1.
Problem A number of parabolic dish antennas have been shipped without a correctly placed feed
horn mounting arm (figure 1), and installation technicians are using trial-and-error to mount the
arm (figure 2)-this is taking too long; our customers want them in-and-out quickly, as do we. For
Figure 1. Out of the Box Antenna mountine arm Figure 2 basic Parabolic Antenna setup
Solution: All installation technicians carry a computer, ruler and the needed drill bits, screws,
antennas, mounting arm, feeder horn, cabling and other tools. Your job is to help the technicians
quickly place the feed horn's mounting arm; to that end, you are to research a formula that
determines feed horn's Focus distance from the base (see figure 3). 2
Solution
Solution:
The position of the focus is found in terms of the diameter of the dish and its depth.
Obtaining the equations the parabola, So that the focal distance appears in the equation.
By using the definition of the parabola :
From the figure,
Let Focal length be f
Depth=d
Diameter=D
Hence the formula obtained is ,
f = ( D * D ) / ( 16 * d )
The above formula helps in positioning the feed of the parabolic antenna as it gives the focal
distance f.