Design of antenna system for short-range wireless sensor network

One of the ways to send the data collected by a wireless sensor network (WSN) to a remote server application is by using the public mobile-telephone network. This usually implies having a WSN node capable of communicating both with sensor nodes and with the GSM/GPRS/3G network, i.e., the node having two independent RF modules. This paper presents the challenges and solutions of design of an antenna system for this type of WSN node. The major problems are imposed by the high difference of the transmitted power level of one RF module and the maximal allowed input power level of the other RF module. Several solutions for the antennas and the feeding networks are presented and evaluated theoretically and experimentally. The best design was proved to be an RF switching scheme.