EP2592691B1 - Receiver antenna for 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. K. HIROSE ET AL: "DOUBLE-LOOP ANTENNAS FOR A CIRCULARLY POLARIZED TILTED BEAM", ELECTRONICS & COMMUNICATIONS IN JAPAN, PART I - COMMUNICATIONS, WILEY, HOBOKEN, NJ, US, VOL. 86, No. 12, PART 01, 16 June 2003 (2003-06-16), pages 12-20, XP001171950, ISSN: 8756-6621 , DOI: 10.1002 / ECJA.10132).

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 in the planning. 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 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. Similarly, patch antennas act. All of the prior art antennas are less efficient in terms of low elevation angle reception.

Although these antenna forms are suitable for the reception of satellite signals, which are emitted by high-flying satellites - so-called HEOS. However, particularly for low elevation angular range incident satellite signals broadcast by GEOS geostationary satellites, there is an improvement in received power, cross-polarization rejection and it is desirable to improve the reception of vertically polarized signals emitted by terrestrial transmitters

The object of the invention is therefore to provide an antenna which, depending on their design, both for a particular powerful reception of low elevation angles in incident circularly polarized satellite signals, as well as for high-power reception of higher elevation angles in incident satellite signals with sufficient gain and high cross-polarization suppression over a large elevation angle range, and in particular the possibility of 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 the reception of linearly vertically polarized and received at low elevation waves with azimuthally nearly homogeneous directional diagram with a particularly high profit. Furthermore, the antenna can advantageously in combination with the above-described and from the DE-A-4008505 and the DE-A-10163793 known antennas and patch antennas according to the prior art to a directional antenna with adjustable or dynamically traceable azimuthal main direction in the radiation pattern are designed. This advantage is explained in more detail below. Another advantage of an antenna according to the invention is its particularly simple manufacturability, which allows the realization by simple curved sheet metal structures.

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 of the conductor loop connected to an antenna connection 43. The conductor loop is a ring line radiator 2 by a polygonal or circular closed loop in a horizontal plane with the height h above the conductive base. 6 designed to last. The ring line radiator 2 forms a resonant structure and is electrically excitable by the electromagnetic excitation in such a way that the current distribution of a current line wave in a circulation direction, whose phase difference over the extended length of the ring line structure is just M * 2π, is established on the ring line. M is at least two and is an integer. For the technically particularly interesting value M = 2, the particularly high radiation gain for circular polarization results for low elevation angles. In order to support the vertically oriented portions of the electromagnetic field, a plurality of radiators 4 extending vertically on the ring line radiator 2 and towards the conductive base surface are present, which are / 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 ring line emitter 2 at a plurality of ring line coupling points 7 more emitters 4 are present, which has a perpendicular to the polarization of the ring line emitter 2 polarization. In the presence of terrestrially vertically polarized signals, these emitters can advantageously also be used to receive these signals.

• Fig. 1: 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, welche jeweils an einer Unterbrechungsstelle 23 mit einer verlustarmen Blindwiderstandsschaltung 13 der Reaktanz X beschaltet sind
• Fig. 2: Ringleitungsstrahler 2 am Beispiel für M = 2 jedoch mit einer elektromagnetischen Erregung 3 an 8 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 beziehungsweise durch ein Verteilnetzwerk aus Mikrostreifenleitung gewonnen werden.
• Fig. 3: Antenne mit einem als geschlossenen quadratischen Leitungsring für M = 2 mit der Kantenlänge von 2*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. 4: 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. Durch Gestaltung der Reaktanzen X ist es möglich, die Teilabschnitte L/N um den Verkürzungsfaktor k<1 kürzer zu gestalten als es dem Wert L/N = M*λ/N entspräche, so dass vielmehr gilt: L/N = k*M*λ/N.
• Fig. 5: Antenne wie in Figur 4, jedoch mit horizontalen Zusatzelementen zur weiteren Formung des Richtdiagramms
• Fig. 6: Antenne für M = 2 mit einer besonders vorteilhaften kreisförmigen Ausführungsform des Ringleitungsstrahlers 2 mit im Wesentlichen äquidistant auf dem Umfang verteilt befindlichen vertikalen Strahlern 4. Die auf unterschiedliche Weise gestaltbare Erregung 3 ist nicht gezeichnet.
• Fig. 7: Antenne mit einem rechteckförmig gestalteten Strahler wie in Figur 3 jedoch mit elektromagnetischer Erregung 3 durch Einspeisung am unteren Ende an einem der vertikalen Strahler 4 über das Anpassnetzwerk 25 und über die als Kapazität 15 gestaltete Blindwiderstandsschaltung 13. Die Unterstützung der Unidirektionalität der Wellenausbreitung auf dem Ringleitungsstrahler 2 ist durch abwechselnd unterschiedliche Gestaltung der Wellenwiderstände der im Umlaufsinn aufeinander folgenden Teilstücke zwischen zwei benachbarten Ringleitungs-Koppelpunkt 7a -7b beziehungsweise 7b -7c etc. erreicht. Die Feinabstimmung der Unidirektionalität der Wellenausbreitung erfolgt durch geringfügig unterschiedliche Längen der Teilstücke.
• Fig. 8: Antenne wie in Figur 7, wobei das Anpassnetzwerk 25 in Form einer parallel zur elektrisch leitenden Grundfläche 6 gelegten hochohmigen Übertragungsleitung über etwa ¼ der Wellenlänge ausgeführt ist.
• Fig. 9: Grundsätzliche konstruktive Ausführungen eines Ringleitungsstrahlers 2 mit vertikalen Strahlern und Kapazitäten 15 wie in Figuren 3 bis 8. 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 beschichteten Leiterplatte 35 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. 10: Antenne wie in Figuren 9. Zwischen den unteren Enden der vertikalen Strahler 4a, 4b, 4c, 4d und der als leitend beschichtete Leiterplatte ausgeführten elektrisch leitenden 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. 11: Antenne wie in Figuren 11 und 12 für M = 2, wobei die leitende Struktur, bestehend aus dem achteckig geformten Ringleiter 2 und den damit verbundenen vertikalen Strahlern 4 durch eine dielektrische Stützstruktur 36 in der Weise fixiert ist, dass an Stelle der dielektrischen Platte 33 ein Luftspalt zur Bildung des Dielektrikums realisiert ist.
• Fig. 12: 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 Ringleitungsstrahler 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. 13: Ringleitungsstrahler 2 kombiniert mit einem gekreuzten Strahler 24 mit gleichem Zentrum Z nach dem Stand der Technik mit zirkularer Polarisation bei höheren Elevationswinkeln, wobei sich die Phase dessen zirkularer Polarisation mit dem azimutalen Winkel des Ausbreitungsvektors in einfacher Abhängigkeit dreht. Durch Überlagerung der Empfangssignale des gekreuzten Strahlers 24 mit den Empfangssignalen des Ringleitungsstrahlers 2, dessen Phase der zirkularen Polarisation mit dem azimutalen Winkel des Ausbreitungsvektors in M-facher Abhängigkeit gedreht ist, ist eine Richtantenne mit einem Richtdiagramm mit azimutaler Hauptrichtung am Richtantennen-Anschluss 43 gebildet.
• Fig. 14: Richtantenne wie in Figur 13 mit kreisförmigem Ringleitungsstrahler 2 mit N = 8 vertikalen Strahlern 4 und M = 2 vollen Umläufen der Leitungswelle kombiniert mit einem gekreuzten Strahler 24 mit gleichem Zentrum Z nach dem Stand der Technik. Die vertikalen Strahler 4 sind auf dem Ringleitungsstrahler 2 im Wesentlichen äquidistant verteilt und entsprechend einer Phasen-Differenz der laufenden Welle von jeweils π/2 angeordnet. Die Empfangssignale an der Strahler-Anschlussstelle 46 des Ringleitungsstrahlers 2 und der Anschlussstelle des gekreuzten Strahlers 28 werden über ein steuerbares Phasendrehglied 42 im Summations- Netzwerk 44 zur Bildung des Richtdiagramms mit steuerbarer azimutaler Hauptrichtung überlagert.
• Fig. 15: Richtantenne wie in Figur 14 jedoch mit achteckig geformtem Ringleitungsstrahler 2 (Phasendifferenz der laufenden Welle von 4π verteilt über dem Umfang).
• Fig. 16: Räumliches Richtdiagramm der Richtantenne in Figur 15 mit ausgeprägter azimutaler Hauptrichtung (Pfeil) und Nullstelle.

The invention will be explained in more detail below. The accompanying figures show in detail:

• Fig. 1 : Antenna having a resonant structure shaped circular ring radiator 2 for generating a circularly polarized field with an azimuthally dependent phase with a electromagnetic excitation 3, which is given by feeding at λ / 4 apart ring line crosspoints 7 of 90 ° in phase different signals to produce a rotating wave of a wavelength over the circumference of the line. The support of vertical components of the electric radiation field is carried out by the vertical radiator 4, which are each connected at an interruption point 23 with a low-loss reactance circuit 13 of the reactance X.
• Fig. 2 Ring conductor radiator 2 using the example of M = 2, but with an electromagnetic excitation 3 to 8 each by λ / 4 along the loop line offset ring 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 splitting and 90 ° hybrid coupler or by a distribution network of microstrip line.
• Fig. 3 Antenna with a ring line radiator 2 designed as a closed square line ring for M = 2 with the edge length of 2 * λ / 4. The excitation 3 is a contactless coupling to the ring line radiator 2 via the ramp-shaped λ / 4-directional coupling structure 18 to the antenna connection 5 designed. The coupling structure 18 includes the vertical radiator 4
• Fig. 4 : Antenna, by way of example with circular ring line radiator 2 with generally indicated excitation 3 and with circumferentially equidistantly arranged ring line crosspoints 7 with vertical emitters 4 coupled thereto, into which low-loss reactance circuits 13 are necessary at the points of interruption for generating a circulating current wave on the ring line radiator 2 different reactances X are turned on. By designing the reactances X, it is possible to arrange the sections L / N around the Shortening factor k <1 shorter than it would correspond to the value L / N = M * λ / N, so that on the contrary: L / N = k * M * λ / N.
• Fig. 5 : Antenna as in FIG. 4 , but with horizontal additional elements for further shaping of the directional diagram
• Fig. 6 Antenna for M = 2 with a particularly advantageous circular embodiment of the ring line radiator 2 with vertical radiators 4 distributed substantially equidistantly around the circumference. The excitation 3 which can be shaped in different ways is not shown.
• Fig. 7 : Antenna with a rectangular shaped spotlight as in FIG. 3 However, with electromagnetic excitation 3 by feeding at the lower end of one of the vertical radiator 4 via the matching network 25 and the designed as a capacitor 15 reactance circuit 13. The support of the unidirectionality of the wave propagation on the loop antenna 2 is characterized by alternately different design of the wave resistances of the circulating successive sections between two adjacent loop cross-coupling point 7a -7b and 7b -7c etc. achieved. The fine-tuning of the unidirectionality of the wave propagation takes place by means of slightly different lengths of the sections.
• Fig. 8 : Antenna as in FIG. 7 , 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. 9 Basic constructive designs of a ring line radiator 2 with vertical radiators and capacities 15 as in FIGS. 3 to 8 , The capacitances 15 are formed in such a way that the vertical radiator 4 are formed at its lower end to individually shaped planar capacitance electrodes 32a, 32b, 32c, 32d. By means of an intermediate layer between these and the electrically conductive base surface 6 embodied as an electrically coated printed circuit board 35, the capacitances 15 for the coupling of three vertical radiators 4a, 4b, 4c to the electrically conductive base 6 are 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. 10 : Antenna as in Figures 9 , Between the lower ends of the vertical radiators 4a, 4b, 4c, 4d and the electrically conductive base 6 designed as a conductive coated circuit board, 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. 11 : Antenna as in Figures 11 and 12 for M = 2, wherein the conductive structure consisting of the octagonal shaped ring conductor 2 and the associated vertical radiators 4 is fixed by a dielectric support structure 36 in such a way that instead of the dielectric plate 33, an air gap for the formation of the dielectric is realized ,
• Fig. 12 : 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. 13 Ring loop radiator 2 combined with a prior art centered circular beam radiator 24 of circular polarization at higher elevation angles, with the phase of its circular polarization rotating in simple dependence with the azimuthal angle of the propagation vector. By superposition of the received signals of the crossed radiator 24 with the received signals of the ring line radiator 2 whose phase of the circular polarization is rotated with the azimuthal angle of the propagation vector in M-fold dependence, a directional antenna is formed with a directional pattern with azimuthal main direction at the directional antenna port 43.
• Fig. 14 : Directional antenna as in FIG. 13 with circular ring line radiator 2 with N = 8 vertical radiators 4 and M = 2 full revolutions of the line shaft combined with a crossed radiator 24 with the same center Z according to the prior art. The vertical radiators 4 are distributed substantially equidistantly on the ring line radiator 2 and arranged in accordance with a phase difference of the current wave of π / 2 in each case. The received signals at the radiator connection point 46 of the ring line radiator 2 and the connection point of the crossed radiator 28 are superimposed via a controllable phase rotation element 42 in the summation network 44 to form the directional diagram with controllable azimuthal main direction.
• Fig. 15 : Directional antenna as in FIG. 14 However, with octagonal shaped ring line radiator 2 (phase difference of the current wave of 4π distributed over the circumference).
• Fig. 16 : Spatial directional diagram of the directional antenna in FIG. 15 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 = 20 ° (vertical) and theta = 70 ° 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 the following considerations 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 shows the basic form of an antenna with a designed as a resonant structure circular ring radiator 2 for generating a circularly polarized field. To generate the resonance, the elongated length of the ring line in a basic form of the ring line radiator 2 is chosen such that it substantially corresponds to an integer multiple of the full line wavelength, ie M * λ, where M represents an integer and M assumes at least the value 2. An antenna of this type has the particular advantage that, for example, for the value M = 2 for low elevation angles, a comparatively particularly high gain in the reception of circularly polarized waves can be achieved. This property is particularly important for the reception of geostationary satellite signals.

A further advantage of an antenna of this kind is that the phase of the circular polarization is rotated with the azimuthal angle of the propagation vector in M-times and thus in at least 2-fold dependence. Thus, an antenna of this type can be combined with a crossed radiator 24 of the same center Z according to the prior art to a directional antenna with an azimuthal main direction. The directivity with azimuthal main direction results from the combination of the radiation diagram of the crossed radiator 24 with simple dependence of the phase of the azimuthal and the radiation diagram of the ring line radiator. By superposition of the received signals of the crossed radiator 24 with the received signals of the ring line radiator 2 whose phase of the circular polarization is rotated with the azimuthal angle of the propagation vector in M-fold dependence, the directional antenna can be easily formed with a directional pattern with azimuthal main direction. Such crossed radiator 24 are, as already stated, for Example off DE-A-4008505 and DE-A-10163793 known. The from the DE-A-4008505 known antenna is constructed on a substantially horizontally oriented conductive surface and consists of crossed horizontal dipoles, which are mechanically fixed at an azimuthal angle of 90 degrees to each other and attached to the upper end of a fixed to the conductive base linear vertical conductor. 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. The effect of all these crossed emitters is essentially based on the fact that the individual antenna parts are placed at a right angle "crossed" and perpendicular to the ground plane levels and offset the antenna parts of the different planes to produce the circular polarization by 90 ° in phase are interconnected. The effect of patch antennas can also be represented in a similar way. All of these antennas with azimuthal circular pattern, whose polarization is circular, formed from two crossed emitters, have the property that their phase of circular polarization rotates with the azimuthal angle of the propagation vector in simple dependence. They are therefore referred to here for easy distinction as "crossed emitters". Especially for use on vehicles, the compatibility of an antenna system is of particular importance. Antenna systems are often optionally designed as a single antenna system and as antenna diversity systems. A ring line emitter 2 according to the invention has the particular advantage that it can be provided as a basic form for a single antenna system, which by additional placement with a crossed emitter - such as from DE-A-10163793 , of the DE-A-4008505 or as a readily available patch antenna - can be supplemented to a directional antenna that can be tracked in the main direction of the radiation or to an antenna diversity system.

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 ring line 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 feed takes place in FIG. 1 at λ / 4 apart ring line crosspoints 7 of different by 90 ° in 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 a further advantageous embodiment of the invention are in FIG. 2 for generating a continuous line wave with M = 2 wavelengths λ on the ring line radiator 2 N = 8 formed by each λ / 4 along the closed loop structure distant ring line crosspoints 7, to which vertical radiator 4 - im Example are galvanically - coupled. 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 advantageous embodiment of the invention, the ring line radiator 2 in FIG. 3 for M = 2 is formed as a closed square line ring with the edge length of substantially 2 * λ / 4 above 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 a preferably horizontal extent 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 consists in the contactless coupling of the excitation 3 to the square-shaped ring line radiator 2, which according to the invention enables a particularly simple production of the antenna.

Particularly advantageous embodiments of antennas according to the invention are those arrangements in which to the Ring line radiator 2 of the elongated length L at substantially similar distances L / N 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 are coupled via ground connection points 11 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. 4 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 antenna parts, consisting of the ring line structure 2 and the circle group of the vertical radiator 4 at the ring line crosspoints 7, the antenna parts are coupled together in such a way that the antenna parts constructively to a circular contribute to polarized field. The ring line emitter 2 acts as a radiating element which generates a circularly polarized field with a main beam direction at medium elevation angles. 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 very low elevation, this field is vertically polarized and substantially azimuthally independent as well.

The mode of operation of the resonant structure according to the invention is described below with reference to FIG FIG. 4 explained in more detail. As already above described, the resonant structure is connected via an excitation 3 in such a way with the antenna terminal 5, that the line wave on the loop emitter 2 propagates substantially only in one direction of rotation, so that in the direction of rotation of the ring structure, a period of the line shaft is included.

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: $$\underset{}{I}2=\underset{}{I}1•\exp \left(\mathit{j\; M}2\pi /N\right)$$

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

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: $$\underset{}{I}S=\underset{}{I}1•\exp \left(j\mathrm{\Phi }\right)-\underset{}{I}2.$$

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

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: $$\underset{}{I}S=\underset{}{I}1•\left[\exp \left(j2\mathit{\pi L}/\left(\mathit{N\lambda }\right)\right)-\exp \left(\mathit{j\; M}2\pi /N\right)\right]$$

gemäß Gleichung (3) einstellt, welche zusammen mit der Phasendrehung ΔΦ des entsprechenden Filters eine resultierende Phasendrehung über einem Segment von $$\mathrm{\Delta \Phi }+\mathrm{\Phi }=M2\pi /N$$

ergibt. Die elektromagnetische Welle, welche sich im Umlaufsinn entlang der Ringstruktur ausbreitet, erfährt somit bei einem Umlauf die Phasendrehung von M*2π. Mit dieser besonders vorteilhaften Ausgestaltung der Erfindung besteht somit die Möglichkeit, die gestreckte Länge L der Schleifenantenne 2 um den Verkürzungsfaktor k<1 kürzer als die M-fache Wellenlänge λ zu gestalten, sodass L = k*M* λ gilt.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 selected by setting the reactances X so that the filter is adapted on both sides to the conductor impedance of the annular line. 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 L / N of the conductor segments is then adjusted so that over this conductor segment, a phase rotation of $$\mathrm{\Phi }=2\mathit{\pi L}/\left(\mathit{N\lambda }\right)$$

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 $$\mathrm{\Delta \Phi }+\mathrm{\Phi }=M2\pi /N$$

results. The electromagnetic wave, which propagates in the circumferential direction along the ring structure, thus undergoes the phase rotation of M * 2π in one revolution. With this particularly advantageous embodiment of the invention, it is thus possible to make the stretched length L of the loop antenna 2 shorter than the M-fold wavelength λ by the shortening factor k <1, so that L = k * M * 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 and even lower elevation with azimuthal omnidirectional characteristic results. This results in the particular advantage of the main radiation with circular polarization in lower elevation with the present invention. Thus, the antenna is also particularly suitable for receiving 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 and advantageous embodiment of the invention, the vertical radiator 4 as in FIG. 5 coupled via horizontal radiator elements 14 to the loop coupling points 7. The Horizontal radiator elements 14 can be flexibly used 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 perfecting of the omnidirectional radiation of a loop emitter 2, the in FIG. 6 illustrated circular structure with equidistant over the circumference of the ring line radiator 2 formed ring line crosspoints 7 and there galvanically connected vertical radiators 4, each with one at the base point to the ground terminal point 11 introduced capacity 15 as a reactance circuit 13. The excitation 3 of this resonant structure can be designed in different ways and is therefore in FIG. 6 not shown.

In FIG. 7 is one of the vertical radiator 4 of a rectangular shaped ring line radiator 2 with the reactance circuit 13 realized as a capacitor 15 not to the ground terminal 11 on the electrically conductive base 6 but to the formed on the level of the conductive base 6 connection to the matching network 25 and thus coupled to the antenna connector 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. The support of Unidirectionality of the wave propagation on the ring line emitter 2 is achieved by alternately different design of the characteristic impedance of the circulating successive sections between two adjacent loop cross-coupling point 7a - 7b and 7b - 7c, etc. The fine-tuning of the unidirectionality of the wave propagation is also done by slightly different choice of the lengths of the sections with length differences between 5 and 10%.

At the in FIG. 8 illustrated advantageous embodiment of an antenna according to the invention with M = 2, the electromagnetic excitation 3 is designed by partial coupling 20 to one of the vertical radiator 4 at one of the loop coupling points 7. The unidirectional effect of the electromagnetic excitation 3 with respect to the wave propagation is given by partial coupling to a vertical radiator 4 via a coupling conductor 23 guided in parallel to a part of the ring-shaped radiator 2 and the other end of the coupling conductor 23 is to a vertical radiator running to the conductive base 6 4e connected, the latter being connected via a matching network 25 to the antenna connection 5. The matching network 25 is designed in the form of a parallel to the electrically conductive base surface 6 high-impedance transmission line over about ¼ of the wavelength advantageously.

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. 7 designed and in FIG. 9 for reasons of clarity with only four vertical radiators 4a - 4d shown. The ring line emitter 2 with the vertical emitters 4a, 4b, 4c, 4d, together with the flat capacitance electrodes 32a, 32b, 32c, 32d individually shaped at their lower end, can be made, for example, from a continuous, stamped and formed sheet metal part. Also the characteristic impedance of the parts 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 4d to the antenna connector 5, this is designed as a planar counterelectrode 34 isolated from the conductive layer of the printed circuit board. 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 the construction of such an antenna is in FIG. 10 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 4d to the antenna terminal 5, which is designed as a planar counterelectrode 34 isolated from the conductive layer, is provided via the capacitance electrode 32d.

In FIG. 11 is an antenna after the in FIG. 10 illustrated design principle for M = 2 in a further advantageous embodiment of the invention designed such that the conductive structure, consisting of the designed as an octagon 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.

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 of the invention is therefore, as in the Figures 12a and 12b by way of example in cross-section with oblique cavity side surfaces 40, the conductive base 6 extending substantially in a base plane E1 at the location of the ring conduit radiator 2 is formed as a conductive cavity 38 opened upwards. 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 of the invention, 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 between the ring line emitter 2 and the cavity 38 is provided at each location. For the in FIG. 12b 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 of 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 of the horizontal Distance d between the vertical connecting line between ring line radiator 2 and 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. 12a is shown. That is, h is larger than h1 and the antenna 1 is not fully integrated with the vehicle body.

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

As already explained above, in a circular-waveguide radiator 2 with circular polarization and azimuthal circular diagram according to the invention, the phase of the radiated electromagnetic far field M times with the azimuthal angle of the propagation vector due to the propagating in one direction M current wave trains on the loop. Due to the corresponding Length of the loop structure are formed z. B. at M = 2 two complete wave trains of a running wave. In FIG. 13 is in the center Z of a ring line radiator 2, which is exemplified by two λ / 4-spaced crosspoints 7, similar to in FIG Fig. 2 is electrically excited, introduced a crossed radiator 24 with congruent center Z, which by definition also has an azimuthal circular diagram with circular polarization at its radiator connection point 26. As also explained above, meet from the DE-A-4008505 , of the DE-A-10163793 , or the EP 1 239 543 B1 and known as patch antennas crossed emitters 24 of the prior art and other known similar antenna shapes according to the principle of the crossed emitters 24 the condition that the phase of the circular polarization rotates once with the azimuthal angle of the propagation vector - ie at a complete azimuthal Circulation around the angle 2π. In this particularly advantageous embodiment of the invention, the ring line emitter 2 and the crossed emitter are combined with the same center Z, so that the phase reference points of the two emitters are congruent in the common center Z. When superimposing the received signals under suitable weighting and phase relationship of the ring line emitter 2 and the crossed emitter 24, 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 dependence of the phases of the circularly polarized waves of the two emitters on the azimuthal angle of the propagation vector, depending on the phase position of the M current waves on the ring line emitter 2, the radiation depending on the azimuth angle of the propagation vector partially superimposed supportive or attenuating , By amplitude-compliant summary of the signals of the ring line emitter 2 with the crossed emitter via a controllable phase shifter 42 and a summation network 44, thus formed in an advantageous manner in the azimuthal directional diagram of Combined antenna arrangement at the directional antenna terminal 43 from a main direction of the radiation, which is dependent on the setting of the phase rotation member 39. This property allows z. B. the advantageous tracking of the main beam direction in mobile satellite reception.

In an advantageous embodiment of the invention according to FIG. 13 is the ring line emitter 2 as a rotationally symmetrical about the center Z arranged polygonal or circular closed ring line emitter 2 for M = 2 in a horizontal plane with the height h over the conductive base 6 extending designed. In FIG. 14 the ring line emitter 2 is shown with its vertical radiators 4 such a directional antenna circular for M = 2. The reactance circuits 45a-45h are designed in such a way that, when fed in at the radiator junction 46, the current distribution of a current line wave is established whose phase difference over one revolution is just 2 * 2π. As a result of the action of the vertical radiators 4 coupled to the ring line crosspoints 7 with the reactance circuits 45a-45h, the stretched length of the ring line radiator 2a can also be shorter by a shortening factor k <1 than the corresponding dual wavelength 2λ. To reduce the diameter D of the ring line radiator 2, the phase difference of 2 * 2π on the ring line by increasing the line inductance and / or the line capacitance to the conductive base 6 done. Depending on the above-described shortening factor k <1, the ring line sections of the ring line radiator 2 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. The received signals at the radiator connection point 46 of the ring line radiator 2 and the junction of the crossed radiator 28 are via the controllable Phase shifter 42 in the summation and selection network 44 superimposed to form the directional diagram with controllable azimuth main direction.

When superimposing the received signals under suitable weighting and phase relationship of the ring line emitter and the crossed emitter 24, it is possible according to the invention to design a directional antenna with a predetermined azimuthal main direction and elevation. This is done by the different azimuthal dependence of the current phases on the two radiators 2, 24, depending on the phase position of the current wave on the ring line radiators 2 with respect to the phase of the crossed radiator 24, the radiation depending on the azimuth angle of the propagation vector partially supportive or attenuating superimposed. By amplitude-appropriate summary of the signals of the two emitters 2, 24 via the 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 directivity of the superimposition of the received signals goes out of the in FIG. 16 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.

FIG. 15 shows a plan view of the directional antenna in FIG. 14 , wherein the ring line radiator 2 is formed as a substantially regular octagon and the crossed radiator 24 is located centrally in the interior of the ring line radiator 2. The ring line coupling points 7 are each formed at the corners of the octagonal ring line radiator 2. To each of the vertical radiator 4 are connected. Especially with mobile satellite reception with only limited or partial Shaded direct view to the satellite, it is often advantageous due to suddenly occurring signal fading to increase the variety of available reception signals, for example, in the sense of a switching diversity method. By configuring the summation network 44 as summation and selection network 44a, it is possible to select separately between the received signals of the two emitters 2, 24 and the weighted superimposition-possibly with different weightings.

Claims (13)

1. Antenna (1) for the reception of circular polarized satellite radio signals comprising at least one substantially horizontal oriented conductor loop arranged on top of a conductive base surface (6), having an arrangement connected to an antenna terminal (43) for electromagnetic excitation of the conductor loop, comprising the following features:

   - the conductor loop is configured as a loop emitter (2) by a polygonal or circularly closed loop having a length (L) extending in a substantially horizontal plane of height h above the conductive base surface (6),

   - the loop emitter (2) forms a resonant structure and is electrically excitable by the electromagnetic excitation such that on the loop the current distribution of a travelling line wave occurs in one direction of rotation, whose phase difference over one cycle is M*2π, wherein M is an integer and has at least a value M=2,

   - at least one further emitter (24) is provided whose center is coincident with the center of the loop emitter (2) und which is excitable such that its phase of the circular polarization rotates with the azimuthal angle of the propagation vector, i.e. by the angle of 2π for a complete azimuthal cycle, and whose reception signals are superimposed with the reception signals of the loop emitter (2) in a summation network (44) for forming a directional antenna having a directional characteristic with selectable main direction,

   - characterized in that

   - the further emitter (24) is a crossed emitter which is provided for circular polarization by a patch antenna,

   - to support the vertically oriented portions of the electromagnetic field, across the circumference of the length (L) of the loop emitter (2), a plurality (N) of vertical emitters (4) is coupled in elongated length distances (L/N) with substantially equal length as partial sections of the structure spaced from each another via loop coupling points (7) at the loop emitter (2) on the one hand and via ground connection points (11) on the other hand.
2. Antenna according to claim 1, characterized in that the elongated length L of the loop of the resonating loop emitter (2) is shortened by the effect of the vertical emitters (4), from approximately M times the line wavelength to approximately one-half of said length.
3. Antenna according to claim 1 or 2, characterized in that for generation of a travelling line wave on the loop emitter (2), N loop coupling points (7) spaced apart from each other along the loop structure by substantially L/N each are formed, and the electromagnetic excitation is formed in that, by connection of vertical emitters (4) which extend to the conductive base surface, at the loop coupling points (7) of the closed loop, signals of equal size which are shifted in phase by M*360°/N from each other, respectively, are feedable.
4. Antenna according to one of the claims 1, 2 or 3, characterized in that the loop emitter (2) for M=2 is formed as a closed line loop having linear partial sections with an edge length of substantially L/8 above the conductive base surface (6) at a distance h above the conductive base surface (6), and for generation of a travelling line wave on the loop emitter (2) and for contactless coupling to the loop emitter (2), the electromagnetic excitation is formed by a ramp-like directional coupling conductor (12) with an advantageous horizontal extent of substantially L/8, which, starting from the antenna terminal (5) located on the conductive base surface (6), extends via a vertical supply line (4) up to a coupling distance (10) to one of the ends of a partial section of the loop emitter (2), from there encounters the base surface (6) approximately below the end of an adjacent partial section substantially according to a ramp function, and is conductively connected to the base surface (6) via the ground connection point (11).
5. Antenna according to claim 4, characterized in that, for generation of the resonance of the loop emitter (2), at least one of the vertical emitters (4) is connected at an interruption point to a low-loss reactance circuit (13) having the reactance X required therefore.
6. Antenna according to claim 5, characterized in that the coupling of the vertical emitter (4) to the ground connection point (11) is configured capacitive, and the required reactance X of the low-loss reactance circuit (13) is provided by the design of said capacitive coupling.
7. Antenna according to one of the claims 1 to 6, characterized in that the electromagnetic excitation is provided via the connection to one of the vertical emitters (4) with a reactance circuit (13) realized as capacitance (15) such that the vertical emitter (4) is not coupled to the ground connection point (11) to the electrically conductive base surface (6), but to the antenna terminal (5) formed on the plane of the conductive base surface (6).
8. Antenna according to one of the claims 1 to 7, characterized in that the support of unidirectionality of wave propagation on the loop emitter (2) is provided by alternately differing design of the wave impedances of the partial sections succeeding each other in the direction of rotation between adjacent loop coupling points, in combination with fine adjustment of the unidirectionality of the wave propagation by slightly different lengths of the partial sections.
9. Antenna according to one of the claims 6 to 8, characterized in that the reactance circuits (13) realized as capacitances (15) are formed such that the vertical emitters (4) are formed at their lower end as individually shaped planar capacitance electrodes (32a, 32b, 32c, 32d), and by interposition of a dielectric plate (33) between the latter and the electrically conductive base surface (6) configured as an electrically conductive printed circuit board, the capacitances (15) are designed for coupling of three vertical emitters (4a, 4b, 4c) to the electrically conductive base surface (6), and for capacitive coupling of the fourth vertical emitter (4d) to the antenna terminal (5), the latter is formed as a planar counter-electrode (34) isolated from the conductive layer.
10. Antenna according to claim 1, characterized in that the phase difference of the line wave propagating in only one direction of rotation on the loop emitter (2) designed for M=2 is 2*2π for one rotation, and the reception signals at its emitter connection point (46) are passed via a controllable phase rotating element (42) and fed to the summation network (44) and weighted thereat and added to the reception signals of the crossed emitter (24) which are also fed to the summation network (44), at its emitter connection point (28), to form the main direction in the azimuthal directional diagram, so that, by variable adjustment of the phase rotating element (42), the azimuthal main direction of the directional antenna is adjusted variably at the directional antenna terminal (43).
11. Antenna according to claim 10, characterized in that the loop emitter (2) for M = 2 extends as a closed, regular, substantially octagonal loop having an edge length of substantially L/8 at a distance h above the conductive base surface (6) and loop coupling points (7) for coupling of the vertical emitters (4) are formed at each of its corners.
12. Antenna according to claim 11, characterized in that by configuration of the summation network (44) as a summation and selection network (44a), both the reception signals of the two emitters (2, 24) separately and in each case differently weighted superimposed arrangements of the reception signals of the two emitters (2, 24) are available for selection within a switching diversity process, and thereby the variety of the reception signals which can be retrieved at the directional antenna terminal (43) is increased.
13. Antenna according to one of the claims 1 to 12, characterized in that for configuration of a multi-band antenna, apart from the loop emitter (2) with center Z configured for a first frequency, at least a further loop emitter (2) with coincident center is provided, which is configured according to the claims 1 to 13 but for resonance at a different frequency.

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