| 摘要 |
<p>A passive electronic marker (10) uses a plurality of ferrite cores (12, 14) to increase locating range, and the cores (12, 14) are attached in such a manner that a slight bend of the marker (10) at a junction between the cores (12, 14) does not significantly affect the markers performance. Stable locating range and tuned frequency are acheived by controlling the air gap between the cores (12, 14), using specially shaped ends (32, 34) or a sphere (36) which is positioned between the cores (12, 14). By selecting the appropriate geometry for the core ends (32, 34) and winding interconnections, the first order permeability across the air gap is held constant during bending of the marker (10). <IMAGE></p> |
