Antenna unit with automatic tuning
First Claim
Patent Images
1. An antenna unit comprising:
- an antenna comprising at least one turn, andan electronic circuit connected with the antenna, wherein the electronic circuit comprises connection contacts for connecting the antenna unit with a transmitting device,wherein the electronic circuit;
draws operating energy for the electronic circuit from a transmission signal supplied to the connection contacts, andutilizes the operating energy to tune the antenna unit such that the antenna unit has an impedance with substantially no imaginary component in the transmission signal,wherein the electronic circuit comprises a tuning circuit which forms a tuning capacity which is connected with the antenna, and wherein the tuning circuit is arranged to set a magnitude of the tuning capacity,wherein the electronic circuit further comprises;
a supply circuit for taking up the operating energy from the transmission signal; and
a measuring and control circuit comprising the tuning circuit, wherein the electronic circuit is arranged such that the measuring and control circuit, in operation, receives energy required therefor from the supply circuit, and wherein the measuring and control circuit is arranged to;
measure whether the antenna in combination with the tuning circuit comprises an impedance with an imaginary component, andcontrol the tuning circuit such that any measured imaginary component is reduced;
wherein the measuring and control circuit comprises;
a control circuit,a current circuit that generates a first signal representing a phase of a current through the antenna,a voltage circuit that generates a second signal representing a phase of a voltage across the antenna and the tuning circuit, anda phase comparator that compares the first signal and the second signal,wherein the control circuit, on the basis of a phase difference signal generated by the phase comparator that represents a phase difference between the first and second signal, controls the tuning circuit to reduce the imaginary component, andwherein the electronic circuit further comprises a transformation selection circuit comprising;
a settable transformer connected by a first side with the connection contacts and connected by a second side with the tuning circuit, anda selection switch, wherein a ratio between first side turns of the settable transformer and second side turns of the settable transformer is adjusted by the selection switch.
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Abstract
An antenna unit provided with an antenna which comprises at least one turn, wherein the antenna unit is further provided with an electronic circuit which is connected with the antenna, wherein the electronic circuit comprises connection contacts for connecting the antenna unit with a transmitting device, wherein the electronic circuit is arranged to draw energy from a transmission signal which is supplied to the connection contacts and, utilizing this energy, to tune the antenna unit such that this antenna unit has an impedance which has at least substantially no imaginary component in use of the transmission signal concerned.
16 Citations
27 Claims
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1. An antenna unit comprising:
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an antenna comprising at least one turn, and an electronic circuit connected with the antenna, wherein the electronic circuit comprises connection contacts for connecting the antenna unit with a transmitting device, wherein the electronic circuit; draws operating energy for the electronic circuit from a transmission signal supplied to the connection contacts, and utilizes the operating energy to tune the antenna unit such that the antenna unit has an impedance with substantially no imaginary component in the transmission signal, wherein the electronic circuit comprises a tuning circuit which forms a tuning capacity which is connected with the antenna, and wherein the tuning circuit is arranged to set a magnitude of the tuning capacity, wherein the electronic circuit further comprises; a supply circuit for taking up the operating energy from the transmission signal; and a measuring and control circuit comprising the tuning circuit, wherein the electronic circuit is arranged such that the measuring and control circuit, in operation, receives energy required therefor from the supply circuit, and wherein the measuring and control circuit is arranged to; measure whether the antenna in combination with the tuning circuit comprises an impedance with an imaginary component, and control the tuning circuit such that any measured imaginary component is reduced; wherein the measuring and control circuit comprises; a control circuit, a current circuit that generates a first signal representing a phase of a current through the antenna, a voltage circuit that generates a second signal representing a phase of a voltage across the antenna and the tuning circuit, and a phase comparator that compares the first signal and the second signal, wherein the control circuit, on the basis of a phase difference signal generated by the phase comparator that represents a phase difference between the first and second signal, controls the tuning circuit to reduce the imaginary component, and wherein the electronic circuit further comprises a transformation selection circuit comprising; a settable transformer connected by a first side with the connection contacts and connected by a second side with the tuning circuit, and a selection switch, wherein a ratio between first side turns of the settable transformer and second side turns of the settable transformer is adjusted by the selection switch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A system comprising:
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an antenna unit comprising; an antenna comprising at least one turn, and an electronic circuit connected with the antenna, wherein the electronic circuit comprises connection contacts for connecting the antenna unit with a transmitting device, wherein the electronic circuit; draws operating energy for the electronic circuit from a transmission signal supplied to the connection contacts, and utilizes the operating energy to tune the antenna unit such that the antenna unit has an impedance with substantially no imaginary component in the transmission signal; and a reader for reading out a responder, wherein the reader is connected with the connection contacts to supply a transmission signal to the antenna unit to emit an electromagnetic interrogation field with the antenna unit, wherein a responder, when introduced into the interrogation field, responds by emitting a reply signal, wherein the electronic circuit comprises a tuning circuit which forms a tuning capacity which is connected with the antenna, and wherein the tuning circuit is arranged to set a magnitude of the tuning capacity, wherein the electronic circuit further comprises; a supply circuit for taking up the operating energy from the transmission signal; and a measuring and control circuit comprising the tuning circuit, wherein the electronic circuit is arranged such that the measuring and control circuit, in operation, receives energy required therefor from the supply circuit, and wherein the measuring and control circuit is arranged to; measure whether the antenna in combination with the tuning circuit comprises an impedance with an imaginary component, and control the tuning circuit such that any measured imaginary component is reduced; wherein the measuring and control circuit comprises; a control circuit, a current circuit that generates a first signal representing a phase of a current through the antenna, a voltage circuit that generates a second signal representing a phase of a voltage across the antenna and the tuning circuit, and a phase comparator that compares the first signal and the second signal, wherein the control circuit, on the basis of a phase difference signal generated by the phase comparator that represents a phase difference between the first and second signal, controls the tuning circuit to reduce the imaginary component, and wherein the electronic circuit further comprises a transformation selection circuit comprising; a settable transformer connected by a first side with the connection contacts and connected by a second side with the tuning circuit, and a selection switch, wherein a ratio between first side turns of the settable transformer and second side turns of the settable transformer is adjusted by the selection switch. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification