Patent ID: 8493185
Filing Date: 2013-07-23
Classification: G06K

Abstract:
1. A reader circuit for a radio frequency identification (RFID) reader having a dynamically adjustable Q-factor, wherein the reader transmits an activation signal configured to activate half duplex and full duplex transponders, the reader circuit comprising: a signal source configured to drive a resonant antenna; and a dynamic switching circuit configured to set the Q-factor of the resonant antenna to a first value during the transmission of the activation signal; wherein the resonant antenna is a multi-filar antenna comprising a primary filar and a set of secondary filars and a resistor is connected in series with at least one of the filars in the multi-filar antenna; wherein the dynamic switching circuit is configured to set the Q-factor of the resonant antenna to a second value below the first value during detection of a data signal from a full duplex transponder; wherein the dynamic switching circuit is configured to set the Q-factor of the resonant antenna to a third value below the second value when the RFID reader is not transmitting the activation signal; and wherein the dynamic switching circuit is configured to control the Q-factor of the multi-filar resonant antenna by controlling the filars that are incorporated into the resonant antenna circuit by: