Exploring Low-Loss Wideband Substrate-Integrated Image Guides (SIIG) for Terahertz Applications

This article proposes and explores high-performance substrate-integrated image guide (SIIG) techniques for THz applications. Due to its low-loss transmission, planar geometry, and metallic ground plane that can be shared among other circuit components, the SIIG structure is an ideal candidate for THz integrated circuits and systems development. By conducting modal analysis and selecting proper parameters for geometrical design considerations, the SIIG can provide the best possible performances in the THz regime. An alumina substrate is utilized to fabricate two SIIG prototypes for WR-5.1 and WR-3.5 frequency bands. The experimental results show that one fabricated prototype exhibits a mean insertion loss of 0.578 dB/cm over a frequency range of 135-225 GHz using a dual-line parameter extraction technique. The other fabricated prototype of SIIG presents an average insertion loss of 1.431 dB/cm in the frequency range of 215-335 GHz. Those results demonstrate a promising potential of the SIIG techniques for THz applications. A detailed description of an SIIG structural analysis and also its design procedure are provided.