The dish is
across at its opening and
deep at its center.
Set up the problem so that the vertex of the parabola is at
and it opens up.
The equation of the parabola is of the form
.
Since the parabola is
across and
deep at its center the points on the parabola is
and
.
Substiute and solve for
:

Where
is the distance from the distance from the vertex to the focus.
Therefore the receiver which is located at the focus is
or
from the base of the dish along the axis of the parabola.
The receiver should be placed
or
from the base of the dish.