ENHANCED REFLECTION LOSS PERFORMANCE OF SQUARE BASED PYRAMIDAL MICROWAVE ABSORBER USING RICE HUSK-COAL

Rice husk and coal is an innovation in enhancing the microwave absorption properties of pyramidal microwave absorbers to be used in radio frequency anechoic chambers. An anechoic chamber consists of radar absorbing material (RAM) along its wall; floor and ceiling to eliminate unwanted reflections to create electromagnetically quite environment. To design the pyramidal microwave absorber, coal has been added to rice husk. This innovative material combination has been investigated to determine the best reflectivity performance of pyramidal microwave absorbers. In the commercial market, polyurethane and polystyrene are the most popular foam based material that has been used in pyramidal microwave absorber fabrication. Simulation tool that has been used is CST Microwave Studio. Simulation based comparison of rice husk and combination of rice husk plus coal is done in the frequency range of 0-20 GHz. Chemicals used to intact the powdered form of rice husk and coal are polyester resin, methyl ethyl ketone peroxide (MEKP) and cobalt. Pyramidal microwave absorber has been tested using dielectric probe method and radar cross section method (RCS). Reflection loss performance is tested in the frequency range of 8.2 to 12.4 GHz.