Talk:Prediction models

Latest comment: 17 years ago by Kevinz in topic Untitled

Untitled

edit

Tried to improve the appearance of the later equations. Removed the original poster's warning, "NOT FINALIZED, I HAVE PROBLEMS FORMATTING THE EQUATIONS", but somebody with more knowledge than I should check the equations for errors or more conventional formatting. Kevinz 19:26, 5 March 2007 (UTC)Reply

Copied from article

edit

Free Space

edit

The free space path loss model is usually the reference point from which all propagation models are employed and is used for determining free-space path loss. It is based on a   or 20-dB/decade path loss. The following equation shows the free-space or Friis equation:   Equation 1.1

where
  = power available at the receiving antenna
  = power supplied from the transmitting antenna
  = receiving antenna gain
  = transmitting antenna gain
  = distance between two antennas in free space.
  = wavelength

Since loss is generally expressed in dB, Equation 1.1 can be written as:

       Equation 1.2

where
  = free space path loss, in dB
  = distance, in km
  = carrier frequency, in MHz

For 900 MHz and 1800 MHz equation 1.2 can be reduced to the form:  , where A is the path loss at 1km and B is the slope: