Max 802.11b Power?

Anyone know what the maximum legal wattage in the USA is for 801.11b
devices? 500mw like public FRS band stuff? Is there some other method used
by the FCC to measure field strength?

--
John Shirley
Remove SPAM SUCKS to E-mail

Absolute maximum input power to the antenna is 1 Watt assuming the antenna
is less than 6 dBi gain (36 dBi effective isotropic radiated power.) For
antennas of more than 6 dBi gain, one must reduce input power to the antenna
one dBm per dBi of antenna gain over 6 dBi (in other words, the EIRP must
never exceed 36 dBm.) One Watt is 30 dBm.

There is a special case for fixed point to point communications. It's only
necessary to reduce input power to the antenna one dBm for every 3 dBi of
antenna gain over 6 dbi.

Find the FCC rules here under CFR47 Part 15.247(b)3 and 15.247(b)4:
http://tinyurl.com/jgqd

Also notice 15.204:
http://tinyurl.com/jgqy

In most cases it's not necessary to use full 'legal' power. What are you
trying to do? Perhaps there is a less expensive and more desireable
alternative than increasing power. In most cases it does little or no good
to amp an access point if the clients have no amps. In most cases it's more
effective to reduce the length of transmission line by putting the access
point at the antenna than to compensate for transmission line losses with
amplifiers.

Don W.

"John Shirley" <(E-Mail Removed)> wrote in message
news:Xns93D1850369AD6esthermofetmsncom@207.225.159 .6...
> Anyone know what the maximum legal wattage in the USA is for 801.11b
> devices? 500mw like public FRS band stuff? Is there some other method
used
> by the FCC to measure field strength?
>
> --
> John Shirley
> Remove SPAM SUCKS to E-mail

Sometime before 08 Aug 2003, Don W. stated:

> Absolute maximum input power to the antenna is 1 Watt assuming the
> antenna is less than 6 dBi gain (36 dBi effective isotropic radiated
> power.) For antennas of more than 6 dBi gain, one must reduce input
> power to the antenna one dBm per dBi of antenna gain over 6 dBi (in
> other words, the EIRP must never exceed 36 dBm.) One Watt is 30 dBm.
>
> There is a special case for fixed point to point communications. It's
> only necessary to reduce input power to the antenna one dBm for every 3
> dBi of antenna gain over 6 dbi.
>
> Find the FCC rules here under CFR47 Part 15.247(b)3 and 15.247(b)4:
> http://tinyurl.com/jgqd
>
> Also notice 15.204:
> http://tinyurl.com/jgqy
>
> In most cases it's not necessary to use full 'legal' power. What are
> you trying to do? Perhaps there is a less expensive and more
> desireable alternative than increasing power. In most cases it does
> little or no good to amp an access point if the clients have no amps.
> In most cases it's more effective to reduce the length of transmission
> line by putting the access point at the antenna than to compensate for
> transmission line losses with amplifiers.
>
> Don W.
>
> "John Shirley" <(E-Mail Removed)> wrote in message
> news:Xns93D1850369AD6esthermofetmsncom@207.225.159 .6...
>> Anyone know what the maximum legal wattage in the USA is for 801.11b
>> devices? 500mw like public FRS band stuff? Is there some other
>> method used by the FCC to measure field strength?
>>
>> --
>> John Shirley
>> Remove SPAM SUCKS to E-mail
>
>
>

Going through about four residential walls, no line of sight, approx 150
feet straight line distance; from a residence to a detatched garage in an
apartment complex. There will be a DWL900AP+ for the AP in the residence
with some sort of omni-directional antenna to saturate the hell out of the
residence (and anyone driving by) and another DWL900AP+ in client mode in
the garage with a directional antenna. I'll actually end up having to shoot
through another apartment and across a small parking lot to get a signal to
the garage.

It might not need to be amplified at all, I was just wondering how much I
could get away with legally if I needed to boost it on either end.

Then, again, I've seen some prices on various amps... ouch.

--
John Shirley
Remove SPAM SUCKS to E-mail

"John Shirley" <(E-Mail Removed)> wrote in message
news:Xns93D1C2148A88esthermofetmsncom@207.225.159. 6...
> Sometime before 08 Aug 2003, Don W. stated:
>
> > Absolute maximum input power to the antenna is 1 Watt assuming the
> > antenna is less than 6 dBi gain (36 dBi effective isotropic radiated
> > power.) For antennas of more than 6 dBi gain, one must reduce input
> > power to the antenna one dBm per dBi of antenna gain over 6 dBi (in
> > other words, the EIRP must never exceed 36 dBm.) One Watt is 30 dBm.
> >
> > There is a special case for fixed point to point communications. It's
> > only necessary to reduce input power to the antenna one dBm for every 3
> > dBi of antenna gain over 6 dbi.
> >
> > Find the FCC rules here under CFR47 Part 15.247(b)3 and 15.247(b)4:
> > http://tinyurl.com/jgqd
> >
> > Also notice 15.204:
> > http://tinyurl.com/jgqy
> >
> > In most cases it's not necessary to use full 'legal' power. What are
> > you trying to do? Perhaps there is a less expensive and more
> > desireable alternative than increasing power. In most cases it does
> > little or no good to amp an access point if the clients have no amps.
> > In most cases it's more effective to reduce the length of transmission
> > line by putting the access point at the antenna than to compensate for
> > transmission line losses with amplifiers.
> >
> > Don W.
> >
> > "John Shirley" <(E-Mail Removed)> wrote in message
> > news:Xns93D1850369AD6esthermofetmsncom@207.225.159 .6...
> >> Anyone know what the maximum legal wattage in the USA is for 801.11b
> >> devices? 500mw like public FRS band stuff? Is there some other
> >> method used by the FCC to measure field strength?
> >>
> >> --
> >> John Shirley
> >> Remove SPAM SUCKS to E-mail
> >
> >
> >
>
> Going through about four residential walls, no line of sight, approx 150
> feet straight line distance; from a residence to a detatched garage in an
> apartment complex. There will be a DWL900AP+ for the AP in the residence
> with some sort of omni-directional antenna to saturate the hell out of the
> residence (and anyone driving by) and another DWL900AP+ in client mode in
> the garage with a directional antenna. I'll actually end up having to
shoot
> through another apartment and across a small parking lot to get a signal
to
> the garage.
>
> It might not need to be amplified at all, I was just wondering how much I
> could get away with legally if I needed to boost it on either end.
>
> Then, again, I've seen some prices on various amps... ouch.
>
> --
> John Shirley
> Remove SPAM SUCKS to E-mail

Since the client DWL900AP+ in the garage is in a fixed position relative to
the AP, a highly directional antenna on that device would be my first
suggestion. The least expensive and simplest antenna solution would be to
add to the stock antennas a reflector:
http://www.freeantennas.com/

Next, position the client in the garage next to a window facing the house or
put it in a weatherproof enclosure on the roof of the garage.

Finally, consider adding a third DWL900AP+ wired to the AP in the house via
Ethernet and position it in a window facing the garage. This way you can
configure the garage link as a bridge. That will improve security somewhat
since most clients would have a hard time eavesdropping on either end of a
bridge. It's less expensive to add another DWL900AP+ than to add an
amplifier.

Don W.