Cavity perturbation technique for complex permittivity measurement of dielectric materials at X-band microwave frequency

A cavity perturbation technique is presented for measurement of dielectric constant and dielectric loss of the dielectric materials at X-band microwave frequency. A tunable rectangular cavity to operate in TE₁₀₃ mode was designed and fabricated. Tunable cavity is calibrated to read its resonance frequency directly from the micrometer screw arrangement attached with the cavity. Shift in resonance frequency (Deltaf_r) and quality factor (Q) of the cavity without and with dielectric material inside the cavity are measured. Using measured values of Deltaf_r and Q, dielectric constant and dielectric loss of the dielectric materials are determined.