On Mon, 08 Dec 2008 00:59:16 -0800, John Smith
wrote:

Jeff Liebermann wrote:

...
Maybe, but more likely, not enough RF to do anything useful with an
un-amplified meter.

What's missing from everyone's posting is what they plan to do with
this field strength meter.

Let's play with the numbers. The average wi-fi access point belches
about +12dBm (32 mw) RF into an antenna with perhaps 2dBi gain. The

Hmmm, max power for a wifi router is 1 watt!

I said "average wi-fi access point". 1 watt routers are relatively
rare among the common home wireless routers. Most run about 32mw.
Some Buffalo models run about 250mw. 2wire 2701 can run up to about
450mw. I think Enginius also makes one at around 1 watt.

The problem with this is what I call the "alligator" effect. An
alligator is an animal with a big mouth and small ears. Running a 1
watt access point will make the xmitter heard over a much wider area
than it can hear the responses from the clients. Unless the other end
of the link (i.e. client radios) are also running the same high power
level, the range will be limited by the clients tx power. In other
words, the system gain and power levels in both directions have to be
evenly matched to avoid turning the high power access point into what
I consider to be no better than a jamming transmitter. If you need a
slogan, you should use "only as much power as necessary" which doesn't
mean crank it up to the max. Please print this slogan on a large sign
and plaster it in front of your desk until the meaning sinks in. Also,
note that most modern communications technologies includes automatic
transmit power control (usually based on RX SNR or BER) to prevent
alligators and systems like yours from becoming a problem.

Here is a full power one:
http://www.wirelessnetworkproducts.c...OD&ProdID=1425
The router I presently use is "belching" 500mw into a 7.5db antenna
(well, I might question the 7.5db ...)

Turn down the power to about 100mw. The antenna is fine because it
results in a symmetrical improvement in system gain. Also, give
yourself a slap on the wrist, repent your evil ways, and pray for
forgiveness.

Throw out your access point man! Get a decent one ...

You haven't seen my office. I never throw anything away.

Regards,
JS
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558