Résumé
This paper presents and compares three receiver architectures used to detect backscattered signals. These receivers are able to estimate the magnitude and phase of the reflection coefficient between the transponder antenna and the transponder circuit. Thus, the complex reflection coefficient can be estimated remotely. Impedance of the load connected to the antenna can thus be remotely estimated. Prototype is designed and characterized in real environment. Results show that the reflection coefficient and/or load impedance connected to the tag antenna can be determined in real environment.