Active Frequency Selective Rasorber Based on Fiber-Reinforced SiO$_{2}$ Ceramic Matrix Composite

The radome absorber, always be defined as rasorber, is investigated based on the SiO $_{2{\text{f}}}$ /SiO $_{2}$ fiber-reinforced ceramic matrix composite (CMC) for high-strength environment. The prominent advantage of using CMC as the substrate is that it can significantly improve the power capacity and environmental tolerance of the rasorber. The surface roughness and the dielectric stability are considered key factors in the electromagnetic-material codesign. Silica sol is used to densify the surface of fiber CMC for screen printing, and the process is characterized by scanning electron microscopy. The passband can be controlled by integrating p-i-n diodes on the screen-printed silver paste. The equivalent ground condition for the bandpass reflector is theoretically analyzed, and ideal integration of absorbing and transmitting functions is achieved. Afterward, a CMC-based rasorber is manufactured. A dual-polarized transmission window at 1.6 GHz can be triggered, while a low radar cross section (RCS) band is designed from 2.7 to 4 GHz. Transmission and RCS characteristics of the CMC rasorber under 25–700 $^{\circ }$ C environment are both analyzed. The tensile, compressive, and flexural strength of the proposed CMC rasorber are tested, and the electromagnetic properties are verified using compact antenna test range.