The term waveguide refers to a hollow, rectangular transmission line that guides Radio Frequency (RF) energy to interact with material specimens. The transmission and reflection amplitude and phase are measured, which then determine the intrinsic dielectric and/or magnetic properties of a material specimen.
At VHF and UHF frequencies, the very large wavelength makes free-space methods for measuring materials impractical, so waveguide methods provide a viable alternative that requires large, but not unreasonable-sized specimens.
