Drop zone rally point beacon

摘要

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.

主权项

1. A near-field coupling beacon system comprising:
a VLF/ELF band transmit loop antenna at one and only one transmit site; a VLF/ELF band transmitter; a plurality of ferrite loaded loop receive antennas at a receive site; and a receiver detecting field polarity as received by said plurality of ferrite loaded loop receive antennas; whereby near-field coupling between said transmit loop antenna and said plurality of ferrite-loaded loop receive antennas enables communication between said transmit site and said receive site.