Narrow Band High Power Antenna for an Airborne HPM Application

We propose to develop a new narrowband antenna type, termed the "Split-Waveguide Antenna (SWA)," which meets AFRL requirements for high peak power operation with multiple waveguide feeds in a compact, lightweight geometry appropriate to munition-class size and shape factor constraints. The SWA will accept 1 to several waveguide inputs operating at their full transport capacity, typically many 100s MW each for WR650, and will illuminate arbitrarily wide, flat or curved surfaces with multiple phase-locked apertures that occupy virtually the entire aperture area. Air breakdown is mitigated owing to relatively uniform illumination of the large aperture. Aperture efficiency is excellent, exceeding 65% in initial studies, and return loss low, less than -20 dB. Amplitude taper across the aperture to mitigate side-lobes is straightforward, if desired. Depth perpendicular to the aperture is small, less than a free space wavelength. Development and technology demonstration will proceed via stepped stages that include computational geometry optimization, low power array characterization, testing with munition mockup, and tech demo at full 1.2 GW peak power with multiple waveguide drives. The many attributes of the scaleable SWA make it an ideal antenna for any narrowband GW source driven by 1 or more waveguides operating in fundamental TE01 mode.