The vector network analyzer has many functions and is known as the “king of instruments”. It is a multimeter in the field of radio frequency and microwave, and a test equipment for electromagnetic wave energy.
Early network analyzers only measured amplitude. These scalar network analyzers can measure the return loss, gain, standing wave ratio, and perform other amplitude-based measurements. Nowadays, most network analyzers are vector network analyzers, which can measure amplitude and phase simultaneously. Vector network analyzer is a kind of widely used instrument, which can characterize S parameters, match complex impedance, and measure in time domain.
RF circuits need unique test methods. It is difficult to measure voltage and current directly in high frequency, so when measuring high frequency devices, they must be characterized by their response to RF signals. The network analyzer can send the known signal to the device, and then measure the input signal and output signal in a fixed ratio to realize the characterization of the device.
Network analyzer can be used to characterize radio frequency (RF) devices. Although only S parameters were measured at first, in order to be superior to the device under test, the current network analyzer has been highly integrated and very advanced.
Composition block diagram of network analyzer
Figure 1 shows the internal composition block diagram of the network analyzer. In order to complete the transmission/reflection characteristic test of the tested part, the network analyzer includes:;
1. Excitation signal source; Provide excitation input signal of the tested part
2. The signal separation device, including power divider and directional coupling device, extracts the input and reflected signals of the tested part respectively.
3. Receiver; Test the reflection, transmission and input signals of the tested part.
4. Processing display unit; Process and display the test results.
The transmission characteristic is the relative ratio of the output of the tested part to the input excitation. To complete this test, the network analyzer needs to obtain the input excitation signal and output signal information of the tested part respectively.
The internal signal source of the network analyzer is responsible for generating excitation signals that meet the test frequency and power requirements. The output of the signal source is divided into two signals through the power divider, one of which directly enters the R receiver, and the other is input to the corresponding test port of the tested part through the switch. Therefore, the R receiver test obtains the measured input signal information.
The output signal of the tested part enters the receiver B of the network analyzer, so the receiver B can test the output signal information of the tested part. B/R is the forward transmission characteristic of the tested part. When the reverse test is completed, the internal switch of the network analyzer is required to control the signal flow.
Post time: Jan-13-2023