EP3382795A1 - Antenna for receiving circular polarised satellite radio signals for satellite navigation on a vehicle - Google Patents

Abstract

An antenna for receiving circularly polarized satellite radio signals comprises a conductive loop arranged above a conductive base, which is designed as a loop emitter which forms a resonance structure. At the periphery of the ring line radiator, there are vertical radiators running towards the conductive base area, wherein the excitation of the conductor loop takes place via one of the radiators as the active radiator. Furthermore, a certain number of passive vertical radiators galvanically coupled to the loop emitter are provided.

Description

The invention relates to an antenna arrangement for the reception of circularly polarized satellite radio signals, in particular for satellite radio navigation.

Satellite radio signals are transmitted due to polarization rotations in the transmission path usually with circularly polarized electromagnetic waves and are used in all known satellite navigation systems. Modern navigation systems provide, in particular for the global accessibility in connection with a high navigation accuracy in the mobile navigation, to evaluate the simultaneously received radio signals of several satellite navigation systems. Such composite-receiving systems are collectively referred to as GNSS (Global Navigation Satellite System) and include known systems such as GPS (Global Positioning System, GLONASS, Galileo and Beidou, etc.) Satellite antennas for vehicle navigation are typically used on the Circularly polarized satellite receiving antennas are used, such as those from the DE 10 2009 040 910 A or the DE 40 08 505 A are known. For the construction on vehicles are particularly those antennas, which are characterized by a low overall height in conjunction with cost-effective manufacturability. This includes, for example, especially from the DE 102009 040 910 A known, designed as a resonant structure ring line radiator with a small volume, which is imperative especially for mobile applications. The antenna has a small footprint and is very low with a height of less than one tenth of the free space wavelength.

As further antennas for satellite navigation on vehicles patch antennas are known in the prior art, which, however, compared to stamped sheet metal antennas are more complex in construction. A challenge to satellite antennas for GNSS is the demand for a large one Frequency bandwidth, which is given for example in GPS by the frequency band L1 with the center frequency 1575 MHz (required bandwidth about 80 MHz) and the frequency band L2 with the center frequency 1227 MHz (required bandwidth about 53 MHz). This requirement is covered, for example, by separate antennas assigned to one of the frequency bands L1 and L2, respectively, or by a broadband antenna comprising both frequency bands. Systems for the simultaneous evaluation of signal contents in the frequency bands L1 and L2 place particularly high demands on the antennas, and this with little available space, as it is always given especially in vehicle. The use of separate, in close proximity antennas for the two frequency bands involves the problem of mutual electromagnetic coupling with the effect of influencing the directional diagrams and the polarization purity and in particular the cross polarization. Due to the signals of the positioning satellites which are incident at low elevation angles, suppression of the opposite direction of polarization - the cross polarization - is of decisive importance with regard to correct location results, even with sufficient gain in the desired, mostly right-handed circular polarization direction (RHCP). The accuracy of the location result is thus particularly affected by the ratio of the desired direction of polarization to the cross polarization of the satellite receiving antenna, so the Kreuzpolarisationsabstand. On the other hand, the realization of a satellite navigation antenna is technically difficult, which covers both frequency bands with a bandwidth of about 360 MHz and still meets the sometimes stringent requirements for the Kreuzpolarisationsabstand and the antenna gain.

For use on vehicles are particularly satellite receiving antennas with a small volume. Antennas of this type according to the prior art are known as patch antennas. However, these are less efficient in terms of reception at a low elevation angle and more complex in construction. This disadvantage is partially solved by loop antennas, such as those in the DE 10 2009 040 910 A are described. Even for such antennas, it is desirable that To improve cross-polarization distance over the full bandwidth of the above-described frequency bands L1, L2 or L5.

Satellite receiving antennas for satellite navigation are intended for installation on horizontal surfaces of the electrically conductive vehicle body. With respect to the antenna properties, the substantially horizontal vehicle roof acts as a conductive base.

The invention has for its object to provide an antenna for receiving circularly polarized satellite radio signals for satellite navigation, which has a high Kreuzpolarisationsabstand with a sufficient gain and at low elevation angles of the radiation characteristic over the largest possible frequency range and thus for the extraction particularly accurate Locating results in a vehicle is suitable.

This object is solved by the features of claim 1.

With an antenna according to the invention has the advantage that it is particularly inexpensive to produce and thus is particularly suitable for mass production and use in the mass production of vehicles.

According to the invention, an antenna 1 for receiving circularly polarized satellite radio signals comprises at least one horizontally oriented conductor loop arranged above a conductive base surface 6, with an arrangement connected to an antenna connection 5 for the electromagnetic excitation of the conductor loop. 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 electromagnetic excitation in such a way that sets the current distribution of a current line wave in a single direction of rotation on the loop, the phase difference over a revolution is just 2π.

There are on the circumference of the ring line radiator 2 at ring line crosspoints 7 with the ring line emitter 2 galvanically coupled, vertical and the conductive base surface 6 extending radiator 4, 4a-d present, via one of the radiators as the active radiator 4a, the excitation of the conductor loop takes place and the other radiators are coupled as passive radiators 4b, 4c, 4d to the electrically conductive base 6.

At least two vertical passive radiators 4b, 4c, 4d, which are galvanically coupled to the ring main radiator 2 and extend to the conductive base surface 6, of which N are vertical radiators 4d via a reactance circuit with active component 12 whose loss factor is greater than the value 0 , 1 / N, coupled to the electrically conductive base 6. At no point along the ring line radiator 2 are two of these N vertical radiators adjacent to each other. All other passive vertical radiators 4b, 4c are coupled to the base 6 via lossless reactance circuits 13. All radiators are approximately equally distributed along the ring line radiator 2, so that none of the distances between adjacent ring line crosspoints 7 at the circumference of the ring channel radiator 2 is smaller than half the distance, which in equidistant distribution of all radiators over the extended length L of the Ring line radiator (2) would result.

Advantageous embodiments are explained in more detail below:
At least two of the respective sections of the ring line emitter 2 located between two adjacent ring line crosspoints 7 may be present with differing characteristic impedances ZL1, ZL2.

The reactive-resistance circuit 12 for coupling N vertical radiators 4d to a ground terminal 11 on the electrically conductive base 6 may be formed respectively by the series connection of a capacitor 15 and a resistive circuit 12a and each of the remaining passive vertical radiators 4b, 4c can be realized with a capacity of 15 lossless reactance circuit 13 may be provided for coupling to a ground terminal 11 on the electrically conductive base 6.

The elongated length L of the ring line of the resonant ring-type radiator 2 can be shortened to approximately half of the line wavelength λ by the action of the vertical radiators 4, starting from approximately the line wavelength λ.

The active vertical radiator 4a may be provided with a reactance circuit 13 realized as a capacitor 15 for coupling to the antenna terminal 5.

The circuit with resistive losses 12a may be formed of an ohmic resistor 20.

The ohmic resistor 20 may be a parallel resonant circuit - consisting of a parallel capacitor 18 and a parallel inductance 17 - connected in parallel with a resonant frequency in the vicinity of the frequency band center for expanding the frequency bandwidth of the Kreuzpolarisationsabstands.

The ohmic resistor 20 may each have a parallel oscillation circuit - consisting of a capacitor 18 and an inductor 17 - be connected in parallel and the lossless reactance circuits 13, with which the remaining passive vertical radiators 4b, 4c are coupled to the electrically conductive base 6, respectively the series connection of a capacitor 15 and a parallel oscillation circuit - consisting of a parallel capacitor 18 and a parallel inductance 17 - be formed and the resonant frequency of the parallel resonant circuits may each be selected approximately in the vicinity of the center of a predetermined frequency band for expanding the frequency bandwidth of the Kreuzpolarisationsabstands.

The parallel resonant circuit in the lossless reactance circuit 13 and the parallel resonant circuit connected in parallel to the ohmic resistor 20 can be tuned in this way, that in each case in the frequency band center of the two satellite navigation frequency bands L1 and L2, a maximum of the Kreuzpolarisationsabstands is set.

There may be N = 1 vertical radiator 4d with reactance circuit with active component 12 for coupling to a ground terminal 11 on the electrically conductive base 6 and this be the active vertical radiator 4a adjacent.

The ring line emitter 2 can be designed as a rectangle, at the corners of each of which a ring line crosspoint 7 can be formed with a vertical emitter 4a-d which is galvanically connected there.

To support the unidirectionality of the wave propagation on the ring line emitter 2, a further section of the ring line emitter 2 opposite the first section may be present with characteristic impedance (ZL2) deviating from the characteristic impedance (ZL1) of the remaining sections of the ring line emitter 2.

The lossless reactance circuits 13 of the passive radiators realized as capacitances 15 for coupling to the conductive base 6 or for coupling to the circuit with ohmic losses 12a coupled to the conductive base 6 and the capacitance 15 for coupling the active radiator 4a to the antenna terminal 5 can be arranged in FIG the manner in which the vertical radiators 4, 4a-d are formed at their lower end to form individualized area capacitance electrodes 32a, 32b, 32c, 32d, and the capacitances 15 can be formed by interposing a dielectric plate 33 between the areal capacitance electrodes 32a, 32b, 32c, 32d and the electrically conductive base surface 6 embodied as an electrically conductive printed circuit board 35 for coupling the passive radiators 4b, 4c to the electrically conductive base surface 6.

For the capacitive coupling of the active vertical radiator 4a to the antenna terminal 5 and for the capacitive coupling of the active vertical Emitter 4a adjacent passive vertical radiator 4d to the circuit with ohmic losses 12a on the electrically conductive base 6, a surface of this layer insulated, counter electrode 34 can be designed.

The conductive structure consisting of the ring conductor 2 and the associated vertical radiators 4, 4a-d may be fixed by a dielectric support structure 36 so that the dielectric plate 33 is realized in the form of an air gap.

• Fig. 1:
  1. a) Antenne nach der Erfindung mit Ringleitungsstrahler 2 mit an Ringleitungs-Koppelpunkten 7 galvanisch verkoppelten vertikalen Strahlern 4a-4d. Der passive vertikale Strahler 4d, der in dem dargestellten Beispiel dem aktiven vertikalen Strahler 4a benachbart angeordnet ist, ist über die Blindwiderstandsschaltung mit Wirkanteil 12 über den Masse-Anschlusspunkt 11 mit der leitenden Grundfläche 6 verkoppelt. Die Erregung des Ringleitungsstrahlers 2 erfolgt über den aktiven vertikalen Strahler 4a, welcher über die verlustlose Blindwiderstandsschaltung 13 mit dem Antennenanschluss 5 verbunden ist. Die Blindwiderstandsschaltungen 13 sowie die Blindwiderstandsschaltung mit Wirkanteil 12 bilden zusammen mit den reaktiven Eigenschaften des Ringleitungsstrahlers 2 und der vertikalen Strahler 4 die Resonanzstruktur in der Weise, dass sich auf der Ringleitung 2 die Stromverteilung einer laufenden Leitungswelle in einer einzigen Umlaufrichtung einstellt, deren Phasenunterschied über einen Umlauf gerade 2π beträgt.
  2. b) Antenne nach der Erfindung wie in Figur a) jedoch mit geänderter Anordnung der vertikalen Strahler am Umfang des Ringleitungsstrahlers 2. Einem Umlaufsinn folgend sind zwischen aufeinanderfolgenden, mit einer Blindwiderstandsschaltung mit Wirkanteil 12 beschalteten vertikalen Strahlern jeweils zwei mit einer verlustlosen Blindwiderstandsschaltung 13 beschaltete vertikale Strahler angeordnet. Der aktive Strahler 4a ist über die verlustlose Blindwiderstandsschaltung 13 mit dem Antennenanschluss 5 verkoppelt.
  3. c) Antenne nach der Erfindung wie in Figur b), jedoch ist einem Umlaufsinn folgend zwischen aufeinanderfolgenden, mit einer Blindwiderstandsschaltung mit Wirkanteil 12 beschalteten vertikalen Strahlern jeweils nur ein mit einer verlustlosen Blindwiderstandsschaltung 13 beschalteter vertikaler Strahler angeordnet. Der aktive Strahler 4a ist sowohl über die verlustlose Blindwiderstandsschaltung 13 mit der elektrisch leitenden Grundfläche 6 als auch mit dem Antennenanschluss 5 verkoppelt.
• Fig. 2: Antenne nach der Erfindung wie in Figur 1, wobei die Blindwiderstandsschaltung mit Wirkanteil 12 als einfache Serienschaltung aus einer Kapazität 15 und einem ohmschen Widerstand 20 besteht. Die Blindwiderstandsschaltung 13, welche den aktiven vertikalen Strahler 4a mit dem Antennenanschluss 5 verkoppelt, ist durch die Kapazität 15 realisiert. Die Resonanz ist durch geeignete Wahl der Kapazitäten 15 gegeben. Der Widerstand 20 ist im Hinblick auf die Maximierung der Frequenzbandbreite des Kreuzpolarisationsabstands gewählt. Die Blindwiderstandsschaltung 13 am aktiven Strahler 4a ist in der Weise gestaltet, dass sowohl die beschriebene Resonanz gegeben ist, als auch die Impedanz der Antenne an den Wellenwiderstand üblicher Antennenleitungen angepasst ist. Die beiden übrigen vertikalen passiven Strahler 4b und 4c sind über die als Kapazitäten 15 realisierten Blindwiderstandsschaltungen 13 jeweils mit dem Masse-Anschlusspunkt 11 mit der leitenden Grundfläche 6 verbunden.
• Fig. 3:
  • a Antenne nach der Erfindung wie in Figuren 1 und 2 jedoch mit rechteckig geformtem Ringleiter 2. 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 beschichtete Leiterplatte ausgeführten elektrisch leitenden Grundfläche 6 befindlichen dielektrische Platte 33 sind die Kapazitäten 15 zur Ankopplung von zwei vertikalen Strahlern 4b, 4c an die elektrisch leitende Grundfläche 6 gestaltet. Zur kapazitiven Ankopplung des aktiven vertikalen Strahlers 4d, an den Antennenanschluss 5 ist dieser als eine von der leitenden Schicht isolierte, flächige Gegenelektrode 34 gestaltet. Ebenso ist zur Ankopplung des dem aktiven vertikalen Strahler 4a benachbarten Strahles 4d an die Schaltung mit ohmschen Verlusten 12a eine von der leitenden Schicht isolierte, flächige Gegenelektrode 34 gestaltet. Die Blindwiderstandsschaltung mit Wirkanteil 12 ist somit als Serienschaltung der Kapazität 15 und der Schaltung mit ohmschen Verlusten 12a gebildet. Im Bild ist die dielektrische Platte 33 durch einen Luftspalt realisiert.
  • b) Schaltbild der Blindwiderstandsschaltung mit Wirkanteil 12 bestehend aus der Serienschaltung der Kapazität 15 und der Schaltung mit ohmschen Verlusten 12a realisiert durch den ohmschen Widerstand 20.
  • c) Schaltbild der Blindwiderstandsschaltung mit Wirkanteil 12 wie in Figur b) jedoch mit Parallelresonanzkreis, bestehend aus der Parallelkapazität 18 und der Parallelinduktivität 17 in Parallelschaltung zum Widerstand 20.
• Fig. 4: Verlauf des Kreuzpolarisationsabstands und des Gewinns für den niedrigen Einfall der Satellitensignale unter einem Elevationswinkel von 20°, aufgetragen über der Frequenz im Satelliten-Navigations-Frequenzband L1.
  1. a) Realisierter, extrem hoher Kreuzpolarisationsabstand in dB.
  2. b) beispielhaft ausreichender Kreuzpolarisationsabstand in dB.
  3. c) Realisierter Antennengewinn in dB.
• Fig. 5: Selbsterklärende Explosionszeichnung zur Erläuterung des Aufbaus der in Figur 3 beschriebenen Antenne nach der Erfindung. Der rechteckige Ringleiter 2 mit vertikalen Strahlern 4 kann kostengünstig als Stanz- und Biegeteil hergestellt werden.
• Fig. 6: Antenne nach der Erfindung, ähnlich wie in Figur 3. Darstellung der unterschiedlichen Wellenwiderstände ZL1 und ZL2 der Teile des rechteckförmigen Ringleiters 2 zur Unterstützung der Unidirektionalität des Umlaufsinns der bei Resonanz umlaufenden elektromagnetischen Stromwelle. Der ohmsche Widerstand 20 ist als SMD-Bauteil als Brücke zwischen der Gegenelektrode 34 und der leitenden Grundfläche 6 angedeutet. Die Impedanz am Antennenanschluss 5 beträgt 50 Ohm. Typische Abmessungen einer Ringleitungsantenne 2 für den Frequenzbereich L1 sind für Breite und Länge 34*42mm, h=8mm, ohmscher Widerstand 20, R= 130 Ohm. Der Verlustfaktor der Blindwiderstandsschaltung mit Wirkanteil 12 beträgt 0,5. Die Kapazität 15 beträgt ca. 0,3 pF (Kapazitätselektrode 32 gegen elektrisch leitende Grundfläche 6 bzw. Gegenelektrode 34).
• Fig. 7: Antenne nach der Erfindung wie in Figur 6 zum Beispiel für das Frequenzband L1 mit Blick auf die Rückseite der Leiterplatte 35. Hierzu werden zwei Durchkontaktierungen 16 der Leiterplatte 35 verwendet. Eine der zwei Durchkontaktierungen 16 wird im Beispiel über den ohmschen Widerstand 20 von 130 Ohm mit der elektrisch leitenden Grundfläche 6 verbunden, die andere Durchkontaktierung 16 mit dem Antennenanschluss 5.
• Fig. 8: Im Bild ist die Oberseite der Leiterplatte 35 einer Antenne 1 nach der Erfindung dargestellt, auf welche der elektrische Ringleitungsstrahler 2 aufgesetzt wird.
  Für die Gestaltung einer zweibandfähigen Multibandantenne nach der Erfindung - zum Beispiel für die Frequenzbereiche L1 und L2 - ist die Blindwiderstandsschaltung 13 jeweils in der Weise mehrfrequent gestaltet, dass sowohl die Resonanz des Ringleitungsstrahlers 2 als auch die geforderte Laufrichtung der Leitungswelle auf dem Ringleitungsstrahler 2 in den voneinander getrennten Frequenzbändern L1 und L2 gegeben ist.
  Dies ist bei dem Beispiel im Figur 8 dadurch erreicht, dass für alle Kapazitätselektroden 32 jeweils eine Gegenelektrode 34 vorhanden ist und, dass der durch die Kapazitätselektroden 32 bewirkten Kapazität 15 an allen vertikalen Strahlern 4 eine Parallelschaltung aus einer Parallelkapazität 18 und einer Parallelinduktivität 17 - dargestellt als SMD-Bauteile - zwischen der Gegenelektrode 34 und der elektrisch leitenden Grundfläche 6 in Serie geschaltet ist. Der ohmsche Widerstand 20 bei dem Strahler 4d ist etwa für die Frequenzmitte zwischen den beiden Frequenzbändern L1 und L2 im Hinblick auf optimalen Kreuzmodulationsabstand in den beiden Frequenzbändern dimensioniert.
• Fig. 9: Zweiband-Antenne nach der Erfindung wie in Figur 8,
  1. a) mit Blick auf die Oberseite der Leiterplatte 35 mit Durchkontaktierungen 16 auf den Gegenelektroden 34 unter den Kapazitätselektroden 32.
  2. b) Alle SMD-Schaltelemente sind entsprechend auf der Rückseite der Leiterplatte auf Pads 26 angeordnet, die über die Durchkontaktierungen 16 verbunden sind.

The accompanying figures show in detail:

• Fig. 1 :
  1. a) antenna according to the invention with loop antenna 2 with galvanically coupled to ring line coupling points 7 vertical radiators 4a-4d. The passive vertical radiator 4d, which in the example illustrated is arranged adjacent to the active vertical radiator 4a, is coupled to the conductive base 6 via the reactive impedance circuit 12 with the active component 12 via the ground terminal 11. The excitation of the ring line radiator 2 via the active vertical radiator 4a, which is connected via the lossless reactance circuit 13 to the antenna terminal 5. The reactance circuits 13 and the reactance circuit 12 together with the reactive properties of the ring line radiator 2 and the vertical radiator 4, the resonance structure in such a way that sets the current distribution of a current line wave in a single direction of rotation on the ring line 2, the phase difference across a Circulation is just 2π.
  2. b) Antenna according to the invention as in Figure a) but with a changed arrangement of the vertical radiator on the circumference of the ring line radiator 2. According to a sense of circulation between two successive, connected to a reactance circuit with active component 12 vertical radiators each with a lossless reactance circuit 13 connected vertical radiator arranged. The active radiator 4a is coupled to the antenna terminal 5 via the lossless reactance circuit 13.
  3. c) Antenna according to the invention as in Figure b), but is a circulation sense between successive, connected to a reactance circuit with active component 12 vertical radiators only one with a lossless reactance circuit 13 connected vertical radiator arranged. The active radiator 4a is coupled both via the lossless reactance circuit 13 with the electrically conductive base area 6 and with the antenna terminal 5.
• Fig. 2 : Antenna according to the invention as in FIG. 1 , Wherein the reactance circuit with active component 12 as a simple series circuit of a capacitor 15 and a resistor 20 is made. The reactance circuit 13, which couples the active vertical radiator 4a to the antenna terminal 5, is realized by the capacitor 15. The resonance is given by suitable choice of the capacities 15. The resistor 20 is selected to maximize the frequency bandwidth of the cross polarization spacing. The reactance circuit 13 on the active radiator 4a is designed in such a way that both the described resonance is given, and the impedance of the antenna is adapted to the characteristic impedance of conventional antenna lines. The two remaining vertical passive radiators 4b and 4c are connected via the dummy resistance circuits 13 realized as capacitances 15 to the ground base 6 with the ground terminal 11, respectively.
• Fig. 3 :
  • a antenna according to the invention as in FIGS. 1 and 2 However, with rectangular shaped ring conductor 2. 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 conductive printed circuit board, the capacitances 15 for the coupling of two vertical radiators 4b, 4c to the electrically conductive base 6 are designed. For capacitive coupling of the active vertical radiator 4d, to the antenna terminal 5, this is as one of the conductive Layer insulated, flat counter electrode 34 designed. Likewise, for coupling the beam 4d adjacent to the active vertical radiator 4a to the circuit with resistive losses 12a, a planar counterelectrode 34 insulated from the conductive layer is designed. The reactance circuit 12 with active component 12 is thus formed as a series connection of the capacitor 15 and the circuit 12 with ohmic losses. In the picture, the dielectric plate 33 is realized by an air gap.
  • b) circuit diagram of the reactance circuit with active component 12 consisting of the series connection of the capacitor 15 and the circuit with ohmic losses 12a realized by the ohmic resistor 20th
  • c) circuit diagram of the reactance circuit with active component 12 as in Figure b) but with parallel resonant circuit consisting of the parallel capacitance 18 and the parallel inductor 17 in parallel with the resistor 20th
• Fig. 4 : Path of the cross-polarization distance and gain for the low incidence of the satellite signals at an elevation angle of 20 °, plotted against the frequency in the satellite navigation frequency band L1.
  1. a) Realized, extremely high cross-polarization distance in dB.
  2. b) by way of example sufficient cross-polarization distance in dB.
  3. c) Realized antenna gain in dB.
• Fig. 5 Self-explanatory exploded view explaining the structure of in FIG. 3 described antenna according to the invention. The rectangular ring conductor 2 with vertical radiators 4 can be produced inexpensively as a stamped and bent part.
• Fig. 6 : Antenna according to the invention, similar to in FIG. 3 , Representation of the different characteristic impedances ZL1 and ZL2 of the parts of the rectangular ring conductor 2 to support the unidirectionality of the sense of rotation of the circulating at resonance electromagnetic current wave. The ohmic resistor 20 is indicated as an SMD component as a bridge between the counter electrode 34 and the conductive base 6. The impedance at the antenna connection 5 is 50 ohms. Typical dimensions of a loop antenna 2 for the frequency range L1 are for width and length 34 * 42mm, h = 8mm, resistance 20, R = 130 ohms. The loss factor of the reactance circuit with effective component 12 is 0.5. The capacitance 15 is about 0.3 pF (capacitance electrode 32 against electrically conductive base 6 or counter electrode 34).
• Fig. 7 : Antenna according to the invention as in FIG. 6 For example, for the frequency band L1 facing the back of the circuit board 35. For this purpose, two vias 16 of the circuit board 35 are used. In the example, one of the two plated-through holes 16 is connected to the electrically conductive base area 6 via the ohmic resistor 20 of 130 ohms, the other through-connection 16 to the antenna terminal 5.
• Fig. 8 The picture shows the upper side of the printed circuit board 35 of an antenna 1 according to the invention, on which the electric circular line emitter 2 is placed.
  For the design of a two-band multiband antenna according to the invention - for example for the frequency ranges L1 and L2 - the reactance circuit 13 is designed multi-frequency in each case in such a way that both the resonance of the ring line radiator 2 and the required direction of the line shaft on the ring line emitter 2 in the given separate frequency bands L1 and L2.
  This is the example in FIG. 8 achieved in that for each of the capacitance electrodes 32 each have a counter electrode 34 is provided and that caused by the capacitance electrodes 32 capacitance 15 on all vertical radiators 4 is a parallel connection of a parallel capacitance 18 and a parallel inductor 17 - shown as SMD components - between the counter electrode 34 and the electrically conductive base 6 is connected in series. The ohmic resistance 20 at the radiator 4d is dimensioned approximately for the frequency center between the two frequency bands L1 and L2 with regard to optimal cross modulation spacing in the two frequency bands.
• Fig. 9 : Two-band antenna according to the invention as in FIG. 8 .
  1. a) looking at the top of the circuit board 35 with vias 16 on the counter electrodes 34 under the capacitance electrodes 32nd
  2. b) All SMD switching elements are correspondingly arranged on the back of the circuit board on pads 26 which are connected via the vias 16.

The mode of operation of the suppression of the unwanted polarization direction LHCP of an antenna intended for RHCP can be compared with that of a bridge circuit or with a hybrid ring. However, such a bridge can only be perfectly balanced for a particular frequency, generally about the center frequency of a frequency band. At deviating frequencies arises naturally when excited at a gate, so the active vertical radiator 4a in FIG. 1a In addition to the desired radiation in the RHCP mode, the unwanted radiation in the opposite direction, ie the LHCP mode.

The connection of the emitter 4d adjacent to the excited emitter 4a with a reactance circuit 12 with effective component 12 influences the phase position of the voltage at this emitter in such a way that the unwanted LHCP component in the radiation is largely compensated for even at frequency offset from the center frequency. According to the invention, this shows that even with a simple combination of a series circuit of a capacitor 15 with an ohmic resistor 20, as in the Figures 2 and 3b shown, a significantly larger bandwidth of the required Kreuzpolarisationsabstands can be achieved. The slight loss of the antenna gain caused by the active component of the reactance circuit with active component 12 has practically no influence on the localization result. With sufficient antenna gain this is the Bandwidth of the cross modulation distance is crucial. It is well known that antenna characteristics can be made more broadband by attenuation with lossy elements. With the present invention, however, the goal is associated that the bandwidth of the cross modulation distance is greatly increased by the inventive measures, but the weakening of the antenna gain caused by the active components is sufficiently low. This inventive selective effect on the bandwidth of the cross-modulation distance is achieved in a particular way in that in particular those modes of the current are suppressed on the loop emitter 2, which cause the radiation in the unwanted polarization direction LHCP. These modes are generated in particular by selecting different characteristic impedances of the sections of the ring line radiator 2 in combination with the alternating sequence on the ring line radiator periphery of vertical radiators 4 with reactance circuit 12 and such vertical radiators 4, which are each connected to a lossless reactance circuit 13. The characteristic impedance of such a section is given by its distributed capacitance to the conductive base 6 and its distributed longitudinal inductance.

A particular advantage of the invention is that the improvement of the bandwidth of the cross modulation distance already with only N = 1, so only a single vertical radiator with reactance circuit with active component 12 - the loss factor greater is than 0.2 - can be achieved. As a loss factor of the reactance circuit with active component 12 is - in analogy to the usual definition - the ratio of resistance / reactance in serial description or conductance / susceptance referred to in parallel description of the reactance circuit.

According to the invention, as described above, it is provided that with N> 1 a plurality of vertical radiators connected with reactive resistance circuit with active component 12 are arranged along the circumference of the ring-shaped radiator 2. In this case it is According to the invention, the loss factor corresponding to the number N of each of the reactance circuits with effective component 12 is chosen to be not smaller than 0.2 / N.

The bandwidth of the cross modulation pitch can be further increased by using more complicated circuits. The parallel connection of a parallel resonant circuit, consisting of the parallel inductance 17 and the parallel capacitance 18 to the ohmic resistor 20 in Figure 3c promotes the frequency bandwidth of the required Kreuzpolarisationsabstands in the frequency environment of the resonant frequency of the parallel resonant circuit. In such circuits as already described above for maximizing the frequency bandwidth of the cross-polarization distance respectively in the frequency band center of the two satellite navigation frequency bands L1 and L2, losses in the lossless intended resistance circuits 13 due to the limited quality (C and L) of the available Blind elements can not be completely avoided. It turns out, however, that the increase in the bandwidth of the cross-polarization distance envisaged by the invention can already be demonstrated if, with a number of likewise N radiators with reactance circuits 13, their dissipation factor is not greater than about 1/5 of the dissipation factor in the reactance reactance circuits 12th

List of terms

• Antenna 1
• Ring line radiator 2
• electromagnetic excitation 3
• vertical radiators 4, 4a, 4b, 4c, 4d
• active vertical radiator 4a
• passive vertical radiator 4d
• Antenna connection 5
• Conductive base 6
• Ring line coupling points 7,7a, 7b, 7c, 7d
• Distance of height h 9
• Ground connection point 11
• Reactive resistance circuit with active component 12
• Ohmic loss circuit 12a
• Lossless reactance circuit 13
• Capacity 15
• Through-connection 16
• Inductance 17
• Parallel capacity 18
• ohmic resistance 20
• Pad 26
• Capacitance electrode 32a, 32b, 32c, 32d,
• dielectric plate 33
• Counter electrode 34
• Printed circuit board 35
• Support structure 36
• Distance 37
• Characteristic impedance ZL, ZL1, ZL2
• Elongated length of the ring line radiator L

Claims (15)

Antenna (1) for receiving circularly polarized satellite radio signals comprising at least one horizontally oriented conductor loop arranged above a conductive base (6), having an arrangement for electromagnetic excitation of the conductor loop connected to an antenna connection (5), comprising the following features: - The conductor loop is designed as a ring line radiator (2) extending through a polygonal or circular closed loop in a horizontal plane with the height h above the conductive base (6), - The ring line emitter (2) forms a resonant structure and is electrically excited by electromagnetic excitation in such a way that adjusts the current distribution of a current line wave in a single direction of rotation on the loop, the phase difference over a revolution is just 2π, - There are on the circumference of the ring line radiator (2) at ring line crosspoints (7) with the ring line radiator (2) galvanically coupled, vertical and the conductive base (6) extending towards radiator (4, 4a-d), wherein one of the Radiator as an active radiator (4a) the excitation of the conductor loop takes place and the other radiators are coupled as passive radiators (4b, 4c, 4d) with the electrically conductive base surface (6), characterized,
in that there are at least two vertical passive radiators (4b, 4c, 4d) which are galvanically coupled to the ring base radiator (2) and of which N radiators are connected via a reactance circuit with effective component (12), their loss factor in each case is greater than the value 0.1 / N, are coupled to the electrically conductive base (6),
that at no point along the ring line emitter (2) two of these emitters are arranged adjacent to each other,
that all other passive vertical radiators (4b, 4c) are coupled to the base area (6) via lossless reactance circuits (13), and
that none of the distances between adjacent ring line coupling points (7) on the circumference of the ring line radiator (2) is smaller than half the distance that would result in equidistant distribution of all radiators over the extended length L of the loop emitter (2). Antenna (1) according to claim 1,
characterized in that
at least two of each of two adjacent ring line crosspoints (7) located portions of the ring line radiator (2) with differing characteristic impedance ZL1, ZL2 are present. Antenna (1) according to claim 1 or 2,
characterized in that
the reactance circuit (12) for coupling N vertical radiators (4d) to a ground terminal (11) on the electrically conductive base (6) is formed in each case by the series connection of a capacitor (15) and a circuit with resistive losses (12a) .
and each of the remaining passive vertical radiators (4b, 4c) is provided with a lossless reactance circuit (13) realized as capacitance (15) for coupling to a ground terminal (11) on the electrically conductive base (6). Antenna (1) according to one of claims 1 to 3,
characterized in that
the elongated length L of the ring line of the resonant ring line radiator (2) is shortened by the action of the vertical radiators (4), starting from approximately the line wavelength λ to approximately half the line wavelength λ. Antenna (1) according to one of claims 1 to 4,
characterized in that
the active vertical radiator (4a) is provided with a reactance circuit (13) realized as a capacitance (15) for coupling to the antenna connection (5). Antenna (1) according to one of claims 1 to 5,
characterized in that
the active vertical radiator (4a) is coupled to the ground both with the antenna connection (5) and via a lossless reactance circuit (13) realized as a capacitance (15). Antenna (1) according to one of claims 1 to 6,
characterized in that
the circuit with resistive losses (12a) is formed from an ohmic resistor (20). Antenna (1) according to claim 7,
characterized in that
the ohmic resistor (20) is a parallel resonant circuit - consisting of a parallel capacitance (18) and a parallel inductance (17) - connected in parallel with a resonant frequency in the vicinity of the frequency band center for expanding the frequency bandwidth of the Kreuzpolarisationsabstands. Antenna (1) according to claim 7,
characterized in that
the ohmic resistance (20) in each case a parallel resonant circuit - consisting of a capacitor (18) and an inductor (17) - is connected in parallel and the lossless reactance circuits (13), with which the remaining passive vertical radiator (4b, 4c) with the electric conductive base (6) are coupled, each of the series circuit of a capacitor (15) and a parallel resonant circuit - consisting of a parallel capacitance (18) and a parallel inductance (17) - formed and the resonant frequency of the parallel resonant circuits each approximately in the vicinity of the center predetermined frequency band to expand the frequency bandwidth of the Kreuzpolarisationsabstands are selected. Antenna (1) according to claim 9,
characterized in that
However, each of the parallel resonant circuit in the lossless reactance circuit (13) and the ohmic resistor (20) each parallel-parallel resonant circuit is tuned in such a way that in the frequency band center of two satellite navigation frequency bands L1 and L2 is set a maximum of the Kreuzpolarisationsabstands. Antenna (1) according to one of claims 1 to 10,
characterized in that
a passive vertical radiator (4d) with reactance circuit (12) for coupling to a ground terminal (11) on the electrically conductive base (6) is present and this is the active vertical radiator (4a) adjacent. Antenna (1) according to one of claims 1 to 11,
characterized in that
the ring line emitter (2) is designed as a rectangle, at the corners of which a ring line crosspoint (7) is formed with a vertical emitter (4a-d) which is galvanically connected there. Antenna (1) according to claim 12,
characterized in that
to support the unidirectionality of the wave propagation on the ring line radiator (2) a first portion opposite another portion of the ring line radiator (2) of the characteristic impedance (ZL1) of the remaining portions of the ring line radiator (2) deviating Wellenwiderstand (ZL2) is present. Antenna (1) according to one of claims 1 to 13,
characterized in that
the reactance circuits (13) of the passive radiators realized as capacitances (15) for coupling to the conductive base area (6) or for coupling to the circuit with ohmic losses (12a) coupled to the conductive base area (6) and the capacitance (15). for coupling the active radiator (4a) to the antenna connection (5) in such a way that the vertical radiators (4, 4a-d) are formed at their lower end to individually shaped area capacitance electrodes (32a, 32b, 32c, 32d) that the capacitances (15) by interposing a dielectric plate (33) between the sheet capacitance electrodes (32a, 32b, 32c, 32d) and the designed as electrically conductive coated circuit board (35) designed electrically conductive base (6) for coupling the passive radiator (4b, 4c) to the electrically conductive base (6), and that for the capacitive coupling of the active vertical radiator (4a) to the Antenna terminal (5) and for the capacitive coupling of a vertical vertical radiator (4a) adjacent passive vertical radiator (4d) to the circuit with ohmic losses (12a) on the electrically conductive base (6) each one of this layer isolated, flat counter electrode ( 34) is designed. Antenna according to claim 14,
characterized in that
the conductive structure consisting of the ring conductor (2) and the associated vertical radiators (4, 4a-d) is fixed by a dielectric support structure (36) such that the dielectric plate (33) is realized in the form of an air gap.

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