Patent ID: 7057392

Claim:
An apparatus for use in a wellbore in an earth formation comprising: (a) a resistivity tool having a body with a longitudinal axis substantially aligned with a longitudinal axis of the well bore, the body having a external surface; (b) at least one pair of grooves in said external surface having an orientation substantially orthogonal to said longitudinal axis of said body; (c) a first coil antenna placed near the external surface of the tool body, said first coil antenna having an axis substantially orthogonal to said longitudinal axis of said body and to said at least one pair of grooves and positioned in at least one hole intersecting said at least one pair of grooves; (d) an antenna core material positioned in said at least one pair of grooves between said first coil antenna and said longitudinal axis of said body; wherein said first antenna and said core material define a plurality of small antenna loops having axes substantially parallel to an axis of said first coil antenna.