Measurement of small, fast variations in complex permittivity at ultra-high frequencies

Using a slotted line, a method has been developed to measure small and rapid variations, ¿¿¿ and ¿¿¿, in the real and imaginary parts, ¿¿ and ¿¿, of the relative permittivity of a dielectric, at frequencies in the range from 250 to 2000 Mc/s. Some measurements made by this method on ferro-electrics during switching are reported and give consistent results.