High spatial resolution dielectric constant uniformity measurements using microstrip resonant probes

Microstrip resonant probes have been developed which can measure dielectric constant uniformity with spatial resolution of 0.030 in.*0.010 in. and accuracy better than 2% at 10 GHz. The accuracy of the measurement can be improved to be better than 1% by using a closed-loop frequency discriminator to measure the frequency shift automatically. The measurement principle, microstrip resonator design and fabrication, microwave measurement setup, and dielectric constant uniformity measurement are discussed.<>