A coax-to-disk transition and disk transformer system has been designed as a possible replacement for the coax-to-flat plate transformer and cross-over system of the Particle Beam Fusion Accelerator I1 (PBFA 11). Together with a simplification of the coaxial pulseforming lines (PFL's), this predominately closed geometry system increases the energy available for ICF experiments by greater than 50%. Analytical techniques have been combined with single-module scale model experiments and TEM circuit simulations to develop a design that maximizes the energy transport efficiency through the new transmission-line system.Multi-module scale model experiments and 2-D timedependent electromagnetic simulations have verified these techniques can accurately project the energy transfer efficiency and thereby be used to predict full-scale performance.