BigPatents India

A method of making a passive marker (9) for use in locating buried structures, comprising the steps of: a) providing plural tuned circuits (29) with each tuned circuit comprising a coil and a capacitance, said coil having individual turns of wire that are coupled together so as to form a band; b) providing an enclosure (31/61) that has guides therein, said guides forming channels (45A, 47A, 49A) on an inside surface of said enclosure, said channels (45A, 47A, 49A) being substantially orthogonal to each other and intersect each other, said enclosure being formed of plural portions; c) locating a first one of said tuned circuits in a fast one of said channels; d) locating a second one of said tuned circuits in a second one of said channels, said second one of said tuned circuits being located either around or through a portion of said first one of said tuned circuits; e) bringing said enclosure portions together and sealing said enclosure. (FIG.5,8 )