design of commercial radar and calculation of surface reflection coefficient

composite lattice grids reinforced by glass fibers (gfrc) and carbon fibers (cfrc) filled with spongy materials can be designed as lightweight radar absorbing structures (ras). in the present paper, a computational approach based on periodic moment method (pmm) has been developed to calculate reflection coefficients of radar absorbing composite lattice grids. two different mechanisms of reflection reduction for radar absorbing lattice grids are revealed. at low frequency, reflection coefficients increase with the volume fraction of the grid cell wall. at high frequency, several grating lobes propagate away from the doubly periodic plane, and reflection coefficients depend on both the cell wall volume fraction and interelement distance.