Appendix C Wireless LANs
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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 NBG-510S
Page 2: ......
Page 7: ...Safety Warnings NBG 510S User s Guide 7 This product is recyclable Dispose of it properly ...
Page 8: ...Safety Warnings NBG 510S User s Guide 8 ...
Page 18: ...Table of Contents NBG 510S User s Guide 18 ...
Page 26: ...26 ...
Page 44: ...Chapter 5 Setup Wizard NBG 510S User s Guide 44 Figure 20 Wizard Applying Internet Settings ...
Page 58: ...Chapter 6 Tutorials NBG 510S User s Guide 58 ...
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Page 76: ...Chapter 8 WAN NBG 510S User s Guide 76 ...
Page 78: ...Chapter 9 LAN NBG 510S User s Guide 78 ...
Page 88: ...Chapter 11 NAT and Firewall WAN to LAN NBG 510S User s Guide 88 ...
Page 91: ...91 PART III Security Access Control 93 Content Filtering 101 ...
Page 92: ...92 ...
Page 100: ...Chapter 13 Access Control NBG 510S User s Guide 100 ...
Page 103: ...103 PART IV Management UPnP 105 Static Route 113 ...
Page 104: ...104 ...
Page 116: ...Chapter 16 Static Route NBG 510S User s Guide 116 ...
Page 117: ...117 PART V Maintenance System 119 Logs 123 Tools 125 ...
Page 118: ...118 ...
Page 134: ...134 ...
Page 136: ...Chapter 20 Secure Remote Access Title NBG 510S User s Guide 136 ...
Page 140: ...Chapter 21 Secure Remote Access User Info NBG 510S User s Guide 140 ...
Page 150: ...Chapter 23 Manage User Access Permissions NBG 510S User s Guide 150 ...
Page 154: ...Chapter 24 Secure Remote Desktop Control NBG 510S User s Guide 154 ...
Page 162: ...Chapter 25 Secure Remote Access Screens NBG 510S User s Guide 162 ...
Page 164: ...164 ...
Page 170: ...Chapter 26 Troubleshooting NBG 510S User s Guide 170 ...
Page 176: ...Appendix A Product Specifications NBG 510S User s Guide 176 ...
Page 180: ...Appendix B Common Services NBG 510S User s Guide 180 ...
Page 198: ...Appendix D Legal Information NBG 510S User s Guide 198 ...
Page 204: ...Appendix E Customer Support NBG 510S User s Guide 204 ...
Page 209: ...Index NBG 510S User s Guide 209 WPA PSK 189 190 application example 191 ...
Page 210: ...Index NBG 510S User s Guide 210 ...