Method for characterizing the radio link of RFID tags

A method for characterizing a radio link, comprising utilizing a radio frequency interrogator and a first wireless radio frequency transponder, the response of which in an essentially anechoic space is known, comprising:

• (a) measuring the response of the first wireless radio frequency transponder in a target environment using a chosen interrogator-transponder geometry,
• (b) calculating a deviation between the responses of the radio frequency wireless transponder in the target environment and in the essentially anechoic space for characterizing the radio link established in the target environment,
• (c) measuring the response of the first wireless radio frequency transponder at a first distance and a second distance, different than the first distance, from the antenna in the far field of the antenna, and
• (d) determining, based on said two measurements, the location of the apparent phase center of the antenna connected to the interrogator.

A method for calibrating a radio-frequency communications system in a target environment, comprising:

• placing a first wireless transponder to a first location within the target environment,
• measuring the response of the first wireless transponder using an interrogator placed to a second location within the target environment,
• comparing the measured response of the first wireless transponder with a response of the transponder in an essentially anechoic space for obtaining a calibration function characterizing said target environment,
• wherein the response of the transponder is measured by:
• determining the activation threshold power of the transponder, and
• determining the strength of a backscatter signal obtained from the transponder at said activation threshold power.