Design and analysis of checkerboard surface for RCS reduction in X-band

The design and analysis of checkerboard patterned surface for radar cross-section reduction in the X-band is presented. The checkerboard surface consists of two alternating electromagnetic band gap (EBG) structures. A wide-band reduction in RCS is achieved by adopting the methodology of designing the two EBG structures to have the property of an artificial magnetic conductor (AMC), i.e., to have a reflection phase of 0° at separate frequencies, suitably chosen to achieve reduction in RCS in the desired frequency band. The two EBG structures thus designed, have the difference in their reflection phases to be around 180° within the X-band. This property results in effective phase cancellation in the backscatter direction under normal incidence, when the two EBG structures are arranged in a checkerboard pattern. Both the EBG structures are based on the same FR-4 substrate with thickness 2mm, leading to the realization of the checkerboard surface using simple two-layered printed circuit board (PCB) fabrication technique. The reduction in the monostatic RCS for normal incidence in the X-band is demonstrated and validated using both simulations and measurements. Effect of the finite size of the EBG structure, compared to the theoretical design based on the infinitely periodic EBG is investigated by varying the size of both the underlying EBG structures, while maintaining the overall size of the checkerboard surface fixed at 96mm × 96mm. The change in the bistatic RCS of the checkerboard surface compared to a PEC plate, which eventually leads to the reduction in backscattered RCS, is investigated as the size of the finite EBG is varied. Finally, we investigate the phase of the monostatic RCS of the finite individual EBG structures that can be useful to find the number of unit cells required in the finite EBG to realize such checkerboard patterned surfaces with wide-band RCS reduction capabilities.