| 摘要 |
<p>An antenna assembly is provided for use in locating buried objects, particularly long thin objects such as pipes can be located, determining the position, and ascertaining the pipe direction by taking measurements from a single point, without mechanical movement of the antenna, and allowing a better suppression of spurious signals and reduction in false indications; which assembly has a plurality of antenna elements adapted and arranged to transmit and receive radiation into the ground and is characterised in that the elements have, on at least the surface nearest the ground, a cladding of a substantially lossless dielectric material, the relative permittivity of said dielectric being at least 3.5 and the thickness of said coating being at least .lambda.d/20 where .lambda.d is the wavelength of lowest frequency of the radiation to be transmitted from the antenna.</p> |
