Question 1119578
Put the parabola cross section description onto a cartesian plane system with vertex at origin and expect focus to be above the vertex.  You know three points.
(0,0), (5,4), and (-5,4).


{{{y=ax^2}}}


{{{a=y/x^2}}}

{{{a=4/(5*5)}}}

{{{a=4/25}}}

-

{{{y=(4/25)x^2}}}

{{{(25/4)y=x^2}}}

If p is how far focus is from vertex, then  {{{4p=25/4}}}
{{{p=25/16}}}.


Receiver should be  {{{25/16}}} feet or 1 foot 6 inches and {{{3/4}}} inch from the vertex.