Exploitation of Omnidirectional Reflectivity

"Omnidirectional reflectors, with nearly perfect reflectivity, have been demonstrated both in academic laboratories and in industrial applications. These designs are similar to multilayer radome designs in that either wide bandwidth or wide angle coverageis obtained by utilizing many layers of dielectric with differing dielectric constants. In radome design, the objective is to achieve nearly perfect transmission over a specified bandwidth and coverage field-of-view. The omnidirectional reflector turnsthat problem around to achieve nearly perfect reflection without the use of lossy materials such as metals. Another difference between demonstrated omnidirectional reflectors and radomes is the current band of operation (visible and infrared) and numberof layers. Commercial applications to date include films for windows that reduce radiant heat through windows as an energy conservation technology. These films, consisting of something like one thousand layers of alternating materials, have been tunedfor maximum IR reflection and acceptable visible light transmission.Mission Research Corporation (MRC) has over 20 years of experience designing, fabricating, and testing unique radome configurations for the US Air Force and other customers. One of the aspects of MRC's research and design program over the years is thedevelopment of specialized design tools for radome development. One of these, MRC_TLM, uses a transmission line model coupled with a Monte Carlo optimizer to design multilayer radomes. MRC will utilize MRC_TLM to determine the feasibility and anticipatedperformance associated with a planar multilayer stack designed to be an omnidirectional reflector. However, planar configurations are not the only useful geometry. Concentric layers of cylindrical shells is also of tremendous interest as a dielectricwaveguide. Improvements are needed in design to reduce the loss associated with leaky waves. Hence, MRC in collaboration with Michigan State University (MSU), will develop the necessary formulation for implementing a version of