Copyright © 2004 Cisco Systems, Inc. All rights reserved.
Page 4 of 53
1.2.3 Power Levels
The UNII-2 band is intended for wireless bridging both for indoor applications as well as short
range outdoor applications. UNII-3 band, with far greater transmit power and antenna gain
allowances is preferable for
long range
outdoor wireless bridging.
To facilitate this, the regulations allow for connectors and the use of cable and auxiliary antennas for
both of these bands. The effective radiated power allowed in UNII-3 band is 4 watts (36 dBm),
which is much more than the radiated power of 1 watt (30 dBm) allowed in UNII-2 band. Rather,
the UNII-2 band is treated by the Wi-Fi community as being a less-restrictive extension of the
UNII-1 band generally supporting clients and Access Points.
The channel numbers corresponding to the four centre frequencies for UNII-3 band are 149,153,
157 and 161.
Regulatory Domain Frequency Band
Channel number
Centre frequencies
USA
UNII middle band
5.725-5.825 GHz
149
153
157
161
5.745 GHz
5.765 GHz
5.785 GHz
5.805 GHz
Table 1.
Channel Numbers for UNII-3 Band
The maximum antenna gain allowed is 6dBi. The transmit power may be reduced to accommodate
higher gain, more directional antennas while staying within the EIRP limits for a particular band. This
is explained in detail, later in this section.
5.15
5.35
5.725
5.25
4Channe
ls
40mW
250mW
1W
UNII-1:
Indoor Use, antenna must be fixed to the radio
UNII-2:
Indoor/Outdoor Use, fixed or remote antenna
UNII-3:
Primarily used for Outdoor Bridging
UNII-1
UNII-2
UNII-3
Conducted Power
(16dBm
)
(24dBm
)
(30dBm
)
Radiated
Power
Antenna
Gain
6dB
i
6dB
i
6dB
i
22dB
m
30dBm
36dBm
1 W
4W
158mW
5 GHz UNII
Band
4Channe
ls
4Channe
ls