Required Antenna Height
Option on Calculate, Intervisibility menu of a map window with associated DEM.
Pick the location of a fixed antenna (use point selection verification, so that you get a very accurate placement) and its height.
Set these options.

Required antenna heights. This map requires that the
location of the fixed antenna, and its height, be
specified. The computation then determines how high a
mobile antenna would have to be if it were located at
each grid node in the DEM. The resulting surface can be
displayed like a DEM. The split map at the left shows a
reflectance view of the resulting surface, which retains
a recognizable imprint from the landscape, on the top,
and a colored height field on the bottom. Both depictions
have a radial pattern emanating from the location of the
fixed antenna, caused by dead zones behind hills which
project outward. These hills have the greatest impact when
they occur close to the fixed antenna. The map on right
combines elevation and reflectance shading, and probably
provides the best tool for analysis. These two diagrams assume a sensor range that can cover the entire DEM. If the range is less than the DEM size, regions outside the visible range will be missing data. This can also be used to calculate the permissible flying heights that will be visible or masked to a fixed radar. 
Map of grazing angle for a sensor.
Positive angles face the sensor, and negative angles slope away from it. Missing areas are masked. 
Earth curvature (with 3d shading from the DEM). 
Technical Details The algorithm creates a box from the antenna location, going out to the range requested, or the edge of the DEM, whichever comes first. It then draws radials from the location to each DEM grid location on the edges of the box, and fills in the location of the LOS as each grid point along the way. This is the minimum number of radials to be sure that a radial passes over every grid posting in the DEM. It uses a spacing along the radial of half the grid posting. Points close to the fixed antenna will be computed on a number of radials, and the last one computed will be the value retained. Earth curvature will always be a floating point grid; the others will have the same precision as the input DEM.
Applications. This could be used in at least two frames of reference:
Last revision 7/25/2014