Advances in sensor technology and wireless communications have made networked micro-sensors possible, where each sensor individually gathers and transmits informations from the natural environment. Moreover, wireless sensor networks are emerging as a rich domain of active research involving hardware and system design, networking, distributed algorithms, security and data management. In this field, the development and implementation of suitable antennas is a key aspect for the performances of a wireless sensor network. This work aims to present an overview of the benefits and of the most recent advances in antenna technologies, investigating the possibility of integrating enhanced solutions in a large distributed wireless sensor network for the environmental monitoring. Different design techniques are here presented. These techniques have been developed by the authors and they have found applications in a number of fields: from array antennas, to reflectarrays, metamaterials, electromagnetic band gap and antenna miniaturization and integration. The considered radiating structures are divided into two groups: first, base station antennas for data gathering applications are analyzed and different solutions are proposed, in particular considering the compactness, the cost and ease of implementation of the directive structure needed for this kind of application. Second, miniaturized antennas are analyzed, in order to study the integrability and ease of manufacturing of sensor with advanced wireless capabilities. The design technique proposed in this work make use of enhanced global optimization procedures, i.e. evolutionary optimization algorithms, that have been suitably developed to perform the best choice of the most significant parameters in the design phase. These design techniques are finally applied to the design of the radiating structures described previously, in order to obtain suitable radiating structures for wireless sensor networks. The reported results show that the presented procedures can be reliable and effective for a wide spectrum of applications in electromagnetics and in other fields of scientific research.