IFIP-UNU ADVANCED COURSE ON NETWORKING AND SECURITY Module II-Wireless Communications Section 7 Antennas

Overview This module will cover basic antenna theory, including directional and omni directional antenna selection. After discussing antenna theory and types of antennas, cables, connectors and accessories for antennas will be discussed. Additionally, important antenna design considerations, such as link engineering, path planning, and installation are also discussed.

Learning Objectives Define how an antenna is used to propagate an RF signal. Define basic facts of EIRP. Define facts on FCC regulations for UNII-1, UNII-2 and UNII-3. Identify 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.

Key terms Lobes Directional Omnidirectional Beamwidth and Bandwidth Polarization Vertical Horizontal Diversity Plane (H and E) Fresnel Zone

Definition of Terms dB- Decibel- Ratio of one value to another dBx where x = m = compared to 1 milliwatt (0 dBm=1 mW) i = compare to isotropic antenna d = compared to dipole antenna w = compared to 1 watt (0 dBw = 1 watt)

Antennas

Important Antenna Concepts

Beamwidth

Cisco Aironet 802.11b 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 802.11b supplied cables, RF devices and antennas have reverse polarity TNC (RP-TNC) connectors Cisco Aironet supplied antennas meet all FCC rules Wide variety of 802.11b antennas for most applications

Cisco Aironet 802.11a Antennas FCC requires that all radios utilizing the UNII-1 Band (5.15 GHz – 5.25 GHz) must have non-removable or integrated antennas FCC allows radios utilizing the UNII-2 Band (5.25 GHz – 5.35 GHz) to have external or removable antennas The Cisco Aironet 802.11a radios utilize both UNII-1 and UNII-2 bands, therefore cannot have external or removable antennas Cisco 802.11a antennas are integrated into the radio module Cisco 1400 radios utilize UNII-3 bands, therefore have external or removable antennas

Antenna Concepts Directionality Gain Polarization Omni (360º coverage) directional Directional (limited range of coverage) Gain Measured in dBi and dBd (0 dBd = 2.14 dBi) More gain means more coverage - in certain directions Polarization Antennas are used in the vertical polarization

Antenna Issues (cont.) Antennas have gain in particular directions Direction other than the main intended radiation pattern, are typically related to the main lobe gain

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 Angles are referred to as beamwidth Horizontal measurement Vertical measurement

Beamwidth vs. Gain

Antenna Theory A theoretical isotropic antenna has a perfect 360º vertical and horizontal beamwidth This is a reference for ALL antennas

Antenna Theory- Dipole Energy lobes are ‘pushed in’ from the top and bottom Higher gain Smaller vertical beamwidth Larger horizontal lobe Typical dipole pattern Side View (Vertical Pattern) Top View (Horizontal Pattern) New Pattern (with Gain) Vertical Beamwidth

High Gain Omni-Directionals More coverage area in a circular pattern Energy level directly above or below the antenna will become lower

Directional Antennas 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 Side View (Vertical Pattern) Top View (Horizontal Pattern)

FCC Part 15 Antenna Requirements 802.11b antenna Must use a unique, or proprietary connector Cisco Aironet products use RP-TNC connector Part 15 standards Approved antenna may exceed Exceeding may lead to interference problems Penalties could result in fines FCC standards apply to Part 15 users in the United States Different countries will have similar standards

2.4 GHz EIRP Rules for FCC Governed Areas Point-to-Multipoint FCC allows increasing the gain of an antenna/cable system if the transmitter power is reduced below 30 dBm in a 1:1 ratio Reduce Transmit Power below maximum of 30 dBm by 1 dBm and increase antenna/cable system gain by 1dBi Point-to-Point Maximum of 36 dBm EIRP Installations – 30 dBm maximum transmitter power with 6 dBi in gain attributed to antenna and cable combination FCC allows exceeding the 36 dBm EIRP in Point-to-Point installations using the 3:1 rule Reduce Transmit Power below maximum of 30 dBm by 1 dBm and increase antenna/cable system gain by 3 dBi

2.4 GHz EIRP Rules for FCC Governed Areas (cont.) Point-to-Multipoint Transmitter Power Transmitter dBm Maximum Gain EIRP FCC Maximum 1 Watt 30 dBm 6 dBi 36 dBm Cisco Maximum 100 mW 20 dBm 16 dBi 36 dBm The above values reflect the 1:1 rule Point-to-Point Transmitter Power Transmitter dBm Maximum Gain EIRP FCC Maximum 1 Watt 30 dBm 6 dBi 36 dBm Cisco Maximum 100 mW 20 dBm 36 dBi 56 dBm The above values reflect the 3:1 rule

2.4 GHz EIRP Rules for ETSI Governed Countries Currently ETSI stipulates a maximum of 20 dBm EIRP on Point-to-Multipoint and Point-to-Point installations –17 dBm maximum transmitter power with 3 dBi in gain attributed to antenna and cable combination Professional installers are allowed to increase the gain of an antenna/cable system if the transmitter power is reduced below 17 dBm in a 1:1 ratio Reduce Transmit Power below maximum of 17 dBm by 1 dBm and increase antenna/cable system gain by 1 dBi

2.4 GHz EIRP Rules for non-FCC Governed Bodies Governing bodies with 20 dBm ceiling on EIRP: ETSI, France/Singapore, Israel, Mexico Point-to-Multipoint and Point-to-Point Transmitter Power Transmitter dBm Maximum Gain EIRP Gov. Body Maximum 50 mW 17 dBm 3 dBi 20 dBm Cisco Integrated Antennas 50 mW 17 dBm 2.2 dBi 19.2 dBm Reduced TX Power 30 mW 15 dBm 5 dBi 20 dBm Reduced TX Power 20 mW 13 dBm 7 dBi 20 dBm Reduced TX Power 5 mW 7 dBm 13 dBi 20 dBm Reduced TX Power 1 mW 0 dBm 20 dBi 20 dBm The above values reflect the 1:1 rule

802.11a and FCC 5 GHz Specifications FCC regulations for UNII-1 and UNII-2 UNII-1 FCC max 50 mW 802.11a max 40 mW With max 6 dBi antenna gain 802.11a max of 40 mW complies with all countries except Singapore (20 mW) UNII-2 FCC max 250 mW 802.11a max 200 mW

FCC Rules for 802.11a - Antennas FCC requires that all radios utilizing the UNII-1 Band (5.15 GHz – 5.25 GHz) must have non-removable or integrated antennas FCC allows radios utilizing the UNII-2 Band (5.25 GHz – 5.35 GHz) to have external or removable antennas FCC requires radios operating in both UNII-1 and UNII-2 bands must comply with antenna rules regulating UNII-1 band (including indoor use only) The Cisco Aironet 802.11a radios utilize both UNII-1 and UNII-2 bands, therefore cannot have external or removable antennas and must be used indoors only Cisco 802.11a antennas are integrated into the radio module

Omni directional Antennas

2.4 GHz Omni-Directional Antennas 2 dBi Dipole "Standard Rubber Duck"

2.4 GHz Omni-Directional Antennas 5.2 dBi Mast Mount Vertical

2.4 GHz Omni-Directional Antennas 5.2 dBi Ceiling Mount

2.4 GHz Omni-Directional Antennas 5.2 dBi Pillar Mount Diversity

2.4 GHz Diversity Omni-Directional Antennas 2 dBi Diversity Omni-Directional Ceiling Mount

2.4 GHz Omni-Directional Antennas 12 dBi Omni-Directional (Outdoor only)

5 GHz Omni-Directional Antennas 9 dBi omni (Vertical polarization)

5 GHz Integrated Antenna Innovative 5 GHz Combo Antenna: Wall Mount: Fold antenna flat against access point housing for 6 dBi gain patch antenna Ceiling Mount: Fold antenna out at a 90° angle for 5 dBi gain omni antenna In 6 dBi patch position In 5 dBi omni position

Cisco Aironet 1100 Series Internal View 2.2 dBi Omni-Directional Diversity Antennas Mini-PCI Radio Option 1: 802.11b

Cone of reduced coverage Cone of reduced coverage Cisco Aironet 1100 Series Antenna Details Cone of reduced coverage Sphere of influence Sphere of influence Cone of reduced coverage

Cisco Aironet 1100 Series Antenna Details (cont.) H-Plane Pattern E-Plane Pattern Floor Top View Side View

Directional Antennas

2.4 GHz Diversity Antennas 6.5 dBi Diversity Patch Wall Mount – 55 degree

2.4 GHz Directional Antennas (cont.) 6 dBi Patch Antenna – 65 degree

2.4 GHz Directional Antennas (cont.) 8.5 dBi Patch Antenna – 60 degree

2.4 GHz Directional Antennas (cont.) 13.5 dBi Yagi Antenna – 25 degree

13.5 dBi Yagi Antenna—Inside view

2.4 GHz Directional Antennas (cont.) 21 dBi Parabolic Dish Antenna – 12 degree

5 GHz Omni-Directional Antennas 28 dBi dish (H or V polarization)

5 GHz Antenna 9.5 dBi sector (H or V polarization)

Cable and Accessories

2.4 GHz Accessories

RP-TNC Connectors

Lightning Arrestor Designed to protect LAN devices from static electricity and lightning surges that travel on coax transmission lines RP-TNC connectors used on all Cisco Antennas To Antenna Lug Lockwasher Nut Ground Wire From RF Device

Lightning Arrestor

Coax Connection Sealing Number one problems with bridges - water in the connectors Proper sealing is important Coax Seal is one product that is inexpensive and works great

1400 Accessories Antenna Alignment Assistance with status/alignment LEDs and RSSI port on outdoor unit Quick-hang mounting bracket supports weight of radio during installation process Complete solution provided with radio including: Power Injector LR Multi Function Mount 20’ and 50’ length of dual RG-6 cable Power supply and cord Coaxial sealant for all exposed connectors Corrosion proof gel for exposed metal surfaces Management via SNMP, Telnet CLI, HTTP Based upon 802.11a technology

1400 Power Injector LR Converts standard 10/100 baseT Ethernet RJ-45 interface to F-Type connector dual coaxial cable Power provided over dual coaxial cable with power discovery to protect other appliances Support for longer cable runs by resetting the 100 meter, 100baseT Ethernet timer, enabling total cable runs of 200 meters. Surge protection provided at the F-Type connectors to protect infrastructure devices

Link Engineering and RF Path Planning

Path Considerations Radio line of sight Earth bulge Fresnel zone Antenna and cabling Data rate

Line of Sight The following obstructions might obscure a visual link: Topographic features, such as mountains Curvature of the Earth Buildings and other man-made objects Trees Line of sight!

Longer Distances Line of Sight disappears at 6 miles (9.7 Km) due to the earth curve

Fresnel Zone

Improving Fresnel Effect Raise the antenna New structure Existing structure Different mounting point Remove trees

Site to Site Fresnel Zone Antenna Height Fresnel zone consideration Line-of-Sight over 25 miles (40 Km) hard to implement Antenna Height (Value “H”) Total Distance Fresnel @ 60% (Value “F”) Earth Curvature (Value “C”)

Antenna Alignment Line of Sight

High gain omni-directional Antenna Issues High gain omni-directional Directional antenna No Downtilt One-way communications

Antenna Issues (cont.) 8.50 downtilt 200 ft./61 m 14.50 700 ft./213 m 8 Miles/13 Km

Antenna Issues (cont.) Omni-directional antennas provide 3600 coverage Also accepts interference from all directions

Antenna Installation

Antenna Mounting

Mounting (Cont.)

Interference Carrier Detect Test (Spectrum Analyzer) Built into Bridge Run from Console Menu

Antenna Installation Towers and antennas may require permits and must meet local regulations

Antenna Installation (cont.) Antenna Alignment Tool Id Name Address Signal Strength Signal Quality 18 Cisco Bridge #1 00409644fd35 100% -10 dBm 100% 17 Cisco Bridge #1 00409644fd35 100% -10 dBm 100% 16 Cisco Bridge #1 00409644fd35 45% -73 dBm 100% 15 Cisco Bridge #1 00409644fd35 38% -77 dBm 100% 14 Cisco Bridge #1 00409644fd35 100% -10 dBm 100% 13 Cisco Bridge #1 00409644fd35 58% -67 dBm 100% 12 Cisco Bridge #1 00409644fd35 38% -77 dBm 88% 11 Cisco Bridge #1 00409644fd35 63% -64 dBm 100% 10 Cisco Bridge #1 00409644fd35 100% -10 dBm 96% 9 Cisco Bridge #1 00409644fd35 45% -73 dBm 91%

Antenna Installation (cont.) Aironet Client Utility Site Survey Utility for antenna alignment

Labs

Labs of Section 7 Lab 7.1.4 Antenna Setup Lab 7.1.8.1 Configure AP Diversity Settings Lab 7.1.8.2 Configure Bridge Diversity Settings Lab 7.2.6 Omnidirectional Antennas Lab 7.3.4 Directional Antennas