Antenna device and radio frequency IC device
First Claim
1. An antenna device that is arranged to perform radio frequency communication with an external device, the antenna device comprising:
- an antenna element including a resonance circuit and configured to transmit or receive a radio frequency communication signal to or from an antenna element of the external device; and
an additional resonance circuit that is connected to a radio frequency IC and magnetically coupled to the antenna element, that includes at least one inductor, and has a resonance frequency lower than a frequency in the radio frequency communication;
whereina resonance frequency of the resonance circuit and the resonance frequency of the additional resonance circuit are both near the frequency in the radio frequency communication;
the resonance frequency of the resonance circuit and the resonance frequency of additional resonance circuit are in a same frequency band as the frequency in the radio frequency communication;
the resonance circuit is not directly physically connected to the additional resonance circuit; and
the additional resonance circuit is a feeding circuit disposed between the radio frequency IC and the antenna element of the antenna device and is configured to prevent a change in the frequency of the radio frequency communication signal transmitted from the antenna element of the antenna device due to a positional relationship between the antenna device and the external device.
1 Assignment
0 Petitions
Accused Products
Abstract
An antenna device is arranged to transmit or receive a radio frequency communication signal to or from an external device such as a reader/writer, and is arranged such that an antenna resonance circuit including an antenna coil and a capacitor is connected to an additional resonance circuit including an inductor and a capacitor. A radio frequency IC device preferably includes the antenna device and a radio frequency IC. The antenna device is constructed such that a change in characteristics thereof caused by a change in the distance between a radio frequency IC device and a reader/writer is minimized, and the radio frequency IC device performs communication with high reliability.
143 Citations
7 Claims
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1. An antenna device that is arranged to perform radio frequency communication with an external device, the antenna device comprising:
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an antenna element including a resonance circuit and configured to transmit or receive a radio frequency communication signal to or from an antenna element of the external device; and an additional resonance circuit that is connected to a radio frequency IC and magnetically coupled to the antenna element, that includes at least one inductor, and has a resonance frequency lower than a frequency in the radio frequency communication;
whereina resonance frequency of the resonance circuit and the resonance frequency of the additional resonance circuit are both near the frequency in the radio frequency communication; the resonance frequency of the resonance circuit and the resonance frequency of additional resonance circuit are in a same frequency band as the frequency in the radio frequency communication; the resonance circuit is not directly physically connected to the additional resonance circuit; and the additional resonance circuit is a feeding circuit disposed between the radio frequency IC and the antenna element of the antenna device and is configured to prevent a change in the frequency of the radio frequency communication signal transmitted from the antenna element of the antenna device due to a positional relationship between the antenna device and the external device. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification