You also might want to revisit your power figures - radio transmitters are rated (and regulated) in watts
, not amps
As to the question: barring any concrete answer, I'd recommend using the DD-WRT Wiki (and forum FAQs) as a baseline. While they're written with U.S. regulations in mind, Canada's regs are similar. I know I've seen 'legal limits' mentioned there once or twice (even if I don't remember the actual limit stated.)
Well 802.11 equipment is measured in dBi (decibels isotropic) on a rare occasion you run into one using dBd (decibles dipole). The FCC and other domain authorities usually define maximum power output for the intentional radiator (IR) (components making up an IR include the transmitter, all calbes and connectors, and any other equipment between transmitter and antenna with the power being measured in milliwatts (mW) (or decibles relative to 1 milliwatt (dBm)), but does not include the antenna itself) and a maximum equivalent isotropically radiated power (EIRP) that radiates from the antenna. EIRP is the highest RF signal strength that is transmitted from a particular antenna. 802.11 is going to use milliwatt (mW) and not watt (W), because most of the 802.11 equipment that you will be using transmits at power levels between 1 mW and 100 mW. Although the FCC may allow IR power output as much as 1 watt, only rarely in point -to-point communications, such as in building to building bridge links would you use 802.11 equipment with more than 250 mW of transmit power.
US, Canada, and Mexico have entered into the North American Regulatory (something I'll call it NA) and in theory are suppose to be the same, but you might want to check with your countries domain authority (because these numbers may have changed as well).
The NA regulatory domain sets limits for both maximum transmitter power and EIRP. The maximum power level for transmitters is regulated to 1 watt, or +30 dBm. This is for the 900-MHz (their is still some old wireless network equipment out there using this band) and the 2.4-GHz WLAN bands. For the 5-GHz bands the maximum power levels are different.
The NA regulations also specify both a maximum antenna gain and an EIRP limit. The regulations limit the antenna gain to 6 dBi if you are using the full +30 dBm transmitter power. This gives a maximum EIRP value of +36 dBm. The NA regulations do permit high gain antenna, if the transmitter power is reduced according to the rules and topology of the radio network.
The NA regulatory domain identifies the power levels for 5 GHz based on the three different UNII bands. UNII1 band was intended for indoor use, and provides only 50 mW transmitter power. The UNII2 band is intended for both indoor and outdoor usage, and the maximum power is increased to 250 mW. The UNII3 band is intended for use in outdoor systems and has a power limit of 1 W.
In the 5-GHz band in the NA regulatory domain, power may not exceed the lesser of the following:
â€¢ UNII1 50 mW or 4 dBm + 10logB (if you like to do math), where B is the 26-dB emission bandwidth in MHz.
â€¢ UNII2 250 mW or 11 dBm + 10logB, where B is the 26-dB emission bandwidth in MHz.
â€¢ UNII3 1 watt or 17 dBm + 10logB, where B is the 26-dB emission bandwidth in MHz.
Antenna gain is limited, as with the 2.4-GHz band for NA. It is 6 dBi maximum in a PTMP (Point-to-Multipoint) mode. To increase the antenna gain, the transmitter must be reduced by the same amount.
In the UNII3 band fixed point-to-point application antennas of up to 23 dBi gain may be used, without reductions in power. For antennas with higher gain than 23 dBi, a reduction of 1 dB transmitter power is required for every 1 dB increase the antenna has above 23 dBi.
For the UNII1 band, a major restriction that applied in the NA domain has been recently removed. The regulations had required that an antenna must be permanently attached to the radio device. External or removable antennas were not permitted. This caused many issues when trying locate an AP (Access Point) in a secure location, like above the ceiling, in a wiring closet, or a NEMA enclosure. Because you could not separate the antenna from the radio device, you had to mount the AP where you need the antenna. UNII2 and UNII3 bands permitted external antennas, with a maximum EIRP limit of 250 mW for UNII2 and 1 W for UNII3.
ThE restriction has been removed for UNII1, so products can now use external antennas for all channels within the 5-GHz band (UNII2 bands do have other regulations about radar/satellite interference. 802.11h with DFS (Dynamic Frequency Selection) and Transmit Power Control (TPC). Mostly came from what is called the UNII2 extended band, but covers the UNII2 band as well).
If a device combines operation of the UNII1 band with other bands, the device must comply with the UNII1 regulation requiring a permanently attached antenna. They also have rules with the connector ends to try and prevent you from putting too high of a gain antenna on a system.