Radar sensor networks (RSNs) are gaining importance in the context of passive localization and tracking. The performance of RSNs is affected by disturbances, system's parameters, network topology, and the number of radar elements. In this paper, we derive a unified analytical framework that takes all this aspects into account and allows the derivation of probability of detection and localization uncertainty. The results enable the system designer to have a clear understanding on the effects of each system parameter and the trade-off between performance and complexity. Moreover, the potential for high-accuracy passive localization of ultrawide bandwidth (UWB) systems is shown.