Ionospheric holography, Pt. 1, Holographic interpretation of ionospheric data

Various techniques for ionospheric holography are described, and it is shown that the recording of both amplitude and phase of the downcoming signal is technically possible and is preferable to the recording of amplitude or intensity alone. The main limitations are those imposed by the coherent nature of the imagery, and a model has been set up and studied to elucidate these points. Use of the complex output to help identify the various types of scattering objects is discussed. There is no doubt that artifacts of both the bow wave and the self-imaging types can occur, but details are given of ways of identifying and eliminating them by making close comparisons between neighboring reconstruction in the three-dimensional region reconstructed from the hologram. The repeat distances of self-imaging artifacts tend to be high, and formulas are given to help identify them. It is concluded that a polar orbiting satellite carrying phase-locked transmitters at 40 and 400 MHz would be useful.