Provided are a liquid crystal compound satisfying at least one of physical properties such as high stability to heat or light, high maximum temperature of a liquid-crystal phase, low minimum temperature thereof, small viscosity, suitable optical anisotropy, large dielectric anisotropy and good compatibility with other liquid-crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition.

A compound is represented by formula (1), a liquid crystal composition contains the compound and a liquid crystal display device includes the composition.

##STR00001##

In formula (1), Ra and Rb are fluorine or alkyl; A.sup.0, A.sup.1 and A.sup.2 are 1,4-phenylene; Z.sup.1 and Z.sup.2 are a single bond or alkylene; one of Y.sup.1 and Y.sup.2 is fluorine, and the other is hydrogen; Rc is alkyl; and a and b are independently 0, 1, 2 or 3, and a sum of a and b is 0, 1, 2 or 3.

The present invention relates to liquid-crystalline media comprising one or more chiral compounds and one or more compounds selected from the group of compounds of formulae I, II and III,

##STR00001##

in which the parameters have the meaning indicated in Claim 1, and to components comprising these media for high-frequency technology, in particular phase shifters and microwave array antennas.

The present invention relates to liquid-crystalline media comprising one or more polymerisable compounds, preferably of formula P

P.sup.a-(Sp.sup.a).sub.s1-(A.sup.1-Z.sup.1).sub.n1-A.sup.2-Q-A.sup.3-(Z.sup.4-A.sup.4).sub.n2-(Sp.sup.b).sub.s2-P.sup.bP

and one or more compounds selected from the group of compounds of

##STR00001##

in which the parameters have the meaning indicated in Claim 1, and to components comprising these media for high-frequency technology, in particular phase shifters and microwave array antennas.

The present invention relates to liquid-crystalline media comprising one or more compounds selected from the group of compounds of formulae I, II and III,

##STR00001##

in which the parameters R.sup.1-R.sup.3, Z.sup.21, Z.sup.31, Z.sup.32 and rings A.sup.11, A.sup.12, A.sup.13, A.sup.21, A.sup.22, A.sup.31, and A.sup.32 are as defined herein, and to components comprising these media for high-frequency technology, in particular phase shifters and microwave array antennas.

The present invention relates to liquid-crystalline media comprising one or more compounds selected from the group of compounds of formulae I, II and III, ##STR00001##
in which the parameters R.sup.1-R.sup.3, Z.sup.21, Z.sup.31, Z.sup.32 and rings A.sup.11, A.sup.12, A.sup.13, A.sup.21, A.sup.22, A.sup.31, and A.sup.32 are as defined herein, and to components comprising these media for high-frequency technology, in particular phase shifters and microwave array antennas.