4d are galvanic with surface capacitive electrodes 32a, 32b, 32c, 32d printed on the upper surface of the dielectric board to form capacitances 15 for the capacitive coupling of three of the vertical radiators 4 to the electrical ones conductive base 6 connected. For the capacitive coupling of the fourth vertical radiator 4d to the antenna terminal 5, this is designed as a flat counterelectrode 34 isolated from the conductive layer.
• Fig. 17 : Antenna according to the invention as in FIGS. 15 and 16 wherein the conductive structure consisting of the ring conductor 2 and the associated vertical radiators 4 is fixed by a dielectric support structure 36 so that the dielectric plate 33 is realized in the form of an air gap.
• Fig. 18 : Profile view of a ring line radiator 2 in an upwardly opening cavity 38, which z. B. for the purpose of integration in a vehicle body by forming the conductive ground plane. 6 is designed. The height h1 denotes the depth of the cavity and the height h the distance of the ring line radiator 2 above the cavity base surface 39. Too small a distance 41 between the ring line radiator 2 and the cavity side surfaces 40 has a narrowing the frequency bandwidth of the antenna 1 effect ,
  1. a) h> h1: partial integration
  2. b) h = h1: complete integration
• Fig. 19 : Ring line emitter 2 according to the invention combined with another ring line emitter 2a with the same center Z and a phase difference of on the ring line 2a in a single direction propagating line wave over a cycle of just N * 2π with (N> 2) to form a directional antenna with a directional diagram with azimuthal main direction at the directional antenna port 43rd
• Fig. 20 : Directional antenna as in FIG. 19 with circular ring line emitter 2 and further ring line emitter 2a with N = 2. The vertical radiators 13a-d and 45a-h are arranged equidistantly on both ring line radiators and corresponding to a phase difference of the current wave of π / 2 in each case. The received signals at the antenna connection 5 and at the radiator connection point 46 are superimposed via a controllable phase rotation element 42 in the summation and selection network 44 to form the directional diagram with a controllable azimuthal main direction.
• Fig. 21 : Directional antenna as in FIG. 20 however, with a square-shaped ring line radiator 2 (phase difference of the traveling wave of 2π distributed over the circumference) and with an octagonal shaped further ring line radiator 2a (phase difference of the traveling wave of 4π distributed over the circumference).
• Fig. 22 : Spatial directional diagram of the directional antenna in FIG. 21 with pronounced azimuthal main direction (arrow) and zero.

The loop emitter 2 of the invention is designed as a passive resonant structure for a transmit or receive antenna which transmits and / or receives substantially circularly polarized waves in an elevation angle range between theta = 0 ° (vertical) and theta = 65 ° and substantially vertically polarized waves in an elevation angle range between theta = 90 ° and theta = 85 °, where theta describes the angle of the incident wave with respect to the vertical. Azimuthal is generally aimed at broadcasting.

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. 1a shows an antenna with a designed as a resonant structure circular loop emitter 2 for generating a circularly polarized field. To generate the resonance, the stretched length of the ring line of the ring line radiator 2 is chosen such that it substantially corresponds to the line wavelength. The ring line emitter 2 is designed to extend in a horizontal plane with the height h over the conductive base 6, so that it forms an electrical line with respect to the conductive base 6 with a characteristic impedance resulting from the height h and the effective diameter of the im Essentially results in a wire-shaped loop conductor. To generate the desired circular polarization with azimuthally dependent phase of a direction of rotation of the radiation in the far field, it is necessary to excite on the loop emitter 2 exclusively in one direction propagating line wave. This is effected according to the invention by an electromagnetic excitation 3, which causes the rotating shaft of a wavelength over the circumference of the line in only one direction of rotation. For this purpose, the feeding takes place at λ / 4 apart ring line crosspoints 7 of different by 90 ° in the phase signals. A support of vertical components of the electric radiation field is carried out according to the invention by vertical radiators 4, which allow the emission of vertical electric field components, and on the excitation 3 of the ring line radiator 2 takes place in the example shown. Generation of the signals which are different in phase by 90 ° for feeding in at the base points of the vertical radiators 4 can take place, for example, by means of a power divider and phase shift network 31 and in each case via a corresponding matching network 25.

In FIG. 1b is a similar antenna according to the invention is shown in which, however, additional, the excitation 3 not belonging vertical radiators are present, which are coupled at ring line crosspoints 7 to the ring line emitter 2 and guided to the electrically conductive base 6 out and in which at points of interruption low-loss reactance circuits 13 of the Reactance X are turned on. By designing the vertical radiator 4 and the switched reactance X, the propagation of the line wave on the ring line radiator 2 can be brought about with preferably uniform distribution of the spacings of λ / 4 between the ring line crosspoints 7.

In a further embodiment, the generation of a continuous line shaft on the ring line radiator 2 in FIG. 2a with an excitation 3, which is given by a parallel directional coupler 8. This is performed in a respect to the line impedance characteristic coupling distance over a straight length of λ / 4 parallel to the ring line radiator 2. The directional coupling conductor 8 is connected on one side via a vertical radiator 4a and a matching network 25 to the antenna terminal 5 and on the other side via a vertical radiator 4b with the conductive base 6.

In a further advantageous embodiment is in FIG. 2b to generate a continuous line wave on the ring line emitter 2, however, the excitation 3 given by two substantially vertical radiator 4, which are parallel in a respect to the ¼-line wavelength distance 37 and guided via galvanic coupling points 7 to the ring line emitter 2. In this case, one vertical emitter 4a is connected to the antenna terminal 5 via a matching network 25 and the other vertical emitter 4b is connected to the conductive base 6 via a ground terminal 11.

Similar to in FIG. 2a the electromagnetic excitation 3 in FIG. 4 in an advantageous manner with the aid of a first λ / 4 directional coupler, which is given by a parallel directional coupling conductor 8 described above. To illustrate the power divider and phase shifter network 31, a second directional coupler 21 for generating two signals different by 90 ° is coupled to a transmission conductor 30 extending on the conductive base 6 by parallel guidance at a short distance. The second directional coupling conductor 21 is to feed via the vertical radiator 4 with the first directional coupling conductor 8 and the microstrip conductor 30 are connected to the antenna terminal 5.

In FIG. 3 are formed to generate a continuous line wave on the ring line radiator 2 N = 4 by each λ / 4 apart along the closed loop structure remote ring line crosspoints 7, to which vertical radiators 4 - galvanically coupled in the example. The electromagnetic excitation 3 takes place in such a way that equally large signals are fed between the lower ends of the vertical radiator 4 and the electrically conductive base, which are each shifted by 360 ° / 4 to each other in phase.

In a further embodiment of the ring line radiator 2 in FIG. 5 formed as a closed square line ring with the edge length of λ / 4 on the conductive base 6 at a distance h above the conductive base 6. To generate a continuous line wave on the ring line emitter 2 and for coupling to the ring line emitter 2, the electromagnetic excitation 3 is designed as a ramp-shaped directional coupling conductor 12 with an advantageous length of substantially λ / 4. This is designed substantially as a linear conductor, which advantageously extends in a plane which includes one side of the ring line radiator 2 and which is oriented perpendicular to the electrically conductive base surface 6. In this case, the linear conductor, starting from the antenna connection 5 located on the conductive base 6, leads via a vertical feed line 4 to a coupling end spacing 16 to one of the corners of the ring line emitter 2 and is substantially below an adjacent corner from there in accordance with a ramp function led to the base 6 and connected to this via the ground terminal 11 conductive. By adjusting the Koppelendabstands 16, the adaptation to the antenna connector 5 can be easily made. The particular advantage of this arrangement is the non-contact coupling of the excitation 3 to the square-shaped ring line radiator 2, which allows a particularly simple production of the antenna.

In a further advantageous embodiment of an antenna are in FIG. 6 Ring line coupling points 7 formed and the electromagnetic excitation 3 is given over the same length vertical and the conductive base 6 extending radiator 4, which are each connected via an equally long lead 22 to a port of a power distribution network and this on the other hand with the antenna port. 5 connected is. The power distribution network consists advantageously of chain-connected, formed on the conductive base 6 λ / 4-long microstrip conductors 30a, 30b, 30c, wherein their characteristic impedance - starting from a low characteristic impedance at the antenna terminal 5 - to which one of the vertical radiator 4 is directly connected via its supply line 22 - are highly stepped in such a way that the fed at the corners in the ring line emitter 2 signals have the same power and each lag 90 ° in the phase continuously lagging.

Particularly advantageous embodiments of antennas according to the invention are those arrangements in which the ring line radiator 2 of the straight length L at substantially similar distances UN to each other ring line coupling points 7 are designed and to each of which a vertical radiator 4 is coupled, which on the other hand via ground Connection points 11 are coupled to the electrically conductive base 6. To generate a line propagating exclusively in one direction on the ring line emitter 2, it is inventively particularly advantageous to turn in the vertical radiators 4 at break points reactance circuits 13 to determine the propagation direction of this wave by the design of their reactance X and the propagation of a wave in to prevent the opposite direction. FIG. 7 shows an arrangement of this kind, wherein the versatile design excitation 3 is indicated in a general form.

By electromagnetic coupling, that is preferably galvanic or capacitive coupling of the two antenna parts, consisting of the ring line radiator 2 and the circle group of the vertical radiator 4 at the loop coupling points 7, the antenna parts are coupled together in such a way that both antenna parts contribute constructively to a circularly polarized field. The ring line emitter 2 acts as a radiating element which generates a circularly polarized field with a vertical main radiation direction. This field is superimposed on the electromagnetic field generated by the vertical radiators 4. In this case, the electromagnetic field generated by the circle group of the vertical radiator 4 in diagonal elevation is also circularly polarized with the azimuth substantially independent main beam direction. At lower elevation, this field is vertically polarized and substantially azimuthally independent as well.

In the following, the mode of operation of a resonant structure is described by FIG. 7 explained in more detail. As already described above, the resonance structure is connected to the antenna connection 5 via an excitation 3 in such a way that the line wave on the ring line emitter 2 propagates substantially only in one direction of rotation so that one period of the line wave is contained in the direction of rotation of the ring structure.

The ring structure with N vertical radiators can be divided into N segments. As a condition for a continuous wave with a period in the direction of circulation applies to the currents I2 and I1 adjacent segments: $$\underset{\_}{I}2=\underset{\_}{I}1·\mathrm{<figure-callout\; id="2"\; label="exp\; j"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">exp\; </figure-callout>}\left(j\right)\left(2\pi /N\right)$$

und
wobei $$\Phi =2\mathit{\pi L}/\left(\mathit{N\lambda }\right)$$

die Phasendrehung über den Wellenleiter der Länge L/N für ein Segment bildet.It also applies to the current at the ring line crosspoint 7, which flows into the vertical radiator 4: $$\underset{\_}{I}S=\underset{\_}{I}1·\exp \left(\mathit{j\Phi }\right)-\underset{\_}{I}\mathrm{2,}$$

and
in which $$\Phi =2\mathit{\pi L}/\left(\mathit{N\lambda }\right)$$

forms the phase rotation across the waveguide of length L / N for a segment.

Thus, the current IS must be adjusted via the impedance of the vertical radiator 4 together with the reactance X in the foot connection point of the vertical radiator 4 so that: $$\underset{\_}{I}S=\underset{\_}{I}1·\left[\exp (\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathit{\pi L}/\left(\mathit{N\lambda }\right)-\exp (\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathit{\pi L}/\left(N\right)\right]$$

gemäß Gleichung (3) einstellt, welche zusammen mit der Phasendrehung ΔΦ des entsprechenden Filters eine resultierende Phasendrehung über einem Segment von $$\mathit{\Delta \Phi }+\Phi =2\mathit{\pi L}/N$$

ergibt. Die elektromagnetische Welle, welche sich im Umlaufsinn entlang der Ringstruktur ausbreitet, erfährt somit bei einem Umlauf die Phasendrehung von 2π.The vertical radiators 4 together with the reactances X form in their equivalent circuit diagram a filter consisting of a series inductance, a parallel capacitance and a further series inductance. The parallel capacitance is chosen by adjusting the reactances X so that the filter is adapted on both sides to the conductor impedance of the annular transmission line 1. The resonant structure thus consists of N conductor segments of length L / N and in each case a filter connected thereto. Each filter causes a phase rotation ΔΦ. The length UN of the conductor segments is then adjusted so that over this conductor segment, a phase rotation of $$\Phi =2\mathit{\pi L}/\left(\mathit{N\lambda }\right)$$

in accordance with equation (3) which, together with the phase rotation ΔΦ of the corresponding filter, results in a resulting phase shift over a segment of $$\mathit{\Delta \Phi }+\Phi =2\mathit{\pi L}/N$$

results. The electromagnetic wave, which propagates in the circumferential direction along the ring structure, thus undergoes the phase rotation of 2π in one revolution.

With this particularly advantageous embodiment of the invention, it is therefore possible to make the stretched length L of the loop antenna 2 shorter than the wavelength λ by the shortening factor k <1, so that L = k * λ.

By observing the condition given in equation 4 for the current in the vertical radiators 4, according to the invention, their constructive contribution to the circular polarization in diagonal elevation with azimuthal omnidirectional characteristic is obtained. This results in the particular advantage of the main radiation with circular polarization in diagonal elevation with the present invention. Thus, the antenna is also suitable in particular for the reception of signals from low-flying satellites. In addition, the antenna can also be advantageously used for satellite broadcasting systems in which terrestrial, vertically polarized signals are also transmitted in support of the reception.

In a further embodiment, the vertical radiator 4 as in FIG. 8 coupled via horizontal radiator elements 14 to the loop coupling points 7. The horizontal radiator elements 14 can be used flexibly for further shaping of the vertical radiation pattern of the antenna. The above-described requirement for the choice of the reactances X to be introduced into the vertical radiators 4 in order to fulfill the above equations remains unaffected.

In particular, for the low-complexity production of a ring line radiator 2, the in FIG. 9 illustrated quadratic shape, with four formed at the corners of the square ring line crosspoints 7 and there galvanically connected vertical radiators 4, each with a base at the base to the ground connection point 11 introduced capacitance 15 as a reactance circuit 13. The excitation 3 of this resonant structure can on various types Be fashioned and is therefore in FIG. 9 not included.

In an advantageous embodiment of the excitation 3 for a ring line radiator 2 with a square shape, this is non-contact as directed inductively and capacitively coupled conductor loop as a directional coupler 18 as in FIG. 11 designed. The directional coupling conductor 18 is tapered in shape, and is similar as in connection with the excitation 3 in FIG FIG. 5 described, designed substantially as a linear conductor, which advantageously extends in a plane which includes one side of the ring line radiator 2 and which is oriented perpendicular to the electrically conductive base surface 6. Here, the linear conductor, starting from the located on the conductive base 6 ground connection points 11 via a short vertical lead and a ramp function up to a coupling distance 10 to the Ring line emitter 2 introduces, is returned from there via a vertical radiator 4 to the conductive base and connected via a matching network 25 to the antenna terminal 5.

In FIG. 12a For example, one of the vertical radiators 4a with the reactance circuit 13 realized as a capacitor 15 is not coupled to the ground connection point 11 on the electrically conductive base 6 but to the connection formed on the plane of the conductive base 6 to the matching network 25 and thus to the antenna connection 5 , To effect the unidirectionality of the wave propagation on the ring line emitter 2 in this advantageous embodiment of the invention based on the conductive base 6 characteristic impedance of the section of the ring line radiator 2 to adjacent ring line crosspoint 7b designed in deviation from the characteristic impedance of the remaining sections of the ring line radiator 2. With a suitable choice of this characteristic impedance, the propagation of a line wave in the opposite direction of rotation is suppressed. The design of the characteristic impedance can be carried out in a known manner, for example by selecting the effective diameter of the substantially linear ring line emitter 2, or as exemplified by an additional conductor 19 reducing the characteristic impedance. To further support the unidirectionality of the wave propagation on the loop emitter 2 is in FIG. 12b a further portion of the ring line radiator 2 opposite the first section having a different characteristic impedance with characteristic impedance deviating from the characteristic impedance of the remaining sections of the ring line radiator 2.

At the in FIG. 13 illustrated advantageous embodiment of an antenna according to the invention, the electromagnetic excitation 3 is designed by partial coupling to one of the vertical radiator 4 at one of the loop coupling points 7a. The unidirectional effect of the electromagnetic excitation 3 with respect to the wave propagation is achieved by partial coupling to a vertical radiator 4a via a, to a part of the ring line radiator 2 in parallel Coupling conductor 23 given and the other end of the coupling conductor 23 is connected to a vertical and the conductive base 6 extending radiator 4e, the latter being connected via a matching network 25 to the antenna terminal 5.
In FIG. 14 is the matching network 25 in the form of a parallel to the electrically conductive base 6 set high-impedance transmission line over about ¼ of the wavelength advantageously carried out.

For space reasons, it may be necessary to make the ring line emitter 2 while maintaining the resonance condition with smaller dimensions. For this purpose, according to the invention, each section between adjacent ring line coupling points 7 of the ring line radiator 2 can be given a meandering shape 17 that is the same for all sections, as shown by way of example in FIG FIG. 10 is shown.

An essential feature of an antenna according to the present invention is the possibility for particularly low-cost production. In this respect, an outstandingly advantageous form of the antenna with square ring-shaped radiator 2 is similar in nature to that in FIG FIG. 12b designed and in FIG. 15 shown. The ring line emitter 2 with the vertical emitters 4a, 4b, 4c, 4d, together with the flat-shaped capacitance electrodes 32a, 32b, 32c, 32d individually shaped at their lower end, can be made, for example, from a coherent, stamped and formed sheet metal part. The characteristic impedance of the sections of the ring line radiator 2 can be designed individually by choosing the width of the connectors. The electrically conductive base 6 is preferably designed as a conductive coated circuit board. The reactance circuits 13 realized as capacitances 15 are formed in such a way that the capacitance electrodes 32a, 32b, 32c, 32d are provided by interposing a dielectric plate 33 located between them and the electrically conductive base 6 for coupling three vertical radiators 4a, 4b, 4c the electrically conductive base 6 are designed. For the design and the capacitive coupling of the fourth vertical radiator 4 d to the antenna terminal 5, this is one of the conductive layer of the circuit board insulated, flat counter electrode 34 designed. In a particularly low-effort manner, it is therefore possible to produce the essential dimensions necessary for the function of the antenna via a stamped and formed sheet-metal part with the advantages of high reproducibility. The sheet-metal part, the dielectric plate 33 and the electrically conductive base 6 embodied as a printed circuit board can be connected to one another by way of example by low-cost adhesive bonding and thus without costly soldering. The connection to a receiver can be realized in a known manner, for example by connecting a microstrip line or a coaxial line, starting from the antenna connection 5.

In a further variant of such an antenna is in FIG. 16 instead of a dielectric plate 33 between the lower ends of the vertical radiators 4a, 4b, 4c, 4d and the electrically conductive base 6 designed as a conductive coated printed circuit board, a further conductive coated, dielectric circuit board is inserted. On the upper side of the dielectric circuit board there are printed area capacitance electrodes 32a, 32b, 32c, 32d for forming the capacitances 15, which are galvanically connected to the vertical radiators 4a, 4b, 4c, 4d, optionally by soldering. The capacitive coupling of three of the vertical radiators 4a, 4b, 4c to the electrically conductive base 6 via the capacitance electrodes 32a, 32b, 32c. The capacitive coupling of the fourth vertical radiator 4 d to the antenna terminal 5, which is designed as a planar counterelectrode 34 isolated from the conductive layer, is provided via the capacitance electrode 32.

In a further advantageous embodiment of the invention, the antenna is in FIG. 17 similar in the Figures 16 designed, wherein the conductive structure, consisting of the ring conductor 2 and the associated vertical radiators 4, is fixed by a dielectric support structure 36 in such a way that the dielectric plate 33 is realized in the form of an air gap.

For the design of a multiband antenna according to the invention, the reactance circuit 13 is designed in such a way multi-frequency, that both the resonance of the ring line radiator 2 and the required running direction of the line shaft on the ring line radiator 2 in separate frequency bands is given.

In particular, in the automotive industry, there is often the interest to make the visible height of an antenna mounted on the vehicle skin as low as possible. This desire goes all the way to the design of a completely invisible antenna, which is fully integrated into the vehicle skin. In an advantageous embodiment, therefore, as in the Figures 18a and 18b illustrated with oblique Kavitäts-side surfaces 40, the substantially extending in a base plane E1 conductive base 6 at the location of the ring line radiator 2 as an upwardly open conductive cavity 38 formed. This cavity 38 is thus an effective part of the conductive base 6 and consists of a cavity base surface 39 in a base surface plane E2 located at a distance h1 parallel to and below the surface plane E1. The cavity base surface 39 is connected to the planar part of the conductive base 6 via the cavity side surfaces 40. The ring line emitter 2 is introduced into the cavity 38 in a further horizontal ring line plane E at the height h extending above the cavity base surface 39.

The environment of the ring line radiator 2 with the cavity basically has a narrowing the frequency bandwidth of the antenna 1 effect, which is essentially determined by the cavity spacing 41 between the ring line radiator 2 and the cavity 38. Therefore, the conductive cavity base surface 39 should be at least large enough to at least cover the vertical projection surface of the loop emitter 2 to the base surface plane E2 located below the conductive base. In an advantageous embodiment, however, the cavity base surface 39 is larger and selected in such a way that the cavity side surfaces 40 can be designed as vertical surfaces and while a sufficient cavity spacing 41 between the ring line radiator 2 and the cavity 38 is given.

In the event that insufficient space is available for the formation of the cavity with vertical cavity side surfaces 40, it is advantageous to choose the base surface plane E2 to be approximately as large as the vertical projection surface of the ring line radiator 2 to the base surface plane E2 and make the cavity side surfaces 40 along a contour inclined from a vertical line. In this case, the inclination of this contour is to be selected in such a way that, given the required frequency bandwidth of the antenna 1, a sufficiently large cavity spacing 41 is present between the ring line emitter 2 and the cavity 38 at each location. For the in FIG. 18b shown, particularly interesting case of a fully integrated with the vehicle body antenna 1, in which the loop level E is approximately the same height as the base plane E1, results for the above example, the SDARS satellite broadcasting at a frequency of about 2, 33 GHz in two adjacent frequency bands, each with a bandwidth of 4 MHz approximately the following advantageous dimensions for compliance with the necessary cavity spacing 41 between the ring line radiator 2 and the cavity 38. For this purpose, the inclination of the cavity side surfaces 40 is selected in each case in the manner that at a vertical distance z above the cavity base surface 39, the horizontal distance d between the vertical connecting line between the ring tube radiator 2 and the cavity base surface 39 and the nearest cavity side surface 40 assumes at least half the vertical distance z. Naturally, the frequency bandwidth of the antenna 1 increases the further the cavity 38 is opened upwards. If, while maintaining the last-mentioned necessary cavity spacing 41 between the ring line radiator 2 and the cavity 38, the cavity side surfaces 40 are designed vertically, the necessary frequency bandwidth is also ensured. The same also applies if the height h of the ring line plane E is greater than the depth of the cavity base surface 39, as shown in FIG FIG. 18a is shown. That is, h is larger than h1 and the antenna 1 is not fully integrated with the vehicle body.

In particular, for the formation of combination antennas for a plurality of radio services ring line emitters 2 according to the present invention offer the advantage of a particularly space-saving design. For this purpose, for example, a plurality of ring line radiators for the different frequencies of several radio services can be designed around a common center Z. Due to their different resonant frequencies, the different ring line radiators influence only slightly, so that small distances between the ring lines of the ring radiators 2 can be designed.

In a circular-polarized ring-type radiator with an azimuthal circular diagram according to the invention, the phase of the radiated far-field electromagnetic field rotates with the azimuthal angle of the propagation vector due to the current wave propagating in a running direction on the loop. In Fig. 19 is a ring line emitter 2 according to the invention surrounded by another ring line emitter 2a, which is formed according to the rules described above and which also forms a resonant structure and is electrically excited in such a way that on the loop the current distribution of a current line wave in a single Adjusting the direction of rotation, the phase difference is in contrast to the inner loop emitter 2 over a circuit straight N * 2π. N is an integer and is N> 1. The polarization of this azimuthal omnidirectional radiator is also circular and the phase of circular polarization rotates at N = 2 due to the distribution of two complete waves on the ring conductor with double dependence on the azimuthal angle of the propagation vector. In this particularly advantageous embodiment of the invention, the two ring line radiators are combined with the same center Z. Thus, the phase reference points of the two ring line emitters 2, 2a are congruent in the common center Z. The in Fig. 19 illustrated outer loop emitter 2a is exemplified by two λ / 4-spaced crosspoints 7a, similar to in FIG Fig. 2 , electrically excited. Due to the corresponding length of the loop structure, however, in contrast to this, at N = 2, two complete wave trains of a traveling wave are formed. When superimposing the received signals under suitable weighting and phase relationship of the two ring line emitters 2, 2 a, a directional antenna with a predetermined azimuthal main direction and elevation can be designed according to the invention. This is done by the different azimuthal dependency of the current phases on the two ring line radiators 2, 2a, depending on the phase position of the two current waves on the ring line radiators 2, 2a, the radiation depending on the azimuth angle of the propagation vector partially superimposed supportive or attenuating. By amplitude-matched summary of the signals of the two ring line emitters 2, 2a via a controllable phase shifter 42 and a summation network 44, thus formed in an advantageous manner in the azimuthal directional pattern of the combined antenna arrangement at the directional antenna port 43, a main direction of radiation, which depends on the setting the phase shifter 39 is dependent. This property allows z. B. the advantageous tracking of the main beam direction in mobile satellite reception. The mode of operation of the superimposition of the received signals goes out of the in FIG. 22 illustrated directional diagram for an LHCP polarized satellite signal at an adjustment of the phase shifter 42 forth. The main direction in the azimuth with the low elevation is indicated by an arrow.

In an advantageous embodiment of the invention, the further ring line radiator 2a as a rotationally symmetrical about the center Z arranged polygonal or circular closed ring line radiator 2a in a horizontal plane with the height ha on the conductive base 6 extending designed. According to the invention, the ring line 2a is fed in such a way that adjusts itself to the current distribution of a current line wave whose phase difference over a cycle is just 2 * 2π. By the effect of the coupled to the ring line coupling points 7a vertical radiator 4a can also be here the extended length of another ring line radiator 2a shorter by a shortening factor k <1 than the corresponding double wavelength λ. To reduce the diameter D of the ring line radiator 2, 2a, the phase difference of 2π (ring line radiator 2) and 2 * 2π (ring line radiator 2a) on the loop by increasing the line inductance and / or the line capacitance to the conductive base 6 done.

In a particularly advantageous embodiment of the further ring line radiator 2a, this circular or polygonal shape is designed with 8 equidistantly arranged cross-coupling points 7a with vertical radiators 4 coupled thereto. Fig. 20 shows by way of example a circular ring line radiator 2a with further reactance circuits 45a,... 45d, which are introduced into the vertical radiators 4. In these reactance circuits 45a ... 45d, together with the characteristic impedances Zf of the ring line sections between the loop coupling points 7a are matched to each other so that both the running direction of the rotating shaft in the predetermined direction and the resonance of the ring conditioner 2a for the phase condition Set 2 * 2π for this wave. This is achieved in an advantageous manner in that low-impedance and high-impedance characteristic impedance along the circumference of the ring line emitters 2, 2a alternate with each other. Depending on the shortening factor k <1 explained above, the ring line sections of the two ring line emitters 2, 2a can be selected substantially shorter than a quarter wavelength up to λ / 8. Accordingly, in successive loop sections, large and small inductance values and small and large capacitance values of the loop sections alternate.

FIG. 21 shows a plan view of the directional antenna in FIG. 20 , wherein the antenna is formed of a square shaped ring line radiator 2 and an octagonal shaped further ring line radiator 2. The loop coupling points 7 and 7a are respectively formed at the corners of the square inner ring and the octagonal outer ring. To each of the vertical radiator 4 are connected. Particularly in the case of mobile satellite reception with only a limited or partially shadowed direct view of the satellite, it is often advantageous to increase the diversity of the available reception signals, for example in the sense of a switching diversity method, due to suddenly occurring signal fading. By configuring the summation network 44 as summation and selection network 44a, it is possible to select separately there between the received signals of the two ring line emitters 2, 2a and the weighted superimposition-possibly with different weightings.

For the production of the further ring line radiator 2a according to the invention, the same technologies are used, as for the production of the ring line radiator 2 z. B. especially in connection with the FIGS. 15 to 17 are described.

Claims (12)

1. An antenna (1) for the reception of circularly polarized satellite radio signals, comprising at least one horizontally oriented conductor loop arranged above a conductive base surface (6); and an arrangement connected to an antenna connector (5) for the electromagnetic excitation of the conductor loop, comprising the following features:

   - the conductor loop is configured as a ring line radiator (2) extending through a polygonal or circular closed ring line in a horizontal plane at a height h above the conductive base surface (6);

   - the ring line radiator (2) forms a resonant structure and can be electrically excited by electromagnetic excitation in a manner such that the current distribution of a running line wave in a single rotation direction is adopted on the ring line, the phase difference of said line wave amounting over one rotation to just 2π, with the periphery (L) of the ring line radiator (2) corresponding to the line wavelength in the ring line;

   - vertical radiators (4, 4a-d) which are galvanically coupled with the ring line radiator (2) at ring line coupling points (7) and which extend toward the conductive base surface (6) are present at the periphery of the ring line radiator (2), with a radiator being coupled with the electrically conductive base surface (6) and the excitation of the conductor loop taking place via another radiator,

   characterized in that,
   for supporting the vertically oriented portions of the electromagnetic field, at least two further vertical radiators (4, 4a-d) which are galvanically coupled with the ring line radiator (2) and which extend toward the conductive base surface (6) are present and are electromagnetically coupled with the electrically conductive base surface (6); in that the ring line coupling points (7) are distributed equidistantly at the periphery of the ring line radiator (2);
   and in that the vertical radiators coupled with the electrically conductive base surface (6) are coupled with the base surface (6) via reactance circuits (13) having a reactance X.
2. An antenna in accordance with claim 1,
   characterized in that
   the extended length L of the ring line of the ring line radiator (2) in resonance is shortened by the effect of the vertical radiators (4), starting from approximately the line wavelength A, down to approximately half the line wavelength λ.
3. An antenna in accordance with one of the claims 1 or 2,
   characterized in that
   the ring line radiator (2) is configured as a square at whose corners a respective ring line coupling point (7) is formed with a vertical radiator (4, 4a-d) connected there in a galvanically coupled manner; and in that the radiator (4, 4a-d) is respectively provided with a reactance circuit (13) implemented as a capacitor (15) for coupling to a ground connection point (11) on the electrically conductive base surface (6) or to the antenna connector (5).
4. An antenna in accordance with claim 3,
   characterized in that
   a first part piece having a wave resistance differing from the wave resistance of the other part pieces of the ring line radiator (2) is present between two ring line coupling points (7).
5. An antenna in accordance with claim 4,
   characterized in that,
   for supporting the unidirectionality of the wave propagation on the ring line radiator (2), a further part piece of the ring line radiator (2) is present which is disposed opposite the first part piece and which has a wave resistance differing from the wave resistance of the other part pieces of the ring line radiator (2).
6. An antenna in accordance with claim 3,
   characterized in that
   the reactance circuits (13) implemented as capacitors (15) are configured in a manner such that the vertical radiators (4, 4a-d) are formed into individually configured areal capacitor electrodes (32a, 32b, 32c, 32d) at their lower ends; in that the capacitors (15) are configured for coupling three vertical radiators (4a, 4b, 4c) with the electrically conductive base surface (6) by interposing a dielectric plate (33) between the areal capacitor electrodes (32a, 32b, 32c, 32d) and the electrically conductive base surface (6) configured as an electrically conductive coated circuit board; and in that the antenna connector (5) is configured as an areal counter-electrode (34) insulated from the conductive layer for a capacitive coupling of a fourth vertical radiator (4d) with said antenna connector.
7. An antenna in accordance with claim 6,
   characterized in that
   the conductive structure comprising the ring conductor (2) and the vertical radiators (4, 4a-d) connected thereto is fixed by a dielectric support structure (36) such that the dielectric plate (33) is implemented in the form of an air gap.
8. An antenna in accordance with any one of the claims 1 to 7,
   characterized in that
   an additional ring line radiator is present about the center Z of the ring line radiator (2) and has the same center, said additional ring line radiator being configured in accordance with claims 1 to 7, but being in resonance at a different frequency.
9. An antenna in accordance with any one of the claims 1 to 7,
   characterized in that
   a further ring line radiator (2a) is present about the center of the ring line radiator (2) and has the same center, said further ring line radiator being configured in accordance with claims 1 to 7 such that its resonance is the same as that of the ring line radiator in accordance with claims 1 to 7 and, however, differing therefrom, being electrically excited in a manner such that the phase difference of the line wave propagating on the further ring line (2a) in a single rotation direction amounts over one rotation to just N*2π with a whole-number N>1, with the periphery (L') of the further ring line radiator (2a) corresponding to the N-fold line wavelength in the further ring line (2a) and with the reception signals of said further ring line radiator being superimposed with the reception signals of the ring line radiator (2) in a summation and selection network (44) to configure a directional antenna having a directional characteristic with a selectable main direction.
10. An antenna in accordance with claim 9,
    characterized in that
    the phase difference of the line wave propagating on the further ring line radiator (2a) in a single rotation direction amounts over one rotation to just 2*2π and the reception signals at a radiator connection point (46) of said further ring line radiator are passed to a summation network (44) via a controllable phase rotation element (42) and are there added in weighted form to the reception signals of the ring line radiator (2), likewise passed to the summation network (44), at its radiator connection point (5) to form the main direction in the azimuthal directional diagram so that the azimuthal main direction of the directional antenna is variably set at the directional antenna connector (43) by a variable setting of the phase rotation element (42).
11. An antenna in accordance with claim 10,
    characterized in that
    the ring line radiator (2) is configured as a closed square line ring at a spacing h above the conductive base surface (6); in that the further ring line radiator (2a) is configured as a closed, regular octagonal line ring; and in that respective ring line coupling points (7, 7a) for coupling the vertical radiators (4, 4a-d) are formed at the corners of the two ring line radiators (2, 2b).
12. An antenna in accordance with any one of the claims 1 to 11,
    characterized in that
    the ring line radiator (2) and the vertical radiators (4, 4a-d) are manufactured from a contiguous, stamped and curved sheet metal part.

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