The discussion revolves around the evaluation of received power calculations using the Friis Transmission equation, specifically in the context of Zigbee communication at a distance of one mile. Participants are exploring whether the calculated received power values are acceptable and discussing the implications of various parameters such as frequency, transmitter power, and antenna gain.
Participants express uncertainty regarding the adequacy of the received power values and the implications of various parameters. There is no consensus on what constitutes a "good" received power, and multiple viewpoints on the significance of the calculated values remain present.
Participants have not fully resolved the assumptions regarding the inputs to the Friis equation, nor have they clarified the definitions of "good" received power in this context.
btb4198 said: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.
btb4198 said:wait I get
Received Power: 3.396e-7 mW
not sure where that last number came from
Frequency 900 MHzthe_emi_guy said: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)
What is the antenna gain or aperture?btb4198 said: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.
https://en.wikipedia.org/wiki/Antenna_gaintech99 said:What is the antenna gain or aperture?
Sorry, I meant antenna gain in your case, so I can look at the calcs.the_emi_guy said: