This application is a 371 of PCT/SE2005/002030 dated Dec. 23, 2005.
The present invention relates to an array antenna for transmitting and receiving electromagnetic radiation and more particularly to an array antenna with an enhanced ability of steering the antenna lobe, especially the antenna lobe direction.
Array antennas and particularly phased controlled array antennas have become increasingly attractive, not only for military applications but also for civil and commercial applications. Array antennas can be advantageously utilized in radar systems, in radio telescopes or in so-called base stations in a wireless telecommunication network etc. One of the most favourable properties of an array antenna and particularly a phased controlled array antenna is the increased ability to dynamically and very quickly re-forming and/or re-directing the antenna lobe.
In particular, this can be utilized to avoid transmitting and/or receiving interference signals to and from neighbouring transmitters and/or receivers. In many cases the antenna lobe can be formed and/or directed to avoid receiving and/or transmitting such disturbances. In radar systems this ability can e.g. be used to avoid hostile jamming sources. In cellular telecommunication system or similar this ability can e.g. be used to enhance the utilization of the available frequency spectrum, e.g. the frequency spectrum in a GSM-system, a CDMA-system, a WCDMA-system or other similar radio communication systems. This is only examples of applications. There is a vast spectrum of different applications, as is well-known.
The ability to dynamically and very quickly re-forming and/or re-directing the antenna lobe is also advantageous in that the antenna lobe can be directed to transmit and/or receive electromagnetic radiation to and/or from a small geographical area, which increases the energy efficiency of the antenna system. These and other advantages provided by array antennas and particularly by phased controlled array antennas are well-known in the art of array antennas and they need no further explanation.
An array antenna is basically a spatially extended collection of several substantially similar antenna elements. The expression “spatially extended” implies that each element has at least one neighbouring element that is placed at a close distance so as to avoid emission of electromagnetic radiation in ambiguous directions. The expression “similar” implies that preferably all elements have the same polar radiation patterns, orientated in the same direction in 3-d space. However, the elements do not have to be spaced on a regular grid, neither do they have to have the same terminal voltages, but it is assumed that they are all fed with the same frequency and that one can define a fixed amplitude and phase angle for the drive signal of each element.
By adjusting the relative phases of the respective signals feeding the antenna elements in an array antenna the effective radiation pattern (the antenna lobe) of the antenna can be reinforced in a desired direction and suppressed in undesired directions. The relative amplitudes of, and constructive and destructive interference effects among, the signals radiated by the individual antenna elements determine the effective radiation pattern of the array antenna. An ordinary array antenna can be used to accomplish a fixed radiation pattern (fixed antenna lobe), whereas a more sophisticated phase controlled array antenna can be used to rapidly scan the radiation pattern (the antenna lobe) in azimuth and/or elevation.
However, depending on the individual antenna elements chosen for the array antenna in question there is formally at least one direction in which the antenna lobe cannot be readily directed, i.e. there is at least one null point.
The individual antenna elements in an array antenna can e.g. be the well-known dipole 10 or similar, as schematically illustrated in
The individual antenna elements in an array antenna may also be the well-known monopole 20 or similar, as schematically illustrated in
The attention is now directed to a first exemplifying array antenna arrangement, illustrated in
The type of array antenna schematically illustrated in
However, as the phase increment ψ increases so that the scan direction Φ of the main lobe 35 approaches 0°, i.e. approaches the horizontal direction in which the radiating elements 31aa-31cb extend, the impedance of the dipoles 30a-30c in the array antenna 30 changes in such a way that the matching deteriorates. This implies that an array antenna 30 comprising a spatially extended collection of dipoles 30a-30c or similar has a reduced ability to transmit electromagnetic radiation in directions that approaches the direction in which the radiating elements 31aa-31cb extend. In other words, there is substantially no radiation along the axis DP2, i.e. from the short ends of the radiating elements 31aa-31cb, which is consistent with the findings in connection with the single dipole 10 described above. Naturally, the radiation pattern as now described is also valid for reception.
The attention is now directed to a second exemplifying array antenna arrangement, illustrated in
The type of array antenna 40 schematically illustrated in
However, as the phase increment ψ increases so that the scan direction Φ of the main lobe 45 or 45′ approaches 90°, i.e. approaches the vertical direction in which the radiating elements 41a-41f extend, the impedance of the antenna elements 40a-40f in the array antenna 40 changes in such a way that the matching deteriorates. This implies that an array antenna 40 comprising a spatially extended collection of monopoles 40a-40f or similar has a reduced ability to transmit electromagnetic radiation in directions that approaches the vertical direction in which the radiating elements 41a-41f extend. In other words, there is substantially no radiation along the axes MPa-MPf of the radiating elements 41a-41f, i.e. along the normal to the ground plane, which is consistent with the findings in connection with the single monopole 20 described above. Naturally, the radiation pattern as now described is also valid for reception.
To summarize, the well-known dipole 10 and the well-known monopole 20 and variations thereof are frequently used as single antenna elements in array antennas, e.g. as in the broadside antenna 30 in
Consequently there is a need for an improved array antenna and particularly an array antenna with improved ability to direct the antenna lobe, especially so as to reduce possible null points.
The invention provides an improved array antenna, an array antenna system and an improved method of utilizing the improved array antenna and array antenna system.
This is accomplished by an array antenna comprising a region of reference potential, e.g. a ground plane, and a spatially extended collection of at least two antenna elements capable of being at least partly balanced driven and at least partly unbalanced driven. The antenna elements have a first radiating element connected to a first port and a second radiating element connected to a second port. In other words, the antenna element has at least two ports. The radiating elements are arranged substantially adjacent and parallel to each other so as to extend at least a first distance approximately perpendicularly from said region of reference potential. The antenna element is further comprising a radiating arrangement connected to said first and said second radiating elements so as to extend at least a second distance above and approximately parallel to said region of ground reference.
An embodiment of the invention comprises an array antenna wherein said radiating arrangement comprises a substantially continuous radiating element connected to said first radiating element and to said second radiating element. The continuous radiating element may e.g. be a loop element.
Another embodiment of the invention comprises an array antenna wherein said radiating arrangement comprises a third radiating element connected to said first radiating element and a fourth radiating element connected to said second radiating element.
A further embodiment of the invention comprises an array antenna wherein said third and fourth radiating element is chosen from a group of elements comprising: substantially straight thread shaped or cylindrically shaped elements; curved substantially loop shaped elements; substantially flat plate elements. The expression “flat plate elements” is intended to also comprise plate elements that are slightly curved.
The invention is also accomplished by an antenna system comprising an array antenna according to the above wherein the first and second ports of the antenna elements are connected to a feeding arrangement. The feeding arrangement is arranged so as to varying the phase difference φ between: a first signal I1 communicated between the first port and the feeding arrangement; and a second signal I2 communicated between the second port and the feeding arrangement.
An embodiment of the invention comprises a feeding arrangement comprising a device, e.g. a balun. The device is arranged so that a signal I0 (e.g. I0ei(ψn)) communicated with a first terminal SUM of the device is divided with a first substantially fixed phase difference φ1 (e.g. substantially 0°) between a first signal I1 and a second signal I2 communicated between the feeding arrangement and the antenna element. The device is further arranged so that a signal I0 (e.g. I0ei(ψn)) communicated with a second terminal DIFF of said device is divided with a second substantially fixed phase difference φ2 (e.g. substantially 180°) between a first signal I1 and a second signal I2 communicated between the feeding arrangement and the antenna element.
Said device may in an further embodiment have the first device terminal SUM and the second device terminal DIFF connected to a switch, which in a first position enables a signal I0 to be communicated with the first device terminal SUM, and in a second position enables a signal I0 to be communicated with the second device terminal DIFF.
Another embodiment of the invention comprises a feeding arrangement comprising a distribution arrangement (e.g. a combiner/divider) connected to said first and said second port and to a feeding line. The distribution arrangement is arranged so as to combine signals I1, I2 received from said ports into said feeding line, and to divide a signal I0 (e.g. I0ei(ψn)) received from said feeding line between said ports. The feeding arrangement is also comprising at least one phase shifter connected between at least one of said ports and said distribution arrangement so as to varying the phase φ of a signal communicated between that port and the distribution arrangement.
The invention is further accomplished by a method for transmitting or receiving by means of an array antenna comprising: a region of reference potential and a spatially extended collection of at least two antenna elements capable of being at least partly balanced driven and at least partly unbalanced driven. The antenna elements have a first radiating element connected to a first port and a second radiating element connected to a second port. In other words, the antenna element has at least two ports. The radiating elements are arranged substantially adjacent and parallel to each other so as to extend at least a first distance approximately perpendicularly from said region of reference potential. The antenna element is further comprising a radiating arrangement connected to said first and said second radiating elements so as to extend at least a second distance above and approximately parallel to said region of ground reference. The method includes the steps of transmitting or receiving electromagnetic radiation by the antenna elements in a variable direction by varying the phase difference φ between a first signal I1 communicated with the first port of the antenna element and a second signal I2 communicated with the second port.
A method according to an embodiment of the invention accomplishes the phase difference φ by using a feeding arrangement connected to the first and second port of each antenna element. The feeding arrangement is arranged to varying the phase difference φ between: a first signal I1 communicated between said first port and said feeding arrangement; and a second signal I2 communicated between said second port and said feeding arrangement.
An embodiment of the method uses a feeding arrangement comprising a device arranged so that a signal I0 (e.g. I0ei(ψn)) communicated with a first terminal SUM of the device is divided with a first substantially fixed phase difference φ (e.g. substantially 0°) between said first signal I1 and said second signal I2. The feeding device is further arranged so that a signal I0 (e.g. I0ei(ψn)) communicated with a second terminal DIFF of the device is divided with a second substantially fixed phase difference (φ (e.g. substantially 180°) between said first signal I1 and said second signal I2.
Said device may in an embodiment have the first device terminal SUM and the second device terminal DIFF connected to a switch, which is operated so that in a first position the signal I0 is communicated with the first device terminal SUM, and so that in a second position the signal I0 is communicated with the second device terminal DIFF.
Another embodiment of the method uses a feeding arrangement comprising a distribution arrangement (e.g. a combiner/divider) is connected to said first and second ports and to a feeding line; and being arranged so as to combine signals I1, I2 received from said ports into said feeding line, and to divide a signal I0 (e.g. I0ei(ψn)) received from said feeding line between said ports. The feeding arrangement is also comprising at least one phase shifter connected between at least one of said ports and said distribution arrangement so as to varying the phase φ of a signal communicated between that port and the distribution arrangement.
These and other aspects of the present invention will be apparent from the following description of embodiment(s) of the invention.
a is a schematic illustration of a side view of a well-known dipole 10.
b is a schematic illustration of a cross-section of a radiation pattern from the dipole in
c is a schematic illustration of a top view of the radiation pattern in
d is a schematic illustration of a perspective view of the radiation pattern in
a is a schematic illustration of a side view of a well-known monopole 20.
b is a schematic illustration of a cross-section of the radiation pattern from the monopole 20 in
c is a schematic illustration of a top-view of the radiation pattern in
d is a schematic illustration of a perspective view of the radiation pattern in
a is a schematic illustration of a top view of an exemplifying broadside array antenna 30.
b is a schematic illustration of a side view of the array antenna 30 in
a is a schematic illustration of a top view of an exemplifying end-fire array antenna 40.
b is a schematic illustration of a side view of the array antenna 40 in
a is a schematic illustration of a top view of an array antenna 50 according to a preferred embodiment of the present invention.
b is a schematic illustration of a side view of the array antenna 50 in
a is a schematic illustration of the array antenna 50 in
b is a schematic illustration of the array antenna 50 in
a is a schematic illustration of a loop antenna element.
b is a schematic illustration of a dipole having a parasitic or resonator element.
c is a schematic illustration of a dipole having tilted dipole arms.
d is a schematic illustration of a double probe fed bunny-ear antenna element.
e is a schematic illustration of a double probe fed patch antenna element having a parasitic or resonator element.
f is schematic illustration of a double polarized embodiment of a dipole antenna element.
g is schematic illustration of a double polarized embodiment of a dipole antenna element known as the four-square antenna element.
h is a schematic illustration of a patch element array antenna with a corner feeding arrangement.
The present invention will now be described in more detail with reference to exemplifying embodiments thereof. Other embodiments of the invention are clearly conceivable and the invention is by no means limited to the exemplifying array antennas and feeding arrangements described below. It should also be added that the same or similar reference numbers used in the present text indicate the same or similar objects and/or functions throughout the whole text.
The Array Antenna
In particular:
The radiating elements 51aa-51cb of the dipoles 50a-50c are preferably shaped as elongated threads, cylinders or rectangles extending a distance E1 of roughly ¼ (λ/4) of the utilized wavelength along the axis DP3. In other words, the dipoles 50a-50c are arranged in a similar way as the dipoles 30a-30c in the array antenna 30 described above with reference to
It is preferred that the above mentioned ground plane 53 is substantially flat and that the horizontal elements 51aa-51cb extend substantially in parallel to the ground plane 53, i.e. it is preferred that the ground plane 53 is substantially parallel to the axis DP3 along which the horizontal elements 51aa-51cb extend. However, other embodiments of the invention may have a ground plane 53 or a region of ground potential that is curved or assumes other shapes that wholly or partly depart from a flat shape. In some embodiments the ground plane 53 or region of ground potential may e.g. be formed by a grid of conductors or similar or even by a grid of point shaped ground regions.
Regarding the vertical elements 54aa-54cb illustrated in
The feeding lines 52aa, 52ab connected to the feeding ends 57aa, 57ab respectively forms two ports, and feeding lines 52ba, 52bb connected to the feeding ends 57ba, 57bb respectively form another two ports, whereas the feeding lines 52ca, 52cb connected to the feeding ends 57ca, 57cb respectively forms still another two ports.
In addition, the vertical elements 54aa-54cb in
As can be seen in
It is preferred that the schematically illustrated feeding lines 52aa-52cb in
From the above it can be concluded that the substantially horizontal radiating elements 51aa-51cb of the array antenna 50 in
It can also be concluded from the above that the substantially vertical elements 54aa-54cb of the array antenna 50 in
However, before we proceed it should be emphasised that the invention is not in any way limited to a single row of three collinear dipoles 50a-50c as shown in
Scanning the Main Lobe
As previously explained in connection with the single dipole 10 in
In accordance therewith, the differential mode for the three dipole antenna elements 30a, 30b, 30c of the array antenna 30—as described above with reference to FIGS. 3A-3B—has been illustrated by a first current I+ fed to a first feeding line 32aa, 32ba, 32ca of the dipoles 30a, 30b, 30c, and a second current I− fed to a second feeding line 32ba, 32bb, 32cb of the dipoles 30a, 30b, 30c. The currents I+, I− have opposite suffixes to indicate that they are out of phase by 180°, i.e. that the dipoles 30a, 30b, 30c operate according to a differential mode in a well known manner.
As previously established, the three dipoles 30a, 30b 30c of the array antenna 30 in
Hence the dipoles 50a-50c can be excited by supplying the dipoles 50a, 50b, 50c with:
The direction of maximum radiation (the main lobe) of the dipoles 50a-50c in a differential or balanced mode is substantially perpendicular to the axis DP3 along which the radiating elements 51aa-51cb extend. Hence, the main lobe is therefore also substantially perpendicular to the ground plane 53, as explained above. The main lobe has been indicated in
As previously explained in connection with the array antenna 30, the main lobe 55 of the antenna 50 can be scanned by prescribing a phase increment ψ between the antenna elements 50a-50c of the antenna 50. However, if the phase increment ψ increases so that the direction Φ of the main lobe approaches the direction in which the horizontal radiating elements 51aa-51cb extend in
As a contrast, the end-fire array antenna 40 described above with reference to
Hence, it would be advantageous if the ability of the broadside array antenna 30 to transmit electromagnetic radiation in a vertical plane, as described above with reference to
To this end, a similar function as the one of the monopoles in the end-fire array antenna 40 described above can be accomplished in the array antenna 50. In particular, this can be accomplished by utilizing the grouped pairs of elements 54aa, 54ab; 54ba, 54bb; 54ca, 54cb arranged substantially along the line L2 and extending in a substantially vertical direction from the ground plane 53.
Hence, the vertical elements 54aa-54cb of the dipoles 50a-50c in
In the sum-mode the radiation from the opposite pairs of horizontal elements 51aa, 51ab; 51ba, 51bb; 51ca, 51cb will substantially cancel each other, whereas each pair of adjacently arranged vertical elements 54aa, 54ab; 54ba, 54bb; 54ca, 54cb will essentially function as a single quarter-wave monopole, i.e. elements 51aa, 51ab will function as a first monopole, the elements 51ba, 51bb will function as a second monopole and the elements 51ca, 51cb will function as a third monopole in the sum-mode. Naturally, this presupposes that the vertical elements 54aa, 54ab; 54ba, 54bb; 54ca, 54cb in a pair are arranged close enough to be able to cooperate as a single monopole or similar and to allow the horizontal elements 51aa, 51ab; 51ba, 51bb; 51ca, 51cb in the pair to cooperate as a dipole or similar.
In addition, the radiation from the vertical elements of a pair 54aa, 54ab; 54ba, 54bb; 54ca, 54cb do essentially cancel each other when the dipoles 50a-50c are excited in a differential mode, since the currents in the elements of a pair have opposite directions in the differential mode.
From the above it follows that an excitation of the vertical elements 52aa-52cb of the antenna elements 50a-50c in a sum-mode enables the main antenna lobe 55 of the array antenna 50 to be pointed in a direction Φ that approaches or even coincides with the horizontal direction in which the radiating elements 51aa-51cb of the dipoles 50a-50c extend, i.e. substantially as the end-fire antenna 40 described above with reference to
In other words, the substantially horizontal elements 51aa-51cb of the array antenna 50 can be fed in a differential mode and utilized for radiating electromagnetic radiation in a similar way as a broadside dipole array antenna (e.g. as the broadside array antenna 30 in
The point of optimum switch-over between the differential mode and the sum-mode depend i.a. on the E-plane pattern cut for a single polarised antenna element.
The switch-over can be substantially continuous, e.g. a continuous decreasing of the 180° phase difference between the two currents I+, I− fed to the dipoles 50a-50c in a differential mode so as to approach and/or target the 0° phase difference between the currents I+, I+ fed to the dipoles 50a-50c in a sum-mode and back again.
The switch-over can also be a more or less two-way switching, e.g. a switch-over that simply toggles or switches between the 180° phase difference between the currents I+, I− fed to the dipoles 50a-50c in a differential mode and the 0° phase difference between currents I+, I+ fed to the dipoles 50a-50c in a sum-mode.
In particular, a substantially continuous or step-less switch-over between a differential fed (I+, I−) and a sum fed (I+, I+) enables the array antenna 50 to transmit electromagnetic radiation in substantially any direction Φ along a half circle extending substantially perpendicularly from the ground plane 53 in the plane that is defined by the axis DP3 and the line L2, i.e. in the direction of the arrow 55 in
The point of optimum switch-over between the differential mode and the sum-mode, or the optimum mix of a differential mode and a sum-mode—i.e. the optimum phase difference between the two currents fed to a dipole 50a-50c—can e.g. be empirically determined by measuring the antenna pattern, as is well-known in the art. A measuring may e.g. be achieved by exciting the dipoles 50a-50c as described above, and prescribing a phase difference φ between the two feeding currents that is step-wise varied in a plurality of small steps from 0° to 180° (i.e. altering the excitation from a sum-mode 0° to a differential mode 180° by several small steps) and continuously measuring the electromagnetic radiation transmitted in different directions by the array antenna 50.
Naturally, the radiating (transmitting) ability as now described is equally valid for receiving, i.e. a suitably switching between a differential reception (I+,I−) and a sum reception (I+, I+) enables the array antenna 50 to receive electromagnetic radiation in substantially any direction Φ along a half circle extending substantially perpendicularly from the ground plane 53 in the plane that is defined by the axis DP3 and the line L2, i.e. in the direction of the arrow 55 in
To achieve a suitable switch-over between a differential mode (I+, I−) and a sum-mode (I+, I+) it is preferred that the dipoles 50a-50c of the array antenna 50 is connected to a device that feeds the dipole antenna elements 50a-50c with an Idiff=(I1−I2)/2 and an Isum=(I1+I2)/2 in a proportion that enhances or maximizes the power conversion to and from the dipole antenna elements 50a-50c of the array antenna 50. Preferred embodiment of such feeding devices will now be described with reference to
The dipole 50a is the same as the one illustrated in
As can be seen in
The feeding device 60a of the feeding arrangement 600a is preferably implemented by means of a balun or similar. A balun is a device that is particularly designed to convert between balanced (differential mode) and unbalanced (sum-mode) signals, as is well-known in the art. The balun 60a is typically implemented by means of a small isolation transformer, with the earth ground or chassis ground left floating or unconnected on the balanced side in a well-known manner. The balun 60a may also be implemented by means of e.g. a so-called Magic-T or T-Junction, which is a common and well-known component in the art. However, the invention is not limited to have the balun 60a implemented by means of an isolation transformer, a Magic-T or a T-Junction. On the contrary, the balun may be implemented by means of any other suitable device with the same or similar function as said transformer, Magic-T or T-Junction.
The function of the balun feeding device 60a in
It follows that the antenna element 50a can transmit electromagnetic radiation in a sum-mode (unbalanced or end-fire mode) or in a differential mode (balanced or broadside mode) as required by toggling the two-way switch 64aa depending on the direction Φ in which the antenna lobe 55 of the array antenna 50 is intended to radiate.
The expressions below may clarify the function of a feeding device (60a, 60b, 60c . . . 60n).
If the input signal to the DIFF terminal is zero and the input signal to the SUM terminal is ISUM=I0ei(ψn), wherein ψn represents the phase increment for the antenna element, in question, then:
In1=I0′ei(ψn) [1]
In2=I0′ei(ψn) [2]
wherein I0′ is the current I0 adjusted for possible losses etc in the feeding device (60a, 60b, 60c . . . 60n) in question, and wherein In1 is the current I1 for the antenna element in question, and wherein In2 is the current I2 for the antenna element in question.
If the input signal to the SUM terminal is zero and the input signal to the DIFF terminal is IDIFF=I0ei(ψn), wherein ψn represents the phase increment for the antenna element in question, then:
In1=I0′ei(ψn+π/2) [3]
In2=I0′ei(ψn−π/2) [4]
wherein I0′ is the current I0 adjusted for possible losses etc in the feeding device (60a, 60b, 60c . . . 60n) in question, and wherein In1 is the current I1 for the antenna element in question, and wherein In2 is the current I2 for the antenna element in question.
Naturally, the radiating (transmitting) ability as now described is equally valid for receiving, i.e. the antenna element 50a can receive electromagnetic radiation in a sum-mode (unbalanced or end-fire mode) or in a differential mode (balanced or broadside mode) as required depending on the direction Φ from which the antenna lobe 55 of the array antenna 50 is intended to receive.
However, a balun feeding device 60a or similar as described above is not necessarily required in certain embodiments of a feeding arrangement according to the present invention. This is illustrated In
If the input signal to the power divider/combiner 67a in
In1=I0′ei(ψn+φ)=I0′ei(ψn+φ/2)·ei(φ/2) [5]
In2=I0′ei(ψn)=I0′ei(ψn+φ/2)·e−i(φ/2) [6]
wherein I0′ is the current I0 adjusted for possible losses etc in the divider/combiner 67a, and wherein φ represents the phase shift added by the phase shifter 65a, and wherein In1 is the current I1 for the antenna element in question, and wherein In2 is the current I2 for the antenna element in question.
It is clear from equations 5 and 6 that the phase shifter 65a in the feeding arrangement 620a in
The invention has now been described by means of exemplifying embodiments. However, it should be emphasized that the invention is by no means limited to the embodiments now described. On the contrary, the invention is intended to comprise all embodiments covered by the scope of the appended claims. For example, the invention is by no means limited to a single row of three collinear dipoles 50a-50c as shown in
In addition, the antenna elements must not necessarily be a traditional dipole.
In one embodiment the antenna element may e.g. be a loop antenna as the one schematically illustrated in
Another embodiment of the invention may utilize a dipole antenna element having a parasitic or resonator element extending in parallel to the horizontal radiating elements, as schematically illustrated in
Moreover, the antenna element in an embodiment of the invention may be a dipole that has tilted radiating elements e.g. as the V-shaped antenna element schematically illustrated in
In addition, the antenna element in an embodiment of the invention may be a so-called Bunny-Ear antenna, e.g. as the bunny ear antenna schematically illustrated in
Furthermore, some embodiments of the invention may utilize an antenna element in the form of a patch antenna, as schematically illustrated in
The antenna element in an embodiment of the invention may also be a double polarized antenna element, e.g. as the double polarized antenna element shown in
Any of the antenna elements discussed above can be combined with one or several dielectric layers above and/or below the element such as to modify the SUM and DIFF mode scan patterns.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/SE2005/002030 | 12/23/2005 | WO | 00 | 6/17/2008 |
Publishing Document | Publishing Date | Country | Kind |
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WO2007/073266 | 6/28/2007 | WO | A |
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Number | Date | Country | |
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20090051619 A1 | Feb 2009 | US |