Semi-directional antennas

Semidirectional antennas

  • Semidirectional antennas radiate RF in a in a similar way a street lamp shines light down on a street or a parking lot, providing a directional light across a large area.
  • Semidirectional antennas are designed to direct a signal in a specific direction.
  • Semidirectional antennas are used for short- to medium-distance communications
  • It is common to use semidirectional antennas to provide a network bridge between two buildings in a campus environment or down the street from each other.
  • Can be used for outdoor point-to-point communications up to about a mile
  • More commonly used as a central device to provide unidirectional coverage from the access point to the clients in an indoor environment.
  • Can be used effectively in libraries, warehouses, and retail stores with long aisles of shelves
  • Can provide coverage for long hallways with offices on each side or hospital corridors with patient rooms on each side. Antenna can be placed at the end of the hall and aimed down the corridor.
  • The most common use case for deploying a MIMO patch antenna indoors is a high-density environment.
  • MIMO patch and panel antennas are often mounted from the ceiling downward to provide tight “sectors” of coverage. The most common use of indoor MIMO patch antennas is for high-density environments.
  • Semidirectional antennas can be installed high on a wall and tilted downward toward the area to be covered.
  • 3 types of semidirectional category:
    1. Yagi antennas: Yagi-Uda antennas, are typically used for short- to medium-distance point-to-point communications of up to about 2 miles, although high-gain Yagi antennas can be used for longer distances.
    2. Patch antennas: Patch refers to a particular way of designing the radiating elements inside the antenna.
    3. Panel antennas





Radiation patterns of a typical semidirectional panel antenna: