[MLB-WIRELESS] Bullet2 output power, why 1W or 100mW

[Mark Aitken]

mw at freenet.net.au wrote:
> G'day,
>
> Yeah, I can't think of many applications that would need a 1Watt
> transmitter.  That's not to say that there are no applications for one, just
> that I can't think of many ;-)
>
> 1Watt is about 30dBm, which means that your maximum antenna size is just
> 6dBi to keep within the 36dB EIRP limit.
>
> Now, consider a point to point link of about 50Km.  Theoretically you lose
> about 135dB signal through the air, so if you start with 26dB at the
> transmit end, by the time you go 20Km, you only have -99 to work with.  If
> your antenna is a meagre 6dBi, then the best possible result at the receiver
> is a measly -93: barely enough to do anything with it.
>
> BUT, if you used a 170mW transmitter, which is about 22dBm, then you can use
> a 14dBi antenna.  So over a 50Km link, you could potentially get -85dBm of
> signal to the receiver.  That's more likely to produce a reasonably usable
> result.
>
> The only reason I can think of that you would want to use a 1W transmitter
> would be when you want to do a relatively short hop point to point link
> (like less than 5Km perhaps), and you wanted to use small, aesthetically
> unobtrusive, antennas.
>
> Cheers!
>
>   
Or be a Amateur Radio Operator and use the 30dbi into a 24dbi dish 
giving you 54dbi to play with...gotta love it  :)