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Multi‐functional sandwich structure with metamaterial antenna lattice cores: protection, radiation and absorption

In this study, a multi-functional sandwich structure is proposed with mechanical support, electromagnetic radiation and absorption by radome-integrated design of metamaterial antenna array. The pyramid metamaterial absorber (PMA) is used as the radiator of the antenna element, with a fibre-reinforced resin composite radome attached on the top. To enhance mechanical strength of the radome and meanwhile to reduce radar cross-section (RCS) of the antenna, the PMA is used as the lattice core of sandwich structure. By engineering the dispersion, the PMA structure is used as low-loss antenna in-band radiator and broadband out-of-band absorber simultaneously. For instance, an antenna working in the C-band and with RCS reduction in the X-band was designed, manufactured and measured. Radiation performances of the antenna are verified. A 5 × 5 antenna array and a 2 × 2 array were also fabricated to evaluate the absorption and mechanical properties, respectively. Measured results of the 5 × 5 array present that the RCS reduction is more than 20 dB in the X-band. Quasi-static out-of-plane compression tests on the 2 × 2 antenna array verify the good mechanical performances. The sandwich structure can achieve high mechanical strength, good radiation performance and low RCS, which provides a new paradigm of antenna–radome-integrated design for practical applications.