End-fire coupling refers to a method of coupling energy into or out of a waveguide, transmission line, or antenna, where the electromagnetic waves are directed primarily along the axis or direction of the structure. This coupling technique is characterized by the propagation of waves along the end or edge of the waveguide or antenna structure.
In the context of antennas, end-fire coupling is often associated with directional antennas, where the main radiation lobe is directed along the axis of the antenna. This configuration allows for a more focused and directive radiation pattern in a specific direction.
End-fire coupling is utilized in various applications, including radio frequency (RF) systems, radar systems, and communication systems, where directional antennas are essential for focusing signal transmission or reception in specific directions.