This paper investigates the advantages of multispot beam satellite networks, which can leverage power and bandwidth gains through efficient resource management. Efficient resource allocation is essential to reduce losses and improve utilization in satellite systems that operate under resource limitations. Recent developments in satellite technology have considerably increased the feasibility of delivering high-demand services to users. Traditionally, these services are managed by allocating resources through ground stations, which control and distribute communication resources (such as bandwidth and power) between satellites and users. This study focuses on downlink Frequency Division Multiple Access (FDMA) in satellite-terrestrial networks, analyzing an aperture antenna in space communicating with user terminals (UTs) under two Direct Radiating Array (DRA) payload configurations: continuous and fractionated. The fractionated approach allows a collaborating distributed platform to form a complete radiating surface, however introducing challenges such as grating lobes. The research examines the performance of bandwidth allocation among UTs in the same spot beam on overall system capacity. To mitigate interference from grating lobes, an optimization strategy is proposed. The results highlight significant capacity improvements, emphasizing the critical role of effective bandwidth management in enhancing network performance.