A material used in an element for phase control of an electromagnetic wave signal having a frequency of 1 GHz to 10 THz. A liquid crystal composition containing at least one compound selected from a group of compounds represented by Formula (1), at least one compound selected from a group of compounds represented by Formula (2) and at least one compound selected from a group of compounds represented by Formula (3).

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For example, R.sup.1, R.sup.21, R.sup.22, R.sup.31, and R.sup.32 are alkyls having 1 to 12 carbon atoms; a ring A.sup.1 is 1,4-phenylene; Z.sup.11, Z.sup.13, Z.sup.21, Z.sup.23, Z.sup.31, and Z.sup.33 are single bonds; Z.sup.12, Z.sup.22, and Z.sup.32 are —C≡C— or —C≡C—C≡C—; L.sup.13 to L.sup.16, L.sup.21 to L.sup.23, and L.sup.31 to L.sup.36 are hydrogen or fluorine; Y.sup.11 and Y.sup.12 are hydrogen or fluorine; and n.sup.1 is 0.

Liquid-crystalline media having one or more compounds of formula C ##STR00001##
and high-frequency components containing these media, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas (e.g. phased array antennas).

The present invention relates to liquid-crystalline media comprising one or more mesogenic compounds of formula I as set forth hereinafter, wherein the one or more compounds of formula I are contained in the medium in an amount, based on the overall contents of the medium, of at least 15% by weight. The present invention further relates to a switching layer, a switching element and a window element containing the liquid-crystalline medium.

A compound is represented by general formula (I), a liquid-crystal composition contains this compound, and devices are made using this liquid-crystal composition.

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Having a large refractive-index anisotropy Δn and a sufficiently high Tni, highly compatible with liquid-crystal compositions, and exhibiting a high dielectric anisotropy in the radiofrequency range, the compound is a useful material for RF phase shifters, phased-array antennae, image recognition devices, distance meters, liquid-crystal displays, liquid-crystal lenses, and birefringent lenses for 3D image display, among other devices.

A liquid crystal composition and a liquid crystal display device including the liquid crystal composition include at least one compound of general formula I and at least one compound of general formula II. Compared with the prior art, the liquid crystal composition has a smaller voltage change rate at high and low temperatures and a shorter low temperature response time, while maintaining an appropriate optical anisotropy, an appropriate clearing point, an appropriate absolute value of dielectric anisotropy, such that the liquid crystal display device having the liquid crystal composition has a better display and a faster response speed.

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Provided are a liquid crystal composition containing a dibenzo derivative and a liquid crystal display device. The liquid crystal composition includes at least one compound of general formula I and at least one compound of general formula II. The liquid crystal compositions have the characteristics of high clearing point, large optical anisotropy, large dielectric anisotropy, large ε.sub.⊥, large ε.sub.⊥/|Δε|, and large K.sub.ave. The liquid crystal display devices containing these liquid crystal compositions have the effects of good transmittance and high contrast. The liquid crystal composition can meet the requirements of the liquid crystal display device on low power consumption and good display effect and has high application value in liquid crystal displays of in-plane switching (IPS) mode, fringe field switching (FFS) mode, and vertical alignment (VA) mode.

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Compounds of the formula I, liquid-crystalline media which contain at least one compound of the formula I and electro-optical displays which contain the LC mixtures, especially for the self-aligning VA, PSA, PS-VA, PVA, MVA, PM-VA, HT-VA or VA-IPS mode ##STR00001##
in which R.sub.1, R.sub.2, ring A.sub.1, Z.sub.1, Z.sub.2, Sp, P, L.sub.1, L.sub.2, r1, r2, r3, m, n, p1 and p2 have the meanings indicated above.

The present invention relates to an optical component comprising a liquid crystal (LC) medium, operable in the infrared region of the electromagnetic spectrum. The invention further relates to the use of said LC medium in the infrared (IR) region and to devices comprising said optical component. The present invention further relates to an LC medium comprising one or more compounds of the formulae I, II, and III

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in which the occurring groups and parameters have the meanings defined in claim 1, and preferably one or more compounds of the formula RO

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in which the occurring groups and parameters have the meanings defined in claim 2.

A steerable antenna having a plurality of radiating elements and a plurality of modifier elements configured for shifting phase and/or adjusting amplitude of a signal to be emitted by the radiating elements is disclosed. Each of the radiating elements is coupled to one of the modifier elements, wherein the modifier elements each comprise a liquid crystalline medium and wherein the modifier elements are configured such that the adjustment of the phase and/or amplitude is dependent on a state of the liquid crystalline medium. The steerable antenna further comprises a signal generator connected to the modifier elements and configured for generating a signal suited for dielectric heating of the liquid crystalline media of the modifier elements. Further aspects relate to a method for heating and/or controlling the temperature of the liquid crystalline medium of such a steerable antenna.

A liquid crystal composition containing a dibenzo derivative comprising a compound of general formula I and a compound of general formula II, and a liquid crystal display device containing the same, are disclosed. The liquid crystal composition is characterized by its excellent physical properties with respect to a liquid crystal display. The liquid crystal display device containing the liquid crystal composition has a good transmittance and a high contrast. ##STR00001##