The reader can preferably be implemented using two approaches designated herein by Conventional and All-Digital approach: The Conventional approach consists of an emitter/receiver based on an I/O (in-phase and quadrature) architecture. In this approach the I/O signals are generated in baseband (BB) or an intermediate frequency (IF) through a processing unit (Microprocessor, DSP, FPGA) and, in the transmission chain, are converted to RF with the use of digital-to-analog (D/A) converters, followed by a signal mixer. In the receiving chain the signal is translated to BB or IF through a mixer, followed by analog-to-digital (A/D) converters. In the All-Digital approach the emitter/receiver is based on a software-defined radio (SDR) architecture where signal processing functions, such as modulators, demodulators, filters, among others, are implemented in reconfigurable digital software or hardware. In this approach, in the transmission, the signal in BB is converted directly to RF in the digital domain using high-speed serializers and with de-serializers for reception. In both approaches the implementation of amplification and signal filtering stages is necessary.

It is disclosed a passive node for wireless sensor network, comprising:

antenna for data communication and electromagnetic energy reception for obtaining electrical energy for powering said node;

two impedance matching networks attached to said antenna; and

data processor configured to transmit data and powered by the obtained electric energy;

wherein said antenna and impedance matching networks are configured for two distinct frequencies, one network for receiving electromagnetic energy emitted from one electromagnetic energy emitter and another network for backscatter communication.