Design, Fabrication and Characterization of Fused Silica-Based Composites with an LTCC-Derived FSS

Laminated composites with a frequency selective surfaces (FSS) or more complex metamaterials are potential radome materials due to their unique characteristics of electromagnetic wave transmission. For making high-temperature resistant radomes, metamaterials or laminated composites with an FSS should be based on ceramic substrates. However, the processing methods for ceramic metamaterials are very limited and the conventionally used LTCC technique suffers from the shortcoming of large sintering shrinkage rates, which unfortunately impede the production of ceramic-based metamaterials. In this paper, a novel method of a low temperature co-fired ceramic (LTCC) technique combined with a technique of ceramic joining via green tapes was developed to fabricate the fused silica ceramic laminates sandwiched with the FSS. It was found that the newly developed composites with the FSS unit cells of the Ag-Pd strips exhibited near zero shrinkage of the unit cells, showed predictable transmission efficiencies of electromagnetic microwaves, and were able to overcome the poor transmission efficiencies below 11 GHz of the pure fused silica ceramic plates with an identical thickness.