Method for locating items
First Claim
1. A method for extending the range of an RFID system which employs a transmitter for transmitting an interrogation beam towards an RFID tag, the RFID tag using a non-linear element including a diode for extracting the energy from the interrogation beam and backscatters a coded signal, comprising the step of biasing the diode with a tag-carried battery, whereby the range of the RFID system is improved over an unbiased diode and, correlating a received signal with an anticipated signal in order to estimate signal amplitude.
1 Assignment
0 Petitions
Accused Products
Abstract
A convenient handheld locator is provided for locating an item in an urban environment in which the locator is programmed to search for and locate specific items, with the detected item being displayed on the locator as to its identity or name, also displaying where the item is relative to the locator, as to position and range.
-
Citations
16 Claims
- 1. A method for extending the range of an RFID system which employs a transmitter for transmitting an interrogation beam towards an RFID tag, the RFID tag using a non-linear element including a diode for extracting the energy from the interrogation beam and backscatters a coded signal, comprising the step of biasing the diode with a tag-carried battery, whereby the range of the RFID system is improved over an unbiased diode and, correlating a received signal with an anticipated signal in order to estimate signal amplitude.
- 8. A method for extending the range of a parasitically-powered regenerative tag that includes a transmitter and a number of diodes in a diode rectifier circuit used to rectify incoming RF energy from an interrogation beam, comprising the step of biasing one or more of the diodes in the rectifier circuit with a tag-carried battery to improve the efficiency of the diode rectifier circuit and to extend the range of the tag over that of a tag having unbiased diodes wherein the range extension is 10 times over that of a tag having unbiased diodes.
-
9. A method for extending the range of a parasitically-powered regenerative tag that includes a transmitter and a number of diodes in a diode rectifier circuit used to rectify incoming RF energy from an interrogation beam, comprising the step of biasing one or more of the diodes in the rectifier circuit with a tag-carried battery to improve the efficiency of the diode rectifier circuit and to extend the range of the tag over that of a tag having unbiased diodes, wherein said diodes are in a rectenna circuit, wherein the rectenna circuit is coupled to an energy storage element and wherein the energy storage element is coupled to a transmitter, and further including the step of providing a hysteretic switch between the energy storage element and the transmitter, and wherein the hysteretic switch couples the output of the energy storage element to the transmitter upon an output from a nanowatt comparator.
Specification