Investigation of SIW Transmission Loss on Synthetic Fused Silica Substrate for D-Band Array Antennas

The use of wireless communication in the millimeter wave band, where bandwidth can be expanded, is highly anticipated against the backdrop of increasing traffic worldwide. Since attenuation is large in the millimeter wave band, a high-gain antenna is used for long-distance transmission. To form a large planar antenna, a radio frequency power supply network with low transmission loss is required. In frequency bands above 100 GHz, which are attracting attention for 6G and wireless backhauls, quartz glass, which has far superior electrical properties than existing materials, is one of the attractive materials. In this paper, an SIW (Substrate Integrated Waveguide) was designed using a synthetic fused silica substrate in the 140 GHz band, and transmission loss was measured. As a result, synthetic fused silica showed an extremely low transmission loss of 0.06 - 0.08 dB/mm, demonstrating the possibility that it can be applied to large array antennas exceeding 4096 elements.