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In a broadside array of 20 isotropic radiators equally spaced at a distance of λ/2. The beamwidth between first nulls is—
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- 51.3 degrees
- 11.46 degrees
- 22.9 degrees
- 102.6 degrees
Correct Option: B
For broadside array of 20 point sources. We have general formula for the array of n point sources have been as follow
| 2φ = 2 sin-1 |  |  | |
| nd |
where
m = no. of null 1st or 2nd
d = separation between the point sources
n = no. of point sources
for first nulls we take m = 1, n = 20 is given, so we get
| 2φ = 2 sin-1 | | | = 2 ×5.739 | |
| 20 × λ/2 |
= 11.478º
