Which of the following can be measured with a vector network analyzer?

A Vector Network Analyzer (VNA) is an extremely versatile piece of RF test equipment that measures both the amplitude and phase of signals interacting with a Device Under Test (DUT). By measuring the complex reflection of a signal bouncing back from a device (the S11 or S22 parameters), a VNA gathers the raw data needed to calculate several interrelated values. Because input impedance, output impedance, and the reflection coefficient are all mathematically linked to this reflection data, the VNA can seamlessly display all of them. Therefore, 'All these choices are correct' is the right answer. These comprehensive measurements are essential for tuning antennas, designing matching networks, and characterizing RF amplifiers.