Impedance meter

According to the type of electromagnetic wave transmission channel used, impedance meters are coaxial and waveguide.

• Examples of coaxial IPA: IPA-2, Р3-32, Р3-33, Р3-34, Р3-35
• Examples of waveguide IPA: RZ-40, RZ-42, RZ-43, RZ-46, RZ-48

• Coaxial IPSs are implemented as a coaxial tee , the symmetrical shoulders of which are loaded onto the object under study and an exemplary capacitor ; a signal is fed to the asymmetrical shoulder. The normalized, relative to wave , reactance of a capacitor is set equal to a unit by mechanical adjustment. The scale of the tunable capacitor is calibrated in units of frequency . Above the center of the tee there is a vertically located transcendental waveguide , in which there is a coupling loop loaded on the detector . The total current of symmetrical arms I _Σ = I _C + I _Z and the current of an asymmetric arm I _G excite magnetic fields H _Σ and H _Γ in a circular waveguide. The vector of the total field H ₁₁ consists of two vectors rotating towards each other. At the moment of their coincidence, the magnetic field strength is maximum, with opposite directions it is minimal. The design of the loop, rotating about a vertical axis, ensures its unchanged connection with the field. When you rotate the loop through 360 °, two maxima and two minima of tension are observed. The angular displacement of the extremum relative to the position corresponding to the open line is half the phase of the reflection coefficient .
• A waveguide impedance meter consists of rectangular and cylindrical waveguide segments, with a cylindrical waveguide located at a right angle to the wide wall of a rectangular waveguide. The connection between the waveguides is carried out through three slots of the same size, located at an equal distance from the center of the cylindrical waveguide. The principle of operation is similar to the principle of operation of a coaxial IPS.
• The CWS , as in the measuring lines , is determined from the ratio of the readings of the low-frequency indicator at extreme signal values. The impedance of the object under investigation is found in a circular diagram of impedances based on the values ​​of the CWS and the phase of the reflection coefficient.
• IRSs have lower sensitivity than the measuring lines, but they have significantly smaller dimensions, especially in the lower part of the frequency range, and allow you to directly count the phase of the reflection coefficient

• Frequency range
• Own standing wave ratio
• Cross section of the coaxial path or waveguide

Literature

• Handbook of radio measuring instruments : In 3 tons; Ed. V.S. Nasonov - M.: Owls. radio, 1979
• Handbook of electronic devices : In 2 tons; Ed. D.P. Linde - M .: Energy, 1978
• R. Valitov. Radio Engineering Measurements - M., 1963

Regulatory and Technical Documentation

• GOST 8.493-83 State system for ensuring the uniformity of measurements. Coaxial impedance meters. Methods and means of verification
• GOST 18238-72 Ultra-high frequency transmission lines. Terms and Definitions

• Measurement of parameters of electromagnetic waves at microwave frequencies
• Standing wave ratio
• Traveling wave coefficient
• Reflection coefficient (in radio engineering)
• Radio measuring devices
• Pie chart of impedances
• Measuring line