On Thursday, Nov 21, 2002, at 19:20 US/Eastern, Tim Pozar wrote:
At 5.8GHz, TX power is still limited to 1W (30dBm), and if you're runningOf course at 5.8 GHz there are different restrictions on power.
PTP under the UNII rules, you get 23dBi of gain before you start a 1:1 reduction
in dBm for every dBi of antenna gain over 23dBi, while if you're running
PTP the ISM rules, antenna gain is unlimited. Relevant sections quoted:
47CFR15.247:
2)
(b) The maximum peak output power of the intentional radiator shall
not exceed the following:
(1) For frequency hopping systems in the 2400-2483.5 MHz band
employing at least 75 hopping channels, all frequency hopping systems in
the 5725-5850 MHz band, and all direct sequence systems: 1 watt.
[...]
(3) Except as shown in paragraphs (b)(3) (i), (ii) and (iii) of this
section, if transmitting antennas of directional gain greater than 6 dBi
are used the peak output power from the intentional radiator shall be
reduced below the stated values in paragraphs (b)(1) or (b)(2) of this
section, as appropriate, by the amount in dB that the directional gain
of the antenna exceeds 6 dBi.
(i) Systems operating in the 2400-2483.5 MHz band that are used
exclusively for fixed, point-to-point operations may employ transmitting
antennas with directional gain greater than 6 dBi provided the maximum
peak output power of the intentional radiator is reduced by 1 dB for
every 3 dB that the directional gain of the antenna exceeds 6 dBi.
(ii) Systems operating in the 5725-5850 MHz band that are used
exclusively for fixed, point-to-point operations may employ transmitting
antennas with directional gain greater than 6 dBi without any
corresponding reduction in transmitter peak output power.
47CFR15.407
(a) Power limits:
(3) For the band 5.725-5.825 GHz, the peak transmit power over the
frequency band of operation shall not exceed the lesser of 1 W or 17 dBm
+ 10logB, where B is the 26-dB emission bandwidth in MHz. In addition,
the peak power spectral density shall not exceed 17 dBm in any 1-MHz
band. If transmitting antennas of directional gain greater than 6 dBi
are used, both the peak transmit power and the peak power spectral
density shall be reduced by the amount in dB that the directional gain
of the antenna exceeds 6 dBi. However, fixed point-to-point U-NII
devices operating in this band may employ transmitting antennas with
directional gain up to 23 dBi without any corresponding reduction in the
transmitter peak output power or peak power spectral density. For fixed,
point-to-point U-NII transmitters that employ a directional antenna gain
greater than 23 dBi, a 1 dB reduction in peak transmitter power and peak
power spectral density for each 1 dB of antenna gain in excess of 23 dBi
would be required. Fixed, point-to-point operations exclude the use of
point-to-multipoint systems, omni directional applications, and multiple
collocated transmitters transmitting the same information. The operator
of the U-NII device, or if the equipment is professionally installed,
the installer, is responsible for ensuring that systems employing high
gain directional antennas are used exclusively for fixed, point-to-point
operations.
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