| 摘要 |
An antenna structure for transmitting signals from a transmitter at the bottom of a drill well to the earth's surface which includes a drill collar extending in an axial direction and which is adapted to support a transmitter therein, a cylindrical metal sleeve for forming part of an antenna for electromagnetic wave transmission, the cylindrical metal sleeve being disposed around the drill collar and adapted to be connected electrically to the transmitter, an insulating sheath between the cylindrical metal sleeve and the drill collar and a plurality of metal rings disposed between each opposite axial end of the cylindrical metal sleeve and confronting opposite axial end of the insulating sheath. The cylindrical metal sleeve has a diameter greater than the diameter of the drill collar and the insulating sheath has an axial length longer than the axial length of the cylindrical metal sleeve. The plurality of metal rings are electrically insulated from each other, from the cylindrical metal sleeve and from the drill collar. The cylindrical metal sleeve includes a plurality of circumferentially extending slots to provide elasticity to the cylindrical metal sleeve so that it will not become separated from the insulating sheath due to bending of the drill collar during drilling. |
