Loss and Gain in a System

• Gain:

  • Transmitter Output Power (TPO) in dBm or Watts.
    • dBm = 10*log10(power in milliwatts / 1 mW)
    • 0 dBm/1 mW; 15dBm/30mW; 20dBm/100mW; 30 dBm/1 W
  • Transmitter and receiver amplifiers
  • Transmit and receiving antennas.

• Loss:

  • Coax, connectors
    • ie. LMR-400: 0.22 dB per meter.
  • Free-space loss
    • dB = 92.4 + 20 Log10 (distance in km) + 20 Log10 (freq. in GHz)
  • Obstructions and Diffraction (ie. Trees, rain, etc.)
  • Atmospherics (ie. Snow/Rain, Refraction (ie. Ducting)

Notes: