The coming generation of multiband and multi-functional systems within the increasingly congested radio spectrum require high-performance, reliable and low-cost reconfigurable RF electronics. Current low-power systems employ well-understood semiconductor-based elements. More recently, advanced technologies such as MEMS, liquid crystals, and ferromagnetic materials have also been proposed for high-frequency tuning. Although each of these technologies has its own advantages and drawbacks, there is one area that miniaturized technology solutions are practically non-existent: high-power reconfigurable systems. The current tuning technologies are suboptimal for these high-power scenarios and difficult compromises are often required. Bulky, heavy, and expensive mechanically-tunable structures, commercialized in the 1950-1960s, are still the primary options today. However, these are mostly infeasible for modern adaptive wireless systems. To address this need, we have targeted the very challenging problem of Tunable High-Power Microwaves for Adaptive Multi-Functional Systems.