AlGaN/GaN MMICs on SiC substrates will be utilized to achieve Power Added Efficiencies (PAE) in excess of 60%. These wide band-gap solid-state semiconductors will be used in novel Power Amplifier (PA) topologies such as Current Mode Class D (CMCD) and Class J. The power output goal of a single X-band PA module is 50W, and the power output goal of the Ka-band PA module is 10W. In turn, these power modules will be combined using novel combiner topologies including but not limited waveguide and radial power combiners in order to achieve the high power goal of 1kW at X-Band and greater than150W at Ka-band. Phase I will consist of choosing the devices sizes and topologies for the PA modules, and performing extensive modeling and simulation, especially for the large signal non-linear operation with harmonic terminations required to achieve the high efficiency goals. In addition, various power combiner configurations will be simulated using 2.5D and 3D electromagnetic field solvers. The power combining strategies will be evaluated for overall system efficiency, size, and weight trade-offs.