The Antipodal Area with a Rough or Absorbing Ionosphere

Abstract

Since a percentage of the energy in the specular component is removed at each reflection there will always be some specular or pseudo-specular component left. This remaining energy has not been scattered and thus it will always travel on a great circle path and will all pass through the point antipodal to the transmitter; the idealized type of antipodal focussing which was discussed in the first part of chapter 17 will occur there. In any practical case, the departure of the ionosphere from the ideal smooth spherical shape will cause the focussing of the specular energy to be slightly “blurred”. The scattered energy arising at each reflecting point will be “beamed” towards the point antipodal to the transmitter but will not be focussed there since the angular distance from the point where the scattered energy originates to the point which is the transmitter’s antipode is always less than 180°. There will, however, still be a general clustering of the scattered energy in the vicinity of the point which is antipodal to the transmitter.