On Thu, 26 Jul 2007 09:15:44 +0100, Jeff wrote:
"Allodoxaphobia" wrote in message
...
On Wed, 25 Jul 2007 18:12:26 +0100, Jeff wrote:

Note that in almost all places there are legal limitations on EIRP
(Effective Incident Radiated Power). In plain English, the more you
narrow a signal, the stronger it becomes.

Since you did not say where you are, I'll mention the two places I
know for sure. In the U.S. WiFi EIRP is limited to 1 watt for
mobile/portable use (e.g. laptops) and 4 watts for fixed links.

Bear in mind that 2.4GHz is also an amateur band where no erp limits
exist!!

Oh , really ?! cite!

Channels 1 to 6 lie with the 13cms amateur band, which does vary a little
from country to country nut in the UK is 2310-2450MHz, and there is no ERP
restriction in this band just a max power to the antenna, which can have
as much gain as you can muster.

For amateur radio, it's a limit on DC power to the final amplifier, which
you can make as efficient as you want; it's average power, so you can
run 2 KW PEP (peak envelope power) SSB, and gawd knows what kinds of
pulses you're allowed to transmit on the UHF, SHF, and EHF bands, as long
as the average isn't over 1 KW input to the final.

I'm sure it's all covered in the FCC regs, which should be easy to look up
for anyone who's really that interested. ;-)

Cheers!
Rich

In article ,
Rich Grise wrote:

Channels 1 to 6 lie with the 13cms amateur band, which does vary a little
from country to country nut in the UK is 2310-2450MHz, and there is no ERP
restriction in this band just a max power to the antenna, which can have
as much gain as you can muster.

For amateur radio, it's a limit on DC power to the final amplifier, which
you can make as efficient as you want; it's average power, so you can
run 2 KW PEP (peak envelope power) SSB, and gawd knows what kinds of
pulses you're allowed to transmit on the UHF, SHF, and EHF bands, as long
as the average isn't over 1 KW input to the final.

I'm sure it's all covered in the FCC regs, which should be easy to look up
for anyone who's really that interested. ;-)

I thought that the FCC had abandoned the "DC input power to the final"
standard quite some time ago (a decade or more, I think).

Most of the transmitter power standards for hams are in in 97.313,
which describes all of the limits in terms of PEP. Duty cycle,
modulation, and final efficiency are apparently no longer relevant in
most cases.

For most bands, and most operator classes, "legal limit" is 1500 watts
PEP. There are plenty of exceptions based on band, operator class,
and modulation (spread spectrum in particular) but these limits are
almost always defined in terms of PEP, which is referenced at the
transmitter-feedline connection.

There are some time-averaged and/or ERP limits described elsewhere in
Part 97, but these all seem to have to do with deciding when a
particular station must go through an evaluation for just how much RF
it's exposing humans in the area to.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Rich Grise wrote:
On Thu, 26 Jul 2007 09:15:44 +0100, Jeff wrote:

"Allodoxaphobia" wrote in message
...

On Wed, 25 Jul 2007 18:12:26 +0100, Jeff wrote:

Note that in almost all places there are legal limitations on EIRP
(Effective Incident Radiated Power). In plain English, the more you
narrow a signal, the stronger it becomes.

Since you did not say where you are, I'll mention the two places I
know for sure. In the U.S. WiFi EIRP is limited to 1 watt for
mobile/portable use (e.g. laptops) and 4 watts for fixed links.

Bear in mind that 2.4GHz is also an amateur band where no erp limits
exist!!

Oh , really ?! cite!

Channels 1 to 6 lie with the 13cms amateur band, which does vary a little
from country to country nut in the UK is 2310-2450MHz, and there is no ERP
restriction in this band just a max power to the antenna, which can have
as much gain as you can muster.


For amateur radio, it's a limit on DC power to the final amplifier, which
you can make as efficient as you want; it's average power, so you can
run 2 KW PEP (peak envelope power) SSB, and gawd knows what kinds of
pulses you're allowed to transmit on the UHF, SHF, and EHF bands, as long
as the average isn't over 1 KW input to the final.

So in the UK, they still regulate on the basis of DC power?
Interesting. I've always liked that philosophy because it promotes
design of efficient amplifiers.



I'm sure it's all covered in the FCC regs, which should be easy to look up
for anyone who's really that interested. ;-)

1.5 kW PEP, except in certain bands with lower limits (5 MHz, 430-450
MHz (depending on what your location is), etc.)

no averaging for pulses.. 97.3(b)(6)
PEP (peak envelope power). The average power supplied to the antenna
transmission line by a transmitter during one RF cycle at the crest of
the modulation envelope taken under normal operating conditions.

You can transmit pulses on 900 MHz and 2300 MHz and all higher bands,
but not 1.2 GHz (although you might be able to do pulses as part of a
data or spread spectrum modulation).

Clearly, if you want to operate a radar with your amateur license,
you're better off with one using pulse compression and long pulses.



Cheers!
Rich

So in the UK, they still regulate on the basis of DC power? Interesting.
I've always liked that philosophy because it promotes design of efficient
amplifiers.


Not for many years.

The normal UK limit, for a full licence, is 400W pep into the antenna on
most bands.

Jeff