A power amplifying radiator is disclosed that includes an electric field receiver or radio frequency (RF) energy coupling and impedance matching element, a capacitive coupler, a cavity combiner including a coaxial-cavity section providing electromagnetic communication with the capacitive coupler, and a phased-array antenna/one or more phased-array antennas. The RF energy coupling and impedance matching element is in electromagnetic communication with the one or more phased-array antennas via the cavity combiner. The cavity combiner includes a center conductor configured and disposed to project from the coaxal-cavity section such that the cavity combiner defines a co-axial cross-sectional configuration. The power amplifying radiator may be included within a high power microwave system.