A modular solid-state MMW power source based on a topology of the lens array amplifier provides both the flexibility to scale output power and effective thermal management. The modular power source includes a single submodule that uses one or more power dividers and one or more solid-state amplification stages to divide and amplify an RF input signal into R amplified RF signals. The submodule is mounted (suitably in the X-Y plane) on the surface of a heat sink, suitably coupled to a cold backplane, to remove heat. R 1 :N low loss power dividers route the amplified RF signals to R*N radiating elements. Each of the 1 :N power dividers suitably reside in the X-Z plane and are stacked in the Y direction to provide a planar output of the R*N radiating elements in the Y-Z plane. Placement of the amplifier chips on the single submodule decouples the number of amplifier chips, hence output power, from the number of radiating elements. Placement of the amplifier chips away from the radiating face provides a short path with large thermal cross-section through the heat sink to the backplane to remove heat. The topology can produce high output power combined with a high antenna gain to produce large power-aperture products previously only achievable with a Gyrotron. As amplifier chips become more powerful, the topology can be adapted to use fewer chips.