Antenna structure for providing a uniform field
First Claim
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1. An apparatus for powering a transponder within a volume of space having width, height and depth directions, said apparatus being adapted to power the transponder at a substantially uniform level of power irrespective of the transponder'"'"'s orientation and position within the volume of space, said apparatus comprising:
- first, second and third powering coils, each coil being adapted to radiate a respective powering field for reception by the transponder, each coil being further adapted to radiate the powering field respectively in one of the width, height and depth directions in said volume of space, means for applying current to each coil, said current applying means being adapted to excite each respective coil in a predetermined manner, wherein;
said means for applying current sinusoidally exciting any two of the coils at any one time by providing excitation in the form of sine and cosine signals of the same frequency, the sine signal to one of the coils, the cosine signal to another of the coils while the unexcited coil is left idle,said excitation being provided in a sequential and periodic manner in that said excitation is removed from the coil winding excited for the longest time and is applied to the previously unexcited coil, andfurther wherein each signal exciting the coils is unmodulated.
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Abstract
An apparatus for radiating a magnetic field of substantially uniform magnitude along an axis in a volume of space having width, height and depth directions includes a first coil arranged in the width and height directions and has a first imaginary point as its center. A second coil is arranged in the width and height directions with a second imaginary point at its center and is spaced from the first coil. The first and second coils each have a side and a predetermined configuration and are positioned adjacent each other, in opposite and facing configuration. The first and second coils are spaced by a distance in the range of 2.0 to 0.1 times the length of one of the coil sides. The first and second coils provide in response to a current applied to the coils, a substantially uniform field within the volume of space being located between first and second imaginary points and extending in the depth direction. Also an antenna structure for providing a three dimensional powering field of substantially constant magnitude is disclosed and includes three orthogonal coil pairs.
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Citations
27 Claims
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1. An apparatus for powering a transponder within a volume of space having width, height and depth directions, said apparatus being adapted to power the transponder at a substantially uniform level of power irrespective of the transponder'"'"'s orientation and position within the volume of space, said apparatus comprising:
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first, second and third powering coils, each coil being adapted to radiate a respective powering field for reception by the transponder, each coil being further adapted to radiate the powering field respectively in one of the width, height and depth directions in said volume of space, means for applying current to each coil, said current applying means being adapted to excite each respective coil in a predetermined manner, wherein; said means for applying current sinusoidally exciting any two of the coils at any one time by providing excitation in the form of sine and cosine signals of the same frequency, the sine signal to one of the coils, the cosine signal to another of the coils while the unexcited coil is left idle, said excitation being provided in a sequential and periodic manner in that said excitation is removed from the coil winding excited for the longest time and is applied to the previously unexcited coil, and further wherein each signal exciting the coils is unmodulated. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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2. An apparatus for powering a transponder within a volume of space having width, height and depth directions, said apparatus being adapted to power the transponder at a substantially uniform level of power irrespective of the transponder'"'"'s orientation and position within the volume of space, said apparatus comprising:
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first, second and third powering coils, each coil being adapted to radiate a respective powering field for reception by the transponder, each coil being further adapted to radiate the powering field respectively in one of the width, height and depth directions in said volume of space, and means for applying current to each coil, said current applying means being adapted to excite each respective coil in a predetermined manner, wherein; said means for applying current sinusoidally exciting three of the coils by providing excitation in the form of a first sine signal to one coil and a substantially in-phase second sine signal of same frequency to another coil, said means for applying current further providing a same frequency cosine signal to the third coil, and further wherein each of said first and said second sine signals is double side band modulated at a low frequency with a phase shifted angle of substantially 90°
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3. An apparatus for powering a transponder within a volume of space having width, height and depth directions, said apparatus being adapted to power the transponder at a substantially uniform level of power irrespective of the transponder'"'"'s orientation and position within the volume of space, said apparatus comprising:
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first, second and third powering coils, each coil being adapted to radiate a respective powering field for reception by the transponder, each coil being further adapted to radiate the powering field respectively in one of the width, height and depth directions in said volume of space, and means for applying current to each coil, said current applying means being adapted to excite each respective coil in a predetermined manner, wherein; said means for applying current sinusoidally exciting three of the coils by providing excitation in the form of sine and cosine signals of the same frequency, the sine signal to one coil, the cosine signal to another coil, said means for applying current further providing a signal marginally different in frequency from the single frequency sine and cosine signals to the third coil, and further wherein each signal exciting the coils is unmodulated.
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4. An apparatus for powering a transponder within a volume of space having width, height and depth directions, said apparatus being adapted to power the transponder at a substantially uniform level of power irrespective of the transponder'"'"'s orientation and position within the volume of space, said apparatus comprising:
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first, second and third powering coils, each coil being adapted to radiate a respective powering field for reception by the transponder, each coil being further adapted to radiate the powering field respectively in one of the width, height and depth directions in said volume of space, and means for applying current to each coil, said current applying means being adapted to excite each respective coil in a predetermined manner, wherein; said means for applying current sinusoidally exciting three of the coils, one coil with a single frequency first signal, another coil with a single frequency second signal, said means for applying current further providing a third signal to the third coil, each signal differing from each other marginally in frequency, and further wherein each signal exciting the coils is unmodulated.
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22. An apparatus for radiating a magnetic field of substantially uniform magnitude along an axis in a volume of space having width, height and depth directions, said apparatus comprising:
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a first coil arranged in the width and height directions and having a first imaginary axial point at its center; a second coil arranged in the width and height directions and having a second imaginary axial point at its center, said first and said second coils each having a side and a predetermined configuration and being positioned adjacent each other in opposite and facing configuration, means for applying current to the first and second coils, the first and second coils being spaced by a separation distance of up to two times the length of one of the sides of said coils to provide in response to a current applied to the coils from said current applying means, said substantially uniform magnetic field within said volume of space, wherein the volume of space is located between said first and second imaginary axial points and extends in the depth direction in the form of an imaginary tube having a surface defining said volume of space of substantially constant radius from the axis defined by said first and second axial points, and the variation between the maximum and minimum magnetic field strengths within said volume of space is not more than 30% and the radius decreases with increases in the separation distance, wherein said first and second coils define a first coil pair, and further comprising a second coil pair and means for applying current thereto, and wherein each pair of coils is arranged along a different axis, further comprising a mutual coupling element in the form of an inductance in series with at least one of said coils for substantially reducing mutual coupling between coils for different directional fields, each inductance being mutually coupled into the magnetic field of at least one other coil.
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23. An apparatus for radiating a magnetic field of substantially uniform magnitude along an axis in a volume of space, having width, height and depth directions, said apparatus comprising:
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a first coil arranged in the width and height directions and having a first imaginary axial point at its center, a second coil arranged in the width and height directions and having a second imaginary axial point at its center, said second coil being spaced from said first coil, said first and said second coils each having a side and a predetermined configuration and being positioned adjacent each other in opposite and facing configuration, means for applying current to the first and second coils, the first and second coils being spaced by a separation distance of up to two times the length of one of the sides of said coils to provide in response to a current applied to the coils from said current applying means, said substantially uniform magnetic field within said volume of space, wherein the volume of space is located between said first and second imaginary axial points and extends in the depth direction in the form of an imaginary tube having a surface defining said volume of space of substantially uniform magnetic field, said imaginary tube surface being spaced radially at a substantially constant radius from the axis defined by said first and second axial points, and the variations between the maximum and minimum magnetic field strengths within said volume of space is not more than 30% and the radius decreases with increases in the separation distance, wherein said first and second coils define a first coil pair, and further comprising a second coil pair and means for applying current thereto, said second coil pair having third and fourth opposingly positioned coils, and wherein each pair of coils is arranged along a different axis, further comprising a third coil pair having fifth and sixth opposingly positioned coils and means for applying current thereto, the third coil pair being arranged to provide, in response to a third current from the respective current applying means, a third field extending in the height direction, the first, second and third fields being of substantially equal magnitude, each field being of substantially constant magnitude interposed with their respective windings, thereby providing in the depth, width, and height directions a three dimensional substantially constant magnitude field, further comprising signal receiving coils arranged adjacent said first, second and third pairs of coils radiating the substantially uniform magnetic field so as to receive signals provided by a receiving unit powered by said field, wherein the receiving coils are arranged in a cubic arrangement of six loop antennas, each loop antenna defining one plane of a cube and wherein the cube defines said substantially uniform magnetic field radiated by said first, second and third pairs of coils. - View Dependent Claims (24, 25)
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26. An apparatus for radiating a magnetic field of substantially uniform magnitude along an axis in a volume of space having width, height and depth directions, said apparatus comprising:
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a first coil arranged in the width and height directions and having a first imaginary axial point at its center, a second coil arranged in the width and height directions and having a second imaginary axial point at its center, said second coil being spaced from said first coil, said first and second coils each having a side and a predetermined configuration and being positioned adjacent each other in opposite and facing configuration, means for applying current to the first and second coils, the first and second coils being spaced by a separation distance of up to two times the length of one of the sides of said coils to provide in response to a current applied to the coils from said current applying means, said substantially uniform magnetic field within said volume of space, wherein the volume of space is located between said first and second imaginary axial points and extends in the depth direction in the form of an imaginary tube having a surface defining said volume of space of substantially uniform magnetic field, said imaginary tube surface being spaced radially at a substantially constant radius from the axis defined by said first and second axial points, and the variation between the maximum and minimum magnetic field strengths within said volume of space is not more than 30% and the radius decreases with increases in the separation distance wherein said first and second coils define a first coil pair, and further comprising a second coil pair and means for applying current thereto, and wherein each pair of coils is arranged along a different axis, further comprising signal receiving coils arranged adjacent said first and second pairs of coils radiating the substantially uniform magnetic field so as to receive signals provided by a receiving unit powered by said substantially uniform magnetic field, further comprising the least one coil element, each coil element being provided in series with a respective receiving coil, each coil element being adapted to reduce the mutual coupling between the receiving coil and coil element and at least one of said coils providing said powering field.
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27. An apparatus for radiating a magnetic field of substantially uniform magnitude along an axis in a volume of space having width, height and depth directions, said apparatus comprising:
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a first coil arranging in the width and height directions and having a first imaginary axial point at its center, said second coil being spaced from said first coil, said first and second coils each having a side and a predetermined configuration and being positioned adjacent each other in opposite and facing configuration, means for applying current to the first and second coils, the first and second coils being spaced by a separation distance of up to two times the length of one of the sides of said coils to provide in response to a current applied to the coils from said current applying means, said substantially uniform magnetic field within said volume of space, wherein the volume of space is located between said first and second imaginary axial points and extends in the depth direction in the form of an imaginary tube having a surface defining said volume of space of substantially uniform magnetic field, said imaginary tube surface being spaced radially at a substantially constant radius from the axis defined by said first and second axis points, and the variation between the maximum and minimum magnetic field strengths within said volume of space is not more than 30% and the radius decreases with increases in the separation distance, wherein said first and second coils define a coil pair, and further comprising a second coil pair and means for applying current thereto, and wherein each pair of coils is arranged along a different axis, further comprising signal receiving coils arranged adjacent said first and second pairs of coils radiating the substantially uniform magnetic field so as to receive signals provided by a receiving unit powered by said substantially uniform magnetic field, further comprising at least one interference element, each interference element being provided in series with a respective coil, each interference element being a further coil adapted to obviate interference signals radiating from sources external to said apparatus.
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Specification
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Current AssigneeMagellan Technology Pty. Ltd (SATO Holdings Corporation)
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Original AssigneeMagellan Technology Pty. Ltd (SATO Holdings Corporation), Uniscan Limited
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InventorsMurdoch, Graham A. M.
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Primary Examiner(s)Hille, Rolf
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Assistant Examiner(s)BROWN, PETER T
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Application NumberUS07/806,842Time in Patent Office694 DaysField of Search340/551, 340/572, 343/742, 343/867, 324/260, 342/44US Class Current343/742CPC Class CodesG06K 7/10336 the antenna being of the ne...G06K 7/10346 the antenna being of the fa...H01Q 21/20 the units being spaced alon...H01Q 21/29 Combinations of different i...
