A.V. Vorobiev – Engineer, 

NIKA-Microwave, Ltd (Saratov)

E-mail: alexvorxx@mail.ru

B.M. Kats – Ph.D.(Eng.), Head of Department,  

NIKA-Microwave, Ltd (Saratov)

E-mail: brs19520@yandex.ru

A.I. Korchagin – Ph.D.(Eng.), Leading Research Scientist, 

NIKA-Microwave, Ltd (Saratov)

E-mail: korchagin_aleksey@mail.ru

A.Yu. Kuptsov – Leading Design Engineer, 

NIKA-Microwave, Ltd (Saratov)

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

Director of NIKA-MicroWave, Ltd (Saratov) 

E-mail: nika373@bk.ru

K.A. Sayapin – Engineer, 

NIKA-MicroWave, Ltd (Saratov) 

E-mail: sayapin.k.a@mail.ru

Coaxial-waveguide transitions (CWT) are the most important type of passive microwave devices used in antenna-feeder paths of radio systems and in measurements of waveguide devices. CWT belong to the class of two-port non-built devices, the measurement of electrical parameters of which with the help of standard measuring systems is impossible. At the same time, it is possible to measure the electrical parameters of the CWT in single-port mode. This approach makes it possible to significantly simplify measurements by using only one set of calibration measures, as well as to reduce phase and amplitude measurement errors. To find the elements of the scattering matrix of a reversible two-port network, it is sufficient to solve a system of three nonlinear algebraic equations with three unknowns, connecting the elements of the matrix with the input reflection coefficients and the reflection coefficients of the loads at the output. If one of the loads is ideally matched, i.e. the reflection coefficient is zero, then a particular solution of the system can be obtained. In the first technique the one-port measurements, based on a partial solution, typically used in matched load (ML), load short-circuit (SC) and the load SC with a phase shift. The disadvantage of this measurement technique is that the real ML reflection coefficient is not zero, which makes some error. The general solution of the system can be obtained by the Gauss method by replacing the variables. The second method of single-port measurements, based on a common solution, allows the use of loads with any reflection coefficients, for example, loads SC with different values of phase shift. This allows you to completely abandon the use of ML. According to the considered methods, single-port measurements of the prototype of CWT in the channel 58.17×29.08 mm were performed. For this purpose, the vector network analyzer «Rohde&Schwarz» ZVA40 was used. To ensure high accuracy of measurements, single-port OSM calibration was performed in the coaxial connector plane using a coaxial calibration set. At the same time, waveguide ML and waveguide SC loads with different phase shift values were used as measurement standards. Based on the measured data, the frequency characteristics of the elements of the scattering matrix of the experimental sample of CWT were calculated. Comparison of the results showed that the second method is more accurate, as it allows not to use ML.

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