The article describes a low-cost and open IoT platform for rural applications in developing countries. Using the latest low-power, long-range radio technologies and off-the-shelves components, the platform can be quickly deployed and customized for a large variery of rural applications. We present in the article how a low-cost IoT collar device especially addressing the cattle rustling issues can be built from the platform. The article then focuses on the antenna part by presenting how a low-cost integrated antenna design can increase the robustness of the IoT collar by avoiding external fragile parts while preserving a high transmission quality.