In this article we present a study and the corresponding implementation of low cost printed antennas in the 2,4GHz band. These antennas work with low cost transceivers that give a FR input/output signal in the band of interest. The work is part of a project in the field of sensor networks using technology such as Zigbee or even simpler and cheaper systems. We have focused our attention on parameters such as the antenna impedance, which is very important for achieving maximum power transfer with the transceiver while avoiding adaptation circuits. We are also interested in avoiding balums. We have analyzed these printed antennas in terms of their efficiency and radiation pattern using electromagnetic simulation software. Two structures have been evaluated and compared. The first is a structure derived from a monopole and slot antenna and the second is a printed patch antenna.