Phased Array Radar
The larger your antenna, the further your signal will go. One way to make a large antenna at microwave frequencies is to build a parabolic dish and place a point radiator at its focus (Fig. 6.1). With this, spherical field from the point radiator spreads out as it travels toward the dish. When it hits the metal dish, it scatters (bounces) off the dish and radiates out toward the opening of the dish. The wave front is in phase by the time it reaches the opening of the dish, thereby providing a columnated plane wave . Parabolic dish antennas can provide a considerable gain for applications from radar to satellite television reception.