A cavity perturbation technique using a rectangular cavity resonator has been presented for the evaluation of complex permittivity of materials. Theoretical background of the cavity perturbation technique and realization using conventional rectangular resonators is discussed. A detailed analysis on the design of the rectangular cavity resonator (TE₁₀₃ mode) is presented. Feko Simulations are performed on various standard and commercial dielectric samples (Teflon, Quartz, 6010.2LM and 6010.8LM) using the rectangular cavity resonator. The obtained simulated dielectric constant and loss values of the commercial samples are in good agreement with the reference values.

Figure 1(a) Layout of the TE₁₀₃ rectangular cavity resonator. Figure 1(b) E-field distribution of the cavity resonator and sample under test. Figure 1(c) Top view and side view of the cavity resonator. Figure 1(d) simulated resonant frequency of the cavity. 

 Figure 2 Reflection Coefficient responses of the cavity resonator for various standard dielectric samples.