MXPA99006772A - Integrated satellite antenna / terres - Google Patents

Abstract

A dual integrated antenna that includes a quadrifilar antenna and a monopolar antenna placed. The integrated antenna is compact and has no problems blocking signals or isolation

Description

INTEGRATED SATELLITE / TERRESTRIAL ANTENNA DES-CRIPCXOM OF THE INVENTION The present invention relates to an integrated antenna and more particularly, the present invention relates to a dual antenna system. In the prior art, satellite antennas, terrestrial antennas and integrations of these two have been proposed. Referring initially to satellite ancestors of the prior art, the quadrifilar helix has been known for several decades. This antenna includes helical windings fed in quadrature phase. This arrangement provided several well-suited features for satellite communications including hemispherical omnidirectional radiation models with excellent circular polarization throughout the radiation model as well as compact and simple structure. For mobile terrestrial communications, there are the same omnidirectional requirements but the radiation model only needs to be omnidirectional on the horizon due to the restrictions of terrestrial communications in the user's position in relation to base stations. The most common arrangement of this type is the monopolar antenna consisting of a simple cable above a base plane. The most contemporary designs of antennas have included dual systems. These systems give rise to satellite and terrestrial antennas. These systems present important design problems, particularly with respect to the isolation between the two antennas, the minimization of signal blockage and the compact size. The prior art systems tried to solve the design difficulties by simply placing a satellite antenna and a terrestrial antenna spaced a minimum distance in such a way that the isolation and blocking requirements were well met. Although it is a generally useful concept, in order to achieve the most desirable performance, a significant separation between the antennas is required. This did not solve the compact size problem, in fact it did not meet the compact size requirement. In the North American patent no. 5,600,341, published April 4, 1997, by Thrill et al., Provides an antenna structure with dual function to transmit-receive in first and second modalities. The apparatus shown in the North American patent is a simple antenna of dual frequency contrary to the dual antenna of dual mode. According to this in the description of Thill et al, nothing is shown regarding the co-location of two discrete antennas and accordingly there is no recognition or discussion of the problems that arise when attempting to co-locate two antennas The structure provides two power points for two fields but is still a simple dual frequency antenna. This arrangement does not resolve in any way the complications inherent to the co-location of two antennas such the closure of the signal of the antenna to block the communication of the co-located antenna. Prior art related to the present invention is described in U.S. Pat. 4,959,657 of Mochizuki, published on September 25, 1990. This reference presents an omnidirectional antenna with a reflector. The isolation of a monopolar antenna with a quadrifilar antenna is not provided in this reference and according to this this reference only shows a variation of what is already known in the art. Moore et al. , in the North American patent no. 5,656,792, published on July 22, 1997, describes a combined GPS and VHF antenna. The combined antenna provides a volute or quadrifilar antenna together with a monopole. Although the elements are provided, there is no co-location between the two antennas, which clearly does not contribute to making the antenna compact. By simply providing the combination of the two known separate antennas, yes, there are no interference problems. From a review of the description it is clear that the Moore et al reference does not recognize the value of having a co-localized antenna system. The present invention completely overcomes the limitations in the known art and provides a dual antenna system that has outstanding performance in a compact system. An object of the present invention is to provide an improved dual antenna system. Another object of the present invention is to provide an integrated antenna consisting of: a quadrifilar antenna, and a monopolar antenna positioned inside the quadrifilar antenna and independent of the monopolar antenna. Advantageously, the insulation difficulties inherent in the arrangements of the prior art do not represent problems in the present system. In view of the fact that the monopolar antenna has a capo zero at its center, there is no interference or blocking of the monopolar signal, allowing the antenna to function as if it were completely isolated. This feature facilitates the placement of the antennas without loss in performance. Another ot of the present invention is to provide a method for forming a dual integrated antenna, consisting of the steps of: providing a quadrifilar antenna for transmitting-receiving circular polarized fields; provide a monopolar antenna to transmit-receive linear polarized fields; co-locate the monopolar antenna inside the quadrifilar antenna and independent of the quadrifilar antenna; and phase coupling of the monopolar antenna to the quadrifilar antenna. Having described the invention, reference will now be made to the accompanying drawings which illustrate preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a dual antenna according to the prior art; Figure 2 is an elevation view of the antenna according to an embodiment of the present invention; Figure 2A is a cross section of Figure 2; Figure 3 is a graphic illustration of the return loss of the quadrifilar helix; Figure 4 is a graphic illustration of quadrifilar radiation performance; Figure 5 is a graphic illustration of the return loss of the monopole. Figure 6 is a graphic illustration of the elevation cut of the monopole; Figure 7 is a graphic illustration of the azimuth sweep of the monopole; and Figure 8 is a graphic illustration of the frequency isolation between the two antenna ports. Similar numbers in the figures represent similar elements. Referring now to the drawings, Figure 1 illustrates a conventional dual antenna system with a cylindrical quadrifilar antenna 10 placed in a separate relationship with a monopolar antenna 12. The antennas are mounted on a base plane 14 and separated by a distance D with the purpose of isolating them and minimizing signal blocking. Figure 2 shows an example of the antenna system according to an embodiment of the present invention. In the embodiment shown, the monopolar antenna 12 is positioned in the center (coaxially) of the quadrifilar antenna 10. A capacitor is provided with a landing bar, represented overall with the number 18. A connection 20 for the quadrifilar antenna is provided for connecting with an external source (not shown). A similar connection 22 is provided for the monopolar antenna 12. A reinforcement 24 can be placed below the base plane 14 to reinforce the system. The cylindrical quadrifilar system does not show a field zero at its center. The field model of the quadrifilar is formed in its coils 16. As mentioned here before, this significantly reduces the effect of the performance with the presence of the monopolar antenna 12. In the case that the frequency plan of the dual system is such that the frequency of satellite communications is approximately an exact multiple of the frequency of terrestrial communications, the monopolar antenna 12 presents a high impedance further improving the isolation between the two antennas 10 and 12. In figure 2A a cross section of the antenna is shown. antenna in which a rigid foam material 17 is placed between the quadrifilar antenna on its inner surface and the monopolar antenna 12. As illustrated, the monopolar antenna 12 is completely surrounded by the material 17. In cases in which the rigidity of The general antenna unit is not required, then the rigid foam can easily be replaced with rigid or non-rigid foam material. In terms of the material for the foam, suitable examples include polyurethane foam, polystyrene, polyvinyl chloride foam, among others. With respect to the quadrifilar antenna, which is illustrated in figure 2, the antenna includes four coils, these coils have an angle of 45 ° in relation to the monopole. It has been found that a 45 ° arrangement provides the most effective results, however with the arrangement of the coils in the range of 36 to 48 °, adequate results can be obtained. The quadrifilar coils are mounted in a polymeric cylinder as illustrated in Figure 2 and 2A, the polymer being selected from any of the suitable polymers, examples of which include Kaptonr, Mylarmr, etc. As is known, the quadrifilar antenna coils 16 can interfere or otherwise block a radiated model from the monopolar antenna 12 to the free space. The present invention has the advantages that this "enclosing" effect can be minimized. This is achieved by selectively positioning the coils 16 of the quadrifilar antenna 10. It has been found that this is an important feature if the angle of the coils is too pronounced, the closure of the monopolar antenna 12 will present itself. the form of the degradation of the radiation model as well as the coupling complications of the input impedance. If the separation of the coils 16 is not sufficient, the coils 16 will be too close together and this will result in the formation of an electrical wall blocking the radiation from the lower portion of the monopolar antenna 12. It has been found that a separation between the 45 ° coils gives excellent results. Because the coupling of the monopolar antenna 12 to the coils 16 of the four-wire antenna is in phase, the nature of the quadrature feed network in the quadrifilar antenna leads to phase cancellation of the coupled energy. This contributes to the high isolation in the frequency of terrestrial operation. In the figures, the design frequencies were as follows: - Satellite reception (RX): 1525-1575.42 MHz - Satellite transmission (TX): 1610-1660.5 MHz - Ground reception (RX): 806-825 MHz - Land transmission (TX) : 851-870 MHz Figures 3 a & demonstrate the performance results for the present invention. These results were generated using the quadrifilar antenna coils at a 45 ° angle as indicated here. Although embodiments of the invention have been described above, it is not limited thereto and it will be apparent to those skilled in the art that numerous modifications form part of the present invention as long as they do not depart from the spirit, nature and scope of the claimed description and described.

Claims (1)

CLAIMS 1. - A dual integrated antenna, consisting of: a quadrifilar antenna < and a monopolar antenna positioned inside the quadrifilar antenna and independent of the monopolar antenna. 2. - The integrated antenna according to the claim 1, in which the quadrifilar antenna has a plurality of coils. 3 .- The integrated antenna according to claim 2, wherein the coils are separated from each other. 4. - The integrated antenna according to the claim 3, in which the coils have an angle of 45 ° in relation to the monapolar antenna. 5. - The integrated antenna according to claim 1, wherein the monopole is positioned coaxially within the quadrifilar antenna. 6. - The integrated antenna according to the claim 2, in which the coils of the quadrifilar antenna are mounted in a polymeric cylinder. 7. The integrated antenna according to claim 1, wherein a foamed polymer is placed between the quadrifilar antenna and the monopolar antenna. 8. - The integrated antenna according to the claim 7, in which the foam polymer surrounds the monopolar antenna. 9. The integrated antenna according to claim 2, wherein the quadrifilar antenna includes four coils. 10. - The integrated antenna according to claim 1, wherein the coupling of the monopolar antenna with the quadrifilar antenna is in phase. 11. - The integrated antenna according to the claim 1, in which the quadrifilar antenna transmits / receives circularly polarized fields and the monopolar antenna transmits / receives? Apos polarized linearly independently of the quadrifilar antenna. 12. - The integrated antenna according to the claim 2, in which the plurality of the coils are placed equidistant. 13. - A method for forming a dual integrated antenna, comprising the steps: provide one. quadrifilar antenna to transmit / receive circularly polarized fields; provide a monopolar antenna to transmit / receive polarized fields; co-locating the monopolar antenna inside the quadrifilar antenna and independently to the quadrifilar antenna; Y

1 . - The method described in claim 13, further including the step of placing a polymeric foam material between the monopolar antenna and the quadrifilar antenna. 15. The method described in claim 14, wherein the polymeric foam completely surrounds the monopolar antenna. SUMMARY OF THE INVENTION A dual integrated antenna that includes a quadrifilar antenna and a monopolar antenna placed. The integrated antenna is compact and does not present problems of blocking signals or isolation.