Phase Shifter


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phase shifter

[′fāz ‚shif·tər]
(electricity)
A device used to change the phase relation between two alternating-current values.

Phase Shifter

 

a device used in automation, conversion technology, and measuring technology to change the phase of electromagnetic oscillations. The design of a phase shifter depends on the range of operating frequencies, the limits of the phase change, and the accuracy of the equipment. Four-pole networks consisting of resistors, induction coils, and capacitances are usually used as phase shifters for low frequencies and in the radio-frequency range (up to several megahertz).

The simplest type of phase shifter consists of a phase-shift circuit composed of a resistor and a capacitor or of a resistor and an induction coil. Such phase shifters are usually used to produce a fixed phase shift within a range from 0° to 90°. More advanced types consist of a bridge circuit with three resistors and one capacitor; such designs produce an adjustable phase shift in the range from 0° to 180° with small changes in the magnitude of the output signal. Transistor and electron-tube phase shifters with bridge circuits are also used; they feature a phase inverter with a divided load as one of the network components. The phase shift produced is 180°. In the designs mentioned, the phase shift obtained depends on the frequency. This drawback is eliminated in follow-up phase shifters, in which any deviation of the phase shift from a specified value is automatically corrected by changing the parameters in such a way that the deviation is reduced.

Rotary transformers, selsyns, and three-phase asynchronous electric motors with blocked rotors are used for phase adjustment in AC circuits powered from mains rated at frequencies standardized for industry. Phase shifters for decimeter and shorter wavelengths are assembled from sections of coaxial lines and waveguides. The error of phase adjustment is from 0.5° to 1° for electromechanical phase shifters and from 0.05° to 0.1° for electronic phase shifters.

REFERENCES

Valitov, R. A., and V. N. Sretenskii. Radiotekhnicheskie izmereniia. Moscow, 1970.
Avramenko, V. L., Iu. P. Galiamichev, and A. A. Lanne. Elektricheskie linii zaderzhki i fazovrashchateli (handbook). Moscow, 1973.
Kushnir, F. V. Radiotekhnicheskie izmereniia, 3rd ed. Moscow, 1975.
References in periodicals archive ?
The choice of operating frequency for H-tunable phase shifter is determined by combination of low insertion loss, large phase shift, and low SWR.
Due to the phase shifter PS2 we obtain a relative phase shift between the superposing states of [DELTA][phi] = [[phi].
The beam can be scanned anywhere within its coverage volume in the time required to update the phase shifter settings.
The Schiffman phase shifter is a broadband phase shifter where the phase shift [[DELTA].
Since the delay line and the phase shifter together keep the mixer inputs in quadrature, the phase relation can be written as
Earlier efforts to replace phase shifters with coax time delays, which theoretically are linear with frequency, successfully eliminated beam squint.
The amplitude is controlled by the difference between the two phase shifter settings; the PAC's phase setting is just the average of the two phase shifter settings.
Measured values of phase shift and insertion loss as a function of frequency and control voltage for a 12 GHz phase shifter are shown in Figure 10.
In monolithic arrays, the whole structure along with the active devices, phase shifters, etc.
The realization of the receiving phase shifter is identical to the transmitter phase shifter.
Invitation to tender : Chippis Transformation 380/220 kV - 800 MVA transformer phase shifter
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