| 摘要 |
<p>An electromagnetic wave is propagated inside a pipe as an object of inspection from a transmission antenna of a transmitter, and a reception antenna of a receiver is moved along and outside the pipe so as to inspect it by receiving electromagnetic leakage. If a peak signal level is detected by the receiver, a defect is located where the pipe may be corroded or cracked or it has a joint. The transmission antenna can be moved along and outside the pipe while the reception antenna can be disposed at a suitable position of the pipe. The inspection described above can be conducted by moving both the transmission and reception antennas in synchronism with each other. When the transmission antenna and the reception antenna are moved, the frequency of the electromagnetic wave can be the propagation frequency inside the pipe or can be below a cutoff frequency. On the other hand, if an elongated antenna is disposed inside the pipe, a frequency below the cutoff frequency can be utilized without moving the antennas.</p> |
