Subreflector Gain Characteristics
Jim Breakall
April 19, 2015
Subreflector is modeled as a circular parabolic reflector with various focal lengths. Focal Length chosen for original design is 136 feet. The depth of the parabolic reflector can be found from the following formula:
Depth = Diameter ^2 / (16 * Focal Length)
Diameter of Subreflector at widest is 370.4 feet. That is used here for the circular parabolic reflector.
|
Focal Length (ft) |
Subreflector Depth (ft) |
Gain (dBi) |
|
50 |
171.4 |
17.67 |
|
100 |
85.7 |
20.63 |
|
136 |
63.0 |
22.14 |
|
150 |
57.1 |
22.36 |
|
200 |
42.9 |
22.26 |
|
300 |
28.6 |
21.21 |
|
Flat Disk |
|
17.9 |
|
Gain (dBi) |
|
|
150 |
13.27 |
|
175 |
20.62 |
|
200 |
21.65 |
|
225 |
20.88 |
|
250 |
19.68 |
|
260 |
19.99 |
|
270 |
21.02 |
|
280 |
22.17 |
|
284 |
22.14 |
|
290 |
21.74 |
|
300 |
21.14 |
|
350 |
20.24 |