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A transmitting antenna radiates 251 watt isotropically. A receiving antenna locating 100 m away from the transmitting antenna has an effective aperture of 500 cm2. The total received power by the antenna is—
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- 10 µW
- 20 µW
- 1 µW
- 100 µW
Correct Option: D
PR = PT GT GR (λ/4πd)2
where
GR = 1
GT = 1 (for isotropic antenna)
PT = 251 watt (given)
Aeff = 500 cm2 = 500 × 10–4 m2
d = 100 m
Now,
PR = 251 × 1 × 1 × 4π/λ2
| 500 × 10–4 | = 9.99 × 10–5 = 100 µW | |
| (4π)2 × 100 × 100 |
