Patent ID: 7327146

Claim:
A probe ( 1 ) for measuring the electromagnetic properties of a down-hole material (MC, GF, DM) of a well-bore (WB), the probe comprising a metallic pad ( 2 ) in contact with the down-hole material, wherein the pad ( 2 ) further comprises an open-ended coaxial wire ( 4 ) coupled to an electronic circuit ( 3 ), said open-ended coaxial wire ( 4 ) comprising an inner conductor ( 4 A) sunk in an insulator ( 4 B) and being positioned sensibly perpendicularly to a well-bore wall, the electronic circuit ( 3 ) being able to send a high-frequency input signal into the open-ended coaxial wire ( 4 ) and to determine a reflection coefficient based on a high-frequency output signal reflected by the open-ended coaxial wire ( 4 ).