Correct Answer - Option 4 : 1, 2 and 3
A vector voltmeter is a two-channel high-frequency sampling voltmeter that measures phase as well as the voltage of two input signals of the same frequency. It measures the amplitude of a signal at two points and at the same time measures their phase difference.
It is used to measure the following quantities:
1) Amplifier gain and phase shift
2) Filter transfer functions
3) Complex insertion loss
4) Radio-frequency distortions
5) Two-port network parameters
6) 's' parameter of the transistor
7) Amplitude modulation index
8) Complex impedance of mixers