Vector Network Analyzer Basics - RF Page - EU-Vietnam Business Network (EVBN)

Network analyzers are electronic instruments used to measure the characteristics of electrical networks, such as impedance, AC voltage and current, and distortion. RF network analyzers can be used for a variety of applications, such as characterizing filters, amplifiers, and impedance matching networks; measuring noise figure and gain; and troubleshooting RF circuits. Find out some basics of Vector Network Analyzer.

Vector Network Analyzer

A vector network analyzer, on the other hand; measures the magnitude and phase of multiple frequencies at the same time. This makes vector network analyzers more accurate than scalar network analyzers. This information can be used to calculate the impedance of the network, as well as the isolation and coupling between ports.

Vector network analyzers typically use a technique called vector analysis to measure the impedance of a network. In vector analysis, the magnitude and phase of each impedance are measured independently, and the results are combined to calculate the impedance of the network.

Vector network analyzers are used in a variety of applications, including antenna testing, filter design, and microwave circuit design. They can also be used to troubleshoot problems in an electrical network.

Radio frequency (RF) network analyzers are test and measurement instruments used to characterize the performance of RF and microwave components and systems. RF network analyzers can measure insertion loss, return loss, and S-parameters of RF and microwave devices and systems.

RF network analyzers are used in a variety of applications, including microwave engineering, telecommunications, and wireless communications. RF network analyzers are also used in the development and manufacture of RF and microwave components and systems.

Scalar Network Analyzer

A scalar network analyzer is a piece of equipment used to measure the magnitude and phase of a signal at a single point in time. This type of equipment is used in a variety of industries, including telecommunications, aerospace, and defense.

A scalar network analyzer is made up of three basic parts: a signal generator, a detector, and a display. The signal generator is used to create the test signal, the detector is used to detect the signal, and the display is used to show the results.

The signal generator creates a test signal that is sent to the detector. The detector measures the magnitude and phase of the signal and sends the information to the display. The display then shows the magnitude and phase of the signal.

A scalar network analyzer can be used to measure a variety of signals, including RF signals, microwave signals, and audio signals.

Network analyzers and spectrum analyzers

Network analyzers and spectrum analyzers are both types of electronic test equipment used to measure various characteristics of electrical signals. However, there are some key differences between these two types of equipment.

Network analyzers are typically used to measure the electrical properties of circuits, such as impedance, return loss, and insertion loss. They can also be used to measure the frequency response of circuits or individual components.

Spectrum analyzers, on the other hand, are typically used to measure the spectral content of electrical signals. This can be used to identify the frequency of a signal or to measure the power of a signal at different frequencies. Spectrum analyzers can also be used to measure the harmonic content of a signal.

Spectrum analyzers can also be used to detect and measure interference in a signal.

Mục Lục

What are the components of a Network Analyzer?

vector-network-analyzer-block-diagram

A VNA consists of a signal generator, a mixer, a detector, and a display. The signal generator produces a signal of known frequency and amplitude, which is applied to the input of the network under test. The mixer mixes the signal from the generator with a reference signal, and the detector measures the signal that is output from the mixer.

The combination of the mixer and the detector allows the RF network analyzer to measure the gain, loss, and phase shift of the device or system under test.

The magnitude and phase of the output signal can be measured and plotted as a function of frequency. The computer calculates the impedance and transmission parameters and displays them on the screen.

The most important components of a VNA are the signal generator and the receiver. The signal generator must generate a test signal that is accurately calibrated, and the receiver must be able to accurately measure the response. The accuracy of the VNA depends on the accuracy of the signal generator and the receiver.

What are the parameters measured using network analyzers

Network analyzers are used to measure a variety of electrical properties of network devices and circuits. The most common parameters are insertion loss, return loss and SWR. Moreover, the matching impedance of each port can be analyzed with Smith Chart or VSWR format in modern network analyzers.

S-parameter-2port-min

S-parameters are a type of mathematical function that describes the behavior of a two-port network. They are derived from the network’s scattering matrix, which is a mathematical representation of the network’s response to an arbitrary input. The scattering matrix is a square matrix, and the S-parameters are the column vectors of its eigenvalues.

Insertion loss (IL)

VNA-Insertion-Loss

Networks analyzers are devices used to measure the performance of a communication network by injecting a signal into one end of the network and measuring the signal at the other end. Insertion loss is the loss of signal power that occurs as the signal travels through the network.

This loss is caused by the resistance of the wires in the network, the mismatch of the impedance of the wires, and the loss of power in the signal due to radiation and absorption. The insertion loss can be measured in decibels (dB)

Return Loss (RL)

Return loss (RL) is a measure of how much energy is reflected back from a discontinuity in a transmission line, expressed in decibels. It is one of the important parameters that is used to characterize the performance of a transmission line. The higher the return loss, the better the line performance.

A transmission line can be discontinuous in many ways: at a connector, at a load, or at a junction. In each case, energy is reflected back from the discontinuity. The return loss is the ratio of the power that is reflected back to the power that is transmitted.

RL is usually measured at a frequency where the transmission line is operating in the linear region. The return loss at other frequencies may be different. The return loss also depends on the impedance of the line.

There are several factors that can affect the return loss: the type of connector, the type of load, the impedance of the line, and the frequency of the signal.

Voltage Standing Wave Ratio (VSWR)

VNA-VSWR

The voltage standing wave ratio (VSWR) is a measure of the impedance matching of a load to a source. It is the ratio of the maximum voltage amplitude to the minimum voltage amplitude at any point along the line. The higher the VSWR, the worse the match. Impedance mismatch can cause reflections, which can lead to signal distortion and loss.

The VSWR is measured in a network analyzer by generating a sine wave signal and measuring the voltage at various points along the line. The maximum and minimum amplitudes are then compared to calculate the VSWR.

Magnitude and Phase

The magnitude of a signal is the magnitude of the voltage or current at a particular point in the signal. The phase of a signal is the phase shift of the signal relative to some reference point. Phase is measured in degrees or radians.

In a network analyzer, the magnitude and phase of a signal are measured at each node in the network. The magnitude and phase are then plotted as a function of time or frequency. This allows the properties of the network to be studied.

Impedance in Smith Chart

VNA-Smith-Chart

The impedance in a Smith chart of a network analyzer is a measure of the resistance and reactance of a circuit. It is represented by the symbol “Z” on the chart. The impedance can be calculated by using the following equation:

Z = R + jX

Where “R” is the resistance and “X” is the reactance.

Find more about S-parameter formats in Vector Network Analyzers

A large signal vector network analyzer (LSVNA)

A large signal vector network analyzer (LSVNA) is a type of RF network analyzer that is used to characterize RF networks with large signal amplitudes. LSVNA’s are used to measure the magnitude and phase of RF signals with large amplitudes, and to identify the network’s impedance and scattering parameters.

LSVNA’s typically have a higher dynamic range and bandwidth than traditional RF network analyzers, making them the ideal tool for characterizing large RF networks.

A large signal VNA is a specialized type of VNA, designed to measure the performance of high power devices, such as power amplifiers and power converters. A large signal VNA can handle signals with peak power levels up to several hundred watts.

The advantage of using a large signal VNA is that it can provide a more accurate measurement of the device’s performance, under actual operating conditions. The input and output signals of a device, under test, can be very different from the signals that are measured in a laboratory environment. A large signal VNA can compensate for these differences, providing a more accurate measurement.

Calibration of Network Analyzers

Calibration of a vector network analyzer (VNA) is the process of adjusting the VNA’s measurements to correspond to a specific known impedance. The calibration procedure ensures that the VNA’s measurements are accurate and repeatable.

The first step in calibrating a VNA is to measure the impedance of the calibration standard. This can be done using a variety of methods, such as a resistive divider or a load-pull system. Once the impedance of the calibration standard is known, the VNA can be calibrated by adjusting its measurements to match the impedance of the calibration standard.

Several factors can affect the calibration of a VNA. One of the most important factors is the accuracy of the impedance measurement. The impedance measurement must be precise to ensure that the VNA’s measurements are accurate. Additionally, the VNA’s calibration will vary depending on the type of calibration standard used.

Modern multiport Network Analyzers use automated calibration units that simplify the calibration procedure with the help of software support.

When calibrating a vector network analyzer (VNA), it is important to use a calibrated test device to ensure accurate measurements. The calibration procedure varies depending on the type of VNA but typically involves matching the VNA’s response to a known standard.

The calibration procedure for a time-domain or frequency-domain VNA typically involves sweeping the device through its measurement range and comparing the results to a known standard. The VNA is typically calibrated at several points throughout its range, and the results are averaged to produce a calibration curve.

Applications of Vector Network Analyzers