A buried utility marker device , comprising: a marker device antenna ; and an electronic circuit operatively coupled to the marker device antenna, the electronic circuit including: a first resonant circuit formed with the marker device antenna for receiving an excitation signal at a first frequency from a marker excitation device; a power circuit for converting the excitation signal to a power supply for powering the electronic circuit; a processing element for generating an output signal responsive to the excitation signal; and a second resonant circuit for providing the output signal to the marker device antenna, wherein the output signal is generated at a second frequency different from the first frequency, the device being characterized by comprising one or more housings for enclosing and sealing the marker device antenna and the electronic circuit from ingress of environmental solid and liquid contaminants upon underground burial and for minimizing detuning of the marker device in a predetermined environment, the housings shaped in a toroidal shape, or a pipe sleeve shape comprising an interior sleeve onto which the device antenna is wound and an outer sleeve fixed about the interior sleeve, wherein a printed circuit board, PCB, containing the electronic circuit, is located between the interior sleeve and the outer sleeve. a marker device antenna ; and an electronic circuit operatively coupled to the marker device antenna, the electronic circuit including: a first resonant circuit formed with the marker device antenna for receiving an excitation signal at a first frequency from a marker excitation device; a power circuit for converting the excitation signal to a power supply for powering the electronic circuit; a processing element for generating an output signal responsive to the excitation signal; and a second resonant circuit for providing the output signal to the marker device antenna, wherein the output signal is generated at a second frequency different from the first frequency, the device being characterized by comprising one or more housings for enclosing and sealing the marker device antenna and the electronic circuit from ingress of environmental solid and liquid contaminants upon underground burial and for minimizing detuning of the marker device in a predetermined environment, the housings shaped in a toroidal shape, or a pipe sleeve shape comprising an interior sleeve onto which the device antenna is wound and an outer sleeve fixed about the interior sleeve, wherein a printed circuit board, PCB, containing the electronic circuit, is located between the interior sleeve and the outer sleeve. a first resonant circuit formed with the marker device antenna for receiving an excitation signal at a first frequency from a marker excitation device; a power circuit for converting the excitation signal to a power supply for powering the electronic circuit; a processing element for generating an output signal responsive to the excitation signal; and a second resonant circuit for providing the output signal to the marker device antenna, wherein the output signal is generated at a second frequency different from the first frequency, the device being characterized by comprising one or more housings for enclosing and sealing the marker device antenna and the electronic circuit from ingress of environmental solid and liquid contaminants upon underground burial and for minimizing detuning of the marker device in a predetermined environment, the housings shaped in a toroidal shape, or a pipe sleeve shape comprising an interior sleeve onto which the device antenna is wound and an outer sleeve fixed about the interior sleeve, wherein a printed circuit board, PCB, containing the electronic circuit, is located between the interior sleeve and the outer sleeve. <EOS>