Technique using an ionospheric modification instrument to produce controllable and steerable low frequency ionospheric arrays for remote sensing applications

A new low-power ionospheric modification facility or 'ionospheric heater' is now under construction in Alaska that has unique capabilities to generate a wide range of low frequencies. It can also form arrays of low frequency ionospheric dipole elements in the upper atmosphere. When this energy is injected into the earth-ionospheric wave guide it can be steered for remote sensing over the earth's crust in directions preferred by the experimenter performing the probing. This paper discusses the instrument, the generation of low frequency waves and ionospheric VLF arrays that can be effectively used for underground propagation experiments confined to a region of several kilometers centered upon the fixed heater location. Such a technique can be useful for the study of geophysics and the detection of buried metal objects.