An accurate microwave attenuation measurement system using an inductive voltage divider based on a single-channel IF substitution method

Abstract

An accurate microwave attenuation measurement system employing an inductive voltage divider (IVD) operating at 10 kHz as a reference standard, and a single-channel intermediate frequency (IF) substitution method to carry out the null balancing technique is proposed. The system is achieved by stabilizing the IF measurement signal using a phase-locked loop (PLL) technique and by introducing an independent IF reference signal for the null balancing process. The measurement accuracy is verified by evaluating the performance of the attenuation measurements compared with a dual-channel IF substitution method at 10 GHz. The tolerance for frequency purity of the signal sources is also evaluated by using a signal which is frequency modulated by Gaussian noise as a model of an unstable signal source. Experimentally, good stability of the system is obtained even with the severe conditions of the signal sources used.