Appendix E Wireless LANs
NWA1120 Series User’s Guide
199
Antenna Overview
An antenna couples RF signals onto air. A transmitter within a wireless device sends an RF signal to
the antenna, which propagates the signal through the air. The antenna also operates in reverse by
capturing RF signals from the air.
Positioning the antennas properly increases the range and coverage area of a wireless LAN.
Antenna Characteristics
Frequency
An antenna in the frequency of 2.4GHz or 5GHz is needed to communicate efficiently in a wireless
LAN
Radiation Pattern
A radiation pattern is a diagram that allows you to visualize the shape of the antenna’s coverage
area.
Antenna Gain
Antenna gain, measured in dB (decibel), is the increase in coverage within the RF beam width.
Higher antenna gain improves the range of the signal for better communications.
For an indoor site, each 1 dB increase in antenna gain results in a range increase of approximately
2.5%. For an unobstructed outdoor site, each 1dB increase in gain results in a range increase of
approximately 5%. Actual results may vary depending on the network environment.
Antenna gain is sometimes specified in dBi, which is how much the antenna increases the signal
power compared to using an isotropic antenna. An isotropic antenna is a theoretical perfect antenna
that sends out radio signals equally well in all directions. dBi represents the true gain that the
antenna provides.
Types of Antennas for WLAN
There are two types of antennas used for wireless LAN applications.
• Omni-directional antennas send the RF signal out in all directions on a horizontal plane. The
coverage area is torus-shaped (like a donut) which makes these antennas ideal for a room
environment. With a wide coverage area, it is possible to make circular overlapping coverage
areas with multiple access points.
WPA2 TKIP/AES No Enable
WPA2-PSK TKIP/AES Yes Disable
Table 58 Wireless Security Relational Matrix (continued)
AUTHENTICATION
METHOD/ KEY
MANAGEMENT PROTOCOL
ENCRYPTIO
N METHOD
ENTER
MANUAL KEY
IEEE 802.1X
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