|Image of the Waveguide-fed E-plane sectoral horn.|
One of the simplest and probably the most widely used microwave antenna is the horn. Its existence and early use dates back to the late 1800s, and is widely used as a feed element for large radio astronomy, satellite tracking, and communication dishes throughout the world. In addition to its utility as a feed for reflectors and lenses, the pyramidal horn serves as a universal standard for calibration and gain measurements of other high-gain antenna, [Balanis]. As such, it is often referred to as the standard gain horn.