Abstract: A RFID reader includes a radio frequency (RF) multiplexer having a plurality of antenna ports for connecting with a plurality of antennas respectively, a reader module having a first internal port and second internal port and being configured for communicating with a tag proximate to the RFID reader through one of the first and the second internal ports, a network module for connecting the RFID reader to a network, and a micro-controller module being connected to the RF multiplexer, the reader module and the network module. The micro-controller module is configured for controlling the reader module to communicate with the tag through a selected antenna port of the RF multiplexer or an external antenna device and for controlling the network module to communicate with the network. The first internal port of the reader module is connected to the RF multiplexer for the reader module to utilize the antennas connected to the antenna ports of the RF multiplexer.