LEAN ON ME CHORDS (ver 5) by Bill Withers @
The most well-known reflector antenna is the parabolic reflector antenna, commonly known as a satellite dish antenna. Examples of this dish antenna are shown in the following Figures. Figure 1. The "big dish" antenna of Stanford University. Figure 2. A random direcTV dish antenna on a roof. Parabolic reflectors typically have a very high gain (30-40 dB is common) and low cross polarization. They also have a reasonable bandwidth, with the fractional bandwidth being at least 5% on commercially available models, and can be very wideband in the case of huge dishes (like the Stanford "big dish" above, which can operate from 150 MHz to 1. 5 GHz). The smaller dish antennas typically operate somewhere between 2 and 28 GHz. The large dishes can operate in the VHF region (30-300 MHz), but typically need to be extremely large at this operating band. The basic structure of a parabolic dish antenna is shown in Figure 3. It consists of a feed antenna pointed towards a parabolic reflector. The feed antenna is often a horn antenna with a circular aperture.