Accuracy comparison of the multifrequency and the three frequencies computations of loss tangent and relative permittivity of low loss dielectric materials using the dielectric resonator technique

This paper discusses the measurement accuracy of the loss tangent and the relative permittivity of low loss dielectrics. Typically used the "3 dB" method combined with the "Insertion Loss" computations has been compared with the more precise Transmission Mode QFactor Technique for measurements of tan of Rexolite, Polyethylene, LSAT, CaF₂, Teflon, YVO₄ and SLAO at room temperature. Also for teflon, rexolite and polyethylene we conducted the comparison for temperatures from 24K to 84K. For teflon (with tan below 6·10₋₆) errors up to 100% have been obtained; but for dielectric with tan above 5·10₋₅, errors were below 5%. For ∑(r) measurements, errors introduced by the thermal expansion coefficient have been analysed and found to be between 2.4% and 3.5%