The network analyzer is a new type of instrument for measuring network parameters. It can directly measure the complex scattering parameters of active or passive, reversible or irreversible dual-port and single-port networks, and give the amplitude and phase of each scattering parameter in frequency sweep mode. Frequency characteristics. The automatic network analyzer can correct the measurement results point by point and convert other dozens of network parameters, such as input reflection coefficient, output reflection coefficient, voltage standing wave ratio, impedance (or admittance), attenuation (or gain). Transmission parameters such as phase shift and group delay, as well as isolation and orientation.
The network analyzer was developed on the basis of a four-port microwave reflectometer (see standing wave and reflection measurements). In the mid-1960s, automation was realized, and the error caused by the directionality of the directional coupler, mismatch, mismatch, and leakage was corrected at each frequency point by using a computer with a certain error model, so that the measurement accuracy was greatly improved. The measurement accuracy of the most sophisticated measuring line technology in the measuring chamber can be achieved, and the measuring speed is increased by several times.
Before the actual measurement, three instruments with known impedances (such as a short circuit, an open circuit, and a matching load) are used for a series of measurements, called calibration measurements. Comparing the measured results with the ideal results (when there is no instrument error), each error factor in the error model can be calculated and stored in the computer to correct the measurement results of the device under test. This is calibrated and corrected at each frequency point. Measurement steps and calculations are complex and non-manual.