Antenna for a backscatter-based RFID transponder
First Claim
1. An antenna for a backscatter-based RFID transponder comprising:
- an integrated receiving circuit having a capacitive input impedance for receiving a radio signal lying spectrally within an operating frequency range; and
two antenna arms that extend outwardly in a spiral from a central area in which the antenna arms are connected to the integrated receiving circuit,wherein said antenna arms together exhibit a plurality of resonance frequencies including a first plurality of series resonance frequencies when a reactance of said antenna arms passes from a capacitive reactance to an inductive reactance and a second plurality of parallel resonance frequencies when said reactance passes from an inductive reactance to a capacitive reactance,wherein each antenna arm has an arm length along the arm, which is selected so that one of the series resonance frequencies of the antenna is below the operating frequency range and the next higher parallel resonance frequency of the antenna is above the operating frequency range.
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Accused Products
Abstract
An antenna is provided for a backscatter-based RFID transponder with an integrated receiving circuit, having a capacitive input impedance, for receiving a radio signal lying spectrally within an operating frequency range, whereby the antenna has two antenna arms, which extend outwardly in a spiral from a central area, in which the antenna arms can be connected to the integrated receiving circuit. According to the invention, each antenna arm has an arm length along the arm, which is selected so that one of the series resonance frequencies of the antenna is below the operating frequency range and the next higher parallel resonance frequency of the antenna is above the operating frequency range. The invention relates furthermore to a backscatter-based RFID transponder with an antenna of this type.
16 Citations
21 Claims
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1. An antenna for a backscatter-based RFID transponder comprising:
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an integrated receiving circuit having a capacitive input impedance for receiving a radio signal lying spectrally within an operating frequency range; and two antenna arms that extend outwardly in a spiral from a central area in which the antenna arms are connected to the integrated receiving circuit, wherein said antenna arms together exhibit a plurality of resonance frequencies including a first plurality of series resonance frequencies when a reactance of said antenna arms passes from a capacitive reactance to an inductive reactance and a second plurality of parallel resonance frequencies when said reactance passes from an inductive reactance to a capacitive reactance, wherein each antenna arm has an arm length along the arm, which is selected so that one of the series resonance frequencies of the antenna is below the operating frequency range and the next higher parallel resonance frequency of the antenna is above the operating frequency range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A backscatter-based RFID transponder comprising:
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an integrated receiving circuit having a capacitive input impedance; and an antenna connected to the integrated receiving circuit, the antenna comprising; two antenna arms that extend outwardly in a spiral from a central area in which the antenna arms are connected to the integrated receiving circuit, wherein said antenna arms together exhibit a plurality of resonance frequencies including a first Plurality of series resonance frequencies when a reactance of said antenna arms passes from a capacitive reactance to an inductive reactance and a second plurality of parallel resonance frequencies when said reactance passes from an inductive reactance to a capacitive reactance, and each antenna arm having an arm length along the arm, which is selected so that one of the series resonance frequencies of the antenna is below the operating frequency range and the next higher parallel resonance frequency of the antenna is above the operating frequency range. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification