| 摘要 |
An antenna for detecting an subsurface object comprising a plurality of coplanar conductive loops 110, 120 for producing an electromagnetic field, wherein a portion 112, 122 of each loop is coupled with a portion of at least one other loop. The loops are fed in phase so that a current 117, 127 in each loop flows in the same direction along the coupled portions. The loops may be a semi-circular or rectangular shape, and be two identical loops forming a dual-loop structure. There may be a common connection point (313, Fig 3) for establishing electrical connection between the loops with a matching circuit connected thereto, the circuit comprising a tuning capacitor (812, Fig 6) to match a resonant frequency of the antenna to the frequency of a communication device. The antenna may be coupled-fed, and may comprise a laminar dielectric substrate. An antenna assembly (700, Fig 4) has antennas arranged in different parallel planes, the coupled portions of each antenna at an angle to those of another antenna. The coupled portions may be perpendicular, and may be fed with currents of equal magnitude and phase quadrature. The antennas are used in a metal detector for detecting elongated objects |
