Antenna Concepts © 2001, Cisco Aironet Systems, Inc. Chapter5-1

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-2

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-3 ObjectivesObjectives Upon completion of this chapter, you should be able to: Understand how an antenna is used to propagate an RF signal Explain what an isotropic antenna is and why it is used as a reference for other antennas Identify Cisco Aironet antennas, their coverage patterns, and the proper polarization of each antenna

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-4 Cisco Aironet Antennas FCC requires that ALL antennas sold by a spread spectrum vendor be certified with the radio they are to be sold with All Cisco Aironet-supplied cables, RF devices and antennas have reverse TNC (RP-TNC) connectors Cisco Aironet-supplied antennas meet all FCC rules Wide variety antennas for most applications

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-5 Antenna Concepts Directionality Omni (360º coverage) directional Directional (limited range of coverage) Gain Measured in dBi and dBd. (0dBd = 2.14dBi) More gain means more coverage - in certain directions Polarization Antennas are used in the vertical polarization

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-6 Antenna Gain In life you never get “something for nothing;” the same is true in antenna gain. If the gain of an antenna goes up, the coverage area or angle goes down. Coverage areas or radiation patterns are measured in degrees. These angles are referred to as beamwidth, and have a horizontal and vertical measurement.

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-7 Antenna Theory A theoretical isotropic antenna has a perfect 360º vertical and horizontal beamwidth. This is a reference for ALL antennas Side View (Vertical Pattern) Top View (Horizontal Pattern)

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-8 Antenna Theory- Dipole To obtain omni-directional gain from an isotropic antenna, the energy lobes are ‘pushed in’ from the top and bottom, and forced out in a doughnut type pattern. The higher the gain, the smaller the vertical beamwidth, and the larger the horizontal lobe area This is the typical dipole pattern. Gain of a dipole is 2.14dBi (0dBd)

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-9 High Gain Omni-Directionals High gain omni- directional antennas will create more coverage area in away from the antenna, but the energy level directly below the antenna will become lower. Coverage here may be poor. Area of poor coverage directly under the antenna Beamwidth

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-10 Directional Antennas For directional antennas the lobes are pushed in a certain direction, causing the energy to be condensed in a particular area. Very little energy is in the back side of a directional antenna.

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-11 FCC Part 15 Antenna Requirements

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-12 EIRPEIRP Effective Isotropic Radiated Power Power SettingdBm 100 mW20 dBm 50 mW17 dBm 30 mW15 dBm 20 mW13 dBm 15 mW12 dBm 5 mW7 dBm 1 mW0 dBm w/ 6 dBi PatchEIRP 6 dBi26 dBm 6 dBi23 dBm 6 dBi21 dBm 6 dBi19 dBm 6 dBi18 dBm 6 dBi13 dBm 6 dBi6 dBm

Cisco Aironet Antennas © 2001, Cisco Systems, Inc. AWLF 1.0—Chapter5-13

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Omni-Directional Antennas 2.2dBi Dipole “Standard Rubber Duck” Cisco Aironet Part # AIR-ANT4941

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Omni-Directional Antennas 2.2dBi Ceiling Mount Cisco Aironet Part # AIR-ANT3194

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Omni-Directional Antennas 5.2dBi Ceiling Mount Cisco Aironet Part # AIR-ANT1728

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Omni-Directional Antennas 5.2dBi Mast Mount Vertical Cisco Aironet Part # AIR-ANT2506

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Omni-Directional Antennas 5.2dBi Pillar Mount Diversity Cisco Aironet Part # AIR-ANT3213

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Omni-Directional Antennas 5.2dBi Ground Plane Cisco Aironet Part # AIR-ANT2561

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Omni-Directional Antennas 12dBi Omni Directional (Outdoor only) Cisco Aironet Part # AIR-ANT4121

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Directional Antennas 3dBi Patch Antenna – 65 degree Cisco Aironet Part # AIR-ANT3195

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Directional Antennas 6dBi Patch Antenna – 65 degree Cisco Aironet Part # AIR-ANT1729

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Directional Antennas 8.5dBi Patch Antenna – 55 degree Cisco Aironet Part # AIR-ANT3549 H Plane E Plane

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Directional Antennas 13.5dBi Yagi Antenna – 25 degree Cisco Aironet Part # AIR-ANT1949

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter Ghz Directional Antennas 21dBi Parabolic Dish Antenna – 12 degree Cisco Part # AIR-ANT3338

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-26 SummarySummary Upon completion of this chapter you should be able to perform the following tasks: How different antennas can affect the propagation of the RF signal Compare antenna ratings in dBi vs. dBd Assist the customer in choosing the right antenna for their installation

© 2001, Cisco Systems, Inc. AWLF1.0—Chapter5-27 Review Questions 1.A 2.14 dBi antenna is the same as a 3.28 dBd antenna (True/False)? 2.An antenna with more gain is always a better antenna? Why or why not? 3.Ceiling mount antennas are always the best choice for an indoor installation? Why or why not? 4.A higher gain antenna adds more output power to the access point’s output (True/False)?

Cisco Aironet Wireless Training © 2000, Cisco Aironet Systems, Inc.