To measure the dielectric constant in a wide frequency range, an enlarged coaxial line jig having outer conductor diameter of 10 Cm is designed and fabricated. In order to minimize the reflection coefficient of the transition from the coaxial cable to this jig, a mconical waveguide transition is used. Measured voltage standing wave ratio of this testing device is less than 1.16 in the frequency range from 10 MHz to 1800 MHz.
Teflon of 10 cm diameter and 1.94 Cm thick is used as a sample to measure its dielectric constant. The measured real part of the dielectric constant is in the range of 1.95-2.21, and the measured imaginary part is in the order of 10, while the known value of dielectric constant is 2.1-j0.0003.
