Wireless communication is an important tool for economic growth and fostering digital inclusion in society. As the need for wireless services continues to rise, optimizing the use of underutilized frequency bands has become mandatory. This makes effective spectrum sharing a condition to meet novel communication needs. Nevertheless, the existing spectrum management approaches, often centralized, face burdens regarding reliability, and establishing trust among users. This work introduces the Decentralized TV White Spaces Management System (DWS-MS), whose central hypothesis is that a decentralized, blockchain-based system can effectively manage wireless spectrum across extensive geographical regions. In addition, this work presents a real-scale test conducted using a region in Brazil to validate its practical applicability.