A.A. L’vov – D.Sc.(Eng.), Professor, 

Department of Information and Communication Systems and Software Engineering, 

Yuri Gagarin State Technical University of Saratov

E-mail: alvova@mail.ru

V.P. Meschanov – Honored Scientist of RF, D.Sc.(Eng.), 

Director of the JSC «NIKA-SVCH» (Saratov) 

E-mail: nika373@bk.ru

M.S. Svetlov – D.Sc.(Eng.), Leading Research Scientist, 

Institute of Precision Mechanics and Control of Russian Academy of Sciences (Saratov)

E-mail: svetlovms@yandex.ru

N. Semezhev – Post-graduate Student, 

Department of Information and Communication Systems and Software Engineering, 

Yuri Gagarin State Technical University of Saratov

E-mail: supersem00@gmail.com

The use of multi-port reflectometers (MR) as measuring devices in microwave automatic network analyzers (ANA) allows one to create relatively cheap and highly accurate instruments for load parameter research. The paper describes a new approach to the design of microwave ANA based on MR. The proposed method is founded on the analysis of the variance-covariance matrices of estimation errors for state parameters of the system: generator – measuring device – two-port under test, obtained by the maximum likelihood method. Optimization of the MR parameters is performed by selecting the distances between the connection plane of the load under test and the measuring sensors of a multi-port, when the determinant of the variance-covariance error matrix is used as the optimization criterion. When designing the ANA for measurement in a narrow frequency band, an equidistant arrangement of MR sensors along its longitudinal axis was proposed. On the contrary, when designing a broadband analyzer it is impossible to find the arrangement of the MR sensors that allows one to measure with utmost accuracy at any arbitrary taken frequency from the operating range. So, optimization is performed by minimizing the estimation efficiency function (EEF) of the state parameters in the frequency band of measurements. In this case, it is necessary to abandon the concept of optimal measurement and move on to the concept of ensuring sufficient measurement accuracy in the entire frequency band due to the complexity of the resulting expressions for the EEF. The paper describes the computer-aided design of the ANA on the basis of MR, which allowed to find the location of a limited number of multi-terminal sensors (no more than eight) for measurement in a wide frequency range (up to seven octaves). The developed software of this system can be used for design of the real multiport reflectometers, which meet the given requirements. After designing the MP in the measurement process, it is proposed to use a system of measurement process control, when signals from the ports are taken into account with certain weights during estimation procedure. The application of the proposed measurement control system using projected MRs makes it possible to measure with potentially attainable accuracy at any frequency within a specified range.

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