Good Friis Transmission results

[btb4198]

using a online Friis Transmission calculator I found out that my Received Power is 1.509e-9 mW. is that good or bad ? How do I found out ? I am using a zigbee
https://www.sparkfun.com/products/9099
https://www.sparkfun.com/products/9143

 

[btb4198]

If I use this one http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_47&products_id=169,
I would get
Received Power: 9.433e-9 mW
but I do not know if that is good or not.

 

[the_emi_guy]

If I use this one http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_47&products_id=169,
I would get
Received Power: 9.433e-9 mW
but I do not know if that is good or not.

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).

 

[btb4198]

1 Mile is the Distance and the Sensitivity of the receiver is -100 dBM.
https://www.sparkfun.com/datasheets/Wireless/Zigbee/XBee-900-Datasheet.pdf
how did you get -90 dBM?

 

[btb4198]

wait I get
Received Power: 3.396e-7 mW

not sure where that last number came from

 

[the_emi_guy]

wait I get
Received Power: 3.396e-7 mW

not sure where that last number came from

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)

 

[btb4198]

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)

Frequency 900 MHz
Gain 5 dBi
Max. Power 50mW
I used this site :
https://www.pasternack.com/t-calculator-friis.aspx

the gain for the Tx is the same for the Rx because I am using the same antenna for both.

 

[the_emi_guy]

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.

 

[tech99]

Frequency 900 MHz
Gain 5 dBi
Max. Power 50mW
I used this site :
https://www.pasternack.com/t-calculator-friis.aspx

the gain for the Tx is the same for the Rx because I am using the same antenna for both.

What is the antenna gain or aperture?

 

[the_emi_guy]

What is the antenna gain or aperture?

https://en.wikipedia.org/wiki/Antenna_gain

 

[tech99]

https://en.wikipedia.org/wiki/Antenna_gain

Sorry, I meant antenna gain in your case, so I can look at the calcs.