New vectorial automatic technique for characterisation of resonators

A new vectorial technique, in the sense that data are complex magnitudes and are also treated as complex magnitudes, is presented for the complete characterisation of resonators. This technique is based on fitting the experimental data to the expressions relating them to the parameters which characterise the resonator. We have applied this technique to dielectric resonators coupled to a microstrip line, measuring the transmission coefficient. The values of the transmission coefficient measured at different frequencies near the resonant frequency are fitted to a circumference, which enables us to find the coupling coefficient. The quotient between the imaginary part and real part of the transmission coefficient has a linear relation to the frequency, which enables us to obtain the loaded quality factor and resonant frequency. The results obtained in characterising a dielectric resonator are presented and compared with results obtained by another method. Errors in calculating the coupling coefficient and quality factors are in the order of 1% and for the resonant frequency approximately one part in 106.