âIdealâ means that the feed has symmetrical properties and each port has an axial ratio of 0 dB, so each port responds only to signals with the appropriate sense of polarization and signals with the opposite sense are infinitely attenuated. The feed is mounted at the dishâs focal point.
Leizu(å«ç¥) was a legendary Chinese empress and wife of the Yellow Emperor. According to tradition, she discovered silk and invented the silk loom in the 27th century BC.Leizu discovered silkworms while on a walk investigating damage to the emperor's mulberry trees.However there are different accounts of exactly how she discovered that silkworms made silk. One account says that she used her finger to touch a piece of the silk worm causing a strand of silk come out.eizu discovered silkworms while on a walk investigating damage to the emperor's mulberry trees. However there are different accounts of exactly how she discovered that silkworms made silk. One account says that she used her finger to touch a piece of the silk worm causing a strand of silk come out.
Although these techniques were strictly controlled by imperial decree, eventually silkworms were smuggled out to establish sericulture in Korea, Japan, and India. It seems to be first produced in China around 3000 BC. Silk was spun in ancient China from silkworms (b<i>ombyx mori</i>) as early as 5000 BC. Over the period from 2700 BC to 1600 BC, domestication techniques enabled extensive production of silk thread and cloth.