| 摘要 |
PURPOSE:To prevent other radio systems and instruments from being disturbed by arranging a 2nd antenna so that a 1st antenna is given a combination of feed conditions and directivity which cancels an electromagnetic field generate at a remote place. CONSTITUTION:The 1st antenna 3 is arranged at a nearby interval while having signal coupling characteristics close to an open transmission line and the 2nd antenna 6 is so arranged as to give the 1st antenna 3 the combination of feed conditions and directivity which cancels an electromagnetic field produced at a remote place. Then a radio signal is transmitted forth and back between the open transmission line and 1st and 2nd antennas 3 and 6. There, the radio wave signal can be reduced by making opposite-phase radio waves from both antennas cancel each other at the remote place without any influence upon the coupling between the open transmission line and a normal coupling antenna. Consequently, disturbance to other radio systems and measurement system which handle an extremely low level.
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