| 摘要 |
PURPOSE:To make it possible to measure the buried position and the buried depth of only a vacant duct from the position on the earth by controlling a generated magnetic field so that the magnetic field may indicate the directional pattern of twin of truncated-cone type characteristic more than loop antenna theory and avoiding interlinkage of the magnetic field for other buried parallel ducts. CONSTITUTION:Main body 5-1 is made in plastic and is formed into one body together with slide wing bodies 5-2, and wing bodies 5-2 are provided radially from main body 5-1 at a right angle to one another. Further, guide end part 5-4 to insert antenna unit 5 into a duct is provided. Connection part 5-3 for driving material connection is provided at the back end of main body 5-1, and main body 5-1 is provided with antenna part 6 where external circuit matching circuit (impedance matching coil) L1 and circuit L2 tuning to the transmission signals of a transmitter are wound around antenna core 3a independently. Thus, magnetic field H2 generated by unit 5 indicates the directional pattern of twin of truncated-cone type characteristic more than loop antenna theory when high frequency signals modulated by an audible frequency are sent from the transmitter. Consequently, a desired purpose is achieved. |
