Why are dish antennas used in D2h concave in shape?

TV signals received are attenuated by the concave reflecting surface

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TV signals received are focussed at the focal point by the converging action of the concave reflecting surface

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This shape is more immune to noise

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None of the above

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Solution

The correct option is B TV signals received are focussed at the focal point by the converging action of the concave reflecting surface
Dish antennas are concave in shape so as to increase the amount of incident EM wave energy on the antenna. This is done by keeping the receiver at the focal point of the spherical surface where em-waves converge at one point.

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Figure

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(c) Where should the antenna be positioned to receive the strongest possible signals?
(d) Explain what change you would expect in the signals if a larger dish was used.

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