f Polarimetric borehole radar

Directional borehole radars have good potential (or 3-D determination of water-filled fractures and geological boundaries. The choice of polarization of electromagnetic wave used for measurements are quite significant in designing radar systems. Circular polarization has advantages for Ground penetrating radars (GPR), because the reflection efficiency is independent of target orientation to antenna arrangemenis. Radar measurements with circular polarization is possible with antennas such as spiral antennas( lizuka & Freundorfer, 1983) . Another important role of polarization in GPR is isolation of transmitting and receiving antennas. GPR measurements normally use two antennas set closely to each other . Direct coupling often shades small reflection trom targets. A set of cross-polarized antennas increases the antenna isolation and enhances radar reflection. Further possibility of radar signal processing with polarization characteristics are known as radar polarimetry ( Zebker & Zyl 1991) . This paper introduces a possibility of polarimetric radar measurements in a borehole .