Antenna Feeds

Abstract

The term “antenna feeds” describe many types of antennas in common use today. Feeds are a means of supplying energy to (or receiving energy from) a secondary antenna, such as a reflector, lens, reflectarray, or beam waveguide, via a transmission line or waveguide. Everyday applications of antennas with feeds include satellite communications, radar, radio telescopes, deep‐space probes, and terrestrial microwave and millimeter‐wave radiolinks.After a brief historical introduction, the basic characteristics of antenna feeds are explained. Specific feed types are then described under four main headings, namely, aperture, linear, traveling‐wave, and compound antennas. The approach adopted combines a short description of physical attributes with an outline of possible applications.The class of aperture antennas is the most extensive, and details are given of various circular and rectangular waveguides and horns, self‐supporting feeds, and microstrip patches in feed applications. Linear antenna feeds include the Yagi–Uda, log‐periodic, and zigzag arrays. These are reviewed, and the properties of importance are highlighted. Under the heading of traveling‐wave antennas, the antennas discussed include dielectric rods, profiled slots, Vivaldi antennas, and linefeed antennas for cylindrical and spherical reflectors. Finally, the antennas covered in the compound feeds category are arrays, beam waveguides, splash plates, and dichroic reflectors.Antenna feeds are linked intrinsically with feed systems, and some examples given are diplexers, beamforming networks, and comparator networks for monopulse tracking.The article concludes with an outline of modern design methods of importance of feed antennas and some predictions of possible future developments.