| Equipping regular measurement system with computer, stepping motor, hardware circuits, and correlative software according to experimental principles of manual measurement system, we can carry out automatic measurement of microwave in order to meet the requirements of modern experimental teaching of microwave. This system can fulfill the measurement of microwave multi-parameter. The following microwave parameters can be measured conveniently in a state of dot frequency: waveguide wavelength, frequency, standing wave ratio, reflect coefficient, load resistance. In a state of swept frequency, the quality factor of resonant cavity, center frequency and bandwidth can be measured. The measurement can be made in both manual and automatic condition. The computer is the mainstay when the automatic measurement is made and simulates the methods and steps according to scheduled programs in manual state to collect signals, perform operation, analyze errors and process data. Aside from performing measurement functions in manual state, the system can realize the scaling and calibration of general attenuator in automatic state. It also can perform the measurement of transmission coefficients in automatic state. The automatic measurement system makes boring manual operation automatic .It can vividly display real time standing waveform or frequency response curve. Its function has satisfied the measurement requirements. Its simply and easily operated interface increase the flexibility and integrity. This system is cost-effective but also can be used for teaching experiments in manual state and needed by scientific research measurement in automatic state. Especially, it is suitable for upgrading of experimental system of microwave teaching. This paper contains following contents.Microwave measurement technology and development trends nowadays are introduced in chapter 1, then the background of subject and research survey are presented. When the background is presented, the shortcomings of the first generation instrument in hardware and software are analyzed.Chapter 2 injects the concept of virtual instruments, then four advantages of virtual instrument technology comparing with traditional instruments are introduced, in addition the development platform of graphic software——LabVIEW, and its program composition, design and function characteristics are also introduced.Circuit design of scalar network analyzer is introduced in chapter 3. These circuits include: power circuit, direct current amplifier, stepping motor drive circuit, sawtooth generator circuit, adder circuit, peak detection circuit, and acquisition card interface circuit.First the overall design of software including dot frequency section and swept frequency section is introduced in chapter 4, then six main modules with a view to measurement principles and detailed programs are presented at large, finally six key skills in designing software are discussed.Chapter 5 introduces how to use software to make measurements in state of dot frequency and swept frequency, in addition measurement results are discussed. First errors in measurement system are analyzed in detail in chapter 6, then improving methods of reducing system errors are suggested.Chapter 7 summarizes the work and points out the direction of researches in the future.
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