Technological advances in the field of integration of functions in silicon technologies and their miniaturization have allowed the development smart electronic devices for public application. We are interested in this work in those structures commonly known as "wireless sensor" whose purpose is to capture information in their environment and then transmit it. These autonomous structures consist of a sensor, a digital part for data processing and management of the whole structure, a communication system and a power supply. To be discreet, this structure must be small. For this purpose it is necessary that all components be integrated in one chip. The antenna of the communicating part is an obstacle to integration because the frequencies used make its dimensions larger than other dimensions of the module, and even when integrated, its properties will be affected by the packaging of the device. Another parameter is, these antennas are omnidirectional, which in terms of energy saving is critical for these applications. In this context, the first part of this report presents the approaches and applications for networks of wireless sensors. A state of the art is presented to identify the different strategies used in the design of platforms for wireless sensors as well as academic and industrial applications. The synthesis showed that in this context, antennas have not been studied extensively. The second part deals with how to implement antenna arrays in wireless sensors networks. The idea is to use the network nodes as elements of the array, thus creating a network where elements are not physically linked. This prospect is explored through two characteristic scenarios of wireless sensors applications. Each application is tested and solutions are proposed and detailed thanks to the calculation tool Matlab. A final section discusses the limitations of use of antenna arrays in wireless sensors networks and our conclusion is that antennas arrays could be a good solution to optimize the link with the end user. The last part deals with the specific antenna design for wireless sensors for outdoor applications. A concept of antenna-package is introduced and developed on different architectures that use antennas body, therefore, in volume. Cubic and spherical structures are proposed, designed and simulated. We focus on the radiation pattern of package antennas, their robustness and their ability to keep their properties even placed in an environment and with components placed inside. Two structures, a cubic and a half-ball, have interesting profiles; the second is an antenna array. Smart, it can scan the entire upper half-space around him with good efficiency. Finally, a conclusive part shows the contribution and gives work perspectives in conjunction with the antennas and more generally with the communicating part and nodes architecture.
