Method and apparatus for an NMR antenna with slotted metal cover

Abstract

A slotted NMR antenna cover for improved mechanical ruggedness during transmission and reception of NMR signals in a down hole environment during either MWD or wire line operations. A NMR slotted antenna cover is provided comprising an elongated tubular structure with longitudinal gaps or slots filled with a RF transmissive or non-conductive material. The slots can befilled at the slot ends with soft magnetic material to improve efficiency of the antenna. The slots are radial concave to reduce eddy currents induced by alternating magnetic flux entering and leaving the slots surrounding the antenna. In another embodiment, the antenna cover is RF transmissive on only a portion of the antenna, via slots or transmissive material, so that the antenna cover can be used to allow RF transmission from the antenna in a side looking or beam pattern restricted mode only.

Dependencies are inferred from the claim text.