parabolic shape of rx antenna

parabolic shape of rx antenna......:-

For a rx. antenna it is necessary to accumulate signals in a greater extent ,so that the beam area under the major beam lobe as much as possible. in parabolic reflecting antennas a property of light is being used, the reflective property. as the antenna is parabolic in nature, when signals fall in the dish, the dish reflect the signal in a converging manner. at the center of the antenna a sensor (receiver) is placed and it get the signal with high intensity... so a high accuracy signal is being received.

But, in some cases yagi uda antenna is also used as rx. , because it is mainly an array of antenna(BSA or EFA), so its efficiency can be manipulated by adjusting the no. of array elements.........again, the size of an antenna should be optimized according to its efficiency.....