[电] near field Casegrainian antenna

jìn chǎng kǎ shì gé rán tiān xiàn ㄐㄧㄣˋ ㄔㄤˇ ㄎㄚˇ ㄕˋ ㄍㄜˊ ㄖㄢˊ ㄊㄧㄢ ㄒㄧㄢˋ