Horn antennas, colloquially referred to as gain horn antennas, are used for the transmission and reception of microwave signals. This name is derived from their characteristic flared appearance. The flared portion can be square, rectangular, or conical in shape. The maximum radiation and response corresponds with the axis of the horn. In this respect, the antenna resembles an acoustic horn. Horn antennas are usually fed by waveguides in:

• microwave antenna applications
• high gain antenna and high gain wireless antenna applications
• microwave antenna applications

Specifications

The main operating specifications for horn antennas are operating frequency range and gain. The operating frequency is the frequency range through which the horn antenna will meet all functional specifications. Gain is the ratio of the power required at the input of a loss-free reference antenna to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength at the same distance usually in the direction of maximum radiation. Antenna gain is normally expressed in decibels, or dB.

Features

In order to function properly, horn antennas must be a certain minimum size relative to the wavelength of the incoming or outgoing electromagnetic field. If the horn is too small or the wavelength is too large (the frequency is too low), the antenna will not function efficiently. Horn antennas are commonly used as the active element in a dish antenna. The horn is pointed toward the center of the dish reflector. The use of a horn, rather than a dipole antenna or any other type of antenna, at the focal point of the dish minimizes loss of energy (leakage) around the edges of the dish reflector. They also minimize the response of the antenna to unwanted signals not in the favored direction of the dish. Horn antennas can be used without attendant components in short range radar systems, particularly those used by law-enforcement personnel to measure the speeds of approaching or retreating vehicles.

Related Information

IEEE Spectrum—Smart Antennas Could Open Up New Spectrum for 5G

IEEE Spectrum—Swirly Antennas Will Hunt for the Twists of Ancient Gravitational Waves

IEEE Spectrum—Millimeter Waves May Be the Future of 5G Phones

Image credit:

Schwarzbeck Mess-Elektronik / CC BY-SA 3.0