PathLoss(in dB) = 92.45 + 20*log(d) + 20*log(F)

d in kilometers and F in MHz.

Just don't use this formula where significant ground
wave exits  like in the AM broadcast band over open
sea (salt) water!

Note that these seeemingly simplistic formulas take into
account 1) inverse square law and 2) 'antenna aperature'/capture
area.

Transmitter power-> Xmit
                    Ant gain -> Path loss -> Receive
                                             Ant gain -> power at Receiver



RF Jim

----- Original Message -----
From: "Jinx" <joecolquitt@CLEAR.NET.NZ>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, October 07, 2002 6:47 PM
Subject: [EE]: Calculating RF power at a distance


> I'm trying to set up a network of PICs that chatter to each other
> via RF. Everything is ticketyboo so far, but I'd like to know how
> to calculate the transmitter power to meet the requirements of
> the receiver. Say the receiver has 2uV sensitivity, and the distance
> between PICs is 100m - what minimum wattage would the
> transmitter be ? I'm guessing the inverse square law is the guide,
> and V/m too. I've looked up RF calcs with no practical success,
> so if anyone can offer real-world help that would be appreciated
>
> --
> http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> email listserv@mitvma.mit.edu with SET PICList DIGEST in the body
>
>

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