Fast X-band amplitude and phase measurement system based on linear sweep frequency generator

A fast X-band frequency-swept amplitude and phase measurement system is designed. The designed system adopts a fractional-N PLL based X-band linear sweep frequency generator as the signal source. As a result, the frequency locking process in common vector network analyzers is eliminated. Because of using the linear frequency-swept source, the amplitude and phase of the intermediate-frequency are obtained using the methods based on Hilbert transform or quadratic demodulation. The designed system and a commercial vector network analyzer were used to test the frequency responses of the same adjustable X-band phase shifter. Although complete vector calibration was not implemented on the designed system as it is not equipped with enough receivers, through proper using isolators, however, the phase test results obtained using the two systems agree with each other nicely, which demonstrates that the designed system has fast measurement speed and could achieve good measurement accuracy.