Electromagnetic marker devices for buried or hidden use

A marker device for locating a buried object, comprising:

• a housing;
• an antenna element comprising a plurality of conductive windings enclosed n the housing;
• and
• an electronic circuit comprising a circuit board electrically coupled to the conductive windings through a connector, the connector including connecting elements at each side of the circuit board for coupling to outer ends of the conductive windings, wherein the circuit board includes electrical traces and the connecting elements electrically couple the conductive windings to the electrical traces in the circuit board, the circuit board comprising a plurality of circuit elements disposed thereon, the circuit elements including:
• an input circuit to receive, via the antenna element, an input signal from an above-ground transmitter, wherein the input signal has a first frequency;
• a power circuit to convert the input signal to a power supply for powering the electronic circuit;
• a processing element to generate an output signal responsive to the input signal;
• and
• an output circuit to provide the output signal, via the antenna element, to an above-ground receiver to assist in determining a location of the buried object, wherein the output signal has a second frequency different from the first frequency;
• wherein the conductive windings in conjunction with the electronic circuit are arranged in a configuration to provide a signal reception and transmission range of two meters or more, wherein the conductive windings include a first winding, a second winding, and a third winding, the first and second windings are connected in series and the third winding is connected in parallel, each of the first, second and third windings being electrically coupled to the electronic circuit.