Antennas

Polarisation

  • A wave is said to be polarised in the direction of the electric lines of force relative to the surface of the earth.  In the above diagram the wave is vertically polarised
  • Polarisation is determined by the transmitting antenna.  Horizontal antennas transmit horizontally polarised waves and vertical ones vertically polarised waves
  • Polarisation of waves will alter during ionospheric propagation
  • For line-of-sight propagation, transmitting and receiving aerials should have the same polarisation.  If one is horizontally and one vertically polarised there are significant losses