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Good Friis Transmission results

  1. Apr 7, 2016 #1
  2. jcsd
  3. Apr 7, 2016 #2
  4. Apr 7, 2016 #3
    This is -80dBm. What is the sensitivity of your receiver? It should be better than -90dBm if it is a decent radio and you should be fine.
    What is the distance that you are plugging into Friis? Is it line of sight (it will need to be for Friis to apply).
  5. Apr 7, 2016 #4
  6. Apr 7, 2016 #5
    wait I get
    Received Power: 3.396e-7 mW

    not sure where that last number came from
  7. Apr 7, 2016 #6
    If you are getting 3.3e-7mW a mile away from your transmitter, it must be a really powerful transmitter.
    Maybe you should share the inputs that you are supplying to the Friis equation.

    BTW dBm is 10log(milliwatts)
  8. Apr 8, 2016 #7
    Frequency 900 MHz
    Gain 5 dBi
    Max. Power 50mW
    I used this site :

    the gain for the Tx is the same for the Rx because I am using the same antenna for both.
  9. Apr 8, 2016 #8
    Everything looks correct.
    You are getting exceptional range because:
    1 - your transmitter is high power (+17dBm), most zigbees transmit at 0dBm.
    2 - You are at 900MHz, not 2.4GHz. Lower frequency allows significant range increase.
  10. Apr 9, 2016 #9


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  11. Apr 9, 2016 #10
  12. Apr 10, 2016 #11


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