[MLB-WIRELESS] Amplifier question...

[Tony Langdon, VK3JED]

At 04:30 PM 29/04/2002 +1000, Will Lanigan wrote:

>i think its just the cost :-/



> > http://www.x.net.au/wireless.html), it is legal to transmit at up to 4W
> > in the 2.4Ghz range in Australia - Considering that most of the cards
> > that are popular are rated at about 30-100mW, wouldn't this be a massive
> > advantage having that much power available?

Not necessarily.  Remember, this is not 4W RF power, but 4W EIRP (power x 
antenna/feed system gain).  Even with a 30mW card it's easy to exceed this 
limit with a 24dBi Galaxy antenna (if you have a fairly short run of 
LMR-400 as a feedline).  The benefits of using an antenna to reach the 
maximum legal power limit, rather than an amplifier include:

1.  Cost - Galaxy antennas are cheap, amps are $$$$$$

2.  Antenna gain affects transmit and receive performance in an identical 
fashion.  Amplifiers tend to favour transmitter performance (because noise 
at 2.4 GHz is usually dominated by factors beyond one's control).

However, that said, there may be some use in a smallish amplifier for APs 
(say 1/2W into a 10dBi omni - yeah, I know, that's slightly over the limit, 
but by the time you add a dB or two of connector/feeder loss, you'll be legal).

73 de Tony, VK3JED
http://vk3jed.vk.irlp.net