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 TE103mode 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 (Deltafr) and quality factor (Q) of the cavity without and with dielectric material inside the cavity are measured. Using measured values of Deltafrand Q, dielectric constant and dielectric loss of the dielectric materials are determined.