Patent ID: 9087247
Filing Date: 2015-07-21
Classification: G06K,H04B

Abstract:
1. A method of passive triggering, comprising: providing a passive trigger antenna and a separate radio frequency identification (RFID) reader antenna; setting a return loss detection threshold for the passive trigger antenna; monitoring reverse power reflected at a frequency from the passive antenna; detecting a change in return loss value at the monitored frequency, wherein the return loss value change is responsive to a near field obstruction shifting a resonant frequency of the passive antenna away from the monitored frequency to change the return loss value of the amount of power reflected back from the passive trigger antenna to the device at the monitored frequency crossing above the return loss detection threshold; and outputting a trigger, based on detecting the return loss value crossing above the return loss detection threshold, for a radio frequency identification (RFID) reader to use to trigger an interrogation of an RFID tag using the separate RFID reader antenna.