Design and Measurement of COBRA Lens Antenna Prototypes for HPM Effects Testing Applications

Abstract : For high power microwave susceptibility effects testing there is considerable interest in antennas that are high power capable, HPM source compatible and which radiate a broad, circularly polarized main beam. We have shown previously that the Coaxial Beam-Rotating Antenna (COBRA) Lens exhibits these properties, in theory. The COBRA Lens antenna transforms an azimuthally symmetric aperture field distribution, of the type common to many HPM sources, to a form that produces a centrally peaked radiation pattern with lines or circular polarization. The large aperture allow it to accommodate high power. The design, numerical simulation, and for the first time the measurement of two COBRA Lens antenna prototypes are summarized in this note. The resulting radiated patterns exhibit moderate directivity that makes them ideal for susceptibility testing applications where wide area coverage is desired. Finally, a brief discussion of the value of HPM susceptibility with circular polarization is provided.