A new waveguide method for measuring permittivity

The paper describes a new waveguide method for measuring the relative permittivity of low-loss dielectric rods. The specimen rod is mounted on the axis of a circular waveguide with one end contacting a short-circuit plate. By using a rectangular-waveguide standing-wave detector the condition is found for the guide wavelength in the dielectric section to equal the free-space wavelength. A simple formula enables the real part of the relative permittivity to be calculated. The theory of the method is developed, and results obtained in the frequency band 8¿11.5 Gc/s are described.