Abstract: A VLF beacon operates in the near field of the antenna, providing a low impedance (magnetic) wave located by employing simple amplitude gradient and phase alignment direction finding (DF) methods. When rotated, the beacon antenna radiates its signal with little attenuation. Beacon antennas include a loop antenna which has a 1/r3 B-field amplitude relationship with distance. The antenna radiation range is limited, but the detectable near field signal is strong. The receiver comprises a simple 2-channel RF front end with filtering and an A/D converter. The antenna for each channel is a much smaller ferrite rod loaded loop.

Abstract: A protective ensemble hydration monitor configured to be disposed within a face mask of a protective ensemble is disclosed. In one embodiment, the protective ensemble hydration monitor includes a humidity sensor to detect the user's breath within the face mask and output a breath signal based on the detected user's breath. Further, the protective ensemble hydration monitor includes a microprocessor coupled to the humidity sensor to receive the breath signal and output a control signal based on a pre-determined humidity threshold value. Furthermore, the protective ensemble hydration monitor includes a vibrator configured to provide a tactile feedback to the user upon receiving the control signal from the microprocessor.

Abstract: A VLF beacon operates in the near field of the antenna, providing a low impedance (magnetic) wave located by employing simple amplitude gradient and phase alignment direction finding (DF) methods. When rotated, the beacon antenna radiates its signal with little attenuation. Beacon antennas include a loop antenna which has a 1/r3 B-field amplitude relationship with distance. The antenna radiation range is limited, but the detectable near field signal is strong. The receiver comprises a simple 2-channel RF front end with filtering and an A/D converter. The antenna for each channel is a much smaller ferrite rod loaded loop.