US 12523813 B1 / Jan 13, 2026

Dielectric lined waveguides

One or more aspects of the present disclosure include coating the inside of an overmoded, smooth wall metallic waveguide with a thin dielectric layer. Coating the inside of a waveguide with a dielectric layer, as described in more detail herein, may result in similar boundary conditions to corrugated waveguides and may achieve extremely low transmission loss (e.g., propagating the HE11 mode). Such dielectric lined waveguides are an efficient (e.g., cost-effective) alternative to corrugated waveguides (e.g., for broadband microwave transmission, particularly at frequencies above 300 GHz). The systems and techniques described herein may improve hybrid electric mode purity (e.g., HE11 mode purity of approximately 98%). Dielectric lined waveguides described herein may have applications in many fields demanding low attenuation millimeter and terahertz transmission (e.g., such as radar, high-frequency communication systems, THz dynamic nuclear polarization, electron cyclotron heating in magnetically confined fusion experiments, etc.).