CURVED SURFACE DIFFRACTION PHENOMENOLOGY, MODELING & CHARACTERIZATION

Summary form only given. Curved surface diffraction is a phenomenon that is relevant in many areas of communications such as cellular telephony, Wi-Fi access, and ground and vehicle (e.g., aircraft and naval ships) EMI. We have been characterizing electronic warfare (EW) and information, surveillance and reconnaissance (ISR) platform electromagnetic environmental effects (E3) phenomenology. Some of the approaches to mitigate platform EMI include: (i) isolation to re-scatter surface or traveling waves, (ii) patch or conformal antenna replacement architectures for receiving antennas, (iii) adaptive arrays collocated with the receiving antenna, and (iv) selective placement of magnetic radar absorbing material (MagRAM) to attenuate surface (traveling), specular and diffraction induced scattering. We are performing modeling, simulation and validation experiments aimed at quantifying the effectiveness of selected MagRAM treatments to minimize the effect of electromagnetic interference. This effort is developing a robust materials database to optimize electromagnetic 'attenuation versus MagRAM material type, loading fraction, weight and thickness, and accurately measuring intrinsic properties and bulk specular, surface wave and edge diffraction. This approach is allowing us to quantitatively establish a validated database for future applications. In this regards, we have been measuring RF scattering from several curved surface mockups. To ensure we are measuring the energy diffracted from the curved surface, we have to ensure that the mockup is large enough so that the curved surface diffracted energy is large compared to the energy coming from other paths. To this end, we have designed and fabricated a "universal" curved surface test body. This test body can have its dimensions and degree of curvature parametrically altered and can accommodate various surface treatments for test characterization and comparison with modeling & simulation. Highlights of these efforts, to quantitatively ascertain levels of isolation, which can be reasonably obtained by localized passive techniques, were discussed.