Introduction to the use of network analyzers

Network Analyzer Instruction Manual
  1. Purpose
This instruction manual is to standardize the operation of the vector network analyzer to avoid damage to the instrument caused by improper operation; it is used as a training document to enable the company's technicians to understand the use of this instrument.

2 Scope of application
This instruction manual is applicable to the use of all Anglent E50 series vector network analyzers within the company (other models have a certain practical value, but the difference lies in the small differences in button positions and functions).

3 Main responsibilities
3.1 The equipment users of each department are responsible for implementing equipment maintenance.

3.2 Each department assigns special personnel to be responsible for the implementation of regular maintenance management of equipment and supervise the implementation of daily maintenance work.

3.3 When it is necessary for new employees to study this document, conduct training and study.

4 Precautions for instrument operation
4.1 When testing the product, it cannot be directly powered on for testing.

4.2 Before testing the power amplifier, you must check that there is no self-excitation on the spectrum analyzer before you can use the network analyzer to test other indicators.

4.3 Prevent the addition of large direct current, the network instrument can withstand 10V direct current.

4.4 Prevent over signal input.

4.4.1 The allowable input signal of the network analyzer is 20dBm.

4.4.2 When the input signal is greater than 10dBm, the corresponding attenuator should be added.

4.5 Ensure that the instrument is grounded before use.

Introduction to the use of network analyzers

Network Analyzer Overview
The network analyzer is a powerful test and measurement instrument. As long as it is used and operated correctly according to the flow rate, it can achieve extremely high accuracy. It uses its own signal source to compare and measure other electronic equipment and electronic components. , Electronic parts, network connectors, cables and other electrical characteristics and performance parameters meet the standards and requirements, can measure the incident wave, reflected wave, transmission wave amplitude and phase information, quantitatively describe the reflection of the measured device through the ratio measurement method And transmission characteristics. It has a wide range of applications and is indispensable in many industries, especially in measuring the linear characteristics of radio frequency (RF) components and equipment.

This article is mainly aimed at the characteristics of the network analyzer itself, and introduces the use steps, use requirements, basic calibration methods and how to use it to perform test tasks during the use of the network analyzer.

Under the premise of correct use, the network analyzer is a certain radio frequency instrument, and the typical accuracy is ± 0.1 dB and ± 0.1 degree. It can carry out, repeatable RF measurements, and provides configuration and measurement capabilities as wide as their application range. Choosing the right instrument, calibration, function, and the use of reliable RF measurement methods can interpret the results of your test (network analyzer application).

The basic structure of commonly used network analyzers
The network analyzer is mainly composed of a signal source, a signal separation device, a receiver, and a processing display unit. We will explain in detail below.

(1) Signal source: a synthetic signal source composed of 3-6GHz YIG oscillator, 3.8GHz dielectric oscillator, source module components, clock reference and decimal ring, which can provide a variety of signal outputs.

(2) Test device: generally composed of directional coupler and switch, its function is to separate the reflected signal and the incident signal, so as to carry out the initial signal separation and pre-processing.

(3) Signal receiver: The signal preprocessed by the test device is processed again after processing. Its function is to process the down-conversion and intermediate frequency digital signal of the signal for output use or display comparison. The receiver mainly consists of sampling / Mixer, intermediate frequency processing and digital signal processing and other parts.

(4) Display: the function is intuitive, you can see the display output or signal comparison, etc., used for high-brightness and high-speed display of characters and graphics, mainly composed of graphics processor, high-brightness LCD display, inverter, etc. composition.

Introduction to the use of network analyzers

Commonly used technology and performance parameters of network analyzers
(1) Test port output frequency: range, resolution, accuracy, etc.;

(2) Output characteristics: power range, resolution, level accuracy, level linearity, impedance, second harmonic, third harmonic, non-harmonic parasitic signal (typical value), non-harmonic related to mixer Spurious signals, etc.;

(3) Test port input characteristics: frequency range, average noise level, input level, damage level, impedance, harmonics, second harmonic, third harmonic, harmonic measurement accuracy and dynamic range, etc.;

(4) Group delay characteristics: range, aperture, group delay accuracy, etc.;

(5) Structural characteristics: size, weight, etc.

Others should also include understanding its directionality, coupling, insertion loss, output, connectors, and other calibrated accessories.

General network analyzer preparation stage/calibration method/operation procedure/execution method/precautions
(1) Preparation stage

prepare the network analyzer and DUT; clean, check and measure all connectors; if using SOLT calibration, choose a method of handling non-plug-in connections; connect the cable and adapter of the analyzer to the analyzer;

(2) Calibration method

Select the appropriate calibration kit or define the input calibration standard; set the IF bandwidth and average the noise during calibration; manual calibration or use automatic calibration; use well-known verification standards to verify the calibration quality; save the instrument state and calibration.

(3) Operation steps

1. First set the frequency: press the CENTER key (if you set the filter with a center frequency of 506M, set it directly to 506M).

2. When setting the bandwidth (display bandwidth): press the SPAN key, generally set to 100M.

3. Press the CAL button again → CAL IBRATE MENU (the third button) → RESPONSE (the second button) → THRU

4. Press the MARKER button again to set a marker point, and then press MARKER to set the second point, and push in sequence (generally set 5 marker points. For example, design 414M (bandwidth 16M) filter each MARKER should be marked as follows:

Introduction to the use of network analyzers

(4) Execution method

Connect DUT; Obtain appropriate calibration parameters from the calibration step; Measure and save DUT parameters.

(5) Matters needing attention

Cable connectors, impedance converters, standing wave bridges and matching loads should be strictly distinguished between 75Ω and 50Ω characteristic impedance. Because of the same outer diameter and connection thread, they are easy to confuse. Avoid connecting the 75Ω male to the 50Ω female, which will cause the circuit to be discontinuous and unable to test; it should be avoided to connect the 50Ω male to the 75Ω female, because this will completely damage the 75Ω female jack; impedance converter, The matching load, standing wave bridge and measuring probe should be handled with care and kept properly to prevent falling from a height and affecting its performance and final measurement results; when connecting each device, pay attention to the method of connection and rotation, and only allow rotation The nut ensures that the pin and the socket move in a straight line. Otherwise, the pins and jacks will undergo spiral movement and accelerate wear, and the internal pins may be loosened and cannot be used normally; after the cable connector is installed, carefully check whether the pins are in the center, and try to correct them if necessary. , Make it center, avoid damaging the connector jack to be connected

  to sum up
As a new type of test and measurement instrument for measuring network parameters, the network analyzer directly measures the complex scattering parameters of active or passive, reversible or irreversible dual-port and single-port networks, and outputs the amplitude and phase of each scattering parameter in a frequency sweep mode Frequency characteristics for signal comparison and reuse. With the development of technology, an automatic network analyzer with automatic analysis performance is produced, which greatly improves the detection accuracy of electronic components/circuit design/circuit performance. , The calculation ability and accuracy are greatly improved, and it is also more convenient. It can quickly correct the error of the measurement result point by point, and automatically convert dozens of other network parameters, such as input reflection coefficient, output reflection coefficient, and voltage Transmission parameters such as standing wave ratio, impedance (or admittance), attenuation (or gain), phase shift and group delay, as well as isolation and orientation.

It can be seen that for an electronic engineer, no matter whether it is a beginner or an elite who has been engaged in this industry, there is a great possibility that it will need to be used and mastered, so the use of a network analyzer is particularly important. The article is based on its performance, basic structure and some technical and performance parameters that you need to pay attention to when using it. The important thing is to analyze the preparation phase/calibration method/operation steps/execution method/precautions that need to be mastered when using the general network analyzer.