Wave transmission lines and networks – Coupling networks – Delay lines including long line elements
Patent
1996-10-23
1999-08-10
Ham, Seungsook
Wave transmission lines and networks
Coupling networks
Delay lines including long line elements
333157, 333161, 343754, H01P 118
Patent
active
059364840
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a UHF phase shifter and its application to an array antenna. The invention relates more particularly to a liquid-crystal phase shifter for UHF signals.
Such a phase shifter is suitable for controlling signals the frequency of which may typically stretch from 1 to 100 GHz. It essentially includes a UHF waveguide filled with an electrooptical material the permittivity of which is controlled particularly by electrical means.
2. Discussion of Background
The majority of electronic scanning antennae, except for antennae with active modules, use ferrite-type or diode-type phase shifters (such as the antennae of "RADANT" type) controlled magnetically. By virtue particularly of their low insertion losses, ferrite-type shifters have the advantage of withstanding high powers. However, they exhibit the drawbacks of being heavy, bulky and relatively sensitive to variations in temperature.
PIN-diode type phase shifters are used mainly in active antennae. They exhibit the advantages of being light, compact and fairly insensitive to temperature variations as well as the drawbacks of higher insertion losses and thus less good resistance to high powers.
Diode-type phase shifters are essentially of two types.
switching type. They cause the signal to flow over different path lengths and are suitable for high phase shifts (.pi./2 or .pi.).
perturbation type. They bring variable impedances onto the transmission line and are rather intended for low phase shifts (.pi./8 or .pi./4).
SUMMARY OF THE INVENTION
The device described according to the invention uses the electrooptical properties of the material such as a liquid crystal filling a planar guide of the "microstrip" type.
The invention therefore relates to a UHF phase shiftel characterized in that it comprises a UHF waveguide including an element made of electrooptical material lying between two elements made of materials with permittivities higher than those of the element made of electrooptical material, means of applying a polarization electric field making it possible to control the electrooptical material.
More particularly, the invention relates to a UHF phase shifter, characterized in that it comprises:
at least one layer of liquid crystal enclosed between a first and a second plate with permittivities higher than those of the liquid crystal, a first plate including a UHF line conductor capable of transmitting a UHF signal,
as well as means of applying a polarization electric field to the liquid crystal.
According to one preferred embodiment, the means of applying the electric polarization field include electrodes situated on either side of the liquid crystal; one of the electrodes is the UHF line and the other electrode is situated on the second plate.
BRIEF DESCRIPTION OF THE DRAWINGS
The various objects and characteristics of the invention will emerge more clearly in the description which follows and which describes a non-limiting embodiment of the invention, as well as in the attached figures which represent:
FIG. 1, a basic embodiment of the phase shifter according to the invention;
FIG. 2, an example of the phase shifter of FIG. 1, seen from above;
FIG. 3, another embodiment of the invention seen from above;
FIG. 4, an embodiment with several phase shifters of the device of the invention;
FIG. 5, an embodiment of the device of the invention with UHF lines of different lengths;
FIGS. 6 and 7, examples of a stack of phase shifters according to the invention;
FIGS. 8a, 8b, a variant embodiment of the phase-shifter device according to the invention;
FIGS. 9a and 9b, further variant embodiments of the phase-shifter device according to the invention;
FIG. 10, an example of the application of the invention to antenna control.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a basic embodiment of the phase shifter according to the invention will now be described.
A UHF line 2 (or microstrip) is deposited on a substrate plate 3 made of insulating material having high perm
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Dolfi Daniel
Huignard Jean-Pierre
Joffre Pascal
Labeyrie Michele
Lehureau Jean-Claude
"Thomson-CSF"
Ham Seungsook
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