An electrically controlled RF phase shifter having an active medium formedrom 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.

Rf phase shifter

A scanner (13) of ferroelectric material (17) for redirecting the orientation of a beam (22) of millimeter wavelength radiation. The scanner (13) includes parallel input and output sides with matching layers (44). Adjacent and opposite parallel wire grid electrodes (31') are addressed with progressive voltage difference excitation levels across the face of the ferroelectric material in order progressively to modify the refractive index distribution of the scanner and thereby conduct effective beam steering.

Electro-optic beam scanner

A suspension of short graphite fibers was shown to provide an effective medium for nonlinear microwave interactions Using a 18‐GHz pump beam with up to 20 W continuous power, changes in the 94‐GHz refractive index were measured by interferometry The induced birefringence and anisotropic absorption indicate an alignment of the fibers with the electric field of the pump beam The resulting nonlinear refractive index coefficient of n2=26×10−4 cm2/W is of sufficient magnitude to demonstrate microwave bistability

Nonlinear microwave susceptibility measurement of an artificial Kerr medium

A waveguide structure comprises a thin strip of material having a relatively high free charge carrier density surrounded by material having a relatively low free charge carrier density. The width and thickness of the strip are dimensioned such that optical radiation having a wavelength in a predetermined range couples to the strip and propagates along its length as a plasmon-polariton wave. The device includes a waveguide heater for passing a current through the strip to heat it and the surrounding material, so as to vary propagation of the optical radiation, or means for monitoring propagation of the optical radiation to determine a change in temperature of the strip. Some embodiments provide both heating of the strip and monitoring of its temperature.

Thermo-optic plasmon-polariton devices

Conventional (passive) radar-absorbing materials (RAM) have been in use now for over half a century, but it is only with recent advances in conducting polymer composite materials that large-area surfaces having controllable reflection coefficients at radar frequencies have become practicable Techniques for utilizing these new materials in re-configurable electromagnetic, or `smart', surfaces are reviewed, with due emphasis given to the problem of system integration The discussion is complemented by modelled and measured performance data on several smart surface configurations

https://iopscience.iop.org/article/10.1088/0964-1726/6/5/003/pdf

Surfaces with adaptive radar reflection coefficients

Microwave phase shifters and electronic beam steering antennas are described which use an electrically controllable anisotropy dielectric medium in the microwave beam path.

Microwave phase shifter with liquid dielectric having metallic particles in suspension

A novel approach to microwave phase control, utilizing liquid artificial dielectrics, is described. These media have been fabricated with permittivities which vary in magnitude and anisotropy according to the strength of an applied electric control field. Continuously controlled permittivity increases of at least 20 percent in the electric field direction are realizable in liquid suspensions having low loss and very high dielectric strength. A simple waveguide liquid dielectric phase shifter has been built at Ku band and its operating characteristics measured. This approach can be applied to the design of electrically variable microwave lenses, power dividers, and resonant cavities as well as phase shifters.

Controllable liquid artificial dielectrics

The use of liquid suspensions as a new class of microwave artificial dielectrics was explored. Liquid media were constructed with permittivities dependent on the strength of a low-frequency electric control field. Operating characteristics were measured for a 50 KW, 360/spl deg/ Ku-band waveguide phase shifter employing a practical liquid-suspension dielectric. Other applications are in electrically variable wideband lenses and in the analog control of phased arrays.

Harold T. Buscher

Papers

Microwave phase shifter with liquid dielectric having metallic particles in suspension

Controllable liquid artificial dielectrics

Variable-Permittivity Artificial Dielectrics

An Artificial Dielectric Liquid Phase Shifter