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RF Phase Shifter.
Patent application, filed 23 Oct 89,
DEPARTMENT OF THE ARMY WASHINGTON DC
Pagination or Media Count:
This patent application discloses an electrically controlled RF phase shifter having an active medium formed from a ceramic material, the permittivity of which may be varied by varying the strength of an electric field in which it is immersed. The phase shifter includes the ceramic material having electrodes mounted thereon that are connected to an adjustable d-c voltage source. The phase shifter may be placed in an RF transmission line that includes appropriate input and output impedance matching devices such as quarter-wave transformers. The phase of the RF power exiting the phase shifter will depend on the effective electrical length of the material in the active medium. Because changes in the permittivity of the material will produce corresponding changes in the electrical length of the material, changes in the phase of the RF power transmitted therein will be produced. The quarter-wave transformers may also be made of a similar adjustable permittivity material. Control voltages applied to the transformers are used to adjust the amount of output power. An interdigitated electrode is used to reduce the amount of voltage needed to operate the phase shifter. The phase shifter may be embedded as part of a microwave integrated circuit.
APPROVED FOR PUBLIC RELEASE