bidirectional transmission meaning in English

双向传输

( 4 ) according to the values calculated theoretically , electromagnetic radiation beyond 25 m from the transmission lines with the voltage at 500 kv meet the standard , and the radiation beyond 4 m from the unilateralism 220 kv transmission lines , 7 m from the bidirectional transmission lines and anywhere around 110 kv are all meet the standard
( 4 )据理论模式计算， 500kv的线路在走廊两侧25米以外，电场强度满足评价标准； 220kv线路边沿单回4m ，双回7m外满足电场强度评价标准。 110kv线路走廊两侧均满足电场强度评价标准。磁场强度均能满足评价标准。