Appendix D Wireless LANs
PLA450 User’s Guide
171
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 (IEEE 802.11b and IEEE 802.11g) or 5GHz (IEEE
802.11a) 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.
• Directional antennas concentrate the RF signal in a beam, like a flashlight does with the
light from its bulb. The angle of the beam determines the width of the coverage pattern.
Angles typically range from 20 degrees (very directional) to 120 degrees (less directional).
Directional antennas are ideal for hallways and outdoor point-to-point applications.
Summary of Contents for PLA-450 - V3.60
Page 2: ......
Page 7: ...Safety Warnings PLA450 User s Guide 7...
Page 8: ...Safety Warnings PLA450 User s Guide 8...
Page 10: ...Contents Overview PLA450 User s Guide 10...
Page 18: ...List of Figures PLA450 User s Guide 18...
Page 22: ...22...
Page 28: ...Chapter 2 PLA450 User s Guide 28...
Page 34: ...Chapter 3 The ENCRYPT Button PLA450 User s Guide 34...
Page 46: ...Chapter 4 Introducing the Web Configurator PLA450 User s Guide 46...
Page 55: ...55 PART II Network Wireless LAN 57 LAN 81 HomePlug AV 85...
Page 56: ...56...
Page 80: ...Chapter 6 Wireless LAN PLA450 User s Guide 80...
Page 84: ...Chapter 7 LAN PLA450 User s Guide 84...
Page 96: ...96...
Page 110: ...Chapter 11 Tools PLA450 User s Guide 110...
Page 112: ...Chapter 12 Configuration Mode PLA450 User s Guide 112...
Page 114: ...Chapter 13 Language PLA450 User s Guide 114...
Page 122: ...Chapter 14 Troubleshooting PLA450 User s Guide 122...
Page 128: ...128...
Page 176: ...Appendix E Common Services PLA450 User s Guide 176...
Page 180: ...Appendix F Legal Information PLA450 User s Guide 180...
Page 186: ...Appendix G Customer Support PLA450 User s Guide 186...