Evaluation of the load impedance in coaxial cable via time-frequency domain reflectometry

A new impedance measurement methodology based on time-frequency domain reflectometry (TFDR) is proposed. For the evaluation of the reflection coefficient in time-frequency domain reflectometry, the distortion of the reflected wave by the frequency-dependent attenuation is compensated which otherwise results in inaccurate impedance measurement. Also, the phase difference between the incident and reflected waveforms caused by the state of the load impedance is evaluated by the cross time-frequency distribution which provides time-frequency localized phase difference information. The proposed methodology is verified by a set of numerical electromagnectic simulation experiments and the results are compared with classical time domain reflectometry (TDR). Impedance measurement via time-frequency domain reflectometry is more accurate over a wider range of impedances than TDR.