Re: Longer legal links?

I see, this depends though on both ends of the links having this 
same setup.

Unfortunately, I think the major problems of range (within cities) are 
due to obstacles blocking LOS, and not lack of power.

Rob

From:           	"Andy Laurence" <[email protected]>
To:             	<[email protected]>
Subject:        	Re: [consumebristol] Longer legal links?
Date sent:      	Mon, 14 Oct 2002 09:42:25 +0100
Send reply to:  	[email protected]

> > How does having a more sensitive Rx antenna increase Tx range?
> 
> OK, basically, we're limited by a legal maximum transmit power of 20dB.
> Most cards use the same antenna for transmit *and* receive.  By having a
> transmit antenna and a receive antenna, you can increase gain on the receive
> end, as this is not regulated by law.  The distance you can get a signal is
> regulated by the number of decibels your link has.
> 
> For example, my card at home is a 15dB model, and has a 5dB antenna on it.
> If two identical machines like this were setup, then there would be 15db +
> 5dB+ 5dB = 25dB in the link.  That's transmit power (15dB) + transmit gain
> (5dB) + receive gain (5dB).  If
> you can increase receive gain without increasing transmit gain, the numbers
> will be higher, and therefore go further.
> 
> transmit power + transmit gain must be less than 20dB
> transmit power + transmit gain + receive gain relates to distance
> (bigger=further)
> 
> Also, there is leakage between the antennas, so there are other things to
> consider which were explained in the previous mail.  It all boils down to
> longer links whilst staying legal.
> 
> Andy
> 
>