Abstract : A retrodirective antenna array (RDA) is capable of autonomously steering its radiation pattern toward the source of an interrogating signal, without having prior knowledge of the interrogator location. Integrating an RDA into a mobile platform, such as a nanosatellite, presents unique challenges due to the platform's restrictions in terms of size, weight, and power limitations. This project focused on developing novel RDA architectures that are directly suited for this resource-constrained platform. The three new RDA architectures that were developed during this research project are described. They are based on slope detection, null scanning, and a combination of power detection and null scanning.