B1-Free Space Propagation

From its-wiki.no
Revision as of 20:47, 20 September 2014 by Josef.Noll (Talk | contribs)

Jump to: navigation, search

⌘ Free space propagation

develop propagation equation, see (http://www.antenna-theory.com/basics/friis.php)

  • convert into dB
  • provide examples for f = 10 MHz, 1 GHz, 100 GHz
  • discuss influences on radiation pattern

Free space attenuation

⌘Comments

F3-11.png Free space propagation from a transmit (t) to a receive (r) station.

FreeSpaceAttenuation.png

Calculation of free space attenuation. Note the increased free-space attenuation of approx 5 dB from 900 to 1800 Unik/MHz, and a further increase of 3 dB from 1800 (GSM 1800) to 2450 Unik/MHz (802.11b). Note also that increasing the distance by a factor of 10 will increase the power requirements by 20 dB.