The reflector horn type antenna has greater "side lobe" rejection, directionality and sensitivity (efficiency) than a dish type.
The parabolic antenna is really not an antenna at all - but a collector/reflector, which catches and concentrates RF (radio frequency) into a tiny antenna mounted above the dish, pointed into the dish. Since satellites transmit at very high frequencies (microwave), the actual antenna can be shorter than one inch. To strenghen the signal and make aiming the antenna at the satellite easier, the parabolic reflector picks up a wider area of RF.
because patch antenna are used in order to achieve higher gain small dimensions, light weight, slim size and easy manufacturing as compared with parabolic dish or other antenna's
Virtually all terrestrial microwave communication is point-to-point, using parabolic reflector antennas. A small percentage uses yagi, helical, corner reflector, or flat-plate reflector antennas. Essentially no "omnidirectional" antennas are used in microwave.
Warren L. Stutzman has written: 'Antenna theory and design' -- subject(s): Antennas (Electronics), Equipment and supplies, Telecommunication 'Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas' -- subject(s): Antenna arrays, Antenna radiation patterns, Antennas, Reflector, Correction, Errors, Large space structures, Parabolic reflectors, Reflector Antennas, Shapes, Spacetennas
parabolic
Radar and communications are two different applications of radio waves. For radar, directional antennas are used, and the normal antenna for a ship installation would be a parabolic reflector with a rectangular aperture about 5 times wider than its height. This gives a narrow beam in the horizontal direction, and pulses are sent out and detected after being reflected by the target.
Parallel rays, such as those from a very distance source, are focussed by a parabolic antenna so that they all meet at the focus of the parabola. This results in a stronger signal.
plane reflector
It would be a waste of precious metal if there was.
A: For the same reason a heater is parabolic to reflect heat, For the antenna the opposite is true to focus the incoming waves
Craig Scott has written: 'Modern methods of reflector antenna analysis and design' -- subject(s): Antennas, Reflector, Reflector Antennas