Title :
Theory of a directional borehole antenna
Author_Institution :
Nat. Defence Res. Establ., Stockholm, Sweden
Abstract :
The theory of a directional antenna constructed for the RAMAC borehole radar system is described. The radar was developed for the International Stripa Project and is presently widely used for mapping rock in mines and tunnels. The radar operates in the frequency range 20-100 MHz and the antenna can locate fracture zones and other reflectors from single borehole measurements. The antenna design is determined by the small diameter of the antenna compared with wavelength. Four different signals are measured and digitally combined to produce signals corresponding to an ideal directional antenna, a dipole antenna and a checksum testing the function of the system. Tests have shown that the azimuth of fracture zones can be determined within 3°
Keywords :
VHF devices; geophysical equipment; geophysical techniques; radar antennas; radar applications; terrestrial electricity; 20 to 100 MHz; HF radar; RAMAC borehole radar; VHF radar; directional antenna; directional borehole antenna; equipment; fracture zone; geoelectric; geological reflector; geology; geophysical measurement technique; mines; radar antenna; terrestrial electricity; theory; tunnel; well logging; Antenna measurements; Antenna theory; Dipole antennas; Directional antennas; Directive antennas; Frequency; Radar antennas; Radar measurements; Radar theory; Wavelength measurement;
Conference_Titel :
Geoscience and Remote Sensing Symposium, 1995. IGARSS '95. 'Quantitative Remote Sensing for Science and Applications', International
Conference_Location :
Firenze
Print_ISBN :
0-7803-2567-2
DOI :
10.1109/IGARSS.1995.524005
