X-band Scalar Network Analyzer

Electromagnetic waves work as the information propagation carriers which is widely applied in radio communication, remote sensing, space-exploration, military applications, science research and so on. The R&D requirement for microwave and radio-frequency devices rises day by day, which make these products'test accuracy standard higher and higher. It is very urgent to develop high quality measuring instrument for microwave network parameter in order to satisfy manufacture and research's need.Scalar Network Analyzer(SNA) is characterized by its wide dynamic range, high measuring accuracy, easy to use and high cost performance. It is mainly used for measuring amplitude-frequency characteristics of microwave & RF network, including transmission and reflection parameter.Various scalar network parameter measuring error sources are analyzed and investigated. A series of designs are proposed to improve measuring accuracy, and especially we adopt to introduce an ALC(auto-level-control) device to the source port which greatly improve impedance matching of the source and reduce the source reflectance to 0.019(equal to -34.4dB). Finally introduce the calibration process of SNA, and then analyze and calculate the testing system's error.Analyzed and calculated measuring errors of SNA, mainly take directional error, mismatching error and calibration into consideration. By using error deriving formulas and the Matlab software, we calculated the measuring error curves for |S₁₁| and |S₂₁|. The error calculating results indicate that measuring error for |S₁₁| is well below 0.066, for |S₂₁| is just a little more than 5 dB and different |S₁₁| and |S₂₂| of device under test have little influence on |S₂₁| accuracy which means it has good consistency.Theoretical calculation and measured results indicate that theory analysis is correct, measuring accuracy apparently rises and proposed designs for reducing errors are well applied in the scalar network testing system. The instrument's quality and measuring accuracy is greatly improved.