High-frequency phase shifter unit having pivotable tapping element

Information

  • Patent Grant
  • 6850130
  • Patent Number
    6,850,130
  • Date Filed
    Thursday, July 27, 2000
    24 years ago
  • Date Issued
    Tuesday, February 1, 2005
    19 years ago
Abstract
An improved radio-frequency phase shift assembly includes at least one further stripline section arranged concentrically with respect to a first stripline section. Further connection lines are provided, via which an electrical connection is produced at least indirectly from the feed line to the respective tapping section associated with a stripline section. Two different pairs of antenna radiating elements can be driven with different phase angles (Φ) at mutually offset tapping points on the at least two stripline sections. The plurality of connection lines are mechanically connected to one another.
Description
FIELD

The invention relates to a radio-frequency phase shift assembly.


BACKGROUND AND SUMMARY

Phase shifters are used, for example, for trimming the delay time of microwave signals in passive or active networks. As a known principle, the delay time of a line is used to trim the phase angle of a signal and, in consequence, a variable phase angle means that the lines have different electrically effective lengths.


For applications in antennas with an electrically adjustable notch in the polar diagram, the signals have different delay times to the individual radiating elements, for example dipoles. The difference in the delay times between two adjacent radiating elements is approximately the same for a specific notch angle in an array of radiating elements arranged vertically one above the other. This delay time difference is also increased for larger notch angles. If the phase angles of the individual radiating elements are varied by means of phase shift assemblies, then this is an antenna with an adjustable electrical notch in the polar diagram.


According to WO 96/37922, a phase shift is known which has electrically moveable plates in order to produce a phase difference between different outputs, but at least between two outputs. This has the disadvantage that the movement of the dielectric plates also changes the impedance of the respectively affected lines, and the way in which the power of the signals is shared depends on the setting of the phase shifter.


The prior publication WO 96/37009 proposes a symmetrical line branching system in order to emit the same power at both ends of this line. This can be done provided that both ends are terminated by the characteristic impedance of this line. Comparable solutions of these technical principles have already been used for a long time for mobile radio antennas. However, these solutions have the disadvantage that only two radiating elements can be supplied, and they also still receive the same power. A further disadvantage is the moving electrically conductive connection between the input and the respective lines. Electrically high-quality contacts may exhibit undesirable nonlinearities.


In principle, it is also known for a number of phase shifters to be integrated in one antenna. Such phase shifters can supply the individual radiating elements in the entire antenna arrangement. Individual radiating elements have different phase differences, and the phase shift assembly settings differ for the individual radiating elements. This necessitates complex mechanical step-up transmission systems such as illustrated, in principle, in FIG. 1, which shows a corresponding design according to the prior art.


To this end, and in order to illustrate the prior art, FIG. 1 shows, schematically, an antenna array 1 having, for example, five dipole elements 1a, 1b, 1c, 1d, 1e which are fed via a feed input 5.


The feed input 5 is followed by a distribution network (“∥S∥”) 7 which, in the illustrated example, supplies two RF phase shift assemblies 9′, 9″ with each of the two phase shift assemblies supplying two dipoles.


A feed line 13 passes from the distribution network 7 to a central dipole radiating element 1c, which is driven without any phase shift.


The other dipoles are supplied with different phases, depending on the setting of the phase shift assembly 9, with, for example:

  • the dipole 1a supplied with a phase +2Φ,
  • the dipole radiating element 1b supplied with a phase +1φ,
  • the central dipole radiating element 1c supplied with the phase φ=0,
  • the fourth dipole radiating element 1d supplied with the phase −1φ, and
  • the last dipole radiating element 1e supplied with the phase −2φ.


In consequence, the phase shift assembly 9′ therefore ensures a split of +2φ and −2φ, and the second phase shift assembly 9″ ensures a phase shift of +φ and −φ, for the respectively associated dipole radiating elements 1a, 1e and 1b, 1d, respectively. A correspondingly different setting for the phase shift assemblies 9′, 9″ can then be ensured by a mechanical actuating drive 17. In this example, a comparatively complex mechanical step-up transmission drive 17 is used to produce the different phase differences required for the respective individual radiating elements.


A phase shift assembly of this generic type is known from PATENT ABSTRACTS OF JAPAN Vol. 1998 No. 1, Jan. 30, 1998 (1998-01-30) & JP 09 246846 A (NTT IDO TSUSHINMO KK), Sep. 19, 1997 (1997-09-19). This prior publication covers two stripline segments which are in the form of circle segments and are arranged offset with respect to one another in the circumferential direction and at a different distance from a central center point. A tapping element can be moved about this center point, engaging with the respective stripline segment. The tapping element in this case comprises two radial elements. The two radial elements are offset with respect to one another with an angular separation in plan view, and are connected to one another at the center point, which lies on their pivoting axis.


Exemplary illustrative non-limiting implementations of the technology herein provide an improved phase shift assembly which has a simpler design and, particularly in the case of an antenna array using at least four radiating elements, allows an improvement to the control and setting of the phases of the individual radiating elements. In this case, power sharing, in particular in pairs, between at least four radiating elements is preferably intended to be possible at the same time.


Exemplary illustrative non-limiting implementations of the technology herein provide a phase shift assembly which is compact and, has a higher integration density. Furthermore, additional connection lines, solder points and transformation means for providing the power sharing are minimized. There is also no need for the step-up transmission system to produce and to set the different phase angles for the radiating elements.


Exemplary illustrative non-limiting implementations of the technology herein provide at least two stripline segments in the form of circle segments. They interact with a tapping element. The tapping element is connected to a feed point, and forms a moveable tap or coupling point in the overlapping area with the respective circular stripline segment. A common connection line, which extends as far as the outermost circle segment, leads from the common feed point to the individual circle segments.


As mentioned, the stripline segments may be in the form of circle segments. The stripline sections may, in general terms, also be provided arranged concentrically with respect to one another. Such arrangement may also include stripline sections which run in a straight line and are arranged parallel to one another (namely for the situation where the radius of the stripline sections which are in the form of circle segments becomes infinite).


One exemplary simple refinement comprises providing a tapping element which passes over a number of stripline segments in the form of circle segments, like a radially running pointer. Such arrangement hence forms a number of associated tapping points which are located one behind the other in individual stripline segments.


A type of bridge structure is also possible. Connection lines which run in the same direction are arranged one above the other when seen in a horizontal side view. They can be moved about a common pivoting axis, and are rigidly connected to form a common tapping element, which can be handled.


The feed to the common rotation point is preferably capacitive. The tapping point between the tapping element and the respective circular stripline segment is also capacitive.


Exemplary illustrative non-limiting implementations of the technology herein also allow transmitting power to be shared, for example, in such a manner that the power decreases or increases from the inner to the outer circular stripline segment or, if required, even allows the power to all the stripline segments to remain more or less constant.


Furthermore, it has been found to be advantageous for the radio-frequency phase shift assembly to be formed on a metallic base plate, which is preferably formed by the reflector of the antenna. In addition, it has been found to be advantageous for the phase shift assembly to be shielded by a metallic cover.


The distances between the circle segments may differ. The diameter of the stripline segments preferably increases by a constant factor from the inside to the outside. The distances between the circle segments may in this case preferably transmit 0.1 to about 1.0 times the transmitter RF wavelength.


One simple exemplary implementation of the phase shift assembly can also allow the circle segments and connection lines to be formed together with a cover as triplate lines.





BRIEF DESCRIPTION OF THE DRAWINGS

These and other exemplary illustrative non-limiting features and advantages will be better and more completely understood by referring to the following detailed description in conjunction with the drawings, of which:



FIG. 1 shows a schematic illustration of an exemplary prior art radio-frequency phase shift assembly for feeding five dipoles;



FIG. 2 shows a schematic plan view of an exemplary illustrative non-limiting implementation of a phase shift assembly for driving four radiating elements;



FIG. 3 shows a schematic section along the tapping element in FIG. 2, in order to explain the exemplary non-limiting capacitive coupling of the phase shift segment and of the center tap;



FIG. 4 shows a modified exemplary non-limiting implementation of a phase shift assembly having three circle segments;



FIG. 5 shows a modified exemplary implementation using two stripline sections which are not in the form of circle segments (which run in straight lines); and



FIGS. 6
a and 6b show a polar diagram of an antenna array with an adjustable electrical notch at 4°, and 10°, respectively.





DETAILED DESCRIPTION OF EXAMPLE NON-LIMITING IMPLEMENTATIONS

A first exemplary implementation of a radio-frequency phase shift assembly has stripline sections 21 offset with respect to one another as shown in FIG. 2. Stripline segments 21 are provided in the form of circle segments in the illustrated exemplary embodiment. An inner stripline segment 21a and an outer stripline segment 21b are arranged concentrically around a common center point in a plan view and through which a vertical pivoting axis 23 runs at right angles to the plane of the drawing.


A tapping element 25, which is designed such that it runs essentially radially in the plan view shown in FIG. 2, runs from the pivoting axis 23. In each case, tapping element 25 forms a coupled tapping section or tapping point 27 in the respective area in which it overlaps an associated stripline segment 21. Two tapping points 27a, 27b are provided, in this example which are offset in the longitudinal direction of the tapping element 25.


The feed line 13 passes from the feed input 5 to a center tap 29. In that region, a pivoting axis 23 for the tapping element 25 is located.


The tapping element 25 includes a first connection line 31a. Connection line 31a extends from the coupling section 33 in the overlapping area of the center tap 29 to the tapping point 27a on the inner stripline segment 21a. The region which projects as an extension beyond this tapping point 27a forms the next connection section or connection line 31b. Connection line 31b leads to the tapping point 27b which is formed in the region in which it overlaps the outer stripline segment 21b. The distance between the stripline segments 21a-21d may be for example 0.1 to 1.0 times the transmitted RF wavelength.


The entire RF phase shift assembly is designed with the four dipoles 1a, 1b, 1c, 1d which are shown in the exemplary embodiment in FIG. 2 jointly on a metallic base plate 35, which also provides the reflector 35 for the dipoles 1a, 1b, 1c, 1d. Stripline segment 21a (see also FIG. 3) includes ends 39a, 39a′ which connect to antenna elements 1c, 1b through connections 41c, 41b, 41a, respectively and stripline segment 21b (see also FIG. 3) includes ends 39b, 39b′ which connect to antenna elements 1c, 1b through connections 41d, 41a respectively.


In the horizontal cross-sectional illustration shown in FIG. 3, it can be seen that the coupling is capacitive not only at the center tap 29 but also at the tapping points 27a, 27b. In this example case, low-loss dielectrics 37 provide the capacitive coupling and, at the same time, provide the mechanical fixing both for the center tap 29 and for the tapping points 27a, 27b which are radially offset with respect to it.


The base section of the center tap 29 is provided, offset with respect to the reflector plate 35, above a dielectric conical section 37a which has a greater axial height. The coupling layer 33, through which, like the center tap 29, the pivoting axis 23 likewise passes, is located above this, separated by a relatively thin dielectric conical layer 37b.


The cross-sectional illustration in FIG. 3 also shows that the stripline segments 21a, 21b, which are in the form of circle segments, are likewise located at the same distance as the center tap 29 from the reflector plate 35, and are coupled to the tapping element 25 via the dielectric 37 that is formed there. The tapping element 25 is in this case a uniformly rigid lever, which can be moved about the pivoting axis 23. See description of FIG. 2 above for similarly labeled elements. In addition, it has been found to be advantageous for the phase shift assembly to be shielded by a metallic cover M.


Rotation of the tapping element 25 about the pivoting axis 23 now allows the phase to be set, with the appropriate phase offset from +2Φ to −2Φ, jointly for all the dipole radiating elements 1a, 1b, 1c, 1d. See FIG. 2.


Suitable selection of the characteristic impedances and suitable regions of the connections 31a and 31b between the corresponding tapping points 29 as well as tapping points 27a and 27b, respectively, now allows the power to be shared at the same time between the dipole radiating elements 1a and 1d, on the one hand, and the further pair of dipole radiating elements 1b and 1c. The dipole antennas 1a to 1d are connected via antenna lines 41 to each end 39a and 39b, respectively, of the stripline segments 21a, 21b, which are in the form of circle segments (see FIG. 2).


A modified exemplary implementation with a total of six dipole radiating elements 1a, 1b, 1c, 1d, 1e, If is shown in FIG. 4, allowing phase shifts from −3φ, −2φ, −φ0, +φ, +2φ, +3φ to be achieved in this case (similarly labeled elements as compared to FIG. 2 have similar functions). Furthermore, if required, it is possible to achieve power sharing, for example from outside to inside, which allows power steps of 0.5:0.7:1. Description of similarly labeled elements in FIG. 2 will not be repeated here.


In this exemplary embodiment, as in the previous exemplary embodiment, a central dipole radiating element or a central dipole radiating element group, as is shown in FIG. 1, may also be provided, which has a phase shift angle of 0° and is directly connected to the feed line input.



FIG. 5 shows two straight stripline sections 21a and 21b, which are offset with respect to one another and, in the illustrated exemplary implementation, are offset with respect to one another through 180° with respect to the pivoting axis 23 (similarly labeled elements as compared to FIG. 2 have similar functions). A conversion would be feasible to the extent that the stripline sections 21a and 21b, which are shown in FIG. 5, are arranged such that they run parallel to one another and run in straight lines, are arranged on the same side of the center tap 29 and, at the same time, are covered by a single tapping element 25 in the form of a pointer. Description of similarly labeled elements in FIG. 2 will not be repeated here.



FIGS. 6
a and 6b show the effect of a correspondingly designed antenna on the vertical polar diagram. A relatively small phase difference between the five dipoles which are shown schematically there results in a relatively small vertical depression angle (e.g., of 4° as depicted in FIG. 6a), and relatively large phase difference, set via the radio-frequency phase shifter group which has been explained, results in a relatively large vertical depression angle (e.g., of 10° as depicted in FIG. 6b).


While the technology herein has been described in connection with exemplary illustrative non-limiting implementations, the invention is not to be limited by the disclosure. The invention is intended to be defined by the claims and to cover all corresponding and equivalent arrangements whether or not specifically disclosed herein.

Claims
  • 1. A radio-frequency phase shift assembly for coupling to a feed line, comprising: at least first and second stripline sections which are arranged concentrically, said at least first and second stripline sections for coupling to at least two different pairs of antenna radiating elements driven with different phase angles (φ) at mutually offset tapping points, a tapping element pivotable about a pivoting axis, the tapping element having a first tapping section for said first stripline section and having a second tapping section for said second stripline section, said first and second tapping sections being respectively pivotable over the associated first and second stripline sections and being coupled thereto, at least first and second connection lines, the tapping element being connected to said feed line such that the feed line is electrically connected via the first and second connection lines to the first and second tapping sections associated with said first and second stripline sections, wherein the tapping element comprises a pointer element which rotates about the pivoting axis, and wherein the second connection line is disposed with respect to the second stripline section by extending the first connection line which leads to the first tapping section.
  • 2. The phase shift assembly as claimed in claim 1, wherein the at least first and second stripline sections have different impedance values.
  • 3. The phase shift assembly as claimed in claim 1, wherein the first and second connection lines comprise transformers which share power in a predefined manner between the tapping sections of the at least first and second stripline sections.
  • 4. The phase shift assembly as claimed in claim 1, wherein the tapping element comprises a radial point element originating from the pivoting axis.
  • 5. The phase shift assembly as claimed in claim 1, wherein the at least first and second stripline sections comprise an innermost stripline section and an outermost stripline section, respectively, and wherein the share of the power fed in via the feed line decreases from the innermost stripline section to the outermost stripline section.
  • 6. The phase shift assembly as claimed in claim 1, wherein the at least first and second stripline sections comprise an innermost stripline section and an outermost stripline section, the innermost and outermost stripline sections unequally sharing power fed in via the feed line.
  • 7. The phase shift assembly as claimed in claim 1, wherein the at least first and second stripline sections, are fed with virtually the same power.
  • 8. The phase shift assembly as claimed in claim 1, wherein at least one of the radius and diameter of the stripline sections increases by a constant factor.
  • 9. The phase shift assembly as claimed in claim 1, wherein the phase shift assembly operates at a predetermined RF wavelength, and the distances between the stripline sections are 0.1 to 1.0 times the predetermined RF wavelength.
  • 10. The phase shift assembly as claimed in claim 1, wherein the at least first and second tapping sections comprise capacitively coupled tapping sections each composed of flat strip conductors, and a dielectric disposed between said flat strip conductors.
  • 11. The phase shift assembly as claimed in claim 1, further including a center tap electrically connected to the feed line, a capacitive coupling being provided between the center tap electrically connected to the feed line and a coupling section, said coupling section being electrically connected to the tapping element, said capacitive coupling comprising a dielectric provided between the at least first and second stripline sections.
  • 12. The phase shift assembly as claimed in claim 1, further including a conductive, base plate antenna reflector, said at least first and second stripline sections and said tapping element being disposed on said reflector.
  • 13. The phase shift assembly as claimed in claim 1, further including a metallic cover shielding said phase shift assembly.
  • 14. The phase shift assembly as claimed in claim 1, further including a cover, and wherein the connection line and the at least first and second stripline sections, together with a cover defines a stripline.
  • 15. The phase shift assembly as claimed in claim 1, wherein the at least first and second stripline sections each have a defined characteristic impedance.
  • 16. The phase shift assembly as claimed in claim 1, further including a reflector, a dielectric, and a center tap for the tapping element that is separated from, and is held above, the reflector by a dielectric.
  • 17. The phase shift assembly as claimed in claim 1, wherein the at least first and second stripline sections are curved.
  • 18. The phase shift assembly as claimed in 17, wherein the at least first and second stripline sections have center points, the at least first and second stripline sections are in the form of circle segments, said at least first and second stripline section center points being arranged such that they run in the form of circle segments around a common center point.
  • 19. The phase shift assembly as claimed in claim 1, wherein the center points of the at least first and second stripline sections lie on the pivoting axis of the tapping element.
  • 20. The phase shift assembly as claimed in claim 1, wherein the center points of the at least first and second stripline sections and the center point of the pivoting axis are offset with respect to one another.
  • 21. The phase shift assembly as claimed in claim 1, wherein the at least first and second stripline sections have different thicknesses.
  • 22. An RF phase shifter comprising: plural arcuate stripline elements of different lengths; and a pivotable radial tapping element capacitively coupled to tap each of said plural arcuate stripline elements simultaneously, said radial tapping element rotating about a pivoting axis, said radial tapping element dividing power unequally between said stripline elements in a predefined manner while simultaneously adjusting phase angle substantially equally in each of said plural arcuate stripline elements.
  • 23. The phase shifter of claim 22 wherein the plural stripline elements each have first and second ends for connection to respective antenna radiating elements.
  • 24. A radio-frequency phase shift assembly coupled to a feedline, comprising: at least two stripline sections offset with respect to one another, at least two different pairs of antenna radiating elements coupled to the at least two stripline sections and driven with different phase angles (Φ) at mutually offset tapping points, a tapping element pivotable about a pivoting axis, the tapping element having a tapping section for each stripline section, the tapping sections being pivotable over the associated stripline section and being connected thereto, the tapping element connected to the feed line such that the feed line is electrically connected via a number of connection lines to the tapping sections which are associated with respective stripline sections, wherein the stripline sections are disposed in straight lines parallel to one another, the tapping element comprises a pointer element which rotates about the pivoting axis, and the respective connection line is disposed with respect to a next, further outward stripline section by extending an inward connection line which leads to a respective further inward tapping section.
  • 25. The phase shift assembly of claim 1 wherein the stripline sections each have 50 ohms of impedance.
Priority Claims (1)
Number Date Country Kind
199 38 862 Aug 1999 DE national
CROSS-REFERENCES TO RELATED APPLICATIONS

This application is related to applicants' co-pending application Ser. No. 10/240,317 filed Oct. 1, 2002.

PCT Information
Filing Document Filing Date Country Kind 371c Date
PCTEP00/07236 7/27/2000 WO 00 2/19/2002
Publishing Document Publishing Date Country Kind
WO0113459 2/22/2001 WO A
US Referenced Citations (103)
Number Name Date Kind
1764441 Hahnemann Jun 1930 A
1806755 Hansell May 1931 A
2245660 Feldman et al. Jun 1941 A
2247666 Potter Jul 1941 A
2248335 Burkhart Jul 1941 A
2272431 Rankin Feb 1942 A
2300576 Klein Nov 1942 A
2462881 Marchetti Mar 1949 A
2496920 Seeley Feb 1950 A
2535850 Hammond Dec 1950 A
2565334 Wingarden Aug 1951 A
2566897 Koenig Sep 1951 A
2583747 Potter Jan 1952 A
2594115 Berney Apr 1952 A
2597424 Znaidukas May 1952 A
2599048 Dicke Jun 1952 A
2605413 Alvarez Jul 1952 A
2642567 Kimball et al. Jun 1953 A
2648000 White Aug 1953 A
2668920 Barrett Feb 1954 A
2711527 Barrett Jun 1955 A
2736854 Will Feb 1956 A
2745994 Dicke et al. May 1956 A
2787169 Farr et al. Apr 1957 A
2789190 Statham Apr 1957 A
2794162 Lifsey May 1957 A
2797374 Atton et al. Jun 1957 A
2815501 Benson et al. Dec 1957 A
2825240 Gray Mar 1958 A
2830292 Young Apr 1958 A
2831169 Casal Apr 1958 A
2851620 Hausen Sep 1958 A
2861235 Chadowski et al. Nov 1958 A
2872631 Blauvelt et al. Feb 1959 A
2900154 Schweim Aug 1959 A
2922941 Hensler et al. Jan 1960 A
2939335 Braund et al. Jun 1960 A
3005985 Cohn et al. Oct 1961 A
3008140 Rose Nov 1961 A
3043998 Lunn et al. Jul 1962 A
3205419 Voigt Sep 1965 A
3248736 Bohar Apr 1966 A
3276018 Butler Sep 1966 A
3277481 Robin et al. Oct 1966 A
3316469 Dicke Apr 1967 A
3438035 Fling et al. Apr 1969 A
3491363 Young, Jr. Jan 1970 A
3508274 Kesler et al. Apr 1970 A
3527993 Ticknor Sep 1970 A
3728733 Robinson Apr 1973 A
3826964 Byrne Jul 1974 A
3864689 Young Feb 1975 A
3886559 Lanson et al. May 1975 A
3886560 Mortensen et al. May 1975 A
4077000 Grubbs Feb 1978 A
4101902 Trigon Jul 1978 A
4163235 Schultz Jul 1979 A
4263539 Barton Apr 1981 A
4301397 Journey Nov 1981 A
4314250 Hanell et al. Feb 1982 A
4316195 Steffek et al. Feb 1982 A
4335388 Scott et al. Jun 1982 A
4413263 Amitay et al. Nov 1983 A
4460897 Gans Jul 1984 A
4467328 Hacker Aug 1984 A
4496890 Wurdack et al. Jan 1985 A
4542326 Hornback Sep 1985 A
4543583 Wurdack Sep 1985 A
4617572 Hugo Oct 1986 A
4694773 Sparkes et al. Sep 1987 A
4796032 Sakurai et al. Jan 1989 A
4862179 Yamada Aug 1989 A
4882587 Vodopia Nov 1989 A
5012256 Maddocks Apr 1991 A
5021798 Ubhayakar Jun 1991 A
5038148 Aoki et al. Aug 1991 A
5077560 Horton et al. Dec 1991 A
5084708 Champeau et al. Jan 1992 A
5093923 Leslie Mar 1992 A
5099247 Basile et al. Mar 1992 A
5151704 Gunmar et al. Sep 1992 A
5151706 Roederer et al. Sep 1992 A
5175556 Berkowitz Dec 1992 A
5241319 Shimizu Aug 1993 A
5272477 Tashima et al. Dec 1993 A
5281975 Hugo Jan 1994 A
5300935 Yu Apr 1994 A
5303240 Borras et al. Apr 1994 A
5339083 Inami Aug 1994 A
5504466 Chan-Son-Lint et al. Apr 1996 A
5504937 Kangas Apr 1996 A
5539413 Farrell et al. Jul 1996 A
5572219 Silverstein et al. Nov 1996 A
5596329 Searle et al. Jan 1997 A
5917455 Huynh et al. Jun 1999 A
6239744 Singer et al. May 2001 B1
6538619 Heinz et al. Mar 2003 B2
6567051 Heinz et al. May 2003 B2
6590546 Heinz et al. Jul 2003 B2
6600457 Heinz et al. Jul 2003 B2
20020113750 Heinz et al. Aug 2002 A1
20020126059 Zimmerman et al. Sep 2002 A1
20030048230 Heinz et al. Mar 2003 A1
Foreign Referenced Citations (119)
Number Date Country
B-4162593 Jun 1993 AU
B 3874693 Jul 1993 AU
8005794 May 1995 AU
B-3622695 May 1996 AU
2 75 290 Aug 1951 CH
584 383 Sep 1933 DE
827 085 Jan 1952 DE
907 193 Mar 1954 DE
908 748 Apr 1954 DE
945 261 Jul 1956 DE
1 768 660 Jun 1958 DE
1 033 280 Jul 1958 DE
1 826 656 Feb 1961 DE
1 133 775 Jul 1962 DE
1 293 251 Apr 1964 DE
2 249 806 Apr 1973 DE
2 207 894 Aug 1973 DE
2 359 846 Jun 1974 DE
26 25 062 Dec 1977 DE
26 31 273 Jan 1978 DE
24 58 477 May 1978 DE
29 21 712 Dec 1979 DE
29 38 370 Apr 1980 DE
28 55 623 Jul 1980 DE
29 51 875 Jul 1980 DE
31 34 219 Mar 1983 DE
34 25 351 Jan 1985 DE
35 22 404 Jan 1987 DE
38 31 994 A 1 Mar 1990 DE
38 39 945 May 1990 DE
39 02 739 Aug 1990 DE
39 34 716 Apr 1991 DE
39 37 294 May 1991 DE
G 91 08 641.8 Oct 1991 DE
31 02 110 Aug 1992 DE
42 01 933 Jul 1993 DE
42 42 803 Jul 1993 DE
0 156 294 Oct 1985 EP
0 466 080 Jan 1992 EP
0 575 808 Dec 1993 EP
0 579 407 Jan 1994 EP
0 600 715 Jun 1994 EP
0 616 741 Sep 1994 EP
0 618 639 Oct 1994 EP
0 639 035 Feb 1995 EP
0 682 820 Nov 1995 EP
789 938 Aug 1997 EP
789 938 Apr 1999 EP
1 239 534 Sep 2002 EP
1 239 535 Sep 2002 EP
1 239 536 Sep 2002 EP
1 239 538 Sep 2002 EP
959833 Apr 1950 FR
70.39506 Aug 1971 FR
2 603 426 Mar 1988 FR
1 044 789 Nov 1963 GB
1 029 865 May 1966 GB
1 175 365 Dec 1969 GB
1 271 346 Apr 1972 GB
1 314 693 Apr 1973 GB
1 470 884 Apr 1977 GB
1 505 074 Mar 1978 GB
2 034 525 Jun 1980 GB
1 577 939 Oct 1980 GB
2 044 567 Oct 1980 GB
2 161 026 Jan 1986 GB
2 262 009 Jun 1993 GB
57-184303 Nov 1982 JP
63-6906 Jan 1988 JP
1-140802 Jun 1989 JP
02 132 926 May 1990 JP
7-79476 Mar 1991 JP
03 057 305 Mar 1991 JP
3-85906 Apr 1991 JP
3-151701 Jun 1991 JP
4-196904 Jul 1992 JP
5-37222 Feb 1993 JP
3-279795 May 1993 JP
5-121902 May 1993 JP
5-121915 May 1993 JP
5121915 May 1993 JP
6-125216 May 1994 JP
6-204738 Jul 1994 JP
6-232621 Aug 1994 JP
6-268429 Sep 1994 JP
5-110283 Nov 1994 JP
5-110284 Nov 1994 JP
6-326501 Nov 1994 JP
06-326 501 Nov 1994 JP
06-326 502 Nov 1994 JP
06 334 428 Dec 1994 JP
6-338717 Dec 1994 JP
7-170121 Jul 1995 JP
07-245579 Sep 1995 JP
7-318627 Dec 1995 JP
8-32341 Feb 1996 JP
8-172388 Jul 1996 JP
9-246846 Sep 1997 JP
10-508730 Aug 1998 JP
204522 Jan 1986 NZ
208213 Oct 1987 NZ
219746 Aug 1989 NZ
220276 Sep 1989 NZ
235010 Dec 1993 NZ
248075 Mar 1996 NZ
274931 Oct 1996 NZ
293722 May 1997 NZ
334357 Apr 1999 NZ
333811 Apr 2000 NZ
333634 Oct 2000 NZ
1 337 951 Sep 1987 SU
WO 9014563 Nov 1990 WO
WO 9216061 Sep 1992 WO
WO 9312587 Jun 1993 WO
WO 9409568 Apr 1994 WO
9637009 Nov 1996 WO
9637922 Nov 1996 WO
9821779 May 1998 WO
WO 02061877 Aug 2002 WO