Wideband low reflection backward scattering with an inter-band transparent window by phase tailoring of a frequency-selective metasurface

Thin-thickness metasurfaces used for reducing radar cross section (RCS) have attracted much attention due to their promising prospects in many applications, like stealth techniques, antenna radomes, etc. One of the major challenges for antenna radome applications is to achieve inter-band high transmission in addition to broadband RCS reduction by a single device. Here, we propose a frequency-selective metasurface to realize low backward scattering in a wide microwave frequency band while maintaining an inter-band transparent window. To achieve this goal, two basic meta-atoms comprising three cascaded patterned sheets are designed to ensure out-of-phase reflection properties in two sidebands with in-phase high transmission in the center band. Then, we arrange meta-atoms into a checkerboard-like distribution to form the phase cancellation of far-field backward scattering. Simulated results show that the RCS can be reduced by more than 10 dB in a continuous band of 7.5-15.7 GHz while the insertion loss in the transmission window is less than 1.0 dB from 11.8 to 12.1 GHz. Experimental verifications from a fabricated prototype were carried out which agree well with the simulations. This work may provide an effective way to design microwave radomes or find applications in other electromagnetic compatibility devices.